EX LIBRIS.

Bertram C* $L 3EtntrU,

DR ARCHDALL REID'S book on Ike Laws oj Here-
dity (Methuen & Co.: London. 1910. 2is.) is enor-
mously long and uncompromisingly stiff, yet it does not
seem to help us very materially in coming to a conclusion
on the laws with which it deals. Unquestionably the
most interesting and the most novel portion of the book
is that which deals with the relation of modern views
as to the role of bacteria in disease with the question of
Natural Selection. That they are a potent agent in
selection no one can doubt and if anyone does Dr Reid's
pages may be commended to his attention. That there
are other selective agencies at work no person can doubt
who examines the facts of Nature and existence for him-
self with open eyes. But what we have always maintained
is that having got so far upon the road and having con-
ceded, if you like, that Natural Selection exists — which
all scientific men do not concede — and that it is a potent
sieve — if a sieve can be called potent — that even then
we have only started upon the path at the end of which
lies the explanation of variation and of .inheritance
That variations occur everybody knows, that Natural
Selection may tend to perpetuate or to eliminate them
we may admit, but what causes the variations to appear ?
That is the real heart of the question. The Lamarckians
have an answer which is at any rate arguable. Dr Reid
will have none of it, and in our opinion rather underrates
the influence of Lamarckian opinion at the present day.
Weismann also had or has an answer, but his solution of
the difficulty only pushes the question one stage further
back and leaves it there unanswered. Until some solution
of that mystery has been arrived at, if indeed it ever is
arrived at or is arrivable at, we may learn what laws
govern heredity, if one may still be allowed to use the"
misleading nomenclature generally applied to what are
called Natural Laws, one may come to a conclusion as
to Mendel and his views or de Vries and his, but we shall
remain all the time on the threshold only and not within
the recesses of the temple of Nature's secrets.

i ' B.C.A.W.

THE LAWS OF HEREDITY

THE
LAWS OF HEREDITY

BY

G. ARGHDALL REID

M.B., F.R.S.E.

WITH A

DIAGRAMMATIC REPRESENTATION

IJY
HERBERT HALL TURNER

SAVILIAN PROFESSOR OF ASTRONOMY, OXFORD

MET

36 ESS

First Published in

TO THE

MEMORY

OF

THOMAS HENRY HUXLEY

A GREAT EXPONENT OF SCIENTIFIC METHOD

PREFACE

THE present volume covers a wider area than my last :
The Principles of Heredity. No problems can be named
of greater importance to the community than those of
Heredity. I have tried, therefore, to make the argument as plain
as possible to the general reader. And, since facts which we are
able to observe and verify for ourselves, are more impressive and
valuable intellectually than those we are obliged to accept at
second hand, I have used, whenever possible, material that is
familiar to every one.

Some biologists may regard Chapter III., which deals with
scientific method, as unnecessary and even as impertinent. But
every writer hopes to gain wide assent to his reasoning ; and,
there are, apparently, amongst thinkers about living beings, such
fundamental differences of opinion as to what constitutes evidence,
what logical proof, and what science, that no one can hope to
secure wide assent unless he first lay down the principles that
have guided his own thinking and obtains assent to them. If
the history of biology be considered, I believe it will be seen
that many of the controversies, in which its students have en-
gaged, arose and persisted merely because the disputants, holding
what were really divergent views as to the nature of science, failed
to reach a preliminary agreement with respect to their basic
assumptions. As far as my powers permitted, I have followed the
rules of procedure that have been enunciated by every authority
who has both thought and written about the subject. When these
rules have been disregarded, the writers, however right they may
be able to prove themselves ultimately, have never expressed their
dissent in reasoned statements ; they have merely implied it in
their methods of work.

If, then, the reader disagrees with commonly accepted opinions,
if, for example, he especially values evidence not solely because
it is authentic and relevant but because it has been gathered in
some particular way, or if he thinks that we should not use all the

vii

viii THE LAWS OF HEREDITY

authentic evidence available, or that facts newly asserted are
of greater value than truths long familiar and disputed by no one,
or that it is beneath the dignity or not within the mission of
science to furnish proof, or that knowledge derived from a simple
enumeration of instances is superior to knowledge which is
founded on a discovery of causes, or that we should found
hypotheses on the exception rather than the rule, or that it is
right to uphold contradictories, if in short he has individual and
original views as to what constitutes proof and what science, then
I hope he will endeavour to formulate his reasons clearly. Unless
he does so, his opinions, no matter how correct they may be, are
apt to bear the appearance of prejudices.

Professor H. H. Turner has contributed an Appendix in which
some of the main arguments of the text are thrown into diagram-
matic form. No part of the work is likely to prove so interesting
and convincing as this Appendix. I have, besides, to record my
great indebtedness to him for much very valuable advice.

It is impossible to express adequately my deep sense of obliga-
tion to Dr H. B. Donkin. Not only has he been a sort of reference
library, but he has read and re-read the whole of the rough and
the more finished manuscript, and the former has grown into the
latter largely under his guidance.

Other helpers, whom I take this opportunity of thanking most
heartily, are Miss J. Ritter, Mr A. D. Darbishire, Mr. P. C. Glubb,
and Mr D. Waudby.

While writing the volume, I have received great kindness and
encouragement from Dr Alfred Russel Wallace, Sir William
Thiselton-Dyer, and Sir E. Ray Lankester.

SOUTHSEA, April 1910

CONTENTS

CHAPTER I

PAGE

THE CHARACTERS OF LIVING BEINGS ... I

CHAPTER II

THE METHOD OF DEVELOPMENT .... 21

CHAPTER III
THE METHOD OF SCIENCE ... . 30

CHAPTER IV

THE LAMARCKIAN DOCTRINE ...... 56

CHAPTER V

VARIABILITY ....... 78

CHAPTER VI

RETROGRESSION ...... IO/

CHAPTER VII

MENDEL'S LAWS ....... 142

CHAPTER VIII

THE MUTATION THEORY . . . . . . .169

CHAPTER IX

THE FUNCTION OF SEX . . . . . . .187

CHAPTER X

SUMMARY ......... 206

ix

THE LAWS OF HEREDITY

CHAPTER XI

PAGB

HUMAN DISEASES . 2l8

CHAPTER XII

ACQUIRED IMMUNITY . . . . . 237

CHAPTER XIII

THE PRESENT EVOLUTION OF MAN ,: .'"...,; . . . . 256

CHAPTER XIV

EPIDEMIC AND ENDEMIC DISEASE , . I 266

CHAPTER XV
ALCOHOL ... . . , . - ; '- . . . . 284

CHAPTER XVI

THE EVOLUTION AGAINST NARCOTICS . . . . 298

CHAPTER XVII

IDEALISM AND COMMON SENSE . V . . . . 324

CHAPTER XVIII

NECESSARY TRUTH -. . . . . . . 338

CHAPTER XIX

THE RELATION OF MIND TO BODY . . . . ,. 356

CHAPTER XX

REFLEX ACTION, INSTINCT, AND REASON . ,* f. s . 367

CHAPTER XXI

THE EVOLUTION OF MEMORY . . . . . . 393

CONTENTS xi
CHAPTER XXII

PAGE

NATURE AND NURTURE ... • 4I(>

CHAPTER XXIII

PHYSICAL DETERIORATION AND MICROBIC DISEASE . 436

CHAPTER XXIV

INTEMPERANCE AND INSANITY ... . 456

CHAPTER XXV

EDUCATION . . . 477

APPENDIX . 5X7

GLOSSARY . -535

INDEX .... . -539

With Earth's first Clay They did the Last Man knead,
And there of the Last Harvest sow'd the Seed :

And the first Morning of Creation wrote
What the Last Dawn of Reckoning shall read.

THE LAWS OF HEREDITY

CHAPTER I
THE CHARACTERS OF LIVING BEINGS

The cell — Conjugation of cells — The germ-plasm — Hereditary tendencies
or potentialities — The stimuli under which living beings develop — Nutriment,
injury, use, etc. — The evolution of useful reactions to stimuli — Almost all
living structures are capable to some extent of repairing injuries, but not nearly
all are capable of growing under the stimulus of use — The real meaning of
the terms inborn, acquired, and inheritable — The confusion and waste of labour
which has resulted from a use of inaccurate and misleading terms.

I. fTP^HE material basis of all known life is the living 'cell.' A
cell is a mass, usually very minute, of a jelly-like sub-
stance known as protoplasm. The lowest plants and
animals are single cells. Higher living beings are compounded of
two or more, it may be billions of cells, most of which are adherent
together, though some — for example, the blood-cells — may move
freely within the organism. Cells multiply by self-division, the
mother-cell distributing itself between the daughter-cells. In the
case of unicellular or single - cell organisms the daughter-cells
separate, but in higher types they remain together. As a conse-
quence a man, for example, is an organised colony or community,
a family or tribe or race of cells, all of which have descended from
a common cell-ancestor, the fertilized ovum or egg. Speaking in
general terms, the descendants of a unicellular organism closely
resemble their ancestor. Each individual is able to continue the
species by self-division, and each performs all the functions neces-
sary to existence, such as the procurement of food. But the
descendants of the fertilized ovum, though they remain together,
indeed because they remain together, break up into many types.
Thus, in a man there are skin-cells, bone-cells, nerve-cells, various
kinds of gland-cells, and others. In other words, the members of
this community are specialized in form and function. Each has a
special shape and structure whereby it is adapted to perform some

2 THE CHARACTERS OF LIVING BEINGS

particular duty. None are fitted to perform all the functions of
life, and none, therefore, can long maintain a separate existence.
Thus a skin or muscle cell parted from the rest of the community
quickly perishes. Even the duty of continuing the race is dele-
gated to a particular set of cells, the germ-cells, which do not
otherwise share in the labours of the community.

2. Germ-cells derived from a female body (e.g. a woman) are
termed ova ; whereas those derived from a male body are termed
sperms. Sperms and ova differ in appearance, but we have no reason
to suppose that they are not equivalent as * bearers of heredity.'
They are not male and female ; only the bodies, the cell-communi-
ties which they inhabit, are male and female. A sperm from a
male body unites with an ovum from a female body. The single
cell thus formed is termed the fertilized ovum. The fertilized ovum,
dividing and redividing many times, builds up, by means of the
descendants thus arising, a new cell-community, a new ' organism,'
a new body, a new ' individual,' a human being, for instance.

3. That fertilization must precede reproduction is a rule almost
universal amongst multicellular species. Without fertilization
their ova and sperms perish, leaving no descendants. But fertiliza-
tion is not quite universal. Some species consist only of females.
They are parthenogenetic, that is, the virgin females produce
offspring. Without union with another germ-cell, the ovum
becomes the ancestor of a new cell-community. More common,
especially in the vegetable kingdom, is self-fertilization. Here the
individual is both male and female (hermaphrodite) and produces
both sperms (pollen grains) and ova (ovules), which unite with one
another. But cross-fertilization is by far the most common. It
is secured in most animals by the device of sex, in plants more
commonly by the ripening at different periods of the sperms and
ova of the same plant, or by other devices. Neither cross- nor
self-fertilization, then, is necessary to reproduction. But the fact
that fertilization, especially cross-fertilization, the mingling of the
qualities of two separate cell-communities to secure which nature
has evolved sex, is so widespread is evidence that it must possess
some very important function, some very important advantage.
Darwin found that plants, which normally reproduced by crossing,
gave origin to weakly offspring if artificially self- fertilized. It was
argued, consequently, that the function of cross-fertilization was to
invigorate or rejuvenate. But animals and plants which are
parthenogenetic, or which normally fertilize their own ovules, are
vigorous. Clearly, then, though crossing is necessary to the well-

THE GERM-PLASM 3

being of species which are normally cross-fertilized, it is not a
necessary antecedent of vigour, and cannot have arisen as a means
to that end. At present we are hardly in a position to discuss
this subject. Later, when we have collected a large array of facts,
we shall be able to deal with it to greater advantage.

4. The multicellular individual, then, consists of various kinds
of cells (each of which corresponds to a unicellular organism) which
perform different functions, each kind its own special function.
Some of these cells are germ-cells, the rest are body or ' somatic '
cells. The latter, which are usually much the more numerous,
provide the former with shelter and nutrition, much as worker
bees shelter and nourish queens and drones. They never unite,
never ' conjugate,' in the way that sperms and ova do. Only the
germs are marriageable ; and, as we have just seen, in the great
majority of animals and plants they observe the degrees of con-
sanguinity very strictly, and do not unite except with members of
another cell-community, and then only to found a new colony of
cells, an offspring.

5. In each sperm and ovum is a dot, the nucleus. The essential
feature of the union of sperm and ovum is now believed to be the
union, the intimate mixture, of their nuclei, so that the two nuclei
become one. Under high powers of the microscope there may be
seen within the nucleus specks and threads of a substance known
as chromatin. When the fertilized ovum and its descendant cells
divide into daughter-cells, the chromatin, which grows with the
cells, displays remarkable movements, and is distributed, ap-
parently with great quantitative equality, between the daughters,
thus forming their nuclei. Now this chromatin, contained in the
germ-cells, is believed with some reason to be the germ-plasm, the
' bearer of heredity,' the substance that carries the ' hereditary
tendencies,'1 which direct development, and thus determine the
kind of individuals that shall arise from the germ-cells. A man
differs greatly from an elephant because the germ-plasms of the

1 1 fear the expression ' hereditary tendency ' is somewhat clumsy. I use it
for lack of a better and imply nothing mystical. I mean no more by it than those
potentialities for development which are carried by germ-cells. These poten-
tialities differ, of course, with every species, and indeed with every individual.
Thus the hereditary tendencies of a man are those which enable him to develop
from a human germ into a human being. He does not develop into a rabbit
or a tree, because the hereditary tendencies of human germs are such that rabbits
and trees cannot arise from them. From a developmental point of view the germ-
plasm is compounded of structures carrying hereditary tendencies. By this,
however, I do not mean that definite structures in the germ-plasm carry definite
tendencies, each structure a tendency. I know nothing about that.

4 THE CHARACTERS OF LIVING BEINGS

two species are very different. He differs yet more from a plant,
because the germ-plasms are yet more different. One man re-
sembles another because all human germ-plasm is much alike, but
every man differs somewhat from every other, because the germ-
plasm contained in no two germ-cells is exactly similar. A species
undergoes evolution when, and only when, its germ-plasm under-
goes change. When, by careful breeding, we improve our domestic
animals and plants, the alteration is, in essence, always a germinal
change.

6. It is now believed by almost every one who has an adequate
acquaintance with the facts that the organic world, the world of
plants and animals, arose by processes of evolution. Even people
who still deny the whole truth admit, and have always admitted,
a large part of it. Thus all men believe that the various branches
of the human species had origin in a common stem — Adam and
Eve, heathen deities, a species of lower animals, it matters not
which. But human races have since diverged widely in size,
shape, colour, and many other traits. Moreover, the direction of
the change has always been such that every race has become
particularly well-fitted to the surroundings in which it has long
dwelt. Thus Englishmen flourish better in England than Negroes,1
who, on the other hand, are better adapted to conditions of life
prevalent in West Africa. The reality of evolution, therefore, is
not in dispute. Only the extent of it is disputed, and only, as
a rule, by people whose knowledge is correspondingly limited.

7. We need not pin our faith to the hypothesis that the
chromatin is the germ-plasm ; we need not even suppose that the
germ-plasm is contained wholly or even mainly in the nucleus.
Nor need we accept any theories as to the composition of it. But
some such substance there must be in the germ-cell, some sub-
stance which is the germ-plasm, the bearer of heredity ; and
probability points to it being the chromatin of the nucleus.
One very important point to which we shall have to refer again
and yet again should be noted. Since the offspring of the same
parents invariably differ more or less among themselves, it
follows that, though the quantitative division of the chromatin
is apparently exact, the qualitative division may not be so. The
daughter-cells may receive similar quantities ; but it is possible
that they do not receive exactly similar kinds of germ-plasm.

8. The whole of the child, therefore, is derived from a single
cell, the fertilized ovum, which in turn was derived wholly from

1 See § 439-

THE CONTINUITY OF THE GERM-PLASM 5

two germ-cells, one from each parent, and these again were each
derived by single lines of descent (i.e. lines in which no con-
jugation occurred) from the fertilized ovum whence each parent
sprang. Never in all the generations between fertilized ovum
and fertilized ovum does conjugation take place. The somatic
cells of the parent, therefore, as far as we know, contribute no living
elements to the child ; they merely provide temporary shelter and
nutriment. The child, therefore, does not, as is popularly supposed,
resemble his parent because his several parts are derived from
similar parts of the parent — his head from his parent's head, his
hands from his parent's hands, and so forth ; he resembles him only
because the germ-plasm which directed his development was a
split-off portion of the germ-plasm which directed the develop-
ment of the parent. The egg produces the fowl, but the fowl
as a whole does not produce the egg — only one cell from the fowl,
the fertilized ovum, produces it.

9. The germ-cells are, in a real sense, immortal. Saving acci-
dents, they divide perpetually, and at intervals conjugate, and there
is no dead body. In like manner the germ-plasm is potentially
immortal. It grows and divides into separate portions, but does
not die unless killed or starved. Each fertilized ovum builds,
with mortal cell-descendants, a temporary dwelling, the body,
around its potentially immortal descendants, the germs, which
hand on to succeeding generations their all-important trust, the
germ-plasm. Thus there is * continuity of the germ-plasm! This
conception of continuity is one of the main pillars of the modern
science of heredity. It is of very recent origin. Darwin, for
example, believed that the somatic cells emitted minute living
representatives, ' gemmules,' as he termed them, one of which from
each cell found its way to each germ and re-constituted the germ-
plasm. The germ-plasm, therefore, was supposed to be formed
afresh in each germ, when, of course, there could be no continuity ;
and the various parts of the child would be derived from corre-
sponding parts of the parent. It is now known, however, that the
information on which Darwin relied was founded on a mistaken
interpretation of the facts. Contrary to what he supposed, the
evidence is massive that parental ' acquirements ' are never ' trans-
mitted ' to offspring.

10. Under the constant direction of its hereditary tendencies
the fertilized ovum proliferates, and the cell-community thus
originated grows (develops) through the continued but regulated
multiplication of cells, and so takes shape as an 'individual,'

6 THE CHARACTERS OF LIVING BEINGS

animal or plant. Nutriment supplies the materials for all this
increase. But more than material is needed. Neither growth nor
any other form of ''vital' activity ever occurs except as a reaction to
some appropriate kind of stimulus. This capacity to assimilate
nutriment, and to react in certain other peculiar ways to certain
definite stimuli, are the marks of a living being. There are, then,
three necessary factors, in the absence of any of which growth
cannot occur in living beings. The first is tendency (capacity,
potentiality) to grow, which determines the kind of development
that shall occur. The second is stimulus, which awakens the
tendency. The third is nutriment, which supplies the materials
for growth, the clay and the straw out of which the bricks are
made. Hereditary tendencies are internal factors traceable ulti-
mately to the germ-plasm, but both nutriment and stimuli proceed
from the world external to the growing structure. Usually not
only the kind of growth, but the extent of it, is determined by the
hereditary tendencies. Thus, no matter how abundant the supply
of nutriment and stimulus, neither mouse nor elephant, for example,
can increase beyond a certain size, which, within narrow limits, is
definite for the species. In other words, stimuli, which are capable
of exciting growth in one period of life (when the animal is young)
cease to be capable of exciting it at another (when the animal is
adult), no matter how large the supply of nutriment. The limits
of growth, however, are much less rigidly drawn in plants, some of
which, indeed, seem capable of endless growth, as when propagated
by cuttings. It should be noted that nutriment supplies, not only
the materials for growth, but acts — sometimes, not always — as
stimulus as well. Thus female bees develop in one way (becoming
queens) if one kind of food is supplied, and in another way
(becoming workers) if they receive a different kind of food.1

1 May I beg the reader to pay especial attention to this paragraph. There is,
I believe, nothing in it disputable ; but a great deal that, in effect, is disputed
hinges on it. The points to which I wish particularly to call attention are these :
(i) An individual can develop only within limits which are predetermined by
' hereditary tendencies ' that have their roots in his germ-plasm. Thus a man
could not develop a human limb, nor increase the size of his muscles by use, nor
heal a wound of the limb by a scar unless his germ-plasm was of a kind that
enabled him to respond to the right stimuli in the right way. (2) An individual
makes no growth, develops in no way, unless he is stimulated to develop in that way
by the right stimulus, which may be nutriment, or use, or injury, or something
else. (3) Nutriment furnishes the materials (the clay and the straw) for all
growth. It also, as I say, acts, apparently, as the stimulus for some growth. In
other words some growth occurs, apparently, merely because the individual
absorbs nutriment : here nutriment acts both as material for growth and as
stimulus to it. But in other cases growth occurs only under the stimulus of use

THE STIMULI FOR GROWTH 7

11. Living beings develop mainly under the influence of three
distinct kinds of stimuli — nutriment, use, and injury. To take the
example of the human being : up to the time of birth the infant
develops wholly, or at least principally, under the stimulus of
nutriment. After birth some of his structures continue to grow
under this stimulus, for example his hair, his teeth, his external
ears, and his organs of reproduction. But, as regards other of his
structures, though nutriment continues to supply the materials for
growth, it ceases to supply the stimulus. Thus, no matter how
well the child is fed, the muscles of his limbs do not develop unless
they are used. It is a noticeable fact that structures — and those
structures only — which grow under the influence of use, tend to
atrophy when disused. Thus disuse, or lessened use, diminishes
the size of the muscles in a human limb, while under similar con-
ditions the external ears and the reproductive organs persist
unchanged. Since the development which occurs under the
stimulus of use is always a mere extension — though often a most
important extension — of that which occurs under the stimulus of
nutriment, it is frequently difficult to distinguish structures which
owe their growth wholly to nutriment from those which owe it in
part to use. But the tendency of the latter class to atrophy when
disused supplies us with a rough criterion.1 Lastly, if the individual
be injured, as by a cut, the wound supplies the stimulus for the
growth which occurs during the process of healing.

12. Other stimuli to growth besides nutriment, use, and injury,
exist, though we need not pause to discuss them at length. Thus
all organs develop within a certain range of temperature, and best

or injury ; here nutriment furnishes only the materials. The reader will see
later that, for the sake of convenience, I include under ' nutriment ' a number
of other stimuli, but that I sharply distinguish from it use and injury. He will
find that the reason why I include a number of stimuli under the heading of
nutriment, but exclude from that category use and injury, is because biologists
are accustomed to term all characters which arise under the stimulus of use and
injury ' acquirements,' whereas all other characters are termed by them ' inborn '
or ' innate.' The effect of distinguishing characters by means of the stimuli
under which they arise, rather than by the words ' innate ' or ' acquired,' will be
to make us take a view of heredity and evolution, especially mental heredity and
evolution, immensely different, but I think, demonstrably more correct and
comprehensive than the view hitherto accepted.

1 The criterion is very rough, however. If a structure atrophies under disuse
then, as far as I am aware, we may be sure it has grown under the influence of
use. But it is not true that all structures which have grown under the influence
of use atrophy when disused. Thus the bones of the limbs grow under the influence
of use, but they do not atrophy like the muscles, at least to the same extent, when
disused. Apparently this is due to the fact that bones are not to the same extent
composed of living cells.

THE CHARACTERS OF LIVING BEINGS

only within narrow limits which are not the same for every species.
Some organisms develop markedly diverse characters at different
temperatures. Light is essential to the development of very many
species, especially of plants. Certain plants develop in one way
in the water, and in another way on the land. A brine shrimp
(Artemia) develops one form in brackish water and another in
water that is salter. Within the animal body the ' internal '
secretion of various glands exercises an important influence on the
development of many organs. For the purposes of our discussion,
however, all these stimuli, and others besides, may be bracketed
with nutriment, use, or injury ; they are, in effect, in many cases
at least, conditions under which nutriment and use act as stimuli,
or which, when in excess, produce injury.

13. All the characters which it is possible for an individual
under any circumstances to possess are traceable ultimately to an
inter-action between the environment and hereditary tendencies or
potentialities which have their roots in the germ-plasm. Because
the germ-plasm of a dog differs from that of a man, because the
hereditary tendencies are different, the two animals develop into
very different individuals, and would so develop though placed
under identical conditions as regards nutriment, use, and injury.
On the other hand, if, were it possible, two human germs were
exactly alike in all their potentialities, differences of nutriment,
use, and injury would cause corresponding differences between the
individuals that arise from them. The human arm first develops
under the stimulus of the nutriment that reaches it from the world
external to it, because of an antecedent potentiality in the germ-
plasm. For the same reason it continues to grow under the in-
fluence of use, or, when it is damaged, under the stimulus of injury.
Stimulus is the invariable antecedent to all growth.

14. Since no character can be used or injured until it exists,
the power of growing under the stimulus of nutriment must have
been the very first product of evolution, the first peculiarity by
which living beings were distinguished from mere chemical com-
pounds. Possibly the earliest living beings were homogeneous
throughout, consisting altogether of a primitive kind of germ-plasm,
there being no cell-body as distinguished from the nucleus, no
' cyto-plasm ' properly so called, in which case the minutest living
fragment was perhaps capable of continuing the species. Probably
also each organism was capable of indefinite growth, or at least
of an amount of growth which was limited only by the supply of
nutriment. The individual, however, can never have been large ;

GROWTH IN RESPONSE TO INJURY 9

for, with very primitive organization, the passage of food from the
periphery to the centre through living and assimilating tissue
cannot have been great Very possibly, too, these lowly organisms
were so loosely compacted that they easily fell to pieces under
shocks from the environment. Every fragment, then, constituted f
a member of the species. Doubtless definite shape and size, as
well as definite differentiation of structure within the individual
and particular methods of reproduction which resulted therefrom,
such as periodic self-division, were products of prolonged evolution.
Probably the lowest living beings which we are capable of distin-
guishing as living, even under the highest powers of the microscope,
are products, as regards size and in other ways, of ages of evolution.
So far, of course, all is pure conjecture ; but it is something more than
conjecture that early evolution must have consisted of such changes
in the germ-plasm, such changes in the hereditary tendencies, that
each species came to respond, by growing in its own particular
way, to the stimulus of nutriment, and so evolved its own peculiar
characteristics.

15. We can guess only vaguely at the stage of evolution at
which the power of responding by growth to the influence of
injury, and so repairing damaged structures, first appeared. If the
primitive living beings were capable of indefinite growth, but not
of spontaneous self-division, then this continued growth after
fragmentation in itself constituted a sort of repair of injury.
Probably, therefore, the power of responding to the stimulus of
injury was evolved concurrently with that of responding to the
stimulus of nutriment and was originally part of and indistinguish-
able from it. Even in higher types, unicellular and multicellular,
which have evolved heterogeneous structures and are of more
or less definite shapes and sizes, the underlying resemblance
remains ; nutriment stimulates the individual to produce the
characters of the species, injury stimulates him to reproduce them
more or less perfectly when they are lost or damaged.

1 6. This power of reproducing lost or damaged parts, of growing
under the stimulus of injury, varies greatly in different species and
in different structures of the same species. Since it is a product
of evolution, since it is one of the means by which organisms are
adapted to the environment, its degree of development in any
species or structure is proportionate to its utility. Relatively
speaking, the higher animals, which have very complex organiza-
tions and lead very active lives, possess it in small measure. As
a rule they replace important losses of tissue only by scars. It is

io THE CHARACTERS OF LIVING BEINGS

advantageous to a deer, for example, to be able to heal a wound,
but the conditions of its life are such that it would very rarely have
time or opportunity to reproduce a lost limb. In effect the power
to do so would be useless. The stag, however, habitually re-
produces its lost antlers. They are very heavy structures which
are useful to him at the season when he contends with his rivals ;
but burdensome, and therefore, not only useless but worse than
useless, at other times. He sheds them, it is true, in the absence
of injury, but the whole process closely resembles loss and repro-
duction through injury, and demonstrates the difficulty of drawing
a sharply dividing line between nutriment and injury as stimuli.

17. Some plants which sprang originally from germ-cells
multiply indefinitely by budding. Each bud is regarded by botan-
ists as a * person,' but a person in this sense is not quite the same
as an * individual ' which takes origin in a germ. Buds, even when
growing separated from the parent, are, in a real sense, portions of
the individual that rose from the germ. If we amputate the end
of a twig the injury may or may not heal as a scar, but the pro-
duction of buds is commonly increased. Are they to be regarded
as developing under the stimulus of nutriment, or of injury ?
Here again we see the close connexion between the power of
responding to the stimulus of nutriment and that of responding to
the stimulus of injury. Injury, indeed, may be regarded as one of
the conditions under which the stimulus of nutrition comes into
action. It awakens a power which has slumbered.

1 8. Some animals lose living and active parts by injury almost
as regularly and replace them almost as readily as the stag his
antlers or the bear his winter coat. Thus in some newts the
external gills are much exposed and liable to be bitten off by
members of the same species. They are readily replaced, whereas
internal parts of the same animal show small powers of regenera-
tion': they merely heal.1 Lizards which frequently escape from
enemies with the loss of the tail are able to reproduce it; but
they cannot reproduce a limb, the loss of which usually involves
capture and death. The power of regeneration2 possessed by fishes
is apparently no greater than, if as great, as that possessed by
mammals. Some worms, much exposed to injury, are able to

1 Weismann, Theory of Evolution, vol. ii. pp. 12-13.

2 The term regeneration is usually limited to a more or less perfect replace-
ment of the lost part or tissues by similar structures ; whereas in mere healing
a scar, which may differ greatly from the lost part, is developed. The two
processes differ in degree, not in kind, and are united by gradations. Regeneration
is very perfect healing ; healing is imperfect regeneration.

GROWTH IN RESPONSE TO USE n

reproduce the whole individual from a fragment. Great powers of
regeneration are the rule in plants or parts of plants which are
exposed to injury from animals, for example in grasses.

19. The power of responding to the stimulus of injury, then, is
clearly allied to and is derived from the power of responding to
the stimulus of nutriment. The germ-plasm of every type of
animal and plant has so changed from the primitive kind that
under the stimulus of nutriment the individual tends to develop
the characteristics which evolution conferred on his immediate
predecessors ; it has also so changed that wherever the power of
regeneration is useful, and to the extent to which it is useful, injury
stimulates to the replacement or repair of lost or damaged parts.
Like the power of growing under the stimulus of nutriment, the
power of repairing injury is always an adaptation. The kind of
repair that normally occurs is ever the most useful and extensive
possible under the conditions.

20. The characters which develop under the stimulus of injury
are interesting and important, but vastly more interesting, both
from the theoretical and the practical standpoint, are those which
develop under the stimulus of use. If we study almost any work
on the sister subjects, heredity and evolution, published more than
a decade ago, and a great many published since, we frequently
meet an entirely unwarrantable assumption — the assumption that
all structures and organs in all types of living beings tend to grow
and develop if used. For example, the celebrated Lamarck, the
predecessor and in a way almost the peer of Darwin, who during
the nineteenth century exerted an immense influence on biological
thought, founded his theory of racial change on the supposition
that all structures and qualities are capable of increase under the
influence of use and decrease under that of disuse. The same
idea bulks largely in the writings of Spencer, Lewes, Romanes,
Cope, and a multitude of others.

21. In man, as we have seen, certain structures grow under the
influence of use, but the amount even of this growth (i.e. multi-
plication of cells) is by no means strictly proportionate to the
amount of use, and is always rigidly limited. Different men
respond in different degrees to the stimulus of use, but even a
1 natural ' athlete can increase the size of his muscles only up to a
certain point, after which cell-multiplication no longer occurs, no
matter how much he uses his muscles. All growth due to use
occurs mainly during early life ; in old age it practically ceases in
most structures though they are still used. Lastly, the growth of

12 THE CHARACTERS OF LIVING BEINGS

some structures, for example, the hair, teeth, nose, external ears
and reproductive organs, is apparently not influenced in the
slightest degree by use. It is plain, therefore, that the power of
growing under the influence of use, unlike that of responding to
injury, is not a property common to all or nearly all living
structures. It is present only in some structures, and in them
not equally at all periods of life.

22. If we continue to study the matter closely we make another
discovery and a very important one ; we find that this power, like
that of repairing injury, is present only in structures where it is
useful, to the extent to which it is useful, and during the time it is
useful. In man, for example, it long persists in the muscles of the
limbs and in the heart and kidneys, which even in advanced age
hypertrophy under increased strain. But no structures are more
used than the joints. With the rest of the limbs they grow under
the influence of use during youth, after which the power of so grow-
ing, which would then be useless, indeed injurious, departs from
them. The tongue again is a structure which is immensely used.
We do not know whether it grows in part under the stimulus of
use or only under that of nutriment ; but, in any case, growth
ceases when adult life is attained ; for no amount of use, apparently,
can add anything to it subsequently. Manifestly, therefore,
the power of growing under the stimulus of use is also an
adaptation. It is not a necessary property of all living protoplasm,
but a thing which has been implanted in some structures by
evolution.

23. Moreover we have massive evidence that it is a late and a
high product of evolution. It does not date back to the origin of
life like the faculties' of growing in response to the stimuli of
nutriment and injury. It is observable only in the higher organisms,
and in its greatest development only in the highest. Thus a human
infant is born very immature and helpless ; it owes most of its
subsequent growth, its advance towards maturity, mainly to use.
A young foal is born better developed ; it owes less to use and more
to the stimulus of nutriment. There is evidence that amphibians
(e.g. frog) and fish owe little or nothing to use ; they seem to
develop perfectly, or at least very well, when so rigidly confined
that use has no great scope to act as a stimulus. Most insects
seem to grow wholly under the stimulus of nutriment (and injury).
Certainly use plays no part in bringing about the changes which
occur during their metamorphoses. Lower in the animal scale
there is even less probability that use plays any part in develop-

NORMAL GROWTH AN ADAPTATION 13

ment. Some plants grow tougher and more firmly rooted when
exposed to strong winds ; but throughout the vegetable kingdom
the faculty, if present at all, is developed only in the slightest
degree. At present, however, we need not labour this question of
the evolution of the power of growing in response to use. We
shall be in possession of much more definite and decisive evidence,
especially when we consider mind.

24. In brief the notion that the power of growing, especially of
growing adaptively, under the stimulus of use, is present in all
living tissues, is merely a vague guess founded on popular observa-
tion of our familiar human development. There is no veil like the
veil of familiarity. Never yet has this question been made the subject
of close and accurate investigation. Since some human structures
develop in this way, it has been assumed that all structures in all
animals and plants can, and do, so develop. Like many other
popular guesses it has been accepted quite without question even by
thinkers in science. Vast systems of philosophy have been built
on it and acclaimed as the highest products of human wisdom.
But it is very doubtful whether any other error in the whole range
of biology, indeed of scientific thought, has been productive of
more confusion, futile discussion and practical mischief. My
language is strong, but the reader will find it fully justified.1

25. Obviously, then, powers of developing in response to
definite stimuli are, in the case of all species, delicate adjustments
to the environment. If any individual varies from the ancestry so
as to lose this adjustment, this power of responding by growth in
definite ways to definite stimuli, he fails to develop the right char-
acters to the right extent and perishes. Every type of plant and
animal, the lichen, the beetle, and the man, for example, fits its
own niche in nature as the hand does the glove ; but it fits only
because its germ-plasm has been so fashioned by evolution that
every normal individual grows into adaptation to his environment
in response to stimuli.

26. Speaking generally, all growth is either immediately
adaptive or is a provision for future adaptation. Thus human
germ-cells are adapted by their structures and capacities for exist-
ence in the testes and ovaries. Under the stimulus of nutriment
they develop into embryos and thus are able to fit the next
environment, the uterus. Here they continue to develop till they
grow into fitness for life in the mother's arms. Thereafter, use and
injury come into play ; and, with some characters developing under

1 Seejchapter iv.

14 THE CHARACTERS OF LIVING BEINGS

one stimulus, some under another, and some under a third, and all
developing in proportion, the infant gradually becomes adapted to
the environments of the child and the adult. If he be injured,
development begins by stoppage of the blood-flow and continues till
growth is complete and ascar forms. Since every one is injured at one
time or another, without this healing life would be impossible under
conditions normal for the species. As we have just seen, growth
under the stimulus of use is also a part of normal development-
The human being cannot become a normal adult, fit for the struggle
of existence, without it.

27. It is clear then that all characters that it is possible for the
individual to develop are equally rooted, as it were, in the germ-
plasm. Manifestly no character is more closely or less closely
connected with it than any other. But the traits which develop
under the stimulus of nutriment have two characteristics which
have so impressed students of heredity that attention has been
especially concentrated on them.

28. First, since no individual can develop without food as
material for growth, the stimulus of nutriment is always present ;
and, therefore, if the individual lives long enough, all the characters
that arise under its influence inevitably appear unless prevented
by injury.1 On the other hand, characters, which arose in the
parent under the stimulus of injury or use, may not arise in the
child, for similar stimuli may not be received. Thus the only
effect of injury which inevitably appears in the human being is the
navel. Other scars are not reproduced unless, as is unlikely,
exactly similar injuries are received by parent and child. In
every normal child and adult certain effects of use (e.g. the
muscular development of the limbs) are always present, but
though in practice we recognize them as effects of use (for the
physical and mental exercises we give our children are nothing
other than conscious attempts to develop them in this way), yet in
theory they are seldom recognized as such. Like other people,
students of heredity tend to think in compartments, and in their
discussions they have usually argued as if reactions to use were
limited to such exceptional and trivial developments as the extra

1 This statement is not quite correct. Thus, though male characters are
latent in the female and vice versa, and though they arise under the stimulus of
nutriment, they do not develop. The individual has two sets of sexual characters,
the development of one of which is a bar to the development of the other. But,
apart from such cases of alternative reproduction in which the development of
one character prevents the development of another, the statement that characters,
which arise in response to the stimulus of nutriment inevitably appear is true.

ALL CHARACTERS ARE EQUALLY ACQUIRED 15

growth of the blacksmith's arm which results from the nature of
his employment, or the thickening of the skin in the palm of the
hand which results from rough labour.

29. Second, since nothing can be used or injured before it
exists, characters that develop under the stimulus of nutriment are
always the first to reappear. They are the earliest products both
of racial evolution and individual development. Therefore all
characters that arise through use or injury are * modifications ' of
those that arose under the stimulus of nutriment. But this creates
no real distinction, for all growth, whether in the embryo, foetus,
infant, child, or adult, whether arising in response to nutriment,
injury, or use, is a modification, due to cell-multiplication, of
previous growth. Nevertheless, since changes due to the stimulus
of nutriment arise gradually and insensibly, whereas those due to
injury are usually impressed in a very obvious way on pre-existing
characters, and those recognized as due to use are also so impressed,
the first have seldom been recognized as ' modifications,' while the
second and third have been so recognized. At any rate, the names
' modification ' and ' acquirement ' have been especially applied to
the effects of injury and use. That is, it has been implied that these
stimuli alter the individual in such a way as to make him different
from what, if I may use the expression, nature intended him to be.
Obviously, however, the reasoning here is superficial and inexact.
The error arises because the thinking is in terms, not of the germ-
plasm which carries the hereditary potentialities of individual, but
of the individual himself, who only develops such of his traits as he
happens to be stimulated to develop. As I say all characters are
equally rooted in the germ-plasm, all are equally products of
evolution, and all arise equally in response to stimuli. They are
all ready to arise, and they all arise inevitably if the right stimuli
be forthcoming. Whether they do, or do not arise, depends, not
on the nature of the individual, but on that of the environment.
It is as * natural ' for him to develop a scar or a callosity
under the right conditions as to develop a beard or a hand. In
any case he fulfils his nature.

30. Half a century of controversy has resulted from an
insufficient appreciation of the fact that the characters which
develop under the stimulus of injury and use are as closely related
to the germ-plasm, are as natural to the individual, as those which
develop under the stimulus of nutriment. Biologists are accustomed
to divide all the characters of living beings into those which are
* inborn ' and those which are * acquired,' and while all biologists

1 6 THE CHARACTERS OF LIVING BEINGS

maintain that ' inborn ' characters are * germinal ' and tend to be
transmitted to offspring, most of them insist that ' acquirements '
are not germinal and are never inherited. If we consider these
words carefully it becomes clear that by an innate or inborn
character they imply one which has developed under the stimulus of
nutriment^ whereas by an acquirement they imply one which has
developed under the stimulus of use or injury ; when they speak of an
innate character as inherited they imply that in the parent and child
alike it developed under the stimulus of nutriment ; and when, as is
still sometimes the case, they allege the inheritance of a parental
acquirement, they imply that a character which was developed
under the influence of use or injury in the parent, is, in the child,
TRANSFERRED to a different category and developed under the
stimulus of nutriment.

31. But now, bearing in mind the foregoing paragraphs — bearing
in mind that all evolution consists in a germinal change, that a
germinal change consists in an altered potentiality to produce
characters, that obviously no characters can arise unless the poten-
tiality to develop them is present in the germ-plasm and unless it
is awakened by fitting stimuli, that all characters which are poten-
tially present arise with equal certainty if fitting stimuli be applied,
that all growth is a modification of pre-existing characters, that no
characters are derived from similar characters in the parent (e.g.
the child's hand from the parent's hand) but all take origin in the
fertilized ovum, bearing in mind also that the evolution of the higher
animals has consisted mainly in the evolution of a power of develop-
ing * acquirements ' under the stimulus of use, and that the mass
of characters developed under this stimulus is quite as essential a
part of that ' normal ' development whereby the maturity of the
individual is attained and his survival secured as the characters
developed under the stimulus of nutriment — bearing in mind all
this, let the reader ask himself in what respects characters that
develop in response to the stimulus of nutriment are more
germinal, inborn, and hereditary than those which arise in response
to other stimuli. I believe he will be forced to conclude that
these expressions are erroneous in that they altogether fail to
indicate, in that they obscure rather than reveal, the true distinc-
tions between classes of characters. They have come into use
only because biologists, though speaking constantly of germinal
characters, have as constantly thought in terms, not of the germ-
plasm, but of the individual. Manifestly no characters are really
more germinal, inborn, or inheritable than any others. All are

ONLY THE GERM-PLASM IS INBORN 17

germinal, inborn and inheritable in exactly the same sense.1 The
true distinction between the different classes of characters are
indicated when they are described as arising in response to the
different classes of stimuli. If the reader still thinks otherwise —
as he will constantly be tempted to do if he keeps his attention
fixed, not on the germ-plasm, but on the individual — let him en-
deavour to formulate a clear idea as to what makes one character
more inborn than another. He will certainly fail. Moreover, if
he tries to think of a character of the multicellular individual which
is more innate and inheritable than any other, he will succeed only
in recalling characters which appear more regularly than others
merely because the stimulus which evokes the former is received
more certainly than that which evokes the latter.

32. Occasionally what are known as identical twins are born.
They are supposed to be derived from a single fertilized ovum.
They are extremely alike, presumably because their germ-plasms
were similar. It is conceivable that the germ-plasms might be
exactly similar ; in which case, under precisely similar stimuli,
they would develop into individuals precisely similar. But if from
some cause, for example a twisting of the umbilical cord, one twin
received an inferior supply of nutriment, they would differ. Every-
one would then agree that the difference, though one of ' innate '
characters, would be acquired ; but it would puzzle anyone to indi-
cate the twin that made the differentiating acquirement.

33. Only the germ-plasm, its structures, and hereditary tend-
encies, are really inborn and inheritable; for they really pass
from ancestral to descendant germ-cells. The germ-cell is a
unicellular organism which, like other unicellular types, divides
itself between its offspring, which in turn divide themselves in like
manner. The daughter-cells and their descendants, therefore,
inherit the structures and qualities of the parent cell in a sense
quite different from and much more real than that in which a cell-
community ' inherits ' the structures and qualities of the community
from whence it is derived.2

1The only conceivable exception is a temporary change, for example, an
injury (e.g. a cut) considered apart from the reaction by which it is repaired —
a reaction which, however, begins at once, or almost at once, by coagulation of
blood, etc. Even this exception is more apparent than real, for an injury derives
its characteristics not only from the agent which inflicts it, but also from the
structure which receives it, which in turn derived its characters from the egg.

2 It maybe asked " If the germ-cell, the fertilized ovum, divides itself between

its daughter-cells, which, as well as their descendant cells, repeat the process, how

does it happen that all the cell-descendants are not close copies of one another

and of the fertilized ovum whence the community sprang ? Why do some of these

2

1 8 THE CHARACTERS OF LIVING BEINGS

34. The names we use do not greatly matter if they serve to
indicate the truth ; an erroneous term, provided it is obviously
erroneous, may convey a right impression. But the words inborn,
acquired, and inheritable, appear — when we think of individuals,
instead of the germ-plasm as, very naturally, we tend to do — so
obviously correct that their use has been, and is still productive
of endless confusion and controversy.1 For example, it was
formerly believed that parental acquirements were transmissible
to offspring: in other words it was maintained in effect that a
character (e.g. a scar) which the parent was able to acquire in a
certain way (as a reaction to injury), because a long course of
evolution had rendered such acquisition possible to the members
of his race, tended to be reproduced by the child in a different
category of characters and in a way (as a reaction to nutriment) in
which no member of his race had ever acquired it before, and with
which, therefore, evolution had nothing to do. An actual miracle
was supposed to happen, the miraculous nature of which was con-
cealed under a misuse of terms.

descendants become skin-cells, others muscle-cells, and so on ? What brings
about this differentiation amongst the cells of the community ? " Two answers
to this question are conceivable. Though the division of the cells is apparently
equal quantitatively, it does not follow that it is equal qualitatively. Equal
amounts of germ-plasm may pass into daughter-cells ; but the kind of germ-
plasm which passes into one daughter may not be quite similar to that which
passes into the other daughter. Obviously if this differentiation were accentuated
in succeeding cell-divisions it would account for the fact that skin or bone-cells,
for example, are so dissimilar, not only in appearance but more especially in
functions, from germ-cells. That there may be a good deal of truth in this hypo-
thesis is rendered probable by the fact that not only do the body (somatic) cells
differ qualitatively from the germ-cells, but the germ-cells differ in the same way
amongst themselves ; for they give rise to cell -communities (children) which
may present marked differences. The second conceivable explanation is that
the appearances and qualities which cells develop depend on their environments.
According to this hypothesis, a skin-cell assumes the appearance and qualities
of its kind, not because its germ-plasm (' idio-plasm ') differs from that of a germ-
or muscle-cell, but because it is differently situated, and therefore differently
stimulated. That there may be much truth in this suggestion also is proved
by the fact that fragments of many cell-communities, for instance fragments "of
begonia leaf, which apparently contain no germ-cells, are capable of giving rise
to an entire ' person,' an entire cell-community, which contains every kind of
cell, including germ-cells. Possibly the true explanation lies in a combination
of these hypotheses. In other words, it is possible that cells, like individuals,
differ amongst themselves partly because they differ in germ-plasm, and partly
because they differ in environments.

1 In the misuse of them I have sinned as deeply as anyone — see, for example,
The Present Evolution of Man, Alcoholism, and The Principles of Heredity. In
the latter work, however, I made some endeavour to make the situation clear.
See note, p. 249, and especially the second edition, Appendix A.

THE TRANSMUTATION OF CHARACTERS 19

35. Most biologists now reject this, the Lamarckian hypothesis,
on the ground that it is against the weight of evidence. It is not
realized, however, that here we have a question not of the trans-
mission but of the transmutation of characters ; for the child is not
supposed to reproduce that which the parent developed (an effect
of use or injury), but something vastly different (a response to the
stimulus of nutriment). As a fact the evidence against the
Lamarckian hypothesis is very conclusive. Characters which
evolution has fitted parents to develop under the stimulus of use
and injury do not tend to be automatically transmuted in the
offspring into characters which develop under the stimulus of
nutriment. Such a change would be as intrinsically improbable
as a change of eyes into ears. But the language used has raised
a false issue, has diverted attention from the real significance of
responses to use and injury, and of the evolution which enables the
individual to develop them. The belief, reached after long and
heated controversy, that * acquirements ' are not ' inherited/ has
caused nearly all students of heredity to think of them as mere
accidents which have no importance except in so far as they
obscure the outlook and render the discovery of the truth difficult.
Hence, for example, the notion that the acquirements of the
blacksmith — which comprise among other things almost his entire
muscular development since infancy — are limited to the extra
development which results from the nature of his labour. We
shall see how mistaken is this view, and how great a gap in bio-
logical thought and study has resulted in consequence. In effect
it has shorn the study of heredity and evolution not only of one of
its most important branches, but of its main title to practical
utility as well.1

36. Nevertheless, since these terms, innate, acquired, and inherit-
able are firmly established in the literature of heredity, their use
is now in many ways convenient. For the sake of clear thinking
it is necessary, however, to bear their real meanings carefully in
mind — to remember always, when speaking of multicellular organ-
isms, that by an inborn character is meant one which develops
under the stimulus of nutriment, by an acquirement one which
develops under the stimulus of use or injury, and by inheritance
the reproduction, as a nutritional character, by the child of a
parental character of any sort. We shall thus avoid that confusion
of thought which is the common accompaniment of misleading
terminology. " Men believe that their reason rules over words ;

1 See chapters xx.-xxv.

20 THE CHARACTERS OF LIVING BEINGS

but it is also the case that words react, and in their turn use their
influence on the intellect. " l

37. Though the terms innate and acquired are misleading
when used to compare or contrast the characters (which have
developed under different stimuli) of the same individual, they
are quite accurate when used to compare the characters of different
individuals. Thus when we say that an individual is innately like
or unlike another we imply, in effect, that the likeness or unlikeness
is due to a germinal similarity or dissimilarity. On the other hand
when we say that the individuals agree or differ in their acquire-
ments, we imply that the stimuli under which they developed have
been similar or dissimilar in kind or degree. In the latter case
the individuals, as compared to each other, have eaten more, or
less, or different kinds of food, taken more, or less, or different
kinds of exercise, or received more, or less, or different kinds of

injury.

1 Bacon, Novum Organum, i. 59.

CHAPTER II

THE METHOD OF DEVELOPMENT1

The adaptation of the individual — The method of adaptation — Variations —
Modifications — Progression — Retrogression — The recapitulation of the life-
history — The opinions of embryologists.

I

38. ~|~NDIVIDUALS who survive and have offspring, especially
if they have a full quota of offspring, must necessarily
have been well fitted from first to last, from ovum to adult,
to their surroundings. The changes in the individual during
development, especially in the higher animals, are very great, but,
speaking generally, they are always adaptive. Thus the larva of
the dragon-fly which inhabits the water is structurally fitted for a life
in it, and undergoes an adaptive change when, as perfect insect,
it migrates to land. Thus again the human embryo in the womb
is fitted to an environment enormously different to that in which
life is possible to the adult. All, or almost all, the changes it
undergoes during development are adaptive also. Offspring, to
survive in the same environments, must closely resemble their
parents. This necessary resemblance is secured by development
along similar lines. Step by step, from germ to adult, the child
treads in the developmental footsteps of the parent. When, as
occasionally happens, the recapitulation of the parental develop-
ment is not fairly close, the child is a ' monster,' out of harmony
with its environment, and so inevitably perishes.

39. Though every normal child resembles its parent as a whole,
it invariably differs in details, which, though innumerable, are
minute as compared to the likenesses. Thus, though the normal
offspring of a human being is always another human being, it is
never an exactly similar one. These differences, when innate
(i.e. germinal) are known as variations, and must be carefully dis-
tinguished from differences which result merely from an unequal
play of stimuli (nutrition, use, injury, etc.) on parent and child.
The latter are acquired differences or modifications, terms which,
as we have seen, are also used, though incorrectly, to distinguish

1 See Appendix, §§ i-io.

31

22 THE METHOD OF DEVELOPMENT

nutritional characters from those which result from other stimuli.1
Small variations which grade into one another are termed ' con-
tinuous ' : large variations (' sports/ abnormalities, congenital
deformities, ' mutations ') are termed ' discontinuous.' 2 All
variations, all differences between parent and child due to differ-
ences in germ-plasms, may be placed in one or other of two
categories : either they are progressive^ or they are retrogressive. On
progressive variations is founded progressive evolution, as when
the wing of a species of bird undergoes increase in size or power-
On retrogressive variations is founded retrogressive evolution, as
when the wing, owing to lessened utility, undergoes subsequent
decrease.3 An extra digit on the hand of a child of normal parents
is an example of progressive variation ; a missing digit, if founded
on a germinal peculiarity, not on a mutilation, is an example of
retrogressive variation. Of course any given variation may be com-
pound, consisting of both progressive and retrogressive variations.
Thus a congenitally malformed digit may display both additions
and subtractions when compared to the structure in the parent.

40. Obviously, since the child treads in the developmental foot-
steps of the parent, since, like the parent, it is in turn germ, embryo,
foetus, infant, child, youth, and adult, a progressive variation
implies a complete recapitulation of the parental development (as
regards the particular structure or character that has varied), plus
an additional step ; whereas a retrogressive variation implies an
incomplete recapitulation, one or more of the steps of the parental
development being omitted. The line of thought on which we
are now engaged is so very essential to a clear understanding, both
of evolution and heredity, that it will be well worth the reader's
time to close this volume for a space, and to endeavour to think of
a variation which is neither progressive nor retrogressive, but
something else. He will find it impossible. If he then tries to

1 The reader must constantly bear in mind the real, or at least the more
useful distinction between variations and acquired differences. Obviously, to
take an example, there is, between two men one of whom is ' by nature ' lean,
who cannot get fat no matter what he eats, and the other who is thin merely
because he is starved, a difference more radical, more innate than that between
a fat, well-fed man and one who has been starved, but would get fat if afforded
the opportunity.

2 See §§ 249, 286.

3 Sir Ray Lankester has objected to the expression ' retrogressive evolution '
on the ground that retrogression implies an exact and orderly reversal of the
antecedent progression. But if we term the sum of progressive variations ' pro-
gression,' it appears right to term the sum of retrogressive variations ' retrogres-
sion.' At any rate I cannot find a better term and, at least, my meaning is clear.

THE RECAPITULATION OF THE PARENT 23

imagine a progressive variation which is not a prolongation, a step
added to a complete recapitulation of the parental development, or
a retrogressive variation which is not an abbreviation, an incom-
plete recapitulation of the parental development, he will fail again.

41. Amongst typical unicellular organisms there can, of course,
be no recapitulation of the kind that occurs amongst higher types ;
the individual divides into two daughter-cells which resemble itself
and which separate ; there is no development of a cell-community,
and consequently no recapitulation of the process of developing
one. But with multicellular organisms from first to last recapitula-
tion must have been the sole method of development. It is the
only method by which the cell-community, the individual, as
distinguished from the single cell, can grow into the likeness of
the parent community, and so become adapted to the environment
in which it finds itself. Starting from the same point, it must
follow the same road to reach the same goal. The typical uni-
cellular organism, on the other hand, treads no developmental
footsteps ; it remains stationary at the starting-point. If the child
of a man, for example, did not recapitulate the development of his
parent he would be a * monster.' Monsters are known to us, but,
outside mythology, not monsters who survive and have offspring.
Development of the cell-community, otherwise than by recapitula-
tion of the parental development, is indeed not entirely inconceiv-
able ; for we can imagine that an elephant, for instance, may give
birth to a mouse, or a human being to an acorn. But it never
happens. It matters not in the least whether we accept the
popular doctrine that the higher types were specially and divinely
created as highly organized cell-communities, much like their latest
descendants, or whether we hold the scientific theory that they were
derived originally from lowly unicellular forms of which the germ-
cell is the modern representative. In any case there must have
been recapitulation of the parent in every generation.1

42. But, though, in the case of individuals who themselves
survive and have offspring, the recapitulation of the parental
development invariably occurs, it is not necessarily — indeed it
never is — quite complete nor accurate. The child varies from the
parent in every stage of development — as embryo, as fcetus, and

1 The argument is not affected by the occurrence of what is known as alterna-
tion of generations, by the budding of offspring from parents which have arisen
from germ-cells, nor even by the fact that parents and offspring sometimes
develop differently when the conditions under which development occurs are
different. Under similar conditions they would have developed along similar
lines. See § 92.

24 THE METHOD OF DEVELOPMENT

as infant, as well as in the adult stage. Progressive variations,
occurring at the end of the development, add to the parental total
of development : retrogressive variations subtract from it ; both
kinds, occurring during development — interpolated into it — render it
inaccurate, and, in the process of many generations, very inaccurate.

43. But, if the child recapitulates the development of the parent,
the latter also recapitulated that of the grandparent, who in turn
recapitulated that of the great-grandparent, and so on up to the
first multicellular ancestor. Consider, now, the simplest conceiv-
able case of progressive evolution followed by retrogression.
Imagine a line of individuals A, B . . . L, M, in whom a structure
undergoes uninterrupted increase in a single direction — as it were
in a straight line — by successive progressive variations occurring
at the end of the development of each successive individual.
Suppose the structure began in B as a variation from A, and
underwent evolution by successive steps in C, D, . . . till it reached
its culmination in M. Suppose also that it began to retrogress in
N, and that it continued to do so uninterruptedly till it quite
disappeared in Z.

44. Consider first the progression. Clearly, since each individual
down to M recapitulates the development of his parent and makes
in addition another step, the development of B must consist in a
recapitulation of A, followed by his own variation. C, again, since
he recapitulates B, must first recapitulate A, then proceed to B's
variation, and then to his own. D in turn must recapitulate A,
then the variations in order of B and C, and then, and then only,
proceed to his own variation. M, the last of the race in whom a
progressive variation occurs, must found his variation on a re-
capitulation of A, plus a recapitulation in orderly succession of the
variations of all the intervening ancestors. In other words the
development of the structure in M is a recapitulation of its evolution
in the race. In no other way that can be conceived could the
structure have been evolved. Apply this reasoning to every
structure and character in the body, and we perceive that the
theory that every individual in his own development climbs his
own genealogical tree must necessarily be true. Given the un-
questionable fact that the child recapitulates the development of
the parent, any method of development other than by a recapitula-
tion of the life-history of the race is, not only impossible, but
actually unthinkable. One truth necessarily involves the other.

45. But to say that development is a recapitulation of the life-
history is one thing. To say that in every instance it presents a

PROGRESSION AND RETROGRESSION 25

complete and accurate history is quite another thing. On the
contrary, since variations occur in every stage of development, in
every structure, and in every generation, since like other features of
the germ-plasm these variations may be persistent, since, therefore,
they tend to accumulate during the passage of generations, it is
certain that in no single species and even in no organ or structure
is recapitulation complete or accurate. The structure we have just
considered reached its culmination in M, and began to retrogress
in N. Now, obviously, since development is by recapitulation, N
cannot retrogress except by an act of incomplete recapitulation ;
that is by failing to reproduce the variation by means of which M
advanced a step beyond L. Obviously again in that case N reverts
to L ; in effect he is L ; and M, unless his variation becomes latent,
a contingency we shall consider later,1 disappears from the history.
Of course, N's act of retrogression may be larger, and may carry
him back to K or some remote ancestor, say F or E. O's retro-
gressive variation will carry him yet farther. Z, in whom retro-
gression is complete, will, in effect, be A, in whom the structure had
not even its beginnings. In all M's descendants, therefore, the
recapitulation will be incomplete. Even if the structure be evolved
again in some of Z's descendants by a fresh series of progressive
variations, it will still be incomplete. A chapter of the life-history
will be missing even though one like it be added subsequently.

46. For the sake of clear thinking it must be noted that when
we allude to individuals as persisting or disappearing from the
life-history, we are using a mere figure of speech. As we have seen,
the structures of offspring are not derived from the structures of
their progenitors. In reality we are considering alterations in the
germ-plasm, which, though capable of change, is continuous and
potentially immortal. Germ-cells are unicellular organisms, with
unicellular germinal descendants. Multicellular individuals, as we
have seen, are merely episodes in the unending career of the germ-
plasm, dwellings which it periodically builds about itself and from
which it departs as they tend to become outworn. To be precise,
then, the alterations in the germ-plasm are such that individuals
recapitulate, with more or less accuracy, the evolution of the race
of individuals that spring from the slowly changing germ-cells.

47. The case we have imagined — uninterrupted progression
followed by uninterrupted retrogression — is purely ideal. Really
in nature progression tends to alternate irregularly with retro-
gression. Thus, though the hand of every child tends to vary

1 See §§ 186-9 ; see also chapter vii.

26 THE METHOD OF DEVELOPMENT

somewhat from that of his parent, the human hand has not altered
appreciably during thousands of years. Even when progression or
retrogression ensues as a whole, individual members of the race
may reverse the process temporarily. Thus B, C, D may exhibit
progression ; E retrogression, through reversion to C ; while F may
resume the progression and so resemble D.

48. Moreover, structures possess breadth and thickness as well
as length. Their progressions and retrogressions, therefore, are in
three dimensions, and are founded on a number of variations,
internal and external, quantitative and qualitative, which is practi-
cally unlimited. Each of these variations may be independent of
all others ; even single cells may vary independently ; so that while
progression is occurring in some respects, retrogression may be
occurring in others. The apparent result, if we think of the struc-
ture as a whole, is chaos. But we are able to avoid the seeming
confusion if we think of each variation separately. We then
perceive that it must be progressive or retrogressive, that it must
consist in a prolongation or an abbreviation of the life-history of the
part as presented by the parent.

49. Lastly, as we have already noted, offspring vary from their
parents, not only at the end of development, but during the course
of it — not only as adults, but also as embryos. Not only do they
add sentences (progressive variations), or omit sentences (retro-
gressive variations) from the end of the life-history as related by
the parent, but they interpolate, or omit, or alter sentences in the
body of the work. These interpolated progressive and retrogres-
sive variations, like those occurring at the end of development,
may or may not be inherited ; that is, they may or may not repre-
sent persistent changes in the germ-plasm. But many of them are
persistent. They accumulate, and in the course of ages so alter the
life-history, especially in its earlier parts, which have longest been
exposed to change, that it may, and usually does, become un-
recognizable. Nevertheless it ever remains a real history, a real
recapitulation, though in part a recapitulation of past error, of
additions and subtractions, and of interpolations which are com-
pounded of both additions and subtractions. As a result, the
human embryo, for example, differs so greatly from its prototypes
of the life-history, that we cannot, with any degree of accuracy,
trace the early ancestry of our race by watching the develop-
ment of the individual. At first it is unicellular ; then it faintly
resembles very low multicellular types; next it reproduces in
succession, more and more clearly, higher and higher types till it

THE RECAPITULATION OF THE EVOLUTION 27

presents the appearance of an ordinary human being. But mani-
festly the additions and subtractions have been vast. It possesses,
for instance, a placenta, an organ by which it is attached to the
mother, through which it is nourished, and which at one time is
larger than the embryo itself; but which, of course, could not have
been present in its prototypes. On the other hand, the prototypes
were capable of maintaining an independent existence by means
of functionally active organs, which the embryo, fitted as it is only
for a passive parasitic life within the uterus, has lost or almost
lost. Nevertheless the life-history unfolded by the child is just as
real, just as complete, and probably more accurate than any written
chronicle that attempts to describe the whole past of a race.

" There is a history in all men's lives
Figuring the nature of the times deceased."

50. The history is not told in words, but in graphic signs, in
mimicry. It was begun by the first multicellular ancestor, and
then consisted of a single word or sentence, a single cell-division.
Each succeeding generation copied it, and many generations added
sentences. But the copying was never exact. Therefore, as the
history lengthened it became legendary and even mythical in its
earlier parts — the parts which have been longest and most often
copied and emended, and are therefore most altered. Doubtless,
as in written histories, almost every embryonic legend and myth
is founded on fact ; but it is as hard in the one case as in the other
to dig the truth from the concreted mass of fiction. In some
instances the earlier history is not represented even by legend. It
is entirely lost, as in the case of plants which have ceased to
propagate by seeds, and increase only by means of detached
portions of the adult individual, such as buds and suckers. In
other cases, as among the medusae, whole volumes in the middle of
the history have been gradually shortened till they have quite
disappeared.1 In all cases, if the individual lives to complete the
story, the last chapters are usually very full, and in the main
exact — more full and exact than any written history can be.
Thus the offspring of the human being, however shortened and
altered its development, however vague its representation of its
remote ancestors, is always another human being who reproduces,
as a rule with wonderful completeness, all the immensely complex
details that go to the making of a man. But even here, as in a

" In the history of the Hydroidae any phase, planuloid, polypoid, or
medusoid, may be absent." Dr Strethill Wright, quoted by Darwin; Animals
and Plants, vol. ii. p. 364.

28 THE METHOD OF DEVELOPMENT

written history of a recent generation, small details, unimportant
variations of the parent from the grandparent, are often omitted.
Nature is careful to store in the graphic record which is the develop-
ing body of the individual, only those facts that are important and
significant, only those variations which have played a real part in
the evolution of the race. When writing her history she concerns
herself, not with individuals, but with populations ; she preserves,
not the transient details of individual lives, the small variations
which appear in the parent and are lost in the child, but only
those great and enduring general movements by which whole
races or sections of races have differentiated from the ancestral
type. And her aim is strictly practical. Her history of ancestors is
told for the benefit of descendants. Therefore even great general
movements, when they grow remote, are eliminated from the
record, or are replaced by legend and myth if they interfere
with the smooth tenor of the narrative — if they interfere with
the quick development of the child along the shortest and simplest
lines.

51. Hitherto the doctrine of recapitulation has been accepted
by scientific men on the evidence of observed likenesses between the
embryos of the higher and the adults of the lower animals. It
has not yet been realized that, given the undisputed facts that the
organic world arose by evolution, and that the child recapitulates
the parental development, any method of development other than
that by the recapitulation of the life-history is literally incon-
ceivable. When Darwin, succeeding where Lamarck, Spencer,
and others had failed, converted a sceptical world to a belief in
evolution, these vague likenesses were held to furnish the strongest
proof in existence of his contention. Recently, however, some
embryologists, deceived by the frequent unlikenesses, have denied
the recapitulation of the life-history. According to them the
resemblances are due to a "sort of memory" possessed by the
embryo, a suggestion which may possess poetical merits. As a
fact, we should know the doctrine of recapitulation as true even if
an embryo resembling a lower type had never been seen, and it
had been ascertained merely that the embryos of different genera-
tions resembled one another as much as the adult individuals. The
function of an embryologist is not to furnish evidence for, or
against, a necessary truth ; but to ascertain to what extent this or
that type of animal or plant recapitulates its evolution with com-
pleteness and accuracy. It is no excuse to declare that only
complete and accurate recapitulation has been denied. No one,

SUMMARY 29

having even an elementary acquaintance with the facts, has alleged
that recapitulation is ever other than incomplete and inaccurate.
Thus no one has maintained that at one stage of human develop-
ment the embryo is a water-breathing animal, with all its structures
and faculties perfect, or that the ancient prototypes of the embryo
swam about dragging a placenta behind them.

52. Summing up the foregoing, the question I wish to place
before the reader is this : If offspring recapitulate closely but not
exactly the parental development, if progression always implies a
complete recapitulation plus an addition, and retrogression an
incomplete recapitulation (with a step or steps subtracted), if
through all the ages offspring have always recapitulated the
main features of parental development, is it possible, or even
thinkable, that individual development can be anything other than
a recapitulation of the life-history — not an exact recapitulation, but
one with additions and subtractions ? ,

CHAPTER III
THE METHOD OF SCIENCE

Biological sects — Facts patent to our senses — Facts obscured to them — The
function of laboratory methods of inquiry — The methods by which the facts of the
various sciences are observed — ' Exact Methods ' — The nature of science — The
scientific value of facts— The mental processes by means of which facts are classified
— Hypotheses and theories — The necessity for testing thinking — The method
by which it is done — Induction and deduction — Laboratory methods when used
as means of discovery and as tests for thinking — The common neglect of tests —
The essence of the experimental method — The value of controversy — The dis-
tinction between facts and theories — The legitimate and illegitimate uses of
deduction — The contrasts between physical, chemical, and biological theories —
The value of experiment in these sciences — Laws of nature — Deduction an essential
part of the mental processes of rational beings.

T

S3- f | ^HE reasoning by which we have demonstrated that
the development of the individual is a recapitulation
of the evolution of the race, is in some measure de-
ductive. The facts from which we started our thinking have all
been gathered by simple observation. Thus the fact that offspring
tend to recapitulate with variations the parental development has
been simply observed. The language used by some biological
workers indicates an opinion that deduction is illegitimate, or at
least unsafe.1 Others maintain, in effect, that materials furnished
by experiment, or some such aid to observation, affords the only
safe basis or test for reasoning.2 The points thus raised, involv-

1 The statement that deduction — any and every sort of deduction — is con -
sidered illegitimate by any section of scientific workers may be received with
incredulity by people who are aware of the part it has played in the creation of
science. An acquaintance with medical literature and thought would dispel any
doubt. For instance, three years ago there was published a large work (The Food
Factor in Disease, by Francis Hare, M.D. ; Longmans, Green and Co.), the preface
of which actually consists in an apology for the use of the method — an apology
for testing thinking. The book, an exceptionally original, thoughtful, and able
one, failed, I understand, completely.

2 " The recognition that only by experimental methods can we hope to place
the study of Zoology on a footing with the sciences of chemistry and physics
is a comparatively new conception, and one that is by no means admitted as yet
by all zoologists. I do not wish to disparage those studies that deal with the descrip-
tive and the historical problems of biology. They also afford a wide field for activity,
and the more familiar we become with the structure and modes of development

BIOLOGICAL SCHOOLS 31

ing, as they do, questions as to what constitutes valid thinking and
what reliable evidence, are so fundamentally important that it is
necessary to consider them at some length.

54. Students of heredity and evolution who think about, as
well as record, the facts they observe, are divided into schools,
some of which overlap ; for example, the selectionist, the muta-
tionist, the Mendelian, and the biometric. If these divisions
indicated merely associations of men who adopt different methods
of research, then, since a division of labour is advantageous when
dealing with a subject so large and difficult, the existence of
schools would be, not only harmless, but useful. Differences of
opinion could then be settled as they arose by a comparison and
sifting of evidence. But unfortunately the separation is some-

of animals, so much the better can we apply the experimental method. In fact,
many of the problems of biology only become known to us as the result of direct
observation. The wider, therefore, our general information, the greater the
opportunity for experimentation.

" It is undoubtedly true that many zoologists who have spent their lives in
acquiring a broad knowledge of the facts of their science fail to make use of their
information by testing the very problems that their work suggests. This is owing,
no doubt, to their exclusive interest in the observational and descriptive sides
of biology, but also in part, I think, to the fact that the experimental method
has not been sufficiently recognized by zoologists as the most important tool
of research that scientists employ. (T. H. Morgan, Experimental Zoology, p. 3.)

" The essence of the experimental method consists in requiring that every
suggestion (or hypothesis) be put to the test of experiment before it is admitted
to a scientific status. From this point of view the value of a hypothesis is to be
judged, not by its plausibility, but by whether it meets the test of experiment."
(Op. cit.t p. 6.)

"It is sometimes said that nature has already carried out innumerable and
wonderful experiments, and that we can never hope to excel her in this power.
Is it not better, therefore, to examine patiently and reverently what she has
done, and in this way learn how her processes have been carried out ? Let us
not be blinded by rhetorical questions of this kind. No doubt nature has carried
out prodigious experiments ; but we can never be certain that we know how she
has obtained her results until we repeat the process ourselves. What would
the chemist or the physicist say if he were told that nature has already carried out
experiments on a much greater scale than he can hope to accomplish, and that
he should drop his experimental methods and study his physics in a thunder-
storm and his chemistry in an eruption." (Op. cit., p. 8.)

" If the truth must be told, the experimental method was given up for a long
time by the majority of specialists themselves in favour of the controversial,
and, indeed, this tendency has by no means yet died out among the habits of some
professed evolutionists. On the other hand, during the past fifteen to twenty
years, a few scattered workers have diligently applied themselves to the study of
the facts of variation and inheritance, with results which already more than
justify the anticipation in which their work was begun — namely, that by such
methods alone can any real progress in our knowledge of the processes of evolution
be brought about." (R. H. Lock, Variations, Heredity, and Evolution, p. 3.)

32 THE METHOD OF SCIENCE

times more radical. Exactly as in religion, it depends largely on
the fact that the schools, or some of them, value, or seem to their
opponents to value, evidence, not in proportion as it is authentic
and relevant, but in proportion as it has been gathered by this or
that process of inquiry.

55. Now, of course, both the methods of thinking and the
evidence on which the opinions of any school are based may be
altogether wrong, and, therefore, their opponents may be right in
refusing to use them. But, in that case, the reasons for rejection
should be set out plainly and precisely. It is not enough to
ignore evidence, or stigmatize thinking as ' deductive/ or ' philo-
sophic,' or ' obsolete.' Epithets are very unconvincing to opponents.
A reasoned statement ought to justify what in its absence has
the appearance of mere prejudice. Otherwise, in the lack of
common criteria for facts and methods of thinking, differences of
opinion tend to become as irremovable and irrational as those of
religious sects. Scientific men, no matter how open-minded, are
sure, of course, to differ more or less in opinion, for they differ in
knowledge and reflective power ; but sectarian differences arise
only when evidence and modes of thought are accepted or rejected
on improper grounds.

56. In the present chapter I shall discuss the question as to
what kinds of evidence and processes of thought are permissible
in science. Like other men, I belong, more or less exclusively, to
a particular school ; but, very naturally, like them, I believe I am
not a member of a sect. I recognize, however, the possibility that
I, not the people with whom I disagree, may be prejudiced ; at
any rate I recognize that my opinions may appear as prejudices to
opponents, unless I first demonstrate that the facts and thinking
on which they are founded are such as it is right to use. Hereafter,
since I shall not have begged the question by merely assuming
that certain classes of facts and processes of thought are par-
ticularly right or particularly wrong, but shall have stated explicitly
the grounds for my convictions, the reader, if he differs from me,
will at least have it in his power to indicate exactly and easily
where and how I am mistaken. If he finds I am wrong in the
present chapter, I am sure he will be wise not to proceed further ;
for it is not possible that reasoning that is based on initial inac-
curacies of fact or thought can contain anything of value. How-
ever, I do not believe he will think me mistaken. He may wonder,
indeed, why I have taken the trouble to write the chapter. I am
tolerably sure that all of it will seem obviously true and previously

FACTS, PATENT AND OBSCURED 33

known to him ; but, if he has the patience to read the rest of the
book, he will find that it was very necessary. In numbers of recent
publications the rules of ordinary scientific procedure have been
broken, and the breach, so far from being admitted as a fault, has
been claimed, explicitly or implicitly, as a merit. Even a cursory
consideration of scientific controversies renders it evident that the
fundamental source of almost every disagreement has been a
neglect, on one side or the other, to conform in practice with that
which in theory is regarded as a truism. Therefore, if we can
reach a preliminary agreement as to the materials for thought and
modes of thought which it is legitimate to employ, more than half
of the causes of disagreement will be eliminated at a stroke. At
this stage, for lack of illustrations with which to point the argu-
ment, the discussion will not be very complete. For example, I
shall find it impossible to demonstrate that masses of valuable
evidence, bearing on various great problems of heredity, have fre-
quently been ignored without valid excuse. But throughout the
remainder of the work I shall indicate illustrations as they arise.

57. Some facts — by far the greater number of facts known to
us — are patent to our senses ; that is to say, we have only to look,
feel, hear, taste, smell, or invoke the muscular sense, and we become
aware of them. It is the function of our senses to supply us with
facts, and without them we could not maintain existence. But
other facts are of such a nature, or are so obscured by the settings
in which they occur, that they cannot be directly observed by our
senses, or inferred from the evidence supplied by them with any
degree of certainty. We have, then, to resort to experiment,
biometry, or some such 'laboratory' method, to render, if possible,
these obscured facts as certainly known as those which are patent
from the first. When used for purposes of discovery, a laboratory
method is nothing other than a means of eliminating obscuring
conditions and so making hidden facts perceptible, or at least
capable of being inferred with greater certainty. " The object of
experiment is to eliminate unessential conditions in the phenomena ;
. . . when complete knowledge of the essential conditions can be
obtained by observation, experiment is unnecessary." * " Experi-
ment only has an advantage over observation, in so far as it is
capable of supplementing the usual deficiencies of the latter." 2

58. The ascertained facts of some sciences, for example,
systematic zoology, botany, anatomy, and geology, are almost all

1 Welton, Manual of Logic, vol. ii. p. 115.

2 Lotze, Logic, Eng. Trans., vol. ii. p. 40.

34 THE METHOD OF SCIENCE

patent. If we are possessed of normal faculties, we have only to
observe in the right places and at the right times and we are able
at once to note them. Experiment would be useless and absurd,
indeed impossible, here. Thus we could not by experiment ascer-
tain that a species of butterfly was winged and contained several
varieties. There could have been no such sciences as zoology and
botany had we depended on experiment. Therefore their students
have relied almost exclusively on simple observation. The right
times and places in which to observe may be hard to find, but,
once found, the phenomena can be noted.

59. In other sciences, for example, physics and chemistry, many,
indeed most of the facts are obscured. Thus we cannot by our
unaided senses discover the composition of water or alcohol, or the
way in which gases behave under pressure. Therefore physicists
and chemists have been obliged to rely very largely on experiment.

60. The study of heredity, which draws its materials from every
science that deals with life, stands midway. Here the laboratory
cannot create a science ; it can only help to create one. Most of
what we know about life is patent to our senses and can be simply
observed. Especially is this the case with regard to facts ot
structure, for example, the shape, size, and anatomical relations of
the parts of an animal. But some facts, especially those relating
to function (e.g. the function of the thyroid gland), are obscured, and
to discover them, if it be possible, we must resort to a laboratory
method. Therefore, if we say, or imply that facts supplied by
simple observation are useless to the students of heredity, we
declare, in effect, that most facts relating to structure and many
relating to function are useless — we declare, in effect, that when
studying heredity we must not draw our facts from systematic
zoology, botany, comparative anatomy, embryology, palaeontology,
indeed most sciences that deal with life.

61. In contradistinction to simple observation, the laboratory
methods of inquiry have sometimes been termed ' exact ' ; but,
very obviously, the term, implying as it does that simple observation
is necessarily less exact, is erroneous. They are especially exact
on particular occasions only. For example, we do not need them
to make us entirely sure that men resemble apes physically more
than they do other animals, that the offspring of human beings
are human, that every generation follows closely but not exactly
in the developmental footsteps of the one that precedes it, that the
forms of life which have inhabited the earth have changed with the
geological epochs, that stags have antlers and elephants have tusks,

LABORATORY METHODS OF INQUIRY 35

that Englishmen are on the average fairer than negroes and taller
than African pigmies, and so on as regards millions of facts.

62. On the other hand, we cannot without the experiment of
weighing discover the precise weight of a stag, nor without biometry
the exact degree in which Englishmen are on the average fairer
than negroes and taller than pigmies. In a sense, of course, the
statement, for example, that Englishmen are on the average exactly
so many inches and fractions of an inch taller than pigmies is more
precise than the bare statement that they are taller ; but only in a
sense. For the one statement is not truer, but only contains more
of truth than the other. That is, it is more detailed. Obviously,
whether or not the additional details are needed in any given
inquiry, depends on circumstances. They are not always needed.

63. Beyond question, biological facts discovered in the labora-
tory are often very valuable — as valuable as any other verified
facts, and on particular occasions more valuable because designedly
discovered with a view to fill gaps which prevent the linking
together of facts already known. There is, however, nothing
especially magical, scientific, or accurate in data obscured to our
senses till revealed by a laboratory inquiry. Such an inquiry can
do no more than render them as patent, but no more patent than
the majority of facts on which our knowledge of living beings is
based. The latter class of facts, indeed, are usually more capable
of easy verification than any discovered in the laboratory. In
noting them we have only to guard against errors of observa-
tion, not also against errors in experimenting. If the reader will
think over the evidence on which I shall draw for the purposes of
the present volume, I believe he will conclude that, if any of it
bears a doubtful aspect to his mind, it is that large mass which has
been furnished by laboratory inquiry ; for, while some of the
latter is controverted, and all of it must be accepted by most
people at second hand, nearly all the rest is indisputably true, as
he will know from his own experience of life.

64. Sometimes it is said that we must make biology an exact
science by imitating the methods of physicists and chemists — by
which is meant that we must experiment, or compile statistics. It
is right that we should do both when necessary ; but, plainly,
physics and chemistry are exact sciences, not because the facts on
which they are based are obscured and have to be laboriously dis-
covered by laboratory methods, but because they deal with data
that are capable of being exactly measured, and because physicists
and chemists have had both the means and the will to test their

36 THE METHOD OF SCIENCE

thinking exactly.1 Mathematics, which is not an experimental
science, is exact for similar reasons. The study of heredity is not,
and cannot be, exact in the same sense, for no two individuals,
nor even two of their cells, are ever precisely alike. When we
unite a given quantity of oxygen with a given quantity of hydrogen,
the result, which can always be predicted with absolute confidence,
is ever a definite quantity of water of a definite composition. But,
when two germ-cells are united, it is impossible to foresee the
exact nature of the product. Doubtless, when dealing, not with
individuals, but with populations, biometry, the statistical method
of investigating the phenomena of life, does in some cases enable
us to forecast the future with considerable accuracy; but this
accuracy is infinitely less comprehensive than that obtained in
physics and chemistry where predictions are true, not only as
regards averages, but also as regards particular instances. It is
conceivable, though, owing to the complexity of the conditions, not
at all probable, that biologists will one day be able to predict
with the same accuracy and confidence as physicists and chemists ;
but it is hard to understand how this goal will be the sooner
attained by ignoring everything that is patent to our senses.
Physicists and chemists, as rational beings, would be happy if
their facts were patent, and they were thus spared some of the
labours of the laboratory. It is their good fortune, not their merit,
that they are able to measure and test exactly.

65. In brief terms, sciences are experimental or non-experi-
mental in proportion as the facts on which they are founded are,
or are not, obscured. They are exact or inexact in proportion as
they are, or are not, capable of being founded on precise measure-
ments. Some sciences are both experimental and exact ; but the
two circumstances have no necessary relation. Dogs run and wag
their tails. But they do not run because they wag their tails.
Neither are sciences exact because they are experimental. In
science, as in the ordinary affairs of life, a source of error as
common as or more common than the use of inaccurate data, is a
neglect to use the whole of the facts available. Certainly the use
of all the evidence is, through the exposure of discrepancies, one
of the most effective means of ascertaining whether any of it is
inaccurate or has been misinterpreted.

66. Science is founded on facts. But collections of facts do
not by themselves constitute science. They are only the raw
materials out of which it is manufactured. Science consists in the

1 See § 824.

THE NATURE OF SCIENCE 37

classification, the systematization of facts. When we classify
facts, we indicate their relations one to another ; in other words,
we interpret them in terms of one another. Therefore, not only
observation, but thought, is necessary. " The classification of
facts, the recognition of their sequences and relative significance,
is the function of science." 1 " The goal of science is clear — it is
nothing short of the complete interpretation of the universe." 2
" There is no way to gain a knowledge of the universe except
through the gateway of the scientific method. The hard, stony
path of classifying facts and reasoning upon them is the only way
to ascertain truth." 3 " We must never forget that it is principles,
not phenomena — the interpretation, not the knowledge of facts —
that are the objects of inquiry." 4 " The world only becomes in-
telligible when it is conceived as a systematic unity, the elements
of which are throughout in necessary relation to each other. The
attainment of knowledge is nothing but the more thorough and
complete determination of these relations. Hence, every element
of reality is understood just to the extent to which its necessary
relations to other elements are grasped. No doubt reality as
presented to us is infinitely complex, and consists of various
phenomena which resemble each other generally, yet differ in-
definitely in detail. But every postulate of knowledge compels us
to think every variation and every detail, even the smallest, as so
determined by conditions that, under the circumstances, it could
not1 possibly be other than it is." 5 " Scientific thought does not
mean thoughts about subjects with long names. There are no
scientific subjects. The subject of science is the human universe ;
that is to say, everything that has been or may be related to
man."6

67. As there are no scientific subjects, so there are no scientific
facts. There are only facts which have, or have not, been used in
science — which have or have not been systematically classified.
We have only to think of our houses and friends, of our general
surroundings, to recall countless facts quite as indisputably true
as any that have been incorporated into science, but which, owing
to our deficiencies, are not as yet facts for science ; for though each
of us seeks to classify these everyday facts in such a way as will
enable him to move in comfort and security in his world, yet we
cannot link them together in such categories as will enable man-

1 Pearson, Grammar of Science, ed. 1900, p. 6. 2 Op. cit., p. 14.

3 Op. cit., p. 17. * Herschel, Natural Philosophy, § 10.

6 Welton, Manual of Logic, vol. ii. p. 188. 6 Clifford, Essays, p. 86.

38 THE METHOD OF SCIENCE

kind in general to interpret nature in that systematic way that
constitutes science.

68. The scientific value to us of a fact depends, first, on our
power to verify it, to make ourselves and other people sure that it
is a fact ; and, second, on our power to classify it, to recognize its
relations to other bodies of verified evidence. All classification is,
in essence, a process of reasoning, of interpreting. If, armed with
a note-book, I went into the world and jotted down accurate state-
ments concerning the individual animals and plants I happened
to meet, my collection of facts would not constitute science. But
if, with their help, I were able to classify living beings into species,
orders, genera, and kingdoms, my facts would become, what they
were not before, foundations of science. During the process of
classification, as I passed from individuals to varieties, and from
the latter to species, and so on, my descriptions would become
more and more brief, simple, and generalized. Instead of describ-
ing many individuals I would describe a single variety ; instead of
describing many varieties, I would describe a single species, and so
on. But, since a knowledge of species involves a knowledge of
varieties, which, in turn, involves a knowledge of individuals, each
step in this simplification, this classification, would involve the
manipulation of larger and more complex masses of facts, and,
therefore, more complex thinking. But, as long as my facts were
properly verified and classified, neither they nor the processes of
thought involved would grow any the less, or more, scientific for
being more complex. If, from the data I had gathered, I were
able to formulate a theory of evolution, I should classify an
immense body of facts in a new way that would involve very far-
reaching and complex thought.

69. Obviously, however, the complexity of the mental processes
involved in classification does not depend wholly, or even mainly,
on the number of facts to be classified ; for, however numerous the
facts, their relations may be apparent on the surface. In many
cases, we have only to discover the facts, and they fall, by them-
selves as it were, into the right categories. Thus in anatomy,
though the mass of facts is large, and the discovery of some of
them may be difficult, it is comparatively easy to describe the
bones, ligaments, nerves, and the rest, and state their anatomical
relations. It is different with such a study as heredity. Here the
relations between the facts are not easy to trace, and the mental
processes involved in classification are correspondingly complex
and subtle. Thus, suppose a strong and athletic man, who has

HYPOTHESES AND THEORIES 39

good health and takes plenty of exercise and nourishing food,
has a son resembling himself, then what is the relation between
the facts? To what shall we attribute the likeness between
father and son ? Is the son strong and healthy merely because he
was 'born' with the characteristics with which the father was
' born,' and because he has lived like him ? Or has the life led by
the father altered the germ-plasm and improved the child's heritage ?
Or are both factors to be taken into account ? Obviously, our task
in ascertaining the relations between the facts is harder here than
in anatomy. We are obliged to draw a ' mediate ' inference. The
immense number of erroneous and discarded hypotheses with which
the past of heredity is littered is evidence of the difficulty found by
its students in drawing correct inferences.1

70. An inference is a hypothesis. But at first it is only a
working hypothesis, a mere guess. Before we can be sure it is true,
before we can convert it into an established theory r, we must test the
thinking by which it was reached, and so ascertain whether it is
correct. Now there is one way, and one way only, by which the truth
of hypotheses can be tested. As we test facts by appealing to facts,
so we must test thoughts by appealing to thoughts — to inferences.
We must proceed by two steps. First, we must make a rigorous
deductive inference of consequences. Next, we must ascertain by
an appeal to reality in the world around us whether these predicted
consequences actually do occur.2 For example, when families
dwell under unhealthy conditions, as in the slums of great cities,
the parents tend to be sickly and the children puny. In this case

1 The necessity of adopting diverse methods when observing and classifying
the facts of the various sciences is hardly realized by some students. Occasionally
one hears an anatomist, zoologist, or botanist, a ' systematist,' lament the rage for
speculation and declare that the function of science is merely to observe and
classify facts — by which is meant of course the kind of observing and classifying
that is usually adequate for the purposes of the systematic sciences. But,
obviously, such observing would be of little use to the chemist, and such classifying,
when applied to a subject so abstruse as heredity, would totally fail to establish
the relations between the facts. The difficulty of simply observing compels the
chemist to experiment ; the difficulty of classifying compels the student of
heredity to speculation, which, however, when founded on strictly ascertained
facts and rigorously tested by a deductive inference of consequences, is not un-
scientific, but merely an especially strenuous effort to think accurately — to classify
correctly. See §§ 819 et seq.

2 " Every hypothesis is an attempt to find meaning in observed phenomena,
to constitute reality in a rational way. It follows that the fundamental condition
of a valid hypothesis is that it should explain and give meaning to the facts of
observation. And it can only do this if it embraces those facts in that systematic
whole which is the one form under which it is possible to think the universe. This

40 THE METHOD OF SCIENCE

we have a choice between two hypotheses, two inferences, two
statements of what may be the relations between the phenomena.
First, we may infer that parental ill-health tends to injure the
germ-plasm, and, therefore, that the children are innately puny,
innately incapable of becoming robust. If this hypothesis is true,
then it follows as a necessary consequence that, if the children con-
tinue to dwell in the unhealthy environment, the weakened germ-
plasm will be still more injured and the grandchildren will be still
more puny, and therefore that the race will degenerate step by
step. At any rate, if it can be shown that races become innately
degenerate under such conditions, the hypothesis may be regarded
as a theory the truth of which has been established. Here,

(a) The facts are that the children of unhealthy parents are very
frequently puny.

(fr) The hypothesis, the induction, is that parental ill-health tends
to injure the germ-plasm, and so render the children and their
descendants innately puny.

(c) The deduced consequences are that families, classes, and races,
exposed to unhealthy conditions, tend to become degenerate.

(d) The appeal to reality is the ascertaining whether populations
exposed to unhealthy conditions actually do become degenerate.

By this means we test our thinking, our hypothesis. Second, we
may infer that the puniness of the children is due, not to the
deterioration of the germ-plasm, but merely to inferior development
resulting from the unhealthy conditions to which the children
themselves are exposed. That is, we suppose that the puniness is
not innate. If this second hypothesis is true, the race will not
grow degenerate through being exposed to unhealthy conditions.
On the contrary it will become more resistant to those conditions
through the weeding out of the naturally less resistant individuals.
Having drawn these two contradictory inferences, we have, as I
say, to ascertain which of them is true by appealing to reality in
the world around us.1

general condition, then, may be considered as involving three subordinate
conditions : —

(1) That the hypothesis be self -consistent, and in harmony with all the other
laws included in the conceived system of reality.

(2) That it furnish a basis for rigorous deductive inference of consequences.

(3) That these inferred consequences be in agreement with reality.

Of these conditions the first two are applicable to the formation of every
hypothesis, no matter how provisional a character it may have ; the third is a
condition of the acceptance of a hypothesis as true." (Welton, Manual of 'Logic ,
voi. ii. pp. 95-6.)

1 See § 733.

THE TESTING OF HYPOTHESES 41

71. It is obligatory that we make this deductive appeal to reality.
When it is done, certain facts — all we find it possible to employ in
this way — are used as the basis of the hypothesis. Next other facts
— all the rest which are relevant and known to us — are used, in as
many ways as possible, to test the truth of the hypothesis. The
latter class of facts are usually much the more numerous. In brief,
we found the hypothesis on certain relevant facts and prove it by
means of the rest. In this way only, especially when we are
engaged in the elucidation of some obscure and difficult matter, is
it possible to use all the facts. If we do not proceed thus — first
formulating our hypothesis, next making a rigorous deductive
inference of consequences, and lastly appealing to reality for con-
firmation— our thinking is mere guessing. A hypothesis is quite
I valueless to science unless it permits a deductive appeal to reality,
i and quite unproved until it has been found to stand that test
j "The sole condition to which we need conform in framing any
! hypothesis is that we both have and exercise the power of inferring
I deductively from the hypothesis to the particular results, which
are to be compared to known facts." 1 No scientific worker, that
was not a mere observer, has ever done great work who did not so
test his hypotheses; no hypothesis has ever been permanently
included in science but has been so tested. " If it be an advantage
for the discoverer of truth that he be ingenious and fertile in
inventing hypotheses which may connect the phenomena of nature, it
is indispensably requisite that he be diligent and careful in com-
paring his hypotheses with the facts, and ready to abandon his
invention as soon as it appears that it does not agree with the
course of actual occurrences. This constant comparison of his
own conceptions and supposition with observed facts under all
aspects forms the leading employment of the discoverer; this
candid and simple love of truth, which makes him willing to
suppress the most favourite production of his own ingenuity as soon
I as it appears to be at variance with realities, constitutes the first
I characteristic of his temper. He must have neither the blindness
j which cannot, nor the obstinacy which will not, perceive the
! discrepancy of his fancies and his facts. He must allow no indol-
ence, or partial views, or self-complacency, or delight in seeming
demonstration, to make him tenacious of the schemes which he
devises, any further than they are confirmed by their accordance
with nature. The framing of hypotheses is, for the inquirer after
truth, not the end, but the beginning of his work. Each of his
1 Jevons, Principles of Science, p. 265.

42 THE METHOD OF SCIENCE

systems is invented, not that he may admire it and follow it in all
its consistent consequences, but that he may make it the occasion
of a course of active experiment and observation. And if the
results of this process contradict his fundamental assumptions,
however ingenious, however symmetrical, however elegant his
system may be, he rejects it without hesitation. He allows no
natural yearnings for the offspring of his own mind to draw him
aside from the higher duty of loyalty to his sovereign, Truth : to
her he not only gives his affections and his wishes, but strenuous
labour and scrupulous minuteness of attention." l

72. In science, therefore, we must not only use words that
express our meanings unmistakably,2 we must not only verify our
facts, but we must always test our thinking deductively " by observ-
ing the present state of the world, by assiduously studying the
history of past ages, by sifting the evidence of facts, by carefully
combining and contrasting those which are authentic, by generaliz-
ing with judgment and diffidence, by perpetually bringing the
theory we have constructed to the test of new facts, by correcting
or altogether abandoning it, according as the new facts prove it to
be partially or fundamentally unsound." 3 All this is axiomatic,
and has been axiomatic since men began to think scientifically.
Therefore it would be difficult to conceive anything more absurd
than the statement that we must eschew deduction and rely wholly
on induction. " All inductive reasoning is but the inverse applica-
tion of deductive reasoning. Being in possession of certain
particular facts or events expressed in propositions, we imagine
some more general proposition expressing the existence of a law
or cause ; and deducing particular results of that supposed general
proposition, we observe whether they agree with the facts in
question." 4 Induction and deduction " differ only as the road by
which we ascend from a valley to a mountain does from that by
which we descend from the mountain to the valley, which is no
difference of road, but only a difference in the going." 5 Induction is
that process by which we infer a generalization from a consideration
of particular facts or from a consideration of inferior inductions,
each of which is then used as a fact. Thus it is an induction which
has been drawn a thousand times that parental ill-health results in
innately enfeebled offspring. It is also a common induction that
it has no such effect on offspring. Deduction is the process

1 Whewell, Novum Organum Renovatum, pp. 80- 1.

2 See chapter i. 3 Macaulay.

4 Jevons, Principles of Science, p. 265. 6 Port Royal Logic, p. 314.

THE USES OF EXPERIMENT 43

by which we test the truth of our inductions. Obviously, we
cannot test the truth of either of the foregoing inductions, nor
decide between them, unless we appeal deductively back again to
the facts of the world around us. Experiment is one of the ways
in which we may test an inference. After we have considered a
collection of facts and drawn an induction, we say to ourselves,
" If our hypothesis is true, if we have thought correctly, such and
such consequences must follow " ; and, if possible, we experiment to
ascertain if they do follow. If they do actually follow, then there
is a high probability that our hypothesis is correct, and that
probability is raised to a higher degree by every new and success-
ful appeal to reality. On the other hand, a valid appeal, experi-
mental or other, if unfavourable, immediately and conclusively
demonstrates the falsity of the hypothesis, which therefore must be
abandoned or emended. " Thus Kepler records that he advanced
nineteen hypotheses which he afterwards disproved, before he
arrived at the true statement of the laws of planetary motion." l
" A similar spirit was shown by Newton in respect to his
hypothesis that the moon is retained in her orbit by the force of
gravity. From this hypothesis he calculated that the moon ought
to be deflected from the tangent of its orbit something more than
fifteen feet every minute. But the apparent deflection was only
thirteen feet. This discrepancy, comparatively small though it was,
Newton accepted as a disproof of his hypothesis, and ' laid aside at
that time any further thoughts of this matter.' But some fifteen
years later the distance of the moon from the earth had been more
exactly ascertained, and Newton repeated his calculations, working
with these new values. The agreement between the calculated
and the normal deflection was then seen to be remarkably precise,
and the hypothesis became an established theory." 2

73. Unless an experiment is entirely aimless, entirely a product
of unscientific thought, it is always an outcome of deduction.
Even when it is used, not to test thinking, but merely to elicit
fresh information, it is still an outcome of deduction ; for it is de-
duction which leads us to suppose that our experiment will have
useful results. It follows that there are two ways in which we
may use experiment (or any other laboratory method). First we
may use it as a deductive test of previous thinking, in which it
tends to secure great accuracy in thinking. Second, we may use
it as a means to reveal an obscured fact, when, of course, it tends
to secure accuracy in observing. But, in the latter case, if we base

1 Welton, Manual of Logic, vol. ii. p. 66. 2 Op. cit., vol. ii. p. 88.

44 THE METHOD OF SCIENCE

thinking on the result of the experiment, in other words, if we
reason, not towards the experiment, but from it, then our thinking
is not tested by it. We get information which may be very
accurate and very valuable ; but we get no more than this informa-
tion. The subsequent thinking, if any, may, or may not, be
accurate. To discover its accuracy we have to use tests which that
particular experiment does not furnish. Now it is a very common
delusion that, because experiment when used as a test tends to render
thinking accurate, therefore all thinking connected with experiment
tends to be. accurate. Consequently a neglect to test thinking
founded on experiment, combined with an assumption that such
thinking is necessarily accurate, is very frequent. A hypothesis,
whether resulting from induction or deduction, which has stood a
valid experimental test, has stood a single test so nearly conclu-
sive that it can be made more conclusive only by continued testing
by other appeals to reality. But a hypothesis which is merely
founded on obscured facts revealed by experiment has no special
claims to accuracy. For example, if I, having a notion that Brown
wishes to enter my house surreptitiously, give him the opportunity
and entrap him, my hypothesis is tested by experiment. It is then
very nearly conclusively proved ; the only doubt remaining being
due to the fact that at the time that I supposed Brown wished to
enter my house he might not yet have thought of it. But if, on
the fact revealed by the experiment, I build the notion that he
came to steal the spoons, I must test my new hypothesis by a fresh
appeal to reality. It matters not, however, whether I discover the
spoons on him by a formal experiment (i.e. by searching him), or
whether I simply observe them sticking out of his pocket. In
either case the appeal to reality, if successful, is equally decisive.
In everyday life it is often not worth while to test our hypotheses,
but, however much science occupies our thoughts, our thinking is
never scientific unless we do so.

74. The two functions of experiment, testing and discovery, are
sharply distinct. Nevertheless they are often confused by people
who claim for hypotheses founded on experiment the high scientific
status of theories tested by experiment. We shall see that while many
important biological hypotheses have been founded on experiment,
there is hardly an example of one which has been tested by it, or which
it is practicable to test by it. Moreover, we must ever keep in mind
the manifest truth that the field of biological experiment is limited.
A suitable experiment, whether to test thinking or reveal facts,
cannot always be devised. Thus, in the case we have just considered

THE DISCOVERY AND TESTING 45

as to whether unhealthy conditions are causes of racial degenera-
tion or of evolution, no' suitable or practicable experiment can be
thought of.1 Hundreds or thousands of experiments have been
performed, it is true, but with the most inconclusive results.2 Here,
before we are able to reach a valid conclusion, we must appeal to
a far wider area of reality, which includes not only the experimental
data, but very much more besides.3

75. In biology, then, the essence of the experimental method
does not consist " in requiring every suggestion (or hypothesis) to be
put to the test of experiment before it is admitted to the scientific
status " — an impossible task in many cases and foolish in more ;
but only in requiring that every suggestion which can usefully be
so tested shall be so tested. Since such suggestions are relatively
very few, exclusive reliance on experiment would result in a
classification of facts so imperfect as to be unworthy of the name
of science. The statement, " No doubt nature has carried out
prodigious experiments ; but we can never be certain that we know
how she has obtained her results until we can repeat the process
for ourselves," 4 implies a lack of insight or a singular unawareness
of known facts. For example, every instance of an individual
who has offspring during or after suffering from a general disease
is a very stringent experiment carried out by nature and not to be
bettered by man. The accumulated result of millions or billions of
such experiments, continued for thousands of years on hundreds of
successive generations, are — because the instances are so numerous,
obvious, and confirmatory of one another, because we are able
successfully to employ every known method of induction, and
because we can test the thinking thoroughly by deduction — every
whit as easy to infer with certainity as if they had been undertaken
by the most careful experimental worker.5 " Controversy " 6 implies
criticism. To abandon it would be to abandon the critical method,
which, in turn, would mean the rash and unquestioning acceptance
or ignoring of hypotheses. Biological disputes are comparatively
seldom due to disagreements about facts. Almost always the
opponents of a hypothesis suppose that its authors have drawn
wrong inferences, and their objections are attempts to test the
latter by demonstrating that they are not in harmony with the
conceived system of reality. Fortunately, however, the labours
of experimental workers have tended, on the whole, to increase,
rather than diminish, controversy. The experimental method is

1 See § 135. 2 See §§ 132-4, 140-4, 160. 3 See §§ 145 et seq.

4See § S3 (footnote). 5 See chapter xiii. 6 See § 53 (footnote).

46 THE METHOD OF SCIENCE

not new in biology. That which, amid such a wealth of patent
facts, is very new, is exclusive reliance on obscured facts and a
confusing of experimental discovery with experimental testing.
" What would the physicist or chemist say if he were told " that
he must not use patent facts, for example those of astronomy,
when inventing or testing his theories ? An experiment, or any
other laboratory inquiry, is a mode of observing, not of thinking.
It is sometimes an appeal to reality which results from deductive
thinking, but unless correctly thought out, not necessarily a de-
cisive appeal. It is valuable as testing our thinking or as making
patent a fact previously obscured ; but often we are able to appeal
to evidence patent from the first, and an obscured fact, newly
discovered, is not necessarily more valuable to us than a patent
fact that has long been ignored or insufficiently used. An observer
is quite as likely to found illegitimate thinking on the results of
experiment as on any other data. Indeed, thinking founded on
experiment has often been deplorably reckless and inaccurate.

76. The function of deduction is not limited to the testing of
inductions. " If the hypothesis is true, it will generally be possible
to infer deductively from it facts which have not been before ex-
plained or which have even been unobserved. ... As Whewell
says, * When the hypothesis of itself, and without adjustment for
the purpose, gives us the rule and reason of a class of facts not
contemplated in its construction, we have a criterion of its reality,
which has never yet been produced in favour of falsehood.' l The
history of science is full of such extension and prediction. Thus,
for example, the discovery of Neptune was predicted by deductive
reasoning from the principle of gravitation." 2 Again, the universe
is a unity in which every phenomenon is related, however remotely,
to every other. A brief yet comprehensive statement, in which
the relations of a number of phenomena are summarized, is termed
by us a law ; and it is the aim of science not only to express the re-
lations of phenomena in laws, but to indicate the relations of these
laws — to weld them into larger syntheses, more comprehensive
interpretations.3 In this process of welding deduction plays an

1 Novum Organum Renovatum, p. 90.

* Welton, Manual of Logic, vol. ii. p. 100.

3 What is a natural 'law' ? It is commonly described as an "observed
uniformity," " the statement of a general truth ; that is, a truth that holds good
universally in that science, as contrasted with a particular truth, which holds
good in some cases only" (Welton, op. cit., vol. i. p. n). But this definition
is too wide (see § 586, footnote). The flowers of the common primrose are yellow ;
mammals have heads ; birds are bi-pedal. These are observed uniformities,

LAWS OF NATURE 47

essential part. Moreover, here again it is a means of testing ; for
we cannot combine incompatible, that is true and false, deductions.
At any rate, the attempt to combine them tends to sift the true
from the false. First we gather facts, as it were, into bundles by

each of which includes a considerable range of phenomena ; but they are scarcely
what we understand by ' laws of nature.' A law is rather a description of a
uniformity in the way in which bodies affect one another ; or, in other words,
a description of the way in which they behave under uniform conditions.
Material bodies have properties or qualities which bring them into relation with
each other. From uniform relations, consequent on the possession of qualities
of like nature, uniform results follow. Thus, the statement that all material
bodies attract each other directly as their mass and inversely as the square of
their distance is unmistakably a law. A law is, in fact, a theory ; it describes
a uniformity in terms of causation (see § 586) ; therefore it describes a uniformity
in the sequence of phenomena. It is a peculiarity of a natural law in the strict
scientific sense that we are able to deduce consequences from it, and so are able
not only to link up with it, and thereby ' explain ' phenomena not directly mentioned
in it, but we are able also in this way to test the truth of it. At any rate, a law
is valuable to us as a means of systematizing our facts in proportion as we are able
to make deductive inferences of consequences from it. No consequences worth
mentioning can be deduced from the uniformities that common primroses are
yellow, mammals have heads, and birds are bi-pedal. Here we do not describe
ways in which bodies affect one another. But any number of consequences can
be deduced from the law of gravitation. Here we do describe a way in which
bodies are affected by each other. We do not know why material bodies attract
each other, nor why they attract each other in the degrees that they do. But,
if the law of gravitation is a correct statement, if material bodies do attract each
other in the degrees stated in it, then, since contradictories cannot both be true,
given certain conditions, certain consequences must follow. Thus, given a planet
moving in accordance with the laws of motion with a certain momentum, at a
certain distance from the sun, then it must circle in a certain path round the sun ;
given the moon at a certain distance from the earth, then the tides of the ocean
must follow its course ; given lack of support, then stones must fall to the ground ;
given a fluid condition, then the surface of a body (e.g. water) must conform to
the general contour of the surface of the earth at the latitude in which it is situated ;
and so on. " Those ideas that hold good throughout the widest domains of
research and that supplement the greatest amount of experience are the most
scientific" (Mach, Principles of Mechanics, p. 490). Those sciences (e.g. physics
and mathematics) which are the most completely welded together by laws and
deductions from them, are the most completely scientific, the most completely
interpretative, the most completely intelligible. The fewer the laws necessary for
this process of welding the better ; for then the welding is the more perfect since
all the more is included within the range of each law. Those sciences (e.g. anatomy)
that are the least deductive, that are the least interpretative, are the least com-
pletely scientific (see § 819 et seq.). If the reader devotes a moment's consideration
to the subject, he will perceive that nearly all thinking about heredity and evolu-
tion,jlike much of the thinking in mathematics and physics, but unlike all thinking
in the ' systematic ' sciences (e.g. zoology and botany), consists in attempts to
explain the facts, or, in other words, to link them together in chains of causation.
When we link facts in this way, we join them by inferences. An inference is a
hypothesis. Hypotheses can be proved only by deductive appeals to reality.
A law is a hypothesis that has been fully established by such appeals. All the

48 THE METHOD OF SCIENCE

inductions ; next we ascertain by deduction whether the separate
inductions are in harmony with each other and with reality in
general ; and, lastly, treating each induction as a fact, we bind
them together in a wider induction " To the Deductive Method,
thus characterized in its three constituent parts, Induction, Ratio-
cination, and Verification, the human mind is indebted for its
most conspicuous triumphs in the investigation of nature." l " At
any step of Induction . . . the inductive proposition is a Theory
with regard to the Facts it includes, while it is to be looked upon
as a Fact with respect to the higher generalizations in which it is
included. In any other sense . . . the opposition of Fact and
Theory is untenable, and leads to endless perplexity and debate.
Is it a Fact or a Theory that the planet Mars revolves in an ellipse
about the Sun ? To Kepler, employed in endeavouring to combine
the separate observations by the conception of an Ellipse, it is a
Theory ; to Newton, engaged in inferring the law of force from a
knowledge of the elliptical motion, it is a Fact. There are ...
no special attributes of Theory and Fact which distinguish them
from one another. Facts are phenomena apprehended by the
aid of conceptions and mental acts as Theories also are. We
commonly call our observations Facts, when we apply, without
effort or consciousness, conceptions perfectly familiar to us, while
we speak of Theories when we have previously contemplated the
Facts and the connecting Conceptions separately, and have made
the conception by a conscious mental act." 2

established inferences of mathematics and physics have been proved thus. It follows
that the aim of the student of heredity and evolution is to discover laws and so con-
vert biology into a deductive science. If he proceeds according to the method by
which alone interpretative science has been created hitherto, he will begin by col-
lecting and verifying relevant facts ; on these facts he will found inferences ; and
these hypotheses he will endeavour to test in every direction possible by the only
means possible — by deductive appeals to reality. This last step will not only
establish his hypotheses if true, or disprove them if untrue, but it will also bring
within their range numbers of facts which would not otherwise have been thought
of in connection with them. The history of such biological work as has involved
thinking about the sequences of phenomena — about cause and effect — indicates
very clearly that almost every controversy has arisen because the ordinary rules
of logical and scientific method were neglected. Facts have been incorrectly
described, or they have not been verified, or hypotheses incapable of proof have
been formulated, or hypotheses capable of proof have not been tested, or opponents
have ignored the proofs. Owing largely to the care with which facts are verified
and hypotheses tested, and the readiness with which proofs are accepted, contro-
versies are relatively rare amongst the students of physics, and rarer still amongst
mathematicians. (See Mill, Logic, Bk. III., from which a passage is quoted as foot-
note to § 352. See also chapters xviii. and xxv. of the present work.)

1 See Mill, Logic, III. ii. 3. 2 Whewell, Novum Organum Renovatum, p. 116.

EXPERIMENT IN THE SCIENCES 49

77. In biology, especially in medicine, this process of com-
bining inductions is occasionally stigmatized as ' deduction.'
Apparently it is held that any inference which unites two or more
inductions in a larger synthesis ought to be reached, no matter if
impossible, by a single untested inference from particular pheno-
mena. This curious opposition between fact and theory is well
illustrated by the common declaration that this or that inference,
of the truth of which the writer is convinced, " is a fact, not a
theory " ; by which is meant only that in the opinion of the writer
the inference is incontrovertible, or, in other words, that it is a
theory, not a hypothesis.

78. When, as in mechanics and physics generally, nearly all
our accurate knowledge has been gathered in the laboratory, it is
often possible to test a new induction by a deductive appeal to
other laboratory results which have already been achieved or are
possible of achievement. It is largely by such appeals that the
facts, inductions, and deductions of physics have been welded into
a science.1 Moreover, since most of the facts are obscured, the
field of laboratory discovery is limitless, and, therefore, one experi-
mental achievement constantly suggests another, with the result
that new facts are continually discovered and new inductions and
deductions formulated.

79. It is different in most branches of biology, So much is
already known, or can be ascertained by simple observation, that
the opportunities of the laboratory are greatly restricted. If
we depend solely on it, if we close our eyes to the universe
outside its walls, we may, indeed, reach many valuable facts and
inductions. But there will always be the danger that we have
wasted our time — that the facts have already been reached, or
could be reached more quickly, easily, and certainly by simple

1 It must be borne in mind, however, that physicists have, especially in
astronomy, made a very considerable deductive appeal to the material supplied
by simple observation. " The use of a scientific instrument does not make an
observation into an experiment, unless the instrument modifies the object which
is being observed. Thus we invariably speak of observing with a telescope or a
microscope" (Welton, Manual of Logic, p. 116). "The attraction of the sun
accounted for the motions of the planets ; the attraction of the planets was the
cause of the motions of the satellites. But this being assumed, the perturbations
and the motions of the nodes and aphelia only made it requisite to extend the
attraction of the sun to the satellites and that of the planets to each other ; —
the tides, the spheroidal form of the earth, the precession, still required nothing
more than that the moon and sun should attract the parts of the earth, and that
these should attract each other — so that all the suppositions resolved themselves
into the single one, of the universal gravitation of all matter." (Whewell,
Novum Organum Renovatum, p. 92.)
4

So THE METHOD OF SCIENCE

observation.1 In any case, since the inductions reached through
the laboratory are so few and widely separated ; since, in effect,
there is no system of reality to which appeal can be made, or at
most only a very fragmentary system, every induction must remain
isolated and untested. Under such conditions, the only kind of
deduction possible is one which expands the induction without
testing it or linking it up with any other, which cannot be tested
itself, and which, therefore, is valueless and illegitimate.2 We
shall see that, almost without exception, every important biological
induction based on laboratory work — important in the sense of having
attracted wide attention — has been expanded in this way, and that it
is the deduction^ not the induction, on which stress is laid and which is
regarded as the Theory. Moreover, not only have untested induc-
tions often been expanded by untested deductions, but, as often,
the latter have been regarded as proved simply and solely because
the phenomena on which they are remotely based were, like
those of physics and chemistry, observed in the laboratory.3
It is true that we are exhorted to use experiment as a test,
but, especially when the larger problems of heredity are under
consideration, the advice is rarely heeded even by those who
utter it. In effect, biologists have used the laboratory only as a
means of discovery.

80. The theories (laws) of physicists and chemists have usually
stood the test of time, not because their facts were experimentally
observed, nor even because their data were capable of being
exactly measured, but chiefly because, though the facts were
difficult to gather, the thinking founded on them was in many
cases relatively simple, and, more especially, because it was in all
cases very rigorously tested. The formulation of a physical or
chemical law often consists in little more than a bare summary ot
the facts discovered in an experiment or series of experiments, a
summary almost as easy to make as a classification of the facts of
anatomy. In other words the relations of the facts are comparatively
easy to discern. Compare, for example, Boyle's law of the

1 See §§ 22 5 et seq.

2 " The deductions which Bacon abolished were from premises hastily
snatched up or arbitrarily assumed. The principles were neither established by
legitimate canons of experimental inquiry, nor the results tested by that indis-
pensable element of a rational Deductive Method, verification by specific experience.
Between the primitive method of deduction and that which I have attempted
to characterize, there is all the difference which exists between the Aristotelian
physics and the Newtonian theory of the heavens." (J. S. Mill, Logic, III. xiii. 7.)

3 See §§ 208 et seq., see also chapters vii. and viii.

PHYSICAL AND BIOLOGICAL THEORIES 51

behaviour of gases under pressure with Darwin's theory of natural
selection. In the former case much thought was needed to gather

ic data ; but they could be exactly measured, and, once obtained,
single induction sufficed to enable the discoverer to perceive
lis law ; and, though a great deal of testing was still necessary, yet

ie means of performing it were not hard to think of. In the

itter case, the facts lay patent but multitudinous under the eyes
>f every man. Individuals, as regards some of their characters at
my rate, could be measured with exactness ; but the measurements
>f no child agreed with those of its parents. The difficulty lay,

lerefore, not so much in observing facts as in interpreting them —
tracing hidden analogies, in seeing likenesses amid differences,
separating the relevant from the irrelevant, essentials from non-
essentials, in brushing aside the veil of familiarity, in discarding
superstitions, in devising tests. Boyle's difficulties, however
;at, were not of the same order as Darwin's. They lay

lainly in discovering the facts, all of which were obscured.

larwin's difficulties lay in tracking his way through the enormous

id confusing maze of patent facts that spread and grew around
nm.

81. Obviously biology does not lend itself to experiment so
idily as physics and chemistry. Apart from the circumstance

lat many of its facts are patent, it is too complex. The first
iterpretation of a physical or chemical experiment is often
iccepted without cavil, and is comparatively rarely overthrown.
>ut seldom is the first interpretation of a biological experiment
xepted without hot controversy, and it is quite usual for the
>riginal interpretation to be overthrown and replaced by another,
tnd another, and yet another. These difficulties of interpre-
ition indicate the difficulties of satisfying the conditions
rhich make experiment useful — the difficulty of so eliminating
•relevant complications, that in the case of each experiment
ily one interpretation of the result is possible, or at least
jasonable.

82. The notion that deduction is necessarily illegitimate and
langerous is demonstrably incorrect. That opinion has never guided

successful students in their efforts to interpret nature. It is illegiti-
mate only when we start with an unproved assumption, or when it is
used merely to expand untested inductions by thinking which cannot
itself be tested by an appeal to reality. Rightly used, it is our
prime means of securing accuracy when thinking about sequences of
events. Physicists have constantly used it, and with magnificent

52 THE METHOD OF SCIENCE

results.1 Mathematics, the most exact of all sciences, is almost
purely deductive. Many of the more important biological
generalizations could not have been confirmed or even reached
without the employment of deduction.2 Deduction is as essential
a part of human mental operations as induction. We seldom
use the word ' therefore ' except when our thinking is deductive.
All calculation is deduction. Our every-day thinking — that
incessant play of thought, that associating, disassociating,
comparing, discriminating, inferring, in which we are incessantly
engaged — is largely, indeed mainly, deductive. We gather facts
from the world around us and by processes of induction reach
thousands or tens of thousands of conclusions. But, like the parts
of a scattered machine, the universe our mind constructs for us
would have no meaning, no unity, and our knowledge little
utility, unless these inductions were linked together, and amplified,
and multiplied a thousand-fold by deduction. It is hardly possible,
even for a young child, to become aware of a sight, sound, odour,
taste, or tactile sensation without, consciously or unconsciously,
recalling facts and generalizations previously formulated, and
linking the new experience to them by deductive thinking. Nature
drives us ceaselessly to the acquirement of skill in deduction,
without which we would be lost in a chaos. Our intelligence is due
to it. The scientific imagination is usually but another name for
its daring yet restrained and careful employment. Not a single
monument of the power of human thought, embodied in the
literature of the past, but is full of it. No great man of action or
thought, from statesman and general to traveller and scientific
worker, has existed but was a master of it. Not even the simplest
tool was ever thought of, made, or used but through the employ-
ment of it ; indeed the whole history of invention and the application
of invention is but a chapter in the history of deductive thought.
Only by means of it, by appealing from our inductions back again
to the facts, can we, especially when some complex matter is under
consideration, take the whole of the evidence into account. As
a mode of thinking it is an adaptation, the highest product of

1 " Newton's comprehension of logical method was perfect ; no hypothesis
was entertained unless it was definite in conditions, and admitted of unquestion-
able deductive reasoning, and the value of each hypothesis was entirely decided
by the comparison of its consequences with facts." (Jevons, Principles of Science,

P- 583.)

2 For example the theories of evolution and natural selection, both of which,
moreover, were founded on facts that had been collected mainly by simple
observation. See §§ 350-1.

DEDUCTION 53

mental evolution, to the use of which we are continually driven by
the most imperious of our instincts.1 Lacking it we should be
imbeciles of that not very uncommon kind that has a considerable
memory for facts but cannot learn to link them together except in
a very rudimentary way. The only people by whom it is not
habitually used are actual idiots and imbeciles of a low type. I
use the words advisedly and literally in reference to phenomena
which may easily be observed — in reference to idiots and imbeciles
who are medically certified and placed under restraint as such.2
One of the main causes of the mental inferiority of the lower
animals is that, like imbeciles, they are unable to employ it.
Scientific deduction, like scientific induction, differs from our
common use of the process only in the greater precautions we
take to make it accurate. It would be strange if a process, so
useful and necessary in the ordinary affairs of life, should become
valueless and dangerous the moment we endeavoured to use it with
care, and if men, to become scientific, must cease to be rational.

83. All the foregoing is, I take it, quite indisputably true. At
any rate, all that I have said about the right method of scientific
inquiry is indisputably true. No one will maintain that facts
gathered in one way are on that account more valuable than
equally authenticated facts gathered in another way, or that it is a
rational proceeding to found untested judgments on fragmentary
evidence when completer evidence, by which the judgments may
be tested, is available — to use, for example, only data gathered by
one laboratory method (e.g. experiment) when relevant data
gathered by another laboratory method (e.g. biometry) or by
simple observation is at hand. It may be said that no one has
ever maintained that authentic and relevant facts should be
ignored or that hypotheses should be left untested. No one,
indeed, would venture to do so openly and formally. But theory
and practice are not identical, and such astonishing dicta as " The
day of vague and inaccurate thinking is past; we must, like physicists
and chemists, rely on experiment," " The problems of heredity
can only be solved in the laboratory and breeding-pen," are not un-
common, and have meant in practice, as we shall see in numerous
instances, nothing other than an ignoring of relevant data combined
with a neglect to test thinking. Untested hypotheses — hypotheses
which are merely founded on laboratory work, but are taken as
proved by it — are, in fact, exceedingly common in biology.3 At

1 See § 666. 2 See §§ 762 et seq.

3 See, for example, chapters iv. to x.

54 THE METHOD OF SCIENCE

present, however, I desire merely, but as strongly as possible, to
fix the reader's attention on the theory of scientific inquiry and
obtain his assent to it. He must bear in mind that the method
of work on which I insist is no new thing. It is the method
which has been proclaimed as the only right one by every
authority who has both thought about and expressed himself on
the subject ; it is the one which has been followed by every great
scientific worker ; it is the one by which the truth of every law of
nature known to us has been established. At the risk of tiresome
reiteration, this method of work may bejndicated as follows: —
When, as in the study of heredity and evolution, we wish to
establish the relations between facts that occur in sequences (i.e.
when we wish to discover chains of cause and effect), we must
formulate hypotheses. But hypotheses remain mere guesses until
they have been tested and found to be true. They can be tested
only by making deductive inferences of consequences from them
and then appealing to reality to ascertain if these consequences
actually follow. If a hypothesis enables us to predict correctly in
this way, it is in all probability true ; and it is the more certainly
true (and useful) in proportion to the number of different correct
predictions it enables us to make — in proportion as it accords
with the whole universe of relevant truth. Moreover, such deduc-
tive appeals to reality not only enable us to test hypotheses and
so convert them into laws, they not only enable us to bring within
the range of each real law masses of data which had not been
used for the corresponding hypothesis, but they enable us to
perceive the relations between the several laws, and so, by linking
the laws together, to advance towards that harmony of knowledge
which is one of the principal aims of science.

84. To return to the problem of recapitulation — the facts are
that the offspring of each successive generation resemble their
parents closely but not exactly, and that, apart from the differen-
tial play of stimuli, this imcomplete resemblance is due to a
recapitulation with variations of the parental development. The
induction is that the development of the individual is a recapitula-
tion, with additions and omissions, of the evolution of the race.1

1 The thinking here is somewhat complex, and complex thinking is often
denounced as ' deductive/ especially by medical writers. But when we bear in
mind that individual progression depends on a complete recapitulation (as regards
the parts under consideration) of the parental development plus an additional
step, and retrogression on an incomplete recapitulation, and that racial pro-
gressions and retrogressions are nothing other than the sums of progressions and
retrogressions made by individuals during the evolution of the race, the thinking

CAUSATION AND SIMPLE ENUMERATION 55

The deduced consequences are that developing individuals
>robably present traces of ancestral forms. The appeal to reality
the search for such traces. A successful appeal ends in the
liscovery of them and the proof of the induction. It is agreed on
11 hands that they do actually occur.

85. Hitherto, biologists have always founded the notion that
development is a recapitulation of evolution on the evidence
supplied by embryos. Adopting the method of ' induction from
simple enumeration,' they have concluded that the developing
young of living beings often resemble organisms lower in the
scale of life than the adult type, and thence have deduced the
irther conclusion that the resemblance is due to a descent from
>wer forms. That which, rightly used, should have furnished
>ts, has been made the material on which was built the hypothesis
h has remained, therefore, a much controverted working
lypothesis. I have endeavoured to establish it as a theory, an
ivariable law, founded on facts of causation and tested by an
ippeal to reality. " It cannot be too often repeated, that we ought
lever to depend on frequency of occurrance, wherever it is
>ossible to have recourse to facts of causation." 1 " The notion of
:ause " is " the root of the whole theory of Induction." 2 The facts,
ill of which are patent, and the reasoning, some of which is
leductive, are before the reader. If now, bearing in mind the
mdisputed truth that offspring recapitulate (with variations)
>arental development, he is able to conceive individual develop-
lent, as anything other than a recapitulation, however altered, of
ic life-history of the race, he is capable of an intellectual feat
rhich is quite certainly beyond my powers.

seen to be obviously inductive. To reach the notion that development is a
recapitulation of evolution we merely sum up the persistent variations of the
iccessive generations.

1 Fowler, Inductive Logic, pp. 270-1.

2 J. S. Mill, Logic, III. v. 2. If the reader disagrees with the notion that we
2ate better science when we link together our material by facts of causation

ran when we simply enumerate likenesses and differences, it would be well if
he now broke the continuity of this work and, before proceeding further, read
chapters xviii. and xxv. Meanwhile, I should be glad if he took this problem
of recapitulation as a test case and asked himself which is the better science,
the disputable and often disputed guess that is founded on a simple enumeration
of the likenesses between embryos and lower forms of life, or the indisputable
truth that is demonstrated when, starting with the familiar generalisation that
offspring recapitulate the parental development, we establish a chain of causation,
and so reach the necessary conclusion that the development of the individual is
a brief and inaccurate rttsumt of the" evolution of the race ?

CHAPTER IV
THE LAMARCKIAN DOCTRINE

Adaptation — The main problem of heredity — Theories of evolution — The
Lamarckian hypothesis — The Darwinian hypothesis — The incompatibility of
the two— Evidence against the former— The most decisive proof of all— Cor-
relation— Diseases — Maternal impressions — Telegony.

86. fT^O the student of heredity and evolution, who not only
gathers facts but strives to interpret them by ascertain-
ing their causal relations one to another, the cardinal
fact of life may be said to be the close adaptation of every species
to its environment, and the equally close co-adaptation of the
organs, tissues, cells, and functions of the normal individual to one
another. Thus the normal man, the normal ant, and the normal
oak are closely fitted during all stages of development to the con-
ditions of their surroundings, and could exist in no other. Within
plant and animal bodies, with rare and uncertain exceptions, every
structure and function, no matter how vast their multitude and com-
plexity nor how great the changes undergone during development,
works in exquisite co-adaptation with all its neighbours. Hardly one
of all these structures, whether useful in preserving the individual
life, or sexually ornamental and therefore useful in preserving the
species, whether functionally active or vestigial, but serves, or has
served, or will serve during the life of the individual the great
purpose of adaptation, the great purpose of enabling the individual
to survive and transmit his germ-plasm to offspring. Nearly one
and all, their existence has or had no significance other than
utility to the individual or to the race. So surely as we learn
much about a structure, almost so surely do we discover its function,
its utility in the past or the present of the race, or the past or
the present or the future of the individual. It is impossible to use
language too emphatic on the necessity to the student of heredity
and evolution of bearing constantly in mind this all-important
truth of adaptation. Its wonderful completeness has been denied,
but only, I think, when people, even scientific men, have founded
their thinking on exceptions instead of the rule, and even then

ADAPTATION 57

only when they have assumed that structures have no utility if
they have been unable to detect the utility. Such exceptions are
extremely rare in very well-known and understood types, and
correspondingly more frequent in plants and animals less familiar
to us. We may find them in plants, insects, and molluscs, but we
have only to devote a moment's thought to the closely co-
ordinated structures and functions of such a being as man to
perceive how very exceptional is the exception to the rule of
utility.1

87. Adaptation must be the anchor about which the student's
thoughts for ever swing, the touchstone by which he must test
every theory of racial change and individual variation. The
normal individual is a bundle of adaptations. His growth, his
development, is nothing other than a process of individual adapta-
tion. Evolution is nothing other than a process of racial
adaptation. A theory of evolution is, or should be, nothing more
than an attempt to explain, or, if we prefer, summarize in brief
terms the processes by which adaptation is achieved. A theory of
heredity seeks to account for likenesses and differences between
parents and offspring ; if it fails to be compatible with a theory of
evolution which correctly interprets the facts in terms of adapta-
tion, it is sure to be erroneous. Many theories of heredity and
evolution have gone, or are going to the limbo of discarded
hypotheses, merely because they do not accord with the truth that
species are closely adapted by all or nearly all their structures and
functions to the environment. The plain fact that living beings
are able to exist is proof of adaptation. Many students of heredity
and evolution, especially those belonging to the experimental
school, will think that I put the case too strongly, but I shall
justify every statement up to the hilt.

88. To be adapted to the environment in which he is produced,
the child must resemble the parent. The resemblance is due to
his recapitulation of the parental development. Presumably the
recapitulation occurs because the germ-plasm in the fertilized ovum
whence the child sprang resembled (because derived from) the
germ-plasm of the fertilized ovum whence the parent sprang —
because the two portions of germ-plasm had similar hereditary
tendencies which were awakened by stimuli similar in kind and
degree. Thus half the task of the student of heredity is easily
accomplished. He is able — in a way, superficial perhaps, but
valid as far as we know — to account for the resemblances. Of

* i See §§ 648-9.

58 THE LAMARCKIAN DOCTRINE

course, if we choose, we may seek to pry deeper and speculate
about the composition, the ' architecture/ of the germ-plasm, and
the hidden springs of its behaviour. But, in the almost total lack
of verifiable evidence, we should be reduced to mere valueless
guessing — valueless because incapable of being tested. We know,
however, that there must be a germ-plasm, a substance that is the
bearer of heredity, in the germ-cell, and that in the case of every
species of living beings it must possess definite hereditary
tendencies which differ from those of every other species, and we
have very strong reasons for supposing that it is derived by direct
and real descent from the germ-plasm of preceding germ-cells.
On these tolerably sure foundations we are able to build a very
great deal.

89. It is more difficult to account for the differences in detail
between parent and child than for the resemblances in mass.
Some of these differences are readily explained by the fact that
the stimuli under which parent and child develop are never exactly
similar. The nutriment, use, and injury which awakened the
hereditary tendencies of the parent are sure to have differed some-
what from those which awakened the tendencies of the child.
These account for the acquired differences. The real difficulty
arises when we seek to account for * variations,' for those innate
differences which are founded, not on differences in stimuli, but in
germ-plasms. We have to answer the question, " How does it
happen that the child ' varies ' from the parent ? " Or more
precisely, " How does it happen that the germ-plasm of the child
differs from that of the parent ? " If the problem is extremely
complex and difficult, it is also very important. Indeed it is
perhaps the main problem of heredity. If we solve it correctly,
we shall have discovered not only the correct interpretation of
many of the phenomena of heredity, but, since all racial change is
founded on the variations of individuals, of evolution also. In this
matter, just because the problem is so complex and difficult, we
must, linking together a number of principles reached by induction,
consider heredity and evolution together. Variations, taken by
themselves, are capable of a number of interpretations, any one ot
which, as far as we know, may, or may not, be correct ; taken in
conjunction with the facts of adaptation it becomes evident that
only one interpretation can possibly be true.

90. Before beginning our investigations we must make up our
minds to do some very careful thinking. I do not say this because
we are about to deal with exceptionally abstruse matters, nor

THE ORIGIN OF VARIATIONS 59

because I think the reader's task will be especially difficult, but
because we are now coming on very debatable ground where
hardly two scientific men think alike, and because this question of
the causation of variations lies at the very heart of our subject.
Unless we have clear ideas concerning it, we shall have misty ideas
concerning cognate subjects. Accordingly, as we form one or
other opinion, we shall take one or other of several widely
divergent views of heredity, of evolution, of all the problems of
life. We shall have to deal with large and complex bodies of
evidence, a thing which cannot be done without using correspond-
ingly complex processes of thought, though unfortunately attempts
to shirk the necessity have been common enough. I think we
have materials that are amply sufficient to enable us to come to a
definite conclusion. I believe also that the problem is still
regarded as debatable only because men, instead of considering
the whole mass of evidence and so testing their thinking, have
often founded their opinions on isolated bodies of facts. Often,
displaying a superstitious and pedantic reverence for facts collected
by this or that method of inquiry, they have ignored massive and
indisputable evidence, collected in other ways. A simplicity of
view has often been achieved in this manner, but at the expense
of breadth and depth of view, and, therefore, of correctness, clear-
ness, and comprehensiveness of perception. In other words, the
phenomena have not been viewed in their complete setting.

91. Species arose and were adapted to their environments
either by miracle or by natural processes. If by miracle, then
three methods of creation are conceivable, (i) All species, extinct
or persisting, may have been called into being simultaneously, or
nearly so, in full possession of the characters which they have ever
since possessed. If this, the popular hypothesis, be true, there can
have been no evolution, or very little, and, therefore, since untold
numbers of species still persist, the environments can have under-
gone no important alterations. The entirely conclusive evidence
furnished by geology proves, however, that both species and
environments have undergone vast though gradual changes. (2)
Unchanging species and varieties may have been created, not
simultaneously, but successively during a period which extended
over many millions of years, and in a way that exactly mimicked
evolution, and apparently was designed to delude us into a belief
in it. Probably hardly anyone, whether acquainted or not with
le facts, now accepts this solution, which logically should impel

to believe that our domesticated breeds of plants and animals

60 THE LAMARCKIAN DOCTRINE

are special creations. (3) There may have been evolution, but
evolution miraculously directed. This belief implies that species
changed in adaptation to a changing environment, not because the
environment, acting on them, caused the change, but because a
Power, in a sense outside the environment, moulded them into
adaptation to it without using it as an instrument. It is, however,
a rule, as good in science as in the ordinary affairs of life, not to
appeal to the supernaturnal until natural explanations have been
exhausted.

92. A variety of the belief in miracle has sometimes been
advocated by men of science — chiefly botanists. God and miracle
are not mentioned, but we are told that species are fitted to their
environments by means of an inherent adaptive growth-force ; that
is, we are asked to believe that offspring — not merely surviving
offspring, but offspring in general — tend to vary from their parents
in such a way as to be better fitted to the environment, and that
thus evolution results. If we examine the evidence on which the
supporters of this, the ' bathmic,' hypothesis rely, we find no very
strenuous attempt to distinguish between variations and modifica-
tions— between inherent alterations dependent on alterations in the
germ-plasm, and changes that result merely from a differential play
of stimuli. Many of the examples quoted by them appear to be
nothing other than what Mr A. Bacot has termed ' repertoire
patterns.' l Thus the plant Berberis vulgaris bears leaves in a
moist and spines in a dry atmosphere. Hippuris has two forms,
one terrestrial and the other aquatic, which may be converted, the
one into the other, by changing the environment, the leaves under
the water growing long and undulating, those in the air short and
erect. It has been assumed by the supporters of the bathmic
theory that all these differences are germinal — that the individual
that develops in the one way in the one situation, differs innately to
the extent of his differences from the individual that develops in
the other way in the other situation. But, as a fact, we have no
reason to suppose that they are other than acquired. They furnish,
however, very interesting evidence that nature may fit a species
for existence in two separate environments, in each of which it is
capable of flourishing, but in one of which, under one set of stimuli,
it develops characters different from those which it develops in the
other environment under another set of stimuli. Presumably, such
species have evolved under conditions which rendered this capacity
for alternative development useful because the one environment
1 Nature, Jan. 3oth, 1908, p. 294.

ADAPTIVE GROWTH-FORCE 61

was liable to be changed into the other. The evidence in favour
of the existence of an adaptive growth-force, then, is very equivocal.
On the other hand, if it be true, as massive evidence demonstrates,
that organs and structures undergo progressive evolution (i.e.
become larger and more complex) only when they are endowed
with a considerable degree of utility (i.e. selection value), and
retrogression only when they lack utility, the bathmic doctrine is
certainly untrue, and we are able to explain changes in structure
or function, or increase or decrease in them without mysticism.
Normal growth, after all, is only a form of adaptation ; it occurs
only when it fits the species more closely to the environment ; and
it is adaptation, not increase in size or complexity, that is the
main problem. We do not explain why a force is adaptive or
render it less mysterious by terming it an adaptive growth-force.
Moreover, the fact that breeders are able to modify plant and
animal types in innumerable directions is evidence of some value
that variations occur, not in one or two or a few directions, but all
round the specific mean like bullet-marks round a bull's-eye. We
shall see how strongly this latter hypothesis is confirmed by the
facts of human evolution against disease.

93. Rejecting miracle then, there remain only two scientific
hypotheses which are intelligible, at any rate at first sight— the
Lamarckian doctrine of adaptation through the transmitted effects
of use, disuse, and injury, and the Darwinian doctrine of natural
selection. Doubtless, in a way, the Lamarckian doctrine, curiously
combined with a belief in special creations, has been a part of
popular superstition since prehistoric times. Even now " the man
in the street " is firmly convinced that parental ' acquirements ' are
readily transmuted into ' inborn ' traits in the child. But Lamarck
first of all, or at least most consistently, gave scientific form to the
popular belief by allying it to a theory of evolution. His specula-
tions attracted little attention, even amongst students, till Darwin
and Wallace formulated their theory of Natural Selection. Subse-
quently, for a score or more of years, scientific thinkers, including
Darwin himself, believed that the organic world arose partly through
the * transmission ' of acquirements and partly through the natural
selection of favourable variations. During the last twenty years,
however, scientific opinion has veered to a conviction that Darwin
and Wallace, the most modest of men, worked better than they
supposed — or rather than Darwin supposed, for Wallace has long
and consistently repudiated the Lamarckian doctrine. It is now
generally believed that acquirements are never ' transmitted,' and,

62 THE LAMARCKIAN DOCTRINE

therefore, that evolution proceeds entirely on lines of natural
selection. This emended doctrine has received the name of
' Neo - Darwinian.' Often, however, it is termed simply the
'Darwinian,' though, as we see, Darwin did not hold it in its
entirety.

94. The question as to whether acquirements are, or are not,
transmitted has been the subject of probably the most lengthened
and ardently debated of biological controversies. Prolonged
investigation, in the course of which the plant and animal kingdoms
were ransacked, failed to reveal a single convincing and unmistak-
able instance of the transmission of an acquirement. But though
the Lamarckian doctrine is abandoned by the majority of serious
students, it is worth while to devote some space to it, partly because
it is still an article of popular belief, partly because the study of
it will enable us to contrast it with the Darwinian theory and
so achieve a better understanding of what is meant by Natural
Selection, and partly because we shall thus early have an oppor-
tunity to demonstrate the importance of testing every speculation
by a rigorous deductive appeal to reality.

95. The Lamarckian doctrine supposes that parental ' acquire-
ments ' tend to be ' inherited,' in however small a degree, by off-
spring. That is, it supposes that useful characters, which evolution
enables the parent to acquire as a response to use or injury, tend in
the child to betransmutedmto less adaptive characters, which develop
in response to the stimulus of nutriment. In the face of common
experience its scientific adherents did not maintain that the whole
of the parental acquirement was commonly ' inherited.' Thus, if
the tails of a pair of dogs were amputated, it was not thought
probable that the offspring would be born tailless, though it was
believed that this sometimes happened. It was thought merely
that some portion of the parent's loss tended to be ' inherited,' and
therefore, that if the mutilation were repeated during successive
generations, a race with diminished tails and ultimately a tailless
race would result. Again, it was not believed probable that, if a
man increased the size of his muscles by exercise, all of the increase
would be ' inherited,' but only some of it. In fact, it was main-
tained that acquirements were transmitted, as a rule, only ' faintly '
and ' fitfully.1 *

96. Obviously the Lamarckian hypothesis professes to be a
theory both of heredity and evolution, the latter being an induction
from the former. As a theory of heredity it seeks to account for

1 See Romanes, Darwin and after Darwin, vol. ii. p. 152.

THE TRANSMISSION OF ACQUIREMENTS 63

variations by supposing, in effect, that each parental acquirement
tends to alter the germ-plasm in such a particular and remarkable
manner that the 'acquirement' is reproduced by the child, in
whole or part, as an ' inborn ' trait. As a theory of racial change,
it supposes that progression is due mainly to use and to
such injuries and nutritive changes as result in increase of
size (or function), whereas retrogression is due principally to
disuse and to such injuries or nutritive changes as result in
decrease of size or function, for example from mutilations or
starvation.

97. Now, whether acquirements be, or be not, transmitted, we
know that children often vary from their parents (differ innately at
birth from what their parents were at birth) quite apart from such
'transmission.' Thus the child of normal parents may be born
with an extra digit, a character which is never acquired (i.e. de-
veloped) by the parent in response to the stimulus of injury or use.
The problem which we have to solve, then, is not whether the
Lamarckian theory of heredity correctly accounts for the occurrence
of all variations, but only whether it correctly accounts for the occur-
rence of any variations. Similarly many characters are present in
every species the evolution of which cannot conceivably have been
due to the ' transmitted ' effects of use, injury, or any other stimuli,
for example nearly all the characters of plants, and in animals,
such characters as brilliant colour markings, the external ears, the
reproductive organs, and feathers and hairs. It follows, therefore,
that while the Lamarckian doctrine may afford a partial explana-
tion of the occurrence of variations and of evolution, it cannot
afford a complete explanation.

98. The unicellular organism " is a part and usually a half of
the parent." Its structures, therefore, are derived from similar
structures in the parent; that is, there is real inheritance. The
multicellular organism, on the other hand, is derived from a single
cell, which, after dwelling as a parasite in the parent cell-community,
leaves its home to become the ancestor of a new community. The
parts of this new cell-community, therefore, are not derived from
similar parts of the parent ; that is, there is no real inheritance of
the characters of the first community by the second. The two
resemble one another for a totally different reason — because their
development has been directed by similar germ-plasms, the
hereditary tendencies of which have been awakened by similar
stimuli. It is evident, therefore, that the problem of the alleged
transmission of acquirements is not the same in both cases. Indeed,

64 THE LAMARCKIAN DOCTRINE

the question of the transmission of acquirements as presented by
multicellular organisms has no parallel, and can have none amongst
unicellular types. This distinction is clear to most students of
heredity, who, as a rule, maintain that parental acquirements may
be inherited by unicellular, but not by multicellular plants and
animals. Occasionally, however, some writers, chiefly medical men,
attempt to argue from the one question to the other ; but the
reasoning is obviously invalid. On the other hand, multicellular
organisms present a problem which, while totally distinct from the
question of the ' transmission ' of their acquirements, is a real
parallel, though seldom or never recognized as such, to the
problem of the 'transmission' of acquirements as presented by
unicellular types. We shall consider it in its proper place.1
At present we must confine ourselves to the much debated
* transmission,' which Lamarck maintained was the source of the
evolution of the higher organisms.

99. A cell-community, a multicellular plant or animal, is com-
pounded of germ-cells and somatic cells. The Lamarckian doctrine
supposes that when the somatic cells acquire characters under the
influence of use or injury, these acquirements so affect the germ-
plasm contained in the germ-cells that the cell-communities which
spring from them tend to reproduce the acquirements of the somatic
cells, not as ' acquirements,' not as direct effects of use or injury,
but as nutritional characters. Thus, when the muscle cells of a
man, for example, increase in number and power as a result of use,
the germ-cells dwelling within the cell-community are supposed to
be affected in such a remarkable and particular way that the
children which arise from the latter tend to develop larger and
more efficient muscles without the aid of use. Speaking meta-
phorically, the acquirements made by Brown and Jones (the somatic
cells) are supposed to so affect Robinson and White (the germ-
cells) that the descendants of the latter are characterized by traits
which look like those which Brown and Jones ' acquired,' but which,
since they are * inborn,' are really very different. Obviously this
power of transmuting acquirements — if it exists — is a very wonder-
ful thing, which must have arisen de novo amongst the higher types ;
for, as we have just seen, nothing like it occurs, or can occur,
amongst unicellular forms, which separate and do not form cell-
communities, and so cannot influence one another in this way. A
large and complex organism, such as man, may make a million
different acquirements, each of which is distinct from every other ;

1See§ 137.

H. SPENCER'S HYPOTHESIS 65

and therefore, if the Lamarckian hypothesis be true, are differently
recorded in the germ-cells.

100. How did this amazing power arise ? What is the
machinery for it? If we exclude miracle, the only conceivable
causal agent is Natural Selection — at any rate I can conceive no
other, and I do not believe the reader can. But Natural Selection
is concerned only in shaping adaptations. It must be shown,
therefore, that this power of transmuting acquirements is generally
useful to species ; for it is inconceivable that Natural Selection
would or could call into existence so wonderful and complex a
power if the result injured the race and stultified itself. Obviously
it must not be assumed, as is always done by the adherents of
Lamarck, that the existence of this power is ' natural ' and inevit-
able— so natural and inevitable that it is necessary rather to
disprove than to prove the actuality of the transmission.

101. It is argued sometimes that the multicellular individual is
not really multicellular ; but that protoplasmic bridges connect
the cells and convert the whole into a sort of gigantic unicellular
organism. Presumably, on similar grounds, we should regard
Siamese twins, not as two individuals, but as one. But, even if we
agree that the multicellular is really unicellular, the difficulties to
be surmounted by the Lamarckian theorist are not diminished. It
still remains true that the parts of the child are not derived from
similar parts of the parent, but, on the contrary, from a minute
portion of him (the germ-cell). We gain nothing by calling this
portion a portion instead of a separate cell ; for it is just as hard to
understand how this portion can be influenced with percision in
millions of definite different directions by changes occurring else-
where. Herbert Spencer sought to overcome the difficulty by
conceiving the living body as a kind of crystal, the nature of which
was liable to be so radically changed by the action of the environ-
ment that detached portions of it tended to assume the new, not
the old shape. A chip from a crystal, it is true, grows in a
suitable medium into the likeness of the parent crystal ; but there
the analogy ends. The crystal does not spontaneously emit
portions of itself that serve as starting-points for daughter crystals,
which vary from the parent. It is not heterogeneous in structure.
It is not a storehouse of active energy. It does not alter pro-
foundly and continuously in shape during growth as the embryo
does, nor with the seasons like plants or the stag when he sheds
his antlers, nor from moment to moment like a man when he moves.
It does not consist of a fluctuating stream of matter which enters

5

66 THE LAMARCKIAN DOCTRINE

as nourishment and is subsequently exchanged for other matter.
It is not a focus of chemical activity. It grows only on the surface.
In short, the analogy is strained and false.

1 02. The Darwinian hypothesis, at any rate as at first enunciated,
was not a theory of heredity, but only one of evolution. It did
not seek to account for variations, but took them for granted and
built on that foundation. Indeed, the only theory of heredity
formulated by Darwin, that of Pangenesis, was designed more to
satisfy the claims of the Lamarckian conception of evolution than
of the one which has received his name. We shall see, how-
ever, if we submit the theory of Natural Selection to a rigorous
deductive inference of consequences, and appeal to reality for
confirmation, that one particular theory of heredity, and that one
only, fits it, whereas all the others are incompatible with it.

103. The theory of Natural Selection is founded mainly on
two undisputed inductions and two deductions from them. The
inductions are (a) that offspring, while resembling parents on the
whole, always vary from them somewhat in every character,
being perhaps superior in some characters and inferior in others ;
and (ft) that in every species the number of individuals that come
into being exceeds, sometimes very greatly, the number of those
who survive and have offspring. The deductions are (a) that, as
a general rule, the individuals selected by nature for survival are,
on the whole, better adapted to the environment than those
selected for elimination ; and (b) that in this way the ' specific
mean,' the racial average, is raised, and consequently evolution
results. Unlike the doctrine of the transmission of acquirements,
the theory of Natural Selection, as held by its modern followers,
really aspires to account for all adaptations.

104. The main contrast between the Lamarckian and the
Darwinian hypotheses arises from the fact that the former
attributes progressive evolution to influences that act beneficially
on the individual, whereas the latter attributes it to influences
that kill or weaken, and so on the average prevent the un-
fittest, the most affected, from having offspring, or at any rate
their full quota of offspring. Until very recently all students of
heredity were zoologists or botanists, or men who drew their facts
from materials collected by them. Even now it is difficult to per
suade such workers that useful evidence may be drawn from oth
sources. When, therefore, they thought of elimination, their mindsj
turned naturally to quick or sudden death, the only forms o
elimination familiar to us in wild nature. They conceived thelj

LAMARCKIAN AND DARWINIAN DOCTRINES 67

animal as growing strong and active through contending with
rivals, escaping from enemies, or pursuing prey ; or else as perishing
in the fullness of his vigour. They imagined the plant as over-
whelmed by the storm, or as emerging more hardy and firmly
rooted from the struggle. In brief they conceived the same agent
as eliminating the weak and as strengthening the strong. They
had no difficulty, therefore, in believing that a hypothesis which
attributed evolution to the transmission of acquirements was com-
patible with one which attributed it to the survival of the fittest-
They had thought of no facts by which they could test this
opinion. Consequently for many years scientific men were
adherents of both doctrines, as a few still are.

105. But agencies which, while strengthening the survivors,
destroy the weak by violent deaths, are not the only causes of
elimination. Some agencies, for example many human diseases,
both destroy the weak and weaken the strong. Apparently they
are never other than harmful, at any rate they are never beneficial.
Almost every individual of many human races is exposed to one
or more agencies of this sort. If, then, the Lamarckian doctrine is
true, such agencies should be causes of continuous racial deteriora-
tion. On the other hand, if that doctrine is false and the Dar-
winian doctrine true, if the acquirements of the parent end with
the parent and are not inherited by the child, then such agencies
should, through the raising of the racial average in every generation
by the survival of the fittest, be causes of protective evolution.
Here the two theories are in conflict ; we see plainly that they
are incompatible ; if the one gives a true account of racial
change, the other does not ; for it is impossible that a race can
both deteriorate and improve in the same characters at the
same time. Therefore we are able to test them by means of
crucial instances; that is, we are able to appeal to reality for
guidance. The fact that every race (e.g. English and Negro)
that has been exposed to any disease (e.g. tuberculosis or malaria)
has undergone no discoverable deterioration, but has become
resistant to the disease, has evolved against it, precisely in pro-
portion to the length and severity of its past affliction, is decisive
evidence against the Lamarckian and in favour of the Darwinian
doctrine.

106. It is true that some human diseases (e.g. measles) leave
the individual who recovers from them with an increased power of
resisting subsequent attacks, and that generations that have
suffered from these maladies are on that account proportionately

68 THE LAMARCKIAN DOCTRINE

resistant. But it can be shown that the resisting power which the
individual develops is radically different in kind from that which
the race evolves.1 The latter power, therefore, cannot have arisen
through the inheritance of acquirements. In any case, the fact
remains that many diseases and other conditions (e.g. tuberculosis,
slum-life, and alcoholism), which confer increased resisting power
on the race, not only confer none on the individual, but actually
tend to destroy any that he may possess.2 Here the race evolves
in a direction precisely contrary to the direction taken by the
acquirements of the individual.

107. Another point of contrast, important but seldom noted,
between the two hypotheses, is the differing complexity of the
racial change which would necessarily result on the one hand
from natural selection, and on the other from the transmission of
acquirements.

108. The natural inference from the theory of Selection, the
theory which attributes the evolution of a character, not to the
amount of use to which it is subjected but to its utility (selection
value), is that progressive evolution proceeds on lines of comparative
simplicity. We have abundant evidence that structures that do
not assist appreciably in the preservation of life or in the struggle
for offspring, for example the wings of a species of bird to which
flight has become useless, or the special features of our prize breeds
of plants and animals, tend to deteriorate when no longer selected.
It is a reasonable inference, therefore, that a certain stringency of
selection is necessary for progression, that a lower degree of
stringency suffices for the maintenance of a structure, and that a
still lower degree of stringency, or, even more, complete cessation
of selection, is followed by retrogression. These inferences are
borne out by what we observe in nature. For instance, as we
shall see later, the human race is undergoing progression in a few ,
particulars.3 The mass of human characters, however, are
stationary or nearly so. They were evolved during different but
overlapping periods of a long-extended past, and their progression
ceased when further increase was not of utility. No matter how
much used or useful, they are merely maintained at a certain
standard of efficiency. Thus apparently the human hand, heart,
lungs, liver, and many other characters have changed little, if atj
all, during thousands of years. Lastly, many human structures,!
having quite lost utility, have become vestigial, presumably through j
cessation of selection. The germ-plasm has so altered that they!

i See § 432. 2 See § 435. 3 See chapter xiii.

THE INUTILITY OF TRANSMISSION 69

cannot now develop in the individual under any form of stimulus —
neither under nutriment, nor use, nor injury.

109. On the other hand, were the Lamarckian doctrine true,
every structure which was much used (e.g. the lower limbs of man,
and, in particular, the joints) would increase in size proportionately
to the amount of use — with results disastrous to the co-adaption
of structures ; every structure which was little used (e.g. organs
of generation), or was not ' used ' (e.g. hair, bones of skull), or was
disused, would degenerate, and structures which were much exposed
to injury (e.g. wings of butterflies) would tend to deteriorate.
Evolution and degeneration would thus proceed on lines as
complex as the individual and with extraordinary results. Here,
then, again, if acquirements were transmissible, since species
would be affected as wholes, since almost every individual would
alter in the same direction, natural selection would have no scope.
The species would drift helplessly out of harmony with the
environment. In point of fact, therefore, the Lamarckian
hypotheses of heredity and evolution, when closely examined (i.e.
when we make rigorous deductive inferences of consequences),
are found not to be theories of adaptation at all ; and they are
always, not merely sometimes, incompatible with the Darwinian
hypothesis.

no. It is obvious at a glance, that, if actual injuries and
growths (e.g. scars), which arose in response to injuries, were trans-
muted into characters which arose inevitably (because developed
under the stimulus of nutriment), in the absence of injury the result
would be, not adjustive, but distinctly harmful. Similarly, char-
acters which develop under the stimulus of use are particularly
useful when so developed. They possess a quality of usefulness
which is lacking in those developed under the stimulus of
nutriment — a kind of unconscious" intelligence, as it were, which,
within the limits of possible development, enables the individual
to grow just the right characters to just the right extent. Thus
the muscles of the athlete, whose need is greater, are larger and
more efficient than those of the ordinary man ; but they diminish
when he goes out of training. The arms of the sailor tend to
develop more in proportion than his legs, whereas the reverse is
the case with the soldier. The heart and [kidneys develop beyond
the ordinary in disease when life depends on a response to an
increased strain thrown on them. The skin thickens and hardens
when and where such changes are useful. When the need is over,
all use-developments tend to disappear, and the organism is

70 THE LAMARCKIAN DOCTRINE

relieved of unnecessary burdens. The capacity to develop under
the stimulus of use, therefore, renders the individual more adapt-
able than he would otherwise be. In fact, he is doubly adapted
to the environment : first by the evolution of his race, which fits
him to the environment common to all the members of his
species, and second by peculiarities in his own development, which
arise under the stimulus of use and injury and fit him to his own
special surroundings.1

in. Yet another quality of special usefulness is conferred by
the capacity to develop under the strain of use. The only organ-
isms which possess this power to any considerable extent are the
more complex animals. Thus, a man is compounded of thousands
of structures, all of which must be closely co-adapted, or the
individual as a whole lacks efficiency. The greater the complexity,
the more necessary but difficult is nature's task of maintaining
co-adaptation. By the evolution of the power of growing under
the strain of use the difficulty is in great measure surmounted, for
each structure thus endowed develops in proportion to the strain
placed on it. The size and strength of the human heart, for
example, is, in general terms, always in proportion to the needs ot
the individual, be he healthy or diseased, big or small — especially
in early life, when the power of developing under the strain is
greatest. On the other hand, the magnitude of such structures as
the teeth, the ears, the nose, the hair, and the reproductive organs, j
all of which are wholly 'inborn,' is often comparatively dispro-
portionate as compared with associated parts.2

112. It follows that if a character which developed in the j

I

1 See chapter xxi.

2 Much has been written on the ' correlation ' of parts and qualities. The word |
has been used to describe at least three distinct classes of phenomena. First, there
is the infrequently observed but much discussed tendency of parts, which have
apparently no close functional connection, to vary together in a non-adaptive j
way — in a way that has not resulted directly from evolution, but is seemingly a
kind of by-product of it. Thus " white cats which have blue eyes are almost
always deaf" (Darwin, Animals and Plants, vol. ii. p. 322) ; "multiplicity of
horns in sheep is generally accompanied by great length and coarseness of the j
fleece" (Youatt on Sheep, pp. 142-69, quoted by Darwin). "White terriers
suffer most from distemper, white chickens from a parasitic worm in their trachea, .
white pigs from scorching in the sun, and white cattle from flies " (Vernon, !
Variations in Plants and Animals, p. 85). A normal individual (e.g. man) is ait
bundle of adaptations. He consists of a thousand or ten thousand parts, each :|
of which is co-adapted, not merely to a single other, but to many others, and must ij
have been so co-adapted during all the shifts and changes of evolution. It is
difficult to understand how this perpetual co-adaptation in all directions can have j
been secured unless each part has been independently variable. Only so can
the species have been sufficiently ductile to the action of Natural Selection. We j

THE ;UTILITY OF USE- ACQUIREMENTS 71

parent under the stimulus of use were ' inherited ' by the child
(i.e. were developed in the latter under the stimulus of nutriment),
a great part of its utility would be lost, for the character would
then develop, not in proportion to the needs of the individual, but,
within limits, in proportion to the supply of nutriment. The
alleged power of transferring characters due to injury and use from
their own category to another, therefore, is clearly not an adapta-
tion. If it exists at all it must have been evolved, not through
Natural Selection, but through miracle — through a miracle which
was designed, not to benefit but to injure the species.

113. Formerly, as noted already, the magnitude of the use-
acquirements made by the higher animals was not realized by
biologists. Indeed it is very seldom realized even now. The
study of them is still the most neglected department of biology.
In fact only exceptional acquirements were and are regarded as
acquirements. Ordinary acquirements, those made by every
normal individual who reaches maturity, were thought to be inborn
traits. For instance, the truth that almost the whole growth of the
infant's limbs after birth is due to use was undreamed of. This
failure to realize the magnitude and importance of the use-acquire-
ments has led to a failure to note the evolution of the c inborn '
power of making them. The use-acquirement was regarded, not as
an adaptation, a product of evolution, but as a kind of. accident
which might befall any structure, and which, being transmitted,
might result in the evolution of inborn characters. Its magnitude
was tacitly assumed to be so small that the great part it plays in
co-adapting, in correlating, the parts of the individual, and otherwise
fitting him to the environment was not thought of. On the other
hand it was believed that the transmission of use-acquirements

are compelled to assume, therefore, in accordance with the facts as far as observed,
at this non-adaptive kind of correlation is very rare — rare, that is, as compared
the total number of the characters of the normal individual. Second, there is
at kind of correlation which results directly from Natural Selection, and which
ures the proportionate development of those characters which develop under
e stimulus of nutrition. For example, a large infant has usually, not only a large
y, but, correlated with it, proportionately large limbs and head. Third,
ere is that kind of correlation which results from the proportionate development
associated structures under the strain of use. Since this kind of. correlation
superimposed on and perfects the correlation of parts which have developed
under the stimulus of nutrition, it is usually the closest of all. Thus the correlation
in size between the muscles of the human adult arm is obviously closer than that
between ear and head. Correlation in the second and third instances is only
another name for co-adaptation, and evidence is hardly needed to establish
the fact that living beings tend to have their parts so adjusted as to render them
capable of existence.

72 THE LAMARCKIAN DOCTRINE

did much in the course of generations to bring about co-adaptation
and correlation. Thus Herbert Spencer maintained that without
the transmission of use-acquirements the evolution of the higher
animals would have been impossible. He instanced the weighty
horns of the elk, pointing out that their usefulness to the individual
depended on the co-adaptation of a thousand parts in head, neck,
trunk, and limbs, and insisted that, since it is unlikely that all of
them can ever have varied favourably together in any individual
and practically impossible that they can have so varied in a
succession of individuals, their co-adaptation was explainable only
on the hypothesis that acquirements tend to become inborn.
Obviously, his reasoning was founded, first on a belief that all
characters grow under the stimulus of use, and second on an
insufficient appreciation of the magnitude of use-acquirements,
which, as in other cases, brought about co-adaptation between the
horns of the elk and the structures associated with them.

1 14. More recently some biologists, more particularly Professors
Lloyd Morgan, Osborn, and Mark Baldwin, while admitting that
use-acquirements are, in all probability, not transmissible, have
argued that their presence, by acting as a screen behind which
progression could occur, may conduce indirectly to evolution of a
kind which closely mimics that which would result from the inherit-
ance of them. Thus suppose drowning were a stringent selective
cause of human elimination, then those individuals who learned
to swim quickest and best would survive in the greatest numbers.
If any of their offspring varied in such a way that they were able,
in some measure, to swim ' naturally ' (i.e. without learning), they
would be at an advantage, and would survive in larger numbers
than contemporaries who had more to learn. In this way a human
race that, like many lower animals, could swim instinctively, would
ultimately be established. In other words, without any inheritance
of acquirements, characters, which in the ancestors developed
under the influence of use, would in the descendants develop
under the influence of nutriment. But the evidence that this view,
which has not been tested by an appeal to reality, though the test is
possible, is mistaken is overwhelming. Characters developed under
the influence of use are, as we see, very much more adaptive than
those developed under the stimulus of nutriment. Therefore,
though there is unlimited evidence of the former replacing the
latter, there is none to the contrary. Thus the helplessness, the
immaturity of the human being, before he has made his use-
acquirements, demonstrates to what an extent the power of

THE STRONGEST EVIDENCE OF ALL 73

developing under the influence of nutriment has been displaced in
him by that of developing under the stimulus of use. For example,
the ability to run and swim instinctively is so general amongst the
lower mammalia that there can be little doubt that the ancestors
of man formerly possessed, but subsequently lost, this power.1

115. Here, indeed, we have the strongest evidence of all against
the Lamarckian hypothesis. When we find it impossible to
formulate a probable hypothesis as to how acquirements can be
transmuted into inborn characters, or to conceive by what process,
short of miracle, the power of thus transmuting them can have
been evolved, it becomes necessary to ask for very strong and
unequivocal evidence of the alleged transmutation. When we
ascertain by a rigorous deductive inference of consequences that
the hypothesis is apparently incompatible with the fact that life
exists and is adapted to its surroundings, our reasons for rejecting
it are greatly strengthened. The only doubt that remains is as to
whether, in spite of all our testing, we have reasoned correctly.
But when we find that the whole course of evolution has been such
that, so far from ' inborn ' characters tending to replace ' acquire-
ments,' the reverse has constantly happened[; when we find that the
human being, for example, has lost so much that was inborn in his
remote ancestors, that he has become incapable of reaching
maturity except under the stimulus of use, all doubt vanishes.
The appeal to reality then furnishes decisive proof. Having
regard to the facts, a supposition directly contrary to the
Lamarckian hypothesis (viz., a supposition that inborn characters
tend to be transmuted into acquirements) may perhaps be main-
tained with some appearance of probability. But a supposition
that acquirements tend to be transmuted into innate characters is
very obviously in conflict with what has occurred in nature.2

116. Though the Lamarckian doctrine is abandoned by nearly

1 See § 673.

2 Most biologists, I think, reject, or rather believe that they reject, the
Lamarckian doctrine on grounds furnished by experiment. I have heard (so
very odd, occasionally, are the notions of scientific men concerning science) all
other evidence and reasoning, all attempts to establish a chain of causation and
make biology, like physics and mathematics, a deductive science, denounced as
' weak.' But it appears to me that the experimental evidence is strongly in favour
of the, at any rate, ' faint and fitful ' transmission of acquirements, a transmission
which, if sufficiently general, would inevitably lead to racial change. We cannot
disprove a statement that an event sometimes happens by proving that some-
times it does not happen. One positive example outweighs a hundred negative
instances, and Brown Sequard, Romanes, and numbers of other observers have
recorded, or thought they recorded, many. To this day French observers,
especially French medical men, frequently announce such experiments as the

74 THE LAMARCKIAN DOCTRINE

all students of heredity and evolution, a belief in it still lingers
among a section of medical men — mainly because the distinction
between ' innate ' and ' acquired ' characters is not drawn by
them with sufficient clearness.1 Gout, haemophilia, syphilis,
mutilations, maternal impressions, and telegony are cases in point.
Gout is an acquirement, an injury which often results from dietetic
errors. It occurs most commonly amongst people who have
exceptional opportunities to eat and drink to excess. Some
people are innately more liable to contract it than others— just as
they may be innately taller, or darker, or different in any other
way. Their germ-plasm is such that they develop the disease
more readily under the fit stimuli. There is even such a thing as
" poor man's gout." Their children tend, of course, to reproduce
the parental peculiarity when placed, as they usually are, under
similar conditions. All this, however, affords no support to
the contention that parental excess, or parental gout resulting
from excess, increases the liability of offspring to the disease.
The well-to-do offspring of poor Irish peasants have been found

excision of the stomachs of dogs, and declare that the stomachs of the offspring
are, on the average, smaller than the normal. Really, I suppose most biologists
think these observers mistaken, because, consciously or unconsciously, they have
become convinced, actually on deductive grounds, that it is impossible and in-
credible that acquirements can be transmitted. Some distinguished supporters
of the Lamarckian hypothesis still exist, however (see, for example, Mr Francis
Darwin's Presidential Address to the British Association, 1908 ; Professor G.
Henslow's book, The Heredity of Acquired Characters in Plants, and Professor
Marcus Hartog's and Dr Mercier's articles in the Contemporary Review, September,
November, and December 1908). They argue very rightly from the experimental
evidence, insist even more rightly that the fact that we are unable to conceive
how acquirements can be transmitted is not proof that they are not transmitted,
and declare finally that they must be transmitted because (according to them) it is
impossible to conceive how plants and animals have evolved into adaptation
to their surroundings without such transmission. I have tried in vain, however,
(see, for example, the Contemporary Review, October 1908) to persuade them to
realize that it is not the transmission of acquirements, but the transmutation of
useful into less useful or actually injurious characters that is really the subject
of discussion, or to persuade them to consider the truth that, while nature furnishes
no clear evidence that inborn traits have replaced acquirements, she furnishes
evidence, perfectly clear and immensely massive, that the contrary has happened
on an enormous scale.

1 " In much of the evidence on causation terms were used without fixed meaning,
in different senses by different witnesses, or in more than one sense by a single
witness. This confusion has been no less noticeable in the medical than in the
general evidence given on the important question of ' Heredity/ both before the
Commission and at other inquiries of a cognate kind ; and it seems to us to be
desirable that this subject, which forms an important part of physiology, should
be more specially emphasized than it now is in the medical curriculum." (Report
of the Royal Commission on the Care and Control ofthe Feeble-Minded, 1908, p. 180.)

THE MEDICAL EVIDENCE

75

to be, on the average, as liable to gout as the scions of the
aristocracy.

117. In haemophilia the blood lacks coagulating power ; there-
fore the flow from a wound in a ' bleeder/ as a sufferer from the
disease is colloquially termed, is difficult to staunch. The
condition is always an innate, a nutritional character, and, as
such, is reproduced by offspring. Often, however, it is spoken of
as ' acquired ' by the parent, and inherited by the child.

1 1 8. On the other hand, syphilis is due to a microbe that
multiplies in the body, and may pass from the parent to the germ-
cell, embryo, or fcetus, precisely as it may pass to an adult
individual. It is no more inherited than a bullet which pierces
a mother and enters her foetus. The microbe elaborates a poison,
a 'toxin,' which likewise passes into the child with the nutrient
fluids, and so may injure it. This injury also is never inherited ;
it is always an acquirement.1

1 19. Medical men see innumerable mutilations. Sometimes —
very rarely indeed — a child is born with a deformity which bears
some resemblance to the parental mutilation. Thereupon the
inheritance of the latter is alleged, the possibility of coincidence
being ignored. The evidence is of the same nature and not
intrinsically superior to that which causes some people to believe
in prophetic dreams.

1 20. Deformities, mutilations, and the like are so common
as to be observed frequently by every one. If a pregnant woman
observes one, and bears a normal child, no notice is taken of the
fact ; but if the child is deformed she is apt to attribute the
misfortune to a maternal impression. Medical men have thought
it worth while to collect and publish many instances of such
happenings. But " Dr William Hunter, in the last century, told
my father that during many years every woman in a large lying-in
hospital was asked before her confinement whether anything had
especially affected her mind, and the answer was written down ;
and it so happened that in no instance could a coincidence be
detected between the woman's answer and any abnormal structure ;
but when she knew the nature of the structure she frequently
suggested a fresh cause."2

121. Telegony is the term applied to the alleged influence of a
previous sire. Thus if a woman bears two children, the first to a

1 For a more detailed discussion of the evidence furnished by syphilis, see
§§ 416-8.

2 Darwin, Animals and Plants, vol. ii. pp. 252-3.

76 THE LAMARCKIAN DOCTRINE

dark and the second to a fair husband, then, if the latter child
happens to be darker than its father, she is apt to attribute the
variation to the influence of her first husband. Though still widely
credited by animal breeders, telegony has been disproved experi-
mentally, at any rate as far as negative evidence can disprove
anything, by Professor Cossar Ewart.1

122. Both maternal impressions and telegony are interesting,
chiefly as indications of the curious looseness of thought and
expression which occasionally prevails in biological discussion.
They were often quoted in support of the Lamarckian doctrine ;
but, plainly, they have no bearing on it In neither case is it
alleged that the mother transmits her acquirement to offspring.
In the one case she receives a mental impression, but the child is
supposed to develop something entirely different, a physical
abnormality. In the other she receives a physical impression, and
the child is said to develop a physical character, but not the
character the mother acquired. Thus a negress who has borne
a child to a white man, and who subsequently bears an ex-
ceptionally fair child to a negro, has not herself become fair. In
brief, the alleged phenomena do not belong to the category of trans-
mitted acquirements. They are marvels even more marvellous.

123. As long as we think superficially the Lamarckian hypo-
thesis presents an appearance of fascinating simplicity and obvious-
ness. Since the multicellular organism is a ' unit ' for most purposes
of life, it is natural to regard it as a unit from the standpoint of
heredity — to think of it as if it were unicellular, to suppose in
effect that the parts of the child are derived from similar parts of
the parent, and, therefore, that when a character is acquired by the
parent, the same character reappears in, is inherited by, the child.
If, in addition, we fail to observe that the complex higher
animals fit their environments mainly because they grow into
adaptation to them through the development of use-acquirements,
it is possible to use this very fact of adaptation in an argument
intended to demonstrate the inadequacy of Natural Selection as a
cause of evolution. But when we delve beneath the surface and
think with precision in terms of the germ-plasm instead of vaguely
in terms of the individual, the simplicity and obviousness vanish,
and the doctrine becomes almost unthinkable. We see that it
depends on a number of assumptions which, to say the least, are
wildly improbable. Manifestly, when an acquirement is said to be
transmitted, no real inheritance can occur ; for a character that is

1 See The Penycuik Experiments (London : Adam and Chas. Black, 1899).

SUMMARY

77

developed by the parent under the influence of use or injury is
profoundly different from one which is developed by the child
under the stimulus of nutriment. The doctrine assumes that all
structures in all living beings are capable of growth under the
stimulus of use, and that the amount of this growth is compara-
tively trivial ; whereas the truth is that only some structures in
some living beings can grow in this way, and in some types the
amount of growth so made is by far the major part of the total
normally achieved. It pretends to account for adaptive variations,
but in almost every instance a character transferred from the
category of those produced by use or injury to that of those
produced under the stimulus of nutriment would become less
adaptive, and often positively harmful. It professes to account for
evolution, but, were it true, every species would drift swiftly out
of harmony with the surroundings, and therefore to destruction.
Except miracle, we can conceive no means through which the
power of transferring characters from one category to another can
have originated. Lastly, there is massive evidence not only that
have inborn traits not replaced acquirements, but that the contrary
has happened.

124. The Lamarckian hypothesis is dead as an accepted inter-
pretation of the facts. Probably none of the younger students of
heredity accept, or will ever again accept it. Indeed, so far as I
am able to judge, nobody, even if he happens to be a professional
biologist, now holds it unless he is unaware of, or ignores much
that has been published of recent years on the subject. At
any rate, while such arguments as those which were used, for
example, by Spencer about the horns of the elk are still advanced,
the reasoning which has demonstrated their invalidity is invariably
ignored.

CHAPTER V
VARIABILITY

Variations as distinguished from modifications — Spontaneous variations as
distinguished from those due to the direct action of the environment — Evidence
of the existence of the latter — Discussion of the evidence — Variability in uni-
cellular and multicellular organisms. — The insusceptibility of the germ-plasm
to direct action of the environment — The fallacies of experimental evidence —
Variation in new environments — Nearly all variations are spontaneous — The cause
of spontaneous variations — The three fundamental laws of heredity.

w:

125. "^H 7"E dismiss, then, the Lamarckian doctrine. The only
intelligible theory of evolution remaining is that
of Natural Selection. Our task, then, is to ascer-
tain^ on the one hand, whether this doctrine accords with all the
facts of adaptation — is contradicted by none — and, on the other
hand, to discover the theory of heredity which accords with it.
Since we are able to account for innate likenesses between parents
and offspring,1 we have, in effect, to study the origin of innate
differences, of variations.

126. The reader may be reminded that a variation — in the
sense in which we use the word, which is that of common scientific
usage — is a difference between parents and offspring, due to a differ-
ence in germ-plasms. It is not a 'modification,' a difference
caused by an unequal play of stimuli on parent and child. While
biologists still believed in the transmission of acquirements, the
term 'variation' was used to indicate any difference, whether
germinal or due to an unequal play of stimuli. But, when the
Lamarckian theory was being discarded, and the importance of
distinguishing between the two kinds of differences was realized,
a tendency to limit the term to differences founded on changes in
the germ-plasm became general. Even now, however, the word is
sometimes given unlike meanings by various writers. Thus some
authors, still using it in its old sense, distinguish by means of an
adjective between " blastogenetic, genetic, or germinal variations "
(i.e. variations properly so called) and "somatogenic variations"
(i.e. modifications). Others imply that any change in the child

1 See § 88.
T8

VARIATIONS AND MODIFICATIONS 79

which arises from a change in the germ-cell is a variation. But it
is conceivable, indeed, as we shall see, it is certain, that the germ-
cell may be affected (e.g. by nutrient fluids or by poisons), and the
child which springs from it altered, while the hereditary poten-
tialities of the gzrm-plasm, which passes on to the descendants,
remain unchanged.1 In such cases the alteration in the child is
just as much a 'modification,' and just as little transmissible, as if
the agency which produced it had acted, not on the germ-cell, but on
its cell-descendants — that is on the tissues of the child. Evidently,
then, if we accept the modern meaning, and the word variation is
to have a signification sufficiently clear and precise to make it
valuable in science, it should be limited to those changes in the
germ-plasm which mark real alterations of the hereditary ten-
dencies ; thus it should not be applied to those temporary alterations
in the well-being of the germ-plasm which result from changes in
nutriment or from the presence of toxins and the like — alterations
which may result in modifications in the child that springs from
the germ-cell in which they have occurred, but are not reproduced
by the descendants. It is in this precise sense we shall use the word.
127. Either variations are 'spontaneous' or else they result
from changes in the hereditary tendencies due to the direct action
of the environment on the germ-plasm. By the term spontaneous,
it is not intended to imply that variations ever arise without
antecedent cause, but merely that the cause or causes of them are
inherent in the germ-plasm itself. Thus, if the germ-plasm gained
or lost qualities as a consequence of the normal nuclear activity,
growth, and change which precede cell-multiplication, or if, owing
to inherent causes, the division of it between the daughter-cells
were qualitatively inexact, the variations thus resulting would be
spontaneous. Again, when offspring have two parents, a father
and a mother,2 the variations from one, or other, or both parents
that may result from that mingling of germ-plasms which occurs
in the conjunction of sperm and ovum, are to be reckoned as
spontaneous, for they do not arise from the action of the environ-
ment external to the germ-plasm. By variations which result from
the action of the environment are meant those variations which
arise through the direct and immediate action of its surroundings
on the germ-plasm. In multicellular organisms, especially warm-
blooded organisms, the cells of the soma and the substances (food,
toxins, etc.) contained in the nutrient fluids constitute the main
effective part of the environment of the germ-cell and its contained

1 See §§ 132 and 136. 2 Some offspring have only one parent, see § 233.

8o VARIABILITY

plasm. I use the words ' direct ' and ' immediate ' because it is
conceivable that spontaneous variations are due indirectly and
remotely to the action of the environment, which, through Natural
Selection in the past, may have so dealt with the germ-plasm of
the species as to create a tendency to spontaneous variability.1

128. Normal offspring resemble their parents on the whok
but differ from them in detail. We have to decide whether these
variations in details are spontaneous or caused by the direct influence
of the environment ', or, if by both, in what proportion, as a general
rule, the two kinds of variations occur. Now the offspring of
the same parents always vary, not only from both the parents,
but among themselves. Thus even ' identical ' twins are never
absolutely alike, and the members of a litter of dogs, pigs, or
kittens often differ greatly in size, shape, colour, strength, activity,
mental disposition, length and texture of hair, and every other
character. These differences cannot be due to the direct action
of the environment, for the germ-cells, embryos, and foetuses
existed from first to last under conditions that were practically
identical. They must, therefore, be spontaneous. At any rate, I,
for one, cannot believe that such small differences of environment
as may have existed before birth can result in one puppy being
big and black and another small and brown, in one being rough
and the other smooth-haired, or in one resembling the father,
another the mother, and a third a remote ancestor, and so on.
Moreover, it has been observed that, when the parents are the
same, differences between members of the same litter are just as
great as those between members of successive litters. It follows,
then, that some variations at least are spontaneous, and our
task in the present chapter is to ascertain, not whether ALL variations
are due to the direct action of the environment, but whether AN}
variations are due to it.

129. With the intention of proving that variations are due to
the direct action of the environment a vast amount of evidence has
been accumulated by biologists. A little of it is fairly conclusive,
much is inconclusive, and much has no bearing on the point
at issue.

130. Zymotic diseases — malaria, tuberculosis, typhoid, dysentery,
cholera, diphtheria, and the like — are produced by different species
of unicellular organisms. Bacteriologists are able to increase or
decrease the virulence of many diseases by altering artificially the
environment of the microbes. Thus small-pox, when removed to

1 See § 163.

THE BIOLOGICAL EVIDENCE 81

the calf, becomes cow-pox ; returned to man, it is that very different
and much milder complaint, vaccinia. Rabies, passed through a
succession of monkeys, grows milder in type for man ; passed
through dogs, more virulent ; through rabbits, still more virulent.
When diseases are passed from one species of animal to another,
they are generally comparatively mild for the second species at
first, but tend to become more virulent to it the longer they afflict
it, till a maximum of virulence is reached. Therefore animals that
are affected by microbes that have inhabited their own, or a nearly
allied species, usually suffer more severely than when the microbes
are derived from a more alien source. The organisms of diphtheria
and tuberculosis may be gradually ' attenuated ' by cultivation in
artificial media, those of anthrax quite quickly by heat. Many
more instances of the same nature have been recorded.

131. Medical men have published voluminous statistics proving
that diseased and intemperate people often have children degene-
rate or defective physically or mentally, and that slum-bred
children are, on the average, inferior in physique to the offspring
of rural folk ; and they have assumed that these filial defects are
innate and due to the parental ill-health.

132. In his Presidential Address to the Zoological Section of
the British Association,1 Professor J. Cossar Ewart maintained
that " there is a considerable amount of evidence in support of the
view that changes in any part of the body or soma which affect the
general welfare influence the germ-cells."

" It may first be asked," he added, " Does disease, in as far as it
reduces the general vigour or interferes with the nutrition of the
germ-cells, act as a cause of variation ? I recently received a
number of blue-rock pigeons from India infected with a blood
parasite (H alter idium), not unlike the organism now so generally
associated with malaria. In some pigeons the parasites were very
few in number, in others they were extremely numerous. The
eggs of a pair of these Indian birds with numerous parasites in the
blood proved infertile. Eggs of a hen-bird with numerous parasites
fertilized by a male with few parasites proved fertile, but the young
died before ready to leave the nest. An old Indian bird, however,
with comparatively few parasites, mated with a half-bred English
turbit, produced a single bird. The half-bred turbit has reddish
wings and shoulders, but is otherwise white. The young bird by
the Indian blue-rock is of a reddish colour all over, but in make
not unlike the cross-bred turbit hen.

1 See Nature, 'vol. Jxiv., 1901.

82 VARIABILITY

"Some time before the second pair of eggs was laid, the
parasites had completely disappeared from the Indian bird, and
he looked as if he had quite recovered from his long journey as
well as from the fever. In due time a pair of young were hatched
from the second eggs, and as they approached maturity it became
more and more evident that they would eventually present all the
distinctive points of the wild rock-pigeon. The striking difference
between the first birds of the second nest might, however, be due,
not to the malaria parasities, but to the change of habitat.

"Against this view, however, is the fact that another
Indian bird, infected to about the same extent as the mate of the
half-bred turbit, counted for little when mated with a second half-
bred turbit ; while two Indian birds in which extremely few
parasites were found at once produced blue-rock-like birds when
bred — one with a fantail and the other with a tumbler.

"Another possible explanation of the difference between
the bird of the first and the birds of the second nest is that the
germ-cells were for a time infected by the minute protozoon
Halteridium in very much the same way as the germ- cells of
ticks are infected by the parasite of Texas fever. But of this
there is no evidence, for even in the half-grown birds hatched by
the pure-bred malarious Indian rocks the most careful examination
failed to detect any parasites in the blood. In all probability
Halteridium can only be conveyed from one pigeon to another by
Culex or some other gnat.

" These results from pigeons suffering from malaria seem
to indicate that the germ-cells are liable to be influenced by
fevers and other forms of disease that for the time being diminish
the vitality of the parents. Further experiments may show that
the germ-cells are influenced in different ways by different
diseases.

" Sometimes the germ-cells suffer from the direct action ot
their immediate environment, from disturbance in or around the
germ glands. If, for example, inflammation by the ducts or other
channels reaches the germ-glands, the vitality of the germ-cells
may be considerably diminished ; if serious or prolonged, the
germ-cells may be as effectively sterilized as are the bacteria of
milk by boiling."

133. Obviously Professor Ewart assumes that if offspring alter
in consequence of an alteration in the germ-^//, the change is
necessarily a variation. His experiments on fertilization are
interesting. He found " that when a well-matured rabbit doe is

THE BIOLOGICAL EVIDENCE 83

prematurely (i.e. some time before ovulation is due) fertilized by a
buck of different strain, the young take after the sire ; when the
fertilization takes place at the usual time, some of the young
resemble the buck, some the doe, while some present new
characters, or reproduce, more or less accurately, one or more of
the ancestors. When, however, the mating is delayed about thirty
hours beyond the normal time, all the young, as a rule, resemble
the doe. It may be inferred that in mammals, as in echinoderms,
the characters of the offspring are related to the conditions of the
germ-cells at the moment of conjugation, the offspring resulting
from the union of equally ripe germ-cells differing from the offspring
developed from the conjugation of ripe and unripe germ-cells, and
still more from the union of over-ripe germ cells." 1

134. A species of butterfly is bright coloured in Germany, but
of a darker hue in Italy. Weismann reared the Italian variety in
a low and the German in a high temperature. The former became
lighter, but not so light as the German variety ; the latter became
darker, but not so dark as the Italian type. Like Professor Ewart,
he does not appear to have ascertained whether the alterations
were reproduced by subsequent generations.2 Hoffman sowed wild
plants very thickly in pots. After several generations they
produced double flowers never observed before. Pictet altered
the colour of butterflies by transferring the caterpillars from the
normal food plant to another. He found that each kind of abnormal
food impressed characteristic effects on offspring. These effects
persisted and increased for some generations, but eventually the
race became adapted to the new food, and thereupon returned to
the primitive type.3 " Dr Bachman states that he has seen turkeys
raised from the eggs of the wild species lose their metallic tints and
become spotted with white in the third generation." 4 Mr Hewitt
" found he could not breed wild ducks true for more than five or six
generations, as they proved so much less beautiful. The white
colour round the neck of the mallard became broader and more
irregular, and white feathers appeared in the ducklings' wings."5
Metzger cultivated in Europe a tall variety of maize brought from the
warmer parts of America. " During the first year the parents
were twelve feet high, and a few seeds were perfected ; ... in the
second generation the plants were from nine to ten feet in height
and ripened their seeds better. . . . Some of the seeds had even

1 Loc. cit., p. 482. 2 The Germ-plasm, p. 389.

3 L' Influence de V Alimentation et de I'Humidite sur la Variation des Papillons.

4 Animals and Plants, vol. ii. p. 250. 5 Op. cit.y vol. i. p. 340.

84 VARIABILITY

become yellow, and in their now rounded form they approached
the common Europeon maize. In the third generation nearly all
resemblance to the original and very distinct American parent was
lost. In the sixth generation the maize perfectly resembled a
European variety." 1 " Clayton allowed six bean plants to grow in a
spot where they would catch all the sunshine of the day, while six
other similar plants were protected by a boarding which effectually
screened off the sun. When freshly gathered in October, the
weight of the beans and the pods of the exposed plants was to that
of the protected as 99 : 29, whilst the weight of the day beans was
as 16 : 5. The next year the weight of the fresh beans and pods
obtained from the sunshine-grown seeds of the previous year,
was half as much again as in the case of the plants from shade-
grown seeds, in spite of the fact that all of the plants were now
grown in sunshine and under precisely similar conditions. In
the fourth year plants with an exclusively shady ancestry pro-
duced flowers but failed to mature fruit."2 European dogs are
said to deteriorate steadily in India, and English horses in the
Falklands.

135. It is unnecessary to multiply examples. Obviously some
of this evidence is capable of an interpretation different from that
given by its observers. For example, the medical statistics are
wholly inconclusive. Not only diseased and intemperate, but
healthy and temperate people have defective offspring; whereas
diseased and intemperate people often have normal children. It
has not been shown that the proportion of defective offspring is
greater in the one case than in the other.3 Even if that were done
it would still have to be shown that the parents were not themselves
defective before they became drunken or diseased; for it is
roundly asserted that people naturally (i.e. innately) defective,
mentally or physically, are especially prone to intemperance and
disease, and, of course, the offspring of such people tend, in any
case, to inherit their defects.4 Next it would have to be proved
that the defects of the children were true variations, true alterations
of the hereditary tendencies reproducible by descendants, not
merely modifications caused by temporary injury (due to the health
or habits of the parents) to the germ-cell, embryo, or foetus. In the
case of slum-bred children, also, it has not been shown that the

1 op. dt., vol. i. p. 340.

2 Vernon, Variations in Animals and Plants, p. 247. 3 See §§ 776-7.

4 See, for example, Branthwaite, The British Journal of Inebriety, January
1908.

THE BIOLOGICAL EVIDENCE 85

defects are innate — that the defects would not develop equally in
country children were they transferred early in life to the slums.1
At present the reader may be inclined to regard these criticisms as
frivolous and overstrained, but he will find later there is ample
warrant for them.

136. Much the same objections may be taken to Professor
Ewart's inferences. Evidently his birds acquired the disease in
their native habitat, and, since so many or all of them had the
malady, it is doubtless very prevalent there. Evidently, again,
since the disease resembles malaria, since it travelled from India
in the birds, and since so many birds were suffering from it, it is
a malady of long duration. If, then, it is a cause of sterility, we
are left to wonder how, under the conditions, the race has persisted
in India. But granting that it is a cause of sterility, it does not
follow that it is a cause of variations. As a fact Ewart's experi-
ments prove only that, like other cells, the germs, and even the
germ-plasm may be enfeebled by toxins ; they do not prove
that the hereditary tendencies are thereby altered. His deduction
might have been, but was not, tested by showing that the so-
called variations were transmissible to descendants. Ewart himself
supplies clear evidence that the germ-plasm was not altered, for
one of his Indian birds, which, when diseased, had offspring
resembling the English parent, after recovery had offspring
resembling itself. Evidently the germ-plasm that remained in
this bird was capable of recovering from its enfeeblement, and
we have no reason to suppose that the germ-plasm which passed
from him and entered a healthy female body was less capable of
recovery. It certainly fertilized the ovum, and the fact that the
offspring resembled the English parent is no proof that succeeding
generations would not have reproduced the Indian characters.
Professor Ewart has, indeed, furnished warrant for believing that
the condition of the germ-plasm at the time of conjugation deter-
mines to some extent the characters of the offspring, but no warrant
for supposing it fixes the characters of subsequent descendants.
All that is demonstrated is that enfeeblement of germ-plasm may
render latent for a generation the characters of the parent whence
it is derived. The force of this objection is even better seen in
the experiments by which he influenced the characters of rabbits.
In fact, his observations seem rather to elucidate the conditions
under which latency occurs than the conditions under which
variations arise. It has long been known that sexual characters

1 See §§ 732-5.

86 VARIABILITY

are transmissible in a state of latency through parents of the
opposite sex,1 and the Mendelian experiments demonstrate that
latency occurs in characters other than the sexual.2

137. The bacteriological evidence is important and deserves
to be considered at length. Every unicellular organism is a germ-
cell, just as every germ-cell is in effect a unicellular organism.
In the last analysis, therefore, the problems of heredity presented
by them are similar. In other words, if we think in terms of the
germ-plasm, not in terms of the cell-community, the problems of
heredity presented by unicellular organisms and germ-cells are
similar. We noted that the question as to whether the acquire-
ments of unicellular organisms are, or are not, inheritable is totally
distinct from the problem of the transmission of acquirements
amongst unicellular types.3 Its real counterpart amongst the
problems of multicellular life is the question whether or not
changes caused in the germ-cells by the direct action of their
environments are inherited by descendant germ-cells. Obviously
this is a very different problem from the question whether the
particular changes caused by the environment in the somatic cells
are inherited by the descendants of the germ-cells, whether
the acquirements of Brown and Jones are inherited by the
descendants of Robinson and White. Now unquestionably a
unicellular organism or a germ-cell may be injured or benefited
by its environment. The problem we have to solve, then, is
whether such changes tend to be inherited by the descendant cells.
In other words we have to discover whether they necessarily
or usually imply alterations (i.e. variations) in the germ-plasm.

138. Of all unicellular organisms the disease-producing (patho-
genic) microbes have been most closely studied, and of all their
characters their powers of offence and defence have claimed the
most attention. When they enter a living body, a man for
instance, a struggle ensues between them and the cells of the
host. They, or at least some species of them, secrete toxins,
soluble poisons which defend them from the cells, which in turn
secrete substances (enzemes) poisonous to the microbes.4 If only
a few microbes enter the body they are destroyed. Thus it has
been found experimentally that if less than sixteen thousand
virulent anthrax bacilli be introduced into a normal young rabbit,
they all perish. A greater number multiply and cause disease
in a suspectible individual, presumably because they so poison
the cells of the body that the latter are unable to poison them.

1 See §238. 2 See §§ 273 et seq. 3 See §§ 98 and 431. J See §413.

THE BACTERIOLOGICAL EVIDENCE 87

If recovery occurs, the cells of the body gradually become accus-
tomed to the toxins, which are digested by them.1 They obtain
the upper hand ; the individual acquires immunity ; the microbes
are destroyed ; and, as a consequence, the sufferer is no longer
infective to his fellows.

139. A human race undergoes evolution against such a disease
as measles or diphtheria when it becomes more resistant. It
becomes more resistant when successive generations become,
through Natural Selection, more capable of reacting to the toxins
and so 'acquiring' immunity. The germ -plasm becomes such
that under the stimulus of nutriment individuals develop, who, if
they experience the disease, are able to develop further and
' acquire ' actual immunity. Therefore, while the power of acquir-
ing immunity is an 'inborn' character, the immunity itself is a
' use-acquirement.' That is to say, the individual who acquires
immunity becomes used\& the disease (develops under its stimulus),
just as the muscles of the athlete become used to endure fatigue,
or the skin of the palm to endure rough labour. The process of
evolution is a long and a slow one, extending over many genera-
tions. The final effect, as we see, is not the creation of a race
the individuals of which resist infection (i.e. are innately immune),
but the creation of a race the individuals of which tend to recover
from infection (i.e. acquire immunity). This is not true of all
diseases, but it is true of the majority.2 We shall study the subject
at length in a subsequent chapter. Meanwhile the points on which
I wish to lay stress are (i) that human races become adapted
through Natural Selection to the presence of diseases, and (2) that
in the case of many diseases this adaptation consists in a swift
reaction to infection — a reaction so swift that the cells of an affected
individual begin to produce their enzymes as soon (within a few
minutes) as the microbes make their presence felt. This produc-
tion of enzymes is a step on the road to immunity — but only a
step, for after the enzymes disappear more or less completely from
the body, the immunity remains. Here we have an instance of
the high organism making a pre-eminently advantageous use-
acquirement in spite of the fact that its cells are continually bathed
in and injured by the toxins.

140. By skilful management it is possible to alter artificially
the characters of unicellular species. Thus certain saprophytic
organisms (which normally obtain their nutriment from dead
organic matter) may, under favourable conditions, be gradually

1 See §§ 410 et seq. 2 See chapter xiii.

88 VARIABILITY

' trained ' to attack living beings ; that is, they may be trained to
produce toxins so protective to themselves, and, therefore, so
injurious to the cells of the host, that they are able to live and
multiply in the dangerous environment till the host dies or acquires
immunity. This training, this conversion of a saprophytic into a
parasitic type, always involves placing the microbes in contact
with living cells. For example, streptococci, which are normally
saprophytic, may be rendered very virulent (i.e. capable of main-
taining existence in living tissues) by passage through a series of
animal hosts, but cannot otherwise be rendered virulent. On the
other hand, purely parasitic organisms may be trained to sapro-
phytic habits of life. If placed in a suitable non-living medium (e.g.
broth) where they are no longer persecuted by the cells, they slowly
lose their toxins, and, while becoming more capable of existing in
that particular medium, become less capable of maintaining them-
selves in the living body. In either case the change, since it
increases in successive generations till fitness to the new environ-
ment is achieved, is both germinal and adaptive. So close is the
adjustment to the environment that, usually, each microbic disease
is limited to a single species of animal. Thus most human diseases
are peculiar to man. When more than one species is attacked by
the same disease, as is often brought about experimentally, the
microbes tend to separate into varieties or races, each of which is
most virulent (i.e. best adapted to, best protected in) the species it
has made its host. Each parasitic species has its peculiar toxin,
a means of defence which is always the same for the same species,
but which differs from that of every other species, as may be judged
from the symptoms of the maladies they produce. Thus, strep-
tococci always produce the same symptoms, the same toxins, when
they become parasitic. The existence of the toxin, a very complex
chemical substance, implies a remarkable producing apparatus.
The evolution from saprophyte to parasite is mainly the evolution
of this apparatus. Unless we assume that the microbes of disease,
highly specialized organisms, were miraculously created to afflict
the higher species, we must assume that they were all evolved from
saprophytic types.

141. Now we reach the problem as to the mode by which
saprophytic species become parasitic. It is probable that
all unicellular species, even the saprophytes, have some sort of
toxins by means of which they dissolve and digest their food or
protect themselves from other unicellular organisms, and which,
like the saliva of snakes, is capable of undergoing evolution till it

THE BACTERIOLOGICAL EVIDENCE 89

becomes poisonous to other forms of life.1 Saprophytes cannot,
under normal circumstances, contend against the living cells of
multicellular types ; but that the toxins are strong in at least
some of their species is proved by the fact that the organisms, for
example, which cause putrefaction in dead bodies may, under
favourable conditions, infect and by poisoning destroy men and
other animals.2 Unicellular organisms multiply very quickly, as
may be judged by the rapidity with which an epidemic of infectious
disease may sweep a large and populous country. Many genera-
tions elapse, therefore, even under the most favourable experimental
conditions, before a saprophytic species becomes truly parasitic.
Now, in this passage from an environment to which they are
adapted to another which at first is very unfavourable, do the
microbes make useful ' acquirements ' which are ' transmitted ' and
accumulated in descendants ? Or do they alter through the Natural
Selection of favourable spontaneous variations ? The former is the
accepted hypothesis. Indeed, bacteriologists do not seem aware
that there is an alternative. Reasoning from the analogy of
the human being, they suppose, in effect, that microbes are able
to make advantageous acquirements under the stimulus of use, and,
further, that, being unicellular, they are capable of transmitting
these acquirements to offspring, so that the latter start develop-
ment where the parents finished.

142. But it is necessary to exercise a little scientific imagination.
The power of making use-acquirements is apparently a late product
of evolution, limited to the higher species, in which alone it is per-
ceptible. At any rate we have no right to assume thus easily that
lowly microbes possess it. Moreover, since the microbes of disease
begin by multiplying and flourishing greatly in an infected person,
manifestly they have at first much the best of the struggle, and
would keep it did they grow stronger under the stimulus of use.
Indeed, it is evident that, if microbes not only made use-acquire-
ments but transmitted them, then, since their multiplication is so
rapid, their virulence would soon become so exalted that the

1 The evolution of a toxin implies the power, not only of producing it, but
of resisting it. Thus the cells of the poison gland of the snake are immune to
the venom, the cells of the alimentary canal are resistant to the digestive ferments,
the body-cells to the poisons which destroy the microbes. So, also, the microbes
are resistant to their own toxins.

2 It is said that the carnivora are particularly immune to septicaemia. If
this is true, it is an interesting example of special evolution. Owing to the
nature of their food and the wounds they are apt to receive in pursuit of it,
carnivora are particularly exposed to infection.

90 VARIABILITY

higher species, which can make but cannot transmit acquirements,
could not contend against them and would soon become extinct.
Again, the human being is capable of making only such use-
acquirements as evolution has fitted his race to develop. The
microbes, while they are becoming parasitic, are in an entirely new
and unfavourable environment, in which they are exposed to poison-
ing and enfeeblement through the enzymes secreted by the cells
of the host. Evolution has not adapted them to make the right
acquirements, any more than it has adapted human beings to make
acquirements fitting them for flight or for life under water.
Under the conditions, what sort of acquirements could they make
which would enable them to produce stronger and stronger and,
therefore, different toxins, and so protect themselves from the cells ?

143. It is conceivable that the toxins might in some way be
enfeebled by injury to the producing apparatus and that this injury
might be transmitted and so accumulated in subsequent genera-
tions till the microbes perished ; but to believe that they are ever
strengthened, that the producing apparatus of the individual is
improved by the accidental effects resulting from the direct action
of the environment, is to believe in a coincidence, a 'fluke' so
remarkable that it amounts to miracle — a miracle that must have
happened to every species of pathogenic microbe during its
transition from saprophyte to parasite, and which the human
operator is able to initiate at will by placing saprophytic species
in contact with living cells, a miracle as marvellous as if chance
blows of a hammer on pieces of metal had produced and fitted
together a delicate and elaborate machine.

144. In brief, if saprophytic microbes, while becoming parasites,
are in any way affected by their new environments — and doubtless
they are affected — then, since they neither cause the extinction of
the species they attack nor themselves become extinct, it is certain
that their acquirements are not transmitted. The notion that,
like the higher animals, they are able to make use-acquirements,
is a mere guess, unsupported by any evidence, but opposed by
much. Even were the guess correct, then, since the higher or-
ganisms do not make acquirements which evolution has not fitted
them to develop, it is hard to understand how unicellular organisms
could react in a way that enabled them to meet contingencies
never before experienced by the race. The analogy between them
and the higher animals, therefore, is strained and inaccurate at all
points.

145. Consider, now, the contrary hypothesis, that saprophytic

THE BACTERIOLOGICAL EVIDENCE 91

species become adapted to a parasitic existence through the Natural
Selection of spontaneous variations. Doubtless unicellular organ-
isms, like the higher types, vary spontaneously. If that be admitted,
then, presumably, in the struggle with the cells, the microbes with
the weaker defensive powers, the weaker toxins, or the weaker
powers of producing toxins under unfavourable conditions, tend to
perish, while those with the stronger powers tend to survive. In
that case evolution must follow till the saprophytic race becomes
adapted to a parasitic habit of life, after which it would be maintained
in adaptation by the same process of selection. The facts that
microbic species evolve virulence only when in a position to be
selected by living cells, that this virulence and their other germinal
changes adapt them precisely to the particular species of animal
they attack, and that they tend invariably to lose the adaptation
(i.e. undergo retrogression) when no longer in a position to be so
selected, that these changes in both directions are continuous and
so gradual that many generations must come and go before they
are completed, and that they proceed no further than enables the
species to persist in the new environment, are so highly significant
that we have no alternative but to attribute them, like the adaptive
changes of the higher species, to selection on the one hand or
cessation of it on the other. They are too adaptive to be due to
any other cause. They fit the many and diverse species of uni-
cellular parasites too closely to their environments to be results of
mere coincidence, of mere accidental effects, produced by the
direct action of the environment.

146. The belief that the increasing virulence of saprophytic
organisms, when they are becoming parasitic, results from the
direct action of the environment on their germ-plasm, is one of those
'obvious' inferences which, when all the evidence is taken into
account, are found to rest on a series of impossible assumptions.
Here, as always when considering any complex and difficult
problem, we cannot link together all the evidence unless we make
a rigorous deductive inference of consequences and follow it by an
appeal to reality. The generalization that microbic species change
adaptively when placed under right conditions in changed environ-
ments is really ' obvious ' ; it is an ' immediate ' inference. The
generalization that they change because their germ-plasm is directly
affected by the environment is not really obvious, and must be
tested. When the test is made, when we do not shirk the hard
thinking necessary, it is seen to be obviously inaccurate.

147. Selection affords an explanation of the adaptive changes

92 VARIABILITY

of microbic species at once probable and in accord with all we
know of nature. Studying these changes, it becomes evident that
Natural Selection is operative only under certain conditions. The
germ - plasm must be variable ; but it must be spontaneously
variable, not variable under the direct action of the environment.
Spontaneous variations, occurring all round the specific mean,
afford materials for Natural Selection and tend to enable the species
to meet all contingencies. But variations caused by the direct
action of the environment have an opposite effect. Under condi-
tions nearly the same for all the individuals exposed to them, they
cannot occur all round the specific mean, but in one general
direction only. Therefore they cause a drift, which may or may
not be adaptive, but which, since a new environment is usually
unfavourable and therefore injurious, can be adaptive only as a
most unlikely coincidence. Even if such a drift were favourable
at first, the accumulation, the exaggeration of it during succeeding
generations would be sure ultimately to ruin the co-adaption of
parts and functions and so render it unfavourable ; for there is no
imaginable reason to suppose that if such a drift occurred in
ancestors it would not continue in descendants. Virulence is not
the only adaptation found in the microbe. The whole organism
is compounded of adaptations, every one of which is co-adapted to
all the others. Except by the theory of evolution through Natural
Selection it is as hard to account for any of them as it is to account
for virulence. As we see, Natural Selection cannot control a drift
in which every individual participates. Only in one way can it
be prevented — by the germ-plasm becoming highly insusceptible,
highly resistant to the direct action of the environment. We are
driven^ then, to the conclusion that the germ-plasm is both spon-
taneously variable and highly resistant to the direct action of the
environment. In other words, we must believe that in any species
that is not undergoing extinction, spontaneous variations greatly
preponderate over those which are caused by the direct action of
the environment.

148. The evidence is conclusive that the germ-plasm of all
persistent species possesses a high power of resisting enforced
change. For example, some — probably all — human diseases are of
great antiquity. Descriptions of them written two or three
thousands of years ago are accurate for the present day. During
all that time, though exposed to enzymes and other potent
influences, the microbes, minute atoms of naked protoplasm,
have not altered appreciably. Fitted closely to a stable environ-

THE INSUSCEPTIBILITY OF THE GERM-PLASM 93

ment, the human being, they have been stable. They have not
drifted.

149. There is nothing especially magical or mysterious about
this germinal power of resisting enforced change. There is
abundant evidence that it exists. If it did not exist no species
could persist. But, when we say that it exists, we do not imply
that the germ-plasm is incapable of being injured, incapable of
enfeeblement, or death, or alteration of its hereditary tendencies.
We imply merely that such enforced alteration of the germ-plasm
of a species that has been fitted by evolution to its environment is
usually an injury, and that the evidence is that when the injury is
severe enough to cause alteration of the hereditary tendencies, it is
usually severe enough to cause the death of the germ-plasm also.
In other words, we imply that the hereditary tendencies are
implanted in the germ-plasm as firmly, or almost as firmly as
life itself. Indeed collectively they are the life ; because of them
the individual (and the germ-plasm) absorbs nutriment, excretes
waste-material, grows, multiplies, and so forth.

150. The power to resist enforced change is essential to
existence. Presumably, therefore, it is, like other essential
characters, a product of evolution. It is, at least, probable that
just as individual unicellular organisms vary as regards other
particulars, so they vary as regards the power of their germ-plasms
to resist enforced change. If this power be weak the germ-plasm
tends to be destroyed or altered by the influences to which it is
inevitably exposed. The descendants of the altered individuals, if
there be any, inheriting the weak resisting power, tend to be still
more changed and ultimately to be eliminated. But, if the
resisting power be great, and if individuals vary as regards it,
while at the same time spontaneous variations occur in all
directions, the race tends to survive ; for in that case there is no
inevitable drift ; natural selection has scope, and the resisting
power tends to grow stronger with selection. The conclusion we
reach, then, is that Natural Selection has established and maintains
the high insusceptibility of the germ-plasm to the direct action of
the environment.1

151. Turn, now, to multicellular animals and plants. Not only

1 Interesting evidence of the stability of the germ-plasm of unicellular organ-
isms is furnished by Dr Pearl in his study of Paramoscium caudatum. These
organisms multiply for many generations without conjugation. But at intervals
conjugant individuals appear. " Dr Pearl grew Pa ramoscia under much variety
of environment, and found that the non-conjugant type was highly correlated
with the environment and the conjugant type singularly little affected by the

94 VARIABILITY

the germ-cell but every cell of the community is a unicellular
organism. We may take the human being, as the type best known
to us, for an example. Consider first his somatic cells. From the
moment the fertilized ovum begins to proliferate to the death of
the aged man, strong influences — want, plenty, disease, health,
hardship, alcohol, and so forth — play upon the cells ; yet each cell
comes true to its type. Thus all sorts of stimulants and irritants
may act on the skin-cells and change them greatly ; but, when the
cause of change is removed, the hereditary tendencies are found to
be unaltered, for the young cells develop into skin-cells of quite
the old kind. I have transferred clippings from an old man's skin
to the scalded and denuded arm of a young woman, and they have
grown with all the vigour of youth. If a lymphatic gland be
diseased (e.g. tuberculous) for a score of years, and recovery then
occurs, the cells are still typical of their kind. Disease enfeebles
cells, but recovery from disease is evidence of the stability of their
hereditary tendencies. Were the latter easily altered, there could be
no recovery, and every attack of measles or chicken-pox, maladies
in which toxins are abundant and in which the enfeeblement of
the cells is shown by the disturbance of function, would be fatal.
Consider the cells which line the alimentary canal and the extra-
ordinary variety of influences to which they are subjected. Life
could not exist if the germ-plasm (idio-plasm) were not resistant.
Evidently, then, as a condition essential to the survival of the
individual and the persistence of the species, somatic cells hold
their hereditary tendencies with extraordinary tenacity — with a
tenacity as great as that displayed by the microbes of disease.

152. Further and very decisive evidence is afforded by the
extreme stability of plants when propagated by slips and suckers.
Centuries may elapse, the plant, continuously so propagated, may

environment. The whole inquiry was, of course, undertaken to illustrate
Weismann's position, that while acquired characters are not inherited, the en-
vironment can influence inheritance when one cell is both soma and germ. In
biology it has become almost axiomatic to assume that the Protozoa can inherit
acquired characters owing to this identity, while in the Metazoa the acquired
character of the soma is at the very least not usually inherited. Dr Pearl brings
out the all -important point that the gamete in Paramoecium is not, like the non-
conjugant cell, markedly influenced by the environment" (Professor Karl
Pearson, Nature, Oct. 18, 1906, p. 609). Mr H. S. Jennings has also published
observations on Paramoecium. He says nothing concerning conjugant indi-
viduals, terms all new characters variations, and concludes, " In order that it
may be inherited (by more than one of the progeny), a characteristic must be the
result of such a modification of the mother cell as will cause it to behave in a
certain way at reproduction." Apparently he means that spontaneous variations
tend to be transmitted, but not acquirements.

THE STABILITY OF THE GERM-PLASM 95

be grown in all the quarters of the globe, yet usually no appreci-
able change is observable. Even when a change is seen it is
generally a mere ' modification,' for the plant, if restored to its
ancestral environment, resumes the original form. ' Bud variations '
occur, it is true, but they are comparatively very few, and we have
little reason to believe that they are due to the direct action of the
environment Thus, when a nectarine appears on a peach tree,
it is more likely that the change in the branch that bore it was
spontaneous than that it was caused by direct action ; for the
latter would imply that the environment of that one branch differed
amazingly from the environments of the other branches.

153. The germ-plasm of the microbe is very complex ; but more
complex to an almost infinite degree is the germ-plasm of such a
being as man. The descendant cells of the fertilized ovum are not
mere copies of that ancestor, but members of a vast community in
which there is great diversity of form and function, and in which
every cell takes its appointed place and does its predestined work.
Presumably the orderly complexity of the body, with its immense
ramifications of large and small blood-vessels, lymphatics and
nerves, its organized groups of muscle, blood, gland, and nerve
cells, its skin, bone, and cartilage, indicates a corresponding
complexity of the germ-plasm. Yet, though this germ-plasm is
constantly exposed to all sorts of potent influences (e.g. toxins), and
has been so exposed for thousands of generations, so great is its
stability that all this great complex and even many developmental
processes which date back to millions of years before the evolution
of the vertebrate type are reproduced with unfailing accuracy by
every normal individual. Quite apart from the fact that Natural
Selection would have no scope if the hereditary tendencies drifted
this way or that at the mercy of the environment, it is evident that
no complex type could maintain the regular development and the
co-adaptation of its parts, unless the germ-plasm were endowed
with very great resisting power.

1 54. Amongst multicellular organisms selection occurs in every
stage of development, amongst germ-cells and embryos as amongst
adults. Germ-cells, like unicellular organisms, are fitted to their
environments by characters which depend on the hereditary
tendencies carried by the germ-plasm. As is proved by the
variations of the individuals that develop from them, they vary
amongst themselves. They are in competition with one another,
some being better adapted for survival and the successful perform-
ance of their functions than their fellows ; some having more and

96 VARIABILITY

some less resistant germ-plasm. Granting that species have arisen
through Natural Selection, then the hereditary potentialities which
enable the germ-cells to develop into higher individuals (embryos
and adults) are of course due to selection occurring amongst the
latter ; but the characters that fit them to their own environments,
for example the locomotory tail of the spermatozoon, are equally of
course due to selection occurring amongst themselves. The selection
that maintains the stability of the germ-plasm, therefore, falls first
of all on the germs which cannot survive as cells if the germ-plasm
is much altered, or develop into higher organisms if it is more than
a little altered. Evolution is never perfect ; it is probable, therefore,
that many, perhaps very many, germs vary unfavourably in this
particular and perish, and that to this circumstance is due the fact
that evidence of germinal alteration resulting from the direct action
of the environment is rarely found amongst adult individuals.

155. Germ-cells are very numerous amongst the higher animals,
though the number of possible offspring is small. Thus, the germ-
cells of such an organism as man exceed a million-fold the number
of his children. This superabundance, like all other characters of
the species, is, presumably, an adaptation. According to accepted
doctrine it serves to ensure fertilization. But nature is very
parsimonious of her materials, and when we remember the per-
fection of her adaptations (e.g. the eye, the ear, or the digestive
organs), the device of providing a vast multitude of cells in order
to secure the fertilization of a very few seems so unnecessarily
wasteful and clumsy as to awaken a suspicion of the correctness
of the interpretation. Such a device may be necessary when the
germ-cells are scattered broadcast in the environment and meet
by chance, as in the case of some plants, but hardly when they
enter a special receptacle in the body of the female. It seems not
improbable, therefore, that the function of the apparent super-
abundance is to provide materials for a selection which serves,
above all, to maintain the resisting power of the germ-plasm. At
any rate material in which such a selection can occur is provided
as abundantly by the higher animals as by the lower.

156. Leaving aside the question as to how precisely the high
insusceptibility of the germ-plasm has been evolved, there can,
as I say, be no doubt of its existence. But though the germ-plasm
possesses high powers of resisting enforced change, though death
usually accompanies such change, it does not follow that con-
ditions cannot be found in which the germ-plasm is altered
and yet not destroyed. Thus, Clayton's beans progressively

THE DIRECT ACTION OF THE ENVIRONMENT 97

deteriorated when placed in the shade, as do European dogs in India
and horses in the Falklands. But in all these cases the change,
when clearly germinal, when it is transmitted and so increases from
generation to generation, is ever a deterioration, not an adaptation.
The germ-plasm in those cells that develop into offspring is altered
and injured, but not sufficiently to cause its death or even to
prevent the development of the individual. Now, obviously, the
deterioration cannot continue, generation after generation, in-
definitely. If not checked, the race must perish eventually.
But there are plants that dwell in the shade, there are native
races of dogs in India, and some varieties of horses flourish in
climates severer than that of the Falklands, and so on. They
are said to have become ' acclimatized,' to have reached an
'equilibrium' — meaningless terms unless it be explained what
they imply. They really imply adaptation, an essential feature
of which consists in the germ-plasm becoming insusceptible to the
direct action of the environment. Thus if, amongst Clayton's
beans, there had been any germs the plasm of which had so varied
as to be unaffected by shade, then, since he obtained seed in the
first three generations, he could have established by Natural
Selection a race as capable of existing away from the influence of
direct sunshine as mosses and ferns. He failed because, instead
of proceeding step by step, he made the conditions too rigorous.
When captive, wild animals are sterile, though still displaying
sexual desires ; it is possible, in some cases at least, that the
germ-plasm in their germ-cells is so altered as to be incapable of
directing development.

157. We observed that medical men are in the habit of
declaring that parental diseases and intemperance usually result
in filial degeneration, and we noted that this inference could not
possibly be correct, for otherwise the human race would have long
ago become extinct ; whereas, on the contrary, it has everywhere
undergone protective evolution. It is possible, nay probable, that
disease and intemperance are sometimes, though rarely — i.e. under
exceptional conditions or in exceptional germ-cells — causes of
variations ; but, in view of their long-continued prevalence, which
has made them quite as * normal ' a part of the environment as the
dangers to which other types of animals and plants are exposed,
in view also of the fact that in every case protective racial evolution,
not deterioration, has occurred, it is hard to understand how
they can be constant or even frequent causes of the variations
which are seen in children and adults. Nevertheless, suppose we

7

98 VARIABILITY

admit for the moment that the medical inference is true for the
present day, and that disease and drink act on the human race as
the climate of India is said to act on recently imported European
dogs. It is not denied, indeed it is a matter of common observation,
that diseased or drunken parents frequently have perfectly normal
offspring. Here, at once, we see Natural Selection at work on the
germ-cells. These normal individuals, whose germ-plasm was
insusceptible, are those that continue the race. If, then, the germ-
plasm of the race is not now, after thousands of years of selection,
as a general rule insusceptible, it is in process of becoming so.
Possibly the American maize mentioned by Metzger furnishes
another instance of this kind of selection.

158. The conclusion we reach, then, is that, though variations
may result from the direct action of the environment, such varia-
tions are, in effect, always injuries, and are of rare occurrence in
individuals who survive and have offspring. Adaptation (i.e.
evolution) depends almost exclusively on spontaneous variations.
These do not imply damage to the germ-plasm, but are products
of its vital activity. Occurring in vast abundance all round the
specific and parental means, they supply the sole material for
Natural Selection.

159. We conceive the germ-plasm, then, as living and active,
closely adjusted to its environment, growing, dividing, varying,
capable of being destroyed and injured, but resisting death and
injury, and within limits capable of repairing damage and
returning to its original state — as behaving exactly as a living
individual does. Plenty of biologists think of it as drifting like a
dead thing at the mercy of circumstances, incapable of making
vital reactions, capable of undergoing all sorts of radical alterations
and yet of surviving. But never yet have I met anyone holding
this opinion who was willing to make a rigorous deductive
inference of consequences, and explain how it happens that
races exposed to unfavourable conditions undergo, not deteriora-
tion, but adaptation. As well might it be maintained that if a
man goes continually down hill he will ultimately arrive at the
top.

1 60. The problem of the causation of variations is, both
theoretically and practically, one of the most important of all
biological problems. A discussion prolonged but singularly futile,
and founded mainly on experiments and observations, innumerable
but peculiarly irrelevant, has raged about it. From such experi-
ments as those of Clayton on beans, men have inferred that all

THE CAUSATION OF VARIATIONS 99

variations are caused by the direct action of the environment. As
a fact it is impossible to solve the problem experimentally.
An experiment cannot be made unless the animal or plant
used for the purpose is removed from its normal environment to
one very different ; and the question is, not whether it is pos-
sible to devise conditions in which the germ-plasm, though not de-
stroyed outright, is injured beyond recovery, but whether, under
the conditions in which species maintain their characters or undergo
adaptive change, variations commonly arise through the direct
action of the environment. In other words, the question is whether
variations are normally spontaneous or due to enforced alteration.
In the search for experimental data and the * obvious inferences '
so often drawn from them, the whole problem of adaptation has
been actually, though not ostensibly, ignored. Men have failed to
make the obligatory deductive inference of consequences followed
by an appeal to reality. They have not asked themselves how the
multitudinous and delicate adaptations and co-adaptations of
animals and plants could have arisen if species had drifted at the
mercy of the environment, nor troubled their heads with such
notorious facts as that human beings persist and for ages have
persisted in lands where every individual is saturated with the
poisons of malaria or other virulent diseases. That is to say they
have not taken the whole of the facts into consideration. If the
reader's thinking, also, is not to be mere guessing, he must follow
the procedure which has led to the creation of all science that is
more than a mere catalogue of likenesses and differences,1 and, bear-
ing in mind that species become adapted to their surroundings, ask
himself to what the adaptation is due, to a vital reaction resulting
from the Natural Selection of favourable spontaneous variations,
or to a helpless drift resulting from germinal changes caused by
the direct action of the environment. In other words, he must ask
himself which of these contradictory hypotheses can be conceived
as being in accord with the facts of existence.

161. Some biologists have argued that influences (e.g. abundant
nutriment) from the environment acting on the germ-plasm tend
to cause variations all round the specific mean. But if the germ-
plasm contained in the germ-cells of the species is everywhere
very similar — as it must be, since the individuals of the species
resemble one another — then a force acting on it, if it causes any
change, must cause everywhere much the same change and there-
fore a general drift in this or that direction. It is only when

ioo VARIABILITY

the germ-plasm in the different cells is dissimilar (i.e. has varied
spontaneously) that the changes, if any, can be dissimilar. But,
if it be admitted that germ-cells vary spontaneously, it is un-
necessary to appeal to the action of the environment ! to explain
facts which are already sufficiently explained. In science " neither
more nor more onerous causes are to be assumed than are necessary
to account for the phenomena."

162. The apparently well authenticated fact that species (e.g.
wild plants) removed to a new environment (e.g. cultivated garden)
tend, though healthy and prolific, to display, especially after the
lapse of several generations, greater variability than in the ancestral
habitats, has also been advanced in support of the hypothesis that
variations are commonly caused by the direct action of the en-
vironment. Here again we are asked to believe that an influence
(i.e. the sum of the new influences in the new environment, which
presumably is much the same for all or nearly all the germ-cells)
causes variations all round the specific mean. But Natural Selec-
tion not only adapts species to changing environments but keeps
adapted species stable in stable environments. Speaking generally,
natural environments are very stable — so stable that all distinct
species are very old, and some have persisted without appreciable
change for enormous epochs of time. During the entire historical
era, though natural varieties may have arisen, not a single species
is known to have altered appreciably as a whole. Variability is
not lacking, since man is able to create varieties very swiftly by
artificial selection. Obviously, any considerable variation in a
species, already closely adapted by thousands of years of selection
to its environment, is almost sure to be disadvantageous. A
superior tendency to vary, itself a variation, is, therefore, disadvan-
tageous, and is eliminated in an environment to which the species
is already well adapted. But it is advantageous in a new
environment to which the species must become adapted, and not
unfavourable, or not so unfavourable in a new environment (e.g.
garden) to which the species is adapted, but where the old causes
of elimination do not act. In brief terms the characters which
adapt species to their environments include a right degree of
variability ; that is, the degree of variability displayed by every
species is itself an adaptation. When monsters, for example,
perish, it is not only unfavourable variations which are eliminated,
but also a tendency to vary to an extent too great to produce fitness
to the parental environment. It follows, then, that the fact that
species tend to become more variable in a new environment is

VARIABILITY IS AN ADAPTATION 101

evidence, not that the germ-plasm is directly affected by its
surroundings, but that Natural Selection, which controls and
which formerly limited the amount of variability, no longer does so
to the same extent.

163. The foregoing leads us to a very important problem.
Though environments as a whole are very stable, yet they are
seldom if ever absolutely stable in every particular for prolonged
periods. One or other factor amongst the complex of which they
are compounded tends always to be undergoing change. New
factors of elimination appear, or old factors become more stringent
or less stringent. Thus, during the last few centuries many new
and fatal diseases have appeared amongst the human inhabitants
of the Western Hemisphere ; while in the Eastern world the
increase of population has accentuated the stringency of selection
by old-established diseases at the same time that elimination by
war, famine, and wild beasts has diminished. Species change in
adaptation to changing environments, and thus all forms of life
known to us have arisen. The fact that they have undergone
evolution is proof that their environments have undergone change.
Man, for example, is not fitted for the same environment as that
in which his pre-human ancestors existed, nor would the latter be
fitted for his present surroundings.1 The evolution of a species
is founded on the variations of its individuals. Were offspring
exact reproductions of parents, the race would persist only if it
were well adapted to a perfectly stable environment. A right
degree of spontaneous variability therefore is an essential condition
of persistence. Presumably, therefore, it is an adaptation — with
insusceptibility to the direct action of the environment, the most useful
and important of all adaptations ; as much an adaptation as hands,
eyes, lungs, or any other of the functioning characters of living
types. It is not, as is often implied, a chance property of germ-
cells, comparable, for example, to the colour of a dead leaf. And,
if it is an adaptation, then, reasoning by analogy, it has, like all
other adaptations, been established and maintained by Nattiral
Selection.

164. We need not attempt to discuss at length the question as
to how variability began in living beings. Like all other problems
relating to the beginnings of life, its origins are involved in
obscurity. Variations of some sort must have preceded Natural
Selection, if only for a moment, for otherwise the latter could have
had no material with which to work. But, probably, even these

1 See § 770.

102 VARIABILITY

earliest variations were spontaneous, for it is at least unlikely that
the multiplication of the primitive living beings involved exact
quantitative and qualitative division. Doubtless early variations,
however caused, were seized upon by Natural Selection, which, as
a necessary antecedent to all else, established the insusceptibility
of the germ-plasm and regulated the tendency to vary in all
directions about the specific mean. In other words, though
Natural Selection cannot have been the original source of varia-
tions, it has established variability as an adaptation and ensures
its constant occurrence, and in each species has regulated the
amount of it according to the needs of the time. At any rate,
however spontaneous variability originally arose, it certainly
exists and presents all the signs of an adaptation controlled by
Natural Selection.

165. Striking evidence that spontaneous variability is a
strictly regulated adaptation, and that germinal insusceptibility to
the direct action of the environment is also an adaptation, is
furnished by four well-authenticated facts. First, plants propagated
asexually (by slips, suckers, etc.) vary very little as long as they
are so propagated, no matter how numerous the pseudo-generations,
nor how diverse the influences to which they are exposed and by
which they may be modified ; wherefore gardeners, whenever
possible, propagate valuable varieties by means of cuttings.1 This
indicates that variations are, at least, rare amongst somatic cells,
for, if they were common, plants propagated asexually would be
changeful. Second, offspring arising by seminal generations (i.e.
from germ-cells) always vary from their parents. This indicates
that variations occur normally within the limits of the germ-tract,
that is in those lines of cells by which the germ-cells of the
individual descend from the fertilized ovum whence he sprang.
Third, the offspring of a plant reared from its seed vary no more
and no less, apparently, when the seed is gathered at the end of
the first season, than when it is gathered after many seasons during
the course of which the plant has been propagated asexually. In
other words, the lengthening of the germ-tract by any number of
pseudo-generations (i.e. slips and suckers) does not appear to
increase the number and magnitude of variations. This indicates
that variations do not arise all along the germ-tract, but once for
all in some particular part of it ; for, if they arose all along the
tract, the lengthening of it would tend to influence their number
and magnitude. Fourth, ' identical ' twins, which originate from a

1 See § 183.

THE PLACE OF ORIGIN OF VARIATIONS

103

single fertilized ovum, are closely alike, while those which arise
from different ova (even in the case of peas in the same pod)
differ as much, or almost as much, as offspring born at suc-
cessive births or seasons. This indicates that the part of the
germ-tract at which variations normally arise is the last, or one of
the last, cell-divisions that precede the ripening of the germ-cells ;
for if variations occurred earlier, not only identical twins, but whole
batches of offspring would tend to be identical, especially when
the reproduction was parthenogenetic.

1 66. The following diagram may help to elucidate the
argument.

A

AAAMAAMAAUAAMAA:

-Z

167. Suppose A is a fertilized ovum from which the cells of the
germ-tract B, C, D . . . Y, Z, are derived. Z represents the
descendant germs. Granting that variations arise at a particular
point in the tract, then, if they arise at A, B1 will differ from B2,
as will their descendants ; but all the descendants of B1 will be
alike, as will be those of B2. If variations arise at B, there will
be four batches of identical descendants. If at C, eight. And so
on. But if the point at which variations arise is at Y, there will
be no identical germs, except (especially in the case of complex
organisms) as a very unlikely coincidence. On the other hand
if variations arose all along the germ-tract, then, though all the
germs would tend to differ, the lengthening of the germ tracts, as
by pseudo-generations, would tend to increase variability, which,
as we see, does not happen.

1 68. Now, the evidence is that all these laws (laws in the
scientific sense of uniformities in the sequences of events), unlike
the laws of physics, have exceptions. Thus somatic cells some-
times vary spontaneously, as when a branch bearing nectarines
appears on a peach tree. Again, when a cancer appears in the
tissues of a man, the variation seems frequently to be caused,

104 VARIABILITY

in some measure at least, by the environment, for such tumours
are seen, especially in irritated tissues. Germ-cells, or cells of the
germ-tract, appear also to be affected sometimes by the direct
action of the environment, as in the case of Clayton's beans and
European dogs in India. But, as we have insisted, evolution is
never perfect ; the ' laws ' created by it have ever exceptions ;
for it is only by eliminating the exceptions that nature creates
and maintains uniformities amongst living beings. The fact that
these exceptions occur is in accordance, therefore, with all we
know concerning the adaptations of living beings.

169. The advantage of the practical limitation of the occur-
rence of variations to a particular part of the germ-tract is
obvious. If variations occurred amongst somatic cells, they would
tend to ruin co-adaptation among the cells that varied (and their
descendants) and the other somatic cells (and their descendants) — a
co-adaptation which has been achieved only by prolonged evolution.
A cancer which results, seemingly, from a variation in a somatic cell
(a variation, like other variations, inheritable by the descendants of
the cell) is an example. Moreover, such variations, even if favourable
to the individual, would be useless to the species, for, save in the
event of the Lamarckian hypothesis being true, they would not be
reproduced by the offspring of the individual. On the other hand,
germinal variations, while affording the necessary materials for
Natural Selection, do not affect the well-being of the community of
which the germs are members, for here the germs have no functions.
Again, if variations occurred all along the germ-tract, they would
accumulate, and offspring would tend to vary, not in the right
degree, but in proportion to the length of the tract and in pro-
portion to the duration of time that clasped between the fertilizing
of the ovum from which the parent arises and the production of
his offspring ; that is, the offspring earliest produced would tend
to vary less than those produced later. Lastly, if the point at
which variations normally occur were situated, not at the end of
the germ-tract, but earlier in it, then, in proportion as the point
was near the beginning and distant from the end of the tract,
larger and larger batches of germ-cells would, as I say, tend to be
identical. By limiting normal variability to the end of the germ-
tract, nature ensures, on the one hand, that all germ-cells shall vary
from one another, and, on the other, secures control over variations,
which are then soonest put to the test of fitness to the environment.

170. It may be thought that I have carried deductive thinking
too far in the preceding paragraphs. But the facts on which I

THE ORIGIN OF VARIATIONS 105

have relied are, I believe, not disputed, and I find it hard — as I
think the reader will — to conceive interpretations of them other
than those I have suggested. Germinal insusceptibility to the
direct action of the environment and a right degree of variability
are just as much adaptations, essential to the survival of the
species, as any of the structures and functions of the individual.
Presumably, therefore, they are just as much under the control of
Natural Selection. The limitation of variations to a particular
part of the germ-tract would not appear a task more difficult for
Natural Selection than the evolution of such wonderfully complex
and delicate structures as the eye and ear.

171. We are often told that the 'cause' or 'origin' of
spontaneous variations is unknown. If it be meant that the
molecular processes in the germ-plasm which result in variations
are unknown, the statement is true. In that sense we do not
know the cause of any kind of variations, not even of those which
clearly result from the direct action of the environment. But in
another sense it is untrue — as untrue as if, knowing that a certain
variation was caused by a certain influence in the environment,
we declared that the origin of it was unknown. The fertilized
ovum has two classes of cell-descendants, both of which vary
spontaneously, the somatic cells and the germ-cells. The former
do not vary away from type ; nevertheless they vary in a regular
manner from the fertilized ovum and amongst themselves, some
becoming skin-cells, others muscle-cells, and so on. We suppose
we know something very definite about the origin of these altera-
tions when we declare that they result from evolution and are
under the control of Natural Selection. Precisely the same
declaration may be made about the less regular but equally
constant variations of germ-cells. A germ-cell which has not
varied, has varied in that it has departed from a type which, in
effect, always varies. People who insist that we do not know the
cause of variations, and that the word 'spontaneous' is nothing
other than a cloak for ignorance, are unaware of the sense in which
that word is used, or they have not considered the evidence,
or they are the kind of people who insist on experimental
evidence and are unaware of the impossibility of devising experi-
ments which would furnish it.

172. We reach, then, three principal laws of heredity — three
summaries of facts, (a) The germ-plasm is highly insusceptible
to the direct action of the environment; (b) the vast majority
of variations — all those on which evolution is founded — are

io6 VARIABILITY

spontaneous ; (c) the development of the multicellular organism
is a recapitulation — however inaccurate and incomplete— of the
evolution of the race. All these three characters, insusceptibility,
regulated variability, and recapitulation are due to Natural Selec-
tion— or miracle. If the reader, bearing in mind the whole of
the evidence, not merely isolated items, will think the matter out
carefully, I believe he will find there is no escape from the
conclusion that all species must possess the first two characters or
perish, and that the third also must be present in all multicellular
types. He will be driven to conclude, also, that they are not
mere chance characters, but products of evolution which Natural
Selection wonderfully and beautifully regulates, which form the
foundation of all other adaptations, and are, therefore, the most
universal and important of all of them. The non-recognition of
them as adaptations, necessary and inevitable adaptations, which
underlies so much of modern thought and research, attests better
than anything else the failure, fatal to a right comprehension of
life, to realize that all normal living beings are, speaking practically,
nothing other than bundles of adaptations.

CHAPTER VI
RETROGRESSION

Evidence of retrogression — Theories of retrogression — Conditions under which
retrogression occurs — The speed of retrogression — The difficulty of recognizing
the identity of retrogression and reversion — Latent characters — The retrogression
of variations — The magnitude of the part played by retrogression — Retrogres-
sion in the developing individual — Reversed selection — ' Ancestral units ' — The
' contributions of ancestors ' — The law of ancestral inheritance — Biometry.

I73- ^ I CHOUGH, speaking practically, the doctrine of evolu-
tion is accepted by all who know the facts, that of
"™~ evolution by Natural Selection has not as yet received
such general assent. A vague terminology, and a belief that
nutritional characters are peculiarly ' innate ' and that ' acquire-
ments ' are not products of evolution, combined with the obvious-
ness of the Lamarckian doctrine and the difficulty of explaining
co-adaptation when the magnitude of ' use-acquirements ' is not
realized, still inclines some biologists to a faith that the * inheritance '
of acquirements accounts, in part at least, for evolution. Others,
because they are unable to perceive the utility of some charac-
ters in types so far removed from the human that our know-
ledge of their dangers and activities is very imperfect, have
supposed that such characters have no utility, that they are not
adaptations, and, therefore, that they do not owe their evolution to
Natural Selection, which, consequently, does not play an exclusive,
but, on the contrary, only a more or less minor part in the causa-
tion of specific change.1 Yet others, because a few species, when
the environment is changed, display quite suddenly considerable
adaptive alterations, pin their faith to that circumlocution for
miracle, an ' adaptive growth-force.' 2

174. But perhaps the main reason against a full acceptance of
the Darwinian doctrine — that, at any rate, which has influenced
most biologists in the past — has been drawn from the retrogression
of useless parts and organs. In all complex types occur traces of
organs which formerly were useful and of considerable relative

1 See §§ 306, 649. 2 See § 92.

107

io8 RETROGRESSION

magnitude, but which are now shrunken to mere vestiges. Thus
in the ostrich the wings are no longer capable of sustaining the
animal in flight. In the apteryx they are quite functionless and
so rudimentary as to be hidden in the feathers of the body. In
the extinct dinornis they had, apparently, disappeared altogether.
In most snakes no traces remain of limbs, but in the python the
hinder pair are still represented by vestiges. In some species of
whales, also, the hinder pair have disappeared ; in others the small
remains of them are buried in the body. Man has numerous
vestiges of structures which formerly were functional, for example,
the hairy covering of his body.

175. Lamarckians have attributed the retrogression of useless
parts to the transmitted effects of disuse. But man, for example,
never ' used ' the hair of his head more than that of his body ;
nevertheless the former persists, whereas the latter has become
vestigial. However, it is unnecessary to discuss the Lamarckian
doctrine here. The reasons which caused us to reject it as an
interpretation of progression are valid against it as an interpreta-
tion of retrogression.

176. At first Darwinians attributed retrogression to reversed
selection, " the selection which effects not increase of an organ, but
decrease of it." They argued that useless structures are worse
than useless, they are burdensome ; therefore nature secures their
disappearance by eliminating the most burdened individuals. But
the evidence is very ample that selection is a cause of racial change
only when it is stringent, and a hairy man is not really burdened
to an appreciable extent as compared with less hairy men ; at any
rate, not to such an extent as to diminish his chances of survival.
Again, pythons and whales, which have vestiges of hind limbs,
and the apteryx, which has vestiges of fore limbs, are hardly at a
disadvantage as compared to species in which retrogression has
been complete. A fortiori, individuals of the same species whichj
have vestiges a trifle smaller than their fellows, have on that
account no greater chance of survival. Osborn was very right
when he declared in reference to this question, " If acquirec
variations are transmitted, there is some unknown principle in
heredity ; if they are not transmitted, there must be some unknown
factor in evolution."

177. Next, Darwinians argued that the struggle for nutriment
is very severe, and that useless structures absorbed nutriment anc
so increased elimination. But useless structures, being inert
especially when composed of a stable tissue like bone, absorb

EXPLANATIONS OF RETROGRESSION 109

very little nutriment. Moreover, it is not the total amount of
nutriment absorbed by the vestiges that is in question, but only
the difference in the amounts consumed in the vestigial struc-
tures of the individual that survives and the one that perishes.
It requires faith of a really magnificent order to believe, for
instance, that the daily addition or subtraction of a grain or less
of nutriment can have influenced the survival rate of the Greenland
whale.

178. Next, it was asserted that the parts of the individual
struggle amongst themselves for nutriment, and the parts most
used being most stimulated received more than their share, and as
a consequence flourish at the expense of the others, which atrophy.
This hypothesis, however, is merely a particular application of the
Lamarckian doctrine.

179. In his hypothesis of Germinal Selection, Weismann has
very ingeniously transferred the struggle for nutriment from the
individual to the germ-plasm. He supposes that the parts of the
individual are represented in the germ-plasm by ' determinants/
which multiply like cells, so that descendant determinants are
present in descendant germ-cells. A weak determinant produces
a minus (retrogressive) variation. Being weak, it is vanquished
in the struggle for food by stonger determinants, and so grows
weaker, and transmits its weakness to offspring and descendants.
If the part it represents be useful, the individual who has the
minus variation tends to perish through Natural Selection, the
race being continued by the individuals in which the determinant
is stronger, and the part therefore better developed. If it is
useless, he tends to survive, and the process of weakening con-
tinues with added force in successive generations, till at length the
determinant perishes and the part disappears. In brief, Weismana
supposes that the determinants of useless parts are not helped by
selection, whereas the determinants of useful parts are helped by
it ; and, therefore, that the former tend to be vanquished by the
latter in the struggle for nutriment.

1 80. Weismann's hypothesis consists of two portions — an
induction and a deduction, the latter being an expansion of the
former. (a) Mere cessation of selection is followed by retro-
gression, (b} because the determinants of useless parts tend to be
starved. It is possible to agree with the first, which is founded
on observed facts and can be tested, without assenting to the
second, which is neither founded on observed facts nor has been
tested. According to this hypothesis, lack of nutriment is a cause

1 1 o RETROGRESSION

of retrogressive variations, and abundance of nutriment a cause of
progressive variations. In other words, it is supposed that varia-
tions are not always spontaneous, but are, very often at least,
caused by the direct action of the environment — a notion which,
in the main, Weismann himself has strenuously controverted. But,
if determinants — supposing they exist as discrete elements in the
germ-plasm — compete for nourishment, the competition should be
sharpest and most destructive when nutriment is least abundant,
and non-existent when it is superabundant. In that case species
which possess very abundant nutritive supplies (e.g. internal
parasites, unicellular and multicellular) should display little or no
retrogression, whereas species, the nutritive supply of which is so
small that they are engaged in an endless struggle for it, in which
many perish (e.g. most, if not all fishes, reptiles, birds, and
mammals) should display little progression and much retro-
gression. The exact opposite is the truth. The microbes of
syphilis remain microscopical though their determinants have
absolutely soaked in nutriment for thousands of years, and of all
known organisms the multicellular pasasites display the greatest
amount of retrogression. Some of them are little more than
egg-cases. Fishes, reptiles, birds, and mammals, on the other
hand, are typical examples of progression. In neither case has
the inevitable drift ensued which would necessarily have followed
were this hypothesis true — a drift which would tend to abolish
Natural Selection, and therefore adaptation.

1 8 1. Of all the splendid services rendered by Weismann to
biology none is more valuable than his long and successful
struggle to overthrow the Lamarckian doctrine. Since merely
useless parts tend to become vestigial and disappear, his success
involves the corollary that simple cessation of selection (i.e. cessa-
tion of utility), which may, or may not, imply cessation of use, is
followed by retrogression, which in turn implies that to prevent
retrogression a certain stringency of selection is necessary, while
to cause progression a still greater degree of stringency is required.
The retrogression of old-established parts is very slow. Thus the
great changes in whales and snakes since their limbs began to
retrogress indicates an enormous lapse of time. Doubtless, also,
geological epochs must pass before Greenland whales and pythons
lose even the small vestiges of hind limbs which they still possess.
On the other hand, newly acquired characters tend to disappear
very rapidly on cessation of selection, as may be noted in the
case of the special traits of our prize breeds. Absolutely new

THE CAUSE OF RETROGRESSION in

characters (i.e. variations) tend to disappear in the next generation
(e.g. birth-marks, moles, etc.).1

182. Since, then, the tendency to retrogression is greater in the
case of new characters than of old-established traits, the stringency
of selection by which the former are maintained, or by which fresh
progression may be caused in them, is proportionately intense.2
In other words, offspring frequently display progressive variations
in the case of old-established characters, whereas in the case of
new traits the great mass of variations is retrogressive. Thus, if
we try to improve the long-established characters of a compara-
tively old race, for example ordinary horses, our task is much less
difficult than if we operate on the new characters which have
recently been evolved under stringent selection, for example the
special traits of race-horses.3 In the latter case the tendency to
retrogression is sometimes so great that our utmost efforts may do
no more than prevent retrogression. In other words, stringent
selection no longer causes progression.

183. Since even old-established characters retrogress on cessa-
tion of selection, it follows that the frequency, or the magnitude^
or both? of retrogressive variations tends to be greater than that of
progressive variations, and that the difference is most considerable
in the case of newly evolved characters. The fact that retrogres-
sive variations tend to exceed progressive variations in magnitude
is well shown by the fact that while many generations of selection
may be needed to evolve a prize breed, the offspring of a pure-bred
prize pair may in a single generation display a loss of the special
characters of the parents and revert to the ancestral type. This
is not uncommon in the case of prize animals, but it is even more

1 Certain variations tend, apparently, to possess a greater degree of
stability than others. We shall deal with them when we discuss Mendelism
and the now popular Mutation theory of evolution. See chapters vii., viii.,
and ix.

2 Some Mutationists maintain that antiquity (i.e. long-continued selection)
has nothing to do with the stability of characters. They insist that all true
variations are absolutely permanent from the first ; whereas ' fluctuating
variations ' depend, not on change in the hereditary tendencies, but on differences
of nutrition and the like — on differences in stimuli. According to them evolution
is founded entirely on the former class of variations. We shall consider this view
also later.

3 " Two years ago thirty-two yearlings were sold for 51,250 guineas. These
thirty-two yearlings are represented by two winners of five races, Florio Rubatino
and La Reine, who have contributed £2000 to the total cost ; and there is not, so
far as can be known, a single one of the thirty with any prospect of making a race-
horse." (Quoted from the Times, December 27th, 1897, bv Sir Walter Gilbey,
Race-horses, p. 6.)

1 1 2 RETROGRESSION

common with cultivated plants.1 Amongst the latter, owing to
the fact that offspring are more numerous, especially when it is
possible to propagate a favourable individual by means of slips
from which seed may be obtained, selection has been more stringent
and progression correspondingly rapid.

184. Now a character (e.g. eye, limb, digestive system) which
is old-established is one the usefulness of which has been tested by
thousands of generations of continued selection. The permanent
usefulness of more recently evolved characters (e.g. special features
of prize-breeds) has been less thoroughly tested. They have
favoured survival, but have arisen under conditions which, speaking
comparatively, may be only temporary. Absolutely new charac-
ters (i.e. variations) have not been tested at all, or have been
tested for one life only. The fact that characters retrogress with
a speed which is inversely proportionate to the length of time
during which their usefulness has been proved at once raises a
suspicion that we are on the track of a very beautiful and very

1 " If a considerable number of improved cattle, sheep, or other animals of
the same race were allowed to breed freely together, with no selection, but with no
change in their conditions of life, there can be no doubt that after a score or a
hundred generations they would be very far from excellent of their kind "
(Darwin, A nimals and Plants, vol. ii. p. 265). " When selection is suspended, rapid
deterioration (from the fancier's standpoint) is the inevitable result. If, e.g., a
number of pigeons, good specimens of a distinct breed, are isolated and left un-
molested for a few years, they rapidly degenerate, i.e. they lose their show points
(be they beaks, frills, ruffs, or metallic tints) and reassume the more fixed char-
acters " (Ewart, Presidential Address to Zoological Section of the British Association,
1901). In 1810-14 Lady Monk and Lord Gambier collected some plants of the
wild heart's-ease and so began the cultivation of the modern pansy. Twenty years
after, " a book entirely devoted to this flower was published, and 400 named
varieties were on sale " (Animals and Plants, vol. i. p. 392). Half a century later
Darwin wrote, " Cultivators speak of this or that kind as being" remarkably con-
stant and true ; by this they do not mean, as in other cases, that the kind transmits
its characters by seed, but that the individual plant does not change much under
culture. The principle of inheritance, however, does hold good to a certain extent,
even with fleeting varieties of the Heartsease, for to gain good sorts it is indis-
pensable to sow the seeds of good sorts. Nevertheless in almost every large
seed-bed a few almost wild seedlings will appear through reversion " (op. cit.,
p. 393). At the present time the seed of the pansy " is of such a quality and is
saved in so many distinct colours that for all ordinary purposes the trouble of
striking cuttings and keeping stocks in pots all the winter through is mere waste
of time and pot room" (The Culture of Vegetables and Flowers from Seeds and
Roots, issued by Messrs Sutton & Co., p. 195). Messrs Sutton give examples
of flowers the varieties of which have been recently fixed by selection carried
through many generations. Indeed, any number of similar examples might be
given. Mendelian experimenters, however, explain the stability of old-established
characters otherwise than by continued selection. We shall discuss their hypo-
thesis presently.

LATENCY AND RETROGRESSION 113

important adaptation. But before discussing this matter it will
be well to inquire more closely into the exact nature of progressive
and retrogressive variations on which all racial change depends.

185. We have seen that, since the child recapitulates, with varia-
tions, the development of the parent, he must necessarily recapitu-
late, with inaccuracies, with additions and subtractions, the life-
history of the race. Whence it follows that a progressive variation
implies a complete recapitulation (as regards the character affected)
of the life-history as presented by the parent, plus an addition ;
whereas a retrogressive variation implies an incomplete recapitulation
of the parental development, and therefore a reversion to the stage of
development reached by some progenitor more remote than the
parent. There is really no escape from these conclusions ; for grant-
ing the undisputed fact that the child recapitulates the development
of the parent, other conclusions are actually, literally, unthinkable.

1 86. The reader, however, must be very careful not to confuse
latency with retrogression. Latency implies, not the loss of a
capacity to develop in this or that direction, but only its inactivity.
We shall see later l that it occurs when two rival hereditary tend-
encies are present in the germ-plasm, one of which becomes
dormant while the other directs the development of the individual.
Thus colour-blindness and haemophilia, which are commonly
restricted to males, tend to be transmitted in a latent condition
through daughters to grandsons. All the sexual characters,
primary and secondary, are latent in individuals of the opposite
sex. Thus the daughters of heavily bearded men tend to have
heavily bearded sons. Male aphides are absent during the summer
months, and reproduction, therefore, is parthenogenetic, but at the
end of the warm season males are produced, which fertilize the
winter eggs. Amongst honey bees also the reproduction of drones
is parthenogenetic. Male characters, therefore, are latent in the
germ-plasm of the females. " It is well known that a large number
of female birds, such as fowls, various pheasants, partridges,
pea-hens, ducks, etc., when old or diseased or when operated on,
assume many or all of the secondary male characters of their
species. In the case of the hen pheasant this has been observed
to occur far more frequently during certain years than during
others. A duck ten years old has been known to assume both the
perfect winter and summer plumage of the drake. Waterton gives
a curious case of a hen which had ceased laying, and had assumed
the plumage, voice, spurs, and warlike disposition of the cock ;

1 See chapter vii.

ii4 RETROGRESSION

when opposed to an enemy, she would erect her hackles and show
fight. Thus every character, even to the instinct and manner of
fighting, must have lain dormant in this hen as long as her ovaria
continued to act. The females of two kinds of deer, when old,
have been known to acquire horns ; and as Hunter has remarked,
we see something of an analogous nature in the human species." *•
C. E. Walker injected an emulsion of testes into hens, thus supply-
ing the necessary stimuli, and caused them to develop the combs,
wattles, and warlike disposition of cocks.2 Professor Giard, Geoffrey
Smith and others have shown that when the testes of crabs are
destroyed by parasites (Rhizocephala) the males may develop all
the characters of females, including ovaries. In some cases the
animal becomes a perfect hermaphrodite.3 Mr J. H. Orton has de-
monstrated that the molluscs Crepidula fornicata and Calyptrcea
chinensis are males at first but become females later.4

187. In addition to the temporary latency typically seen in the
case of the sexual characters, there is a more permanent form.
"Besides visible changes which it [the germ-cell] undergoes, we
must believe that it is crowded with invisible characters proper to
both sexes, to both the right and the left sides of the body, and to
a long line of male and female ancestors separated by hundreds
and even thousands of generations from the present time ; and these
characters, like those written on paper in invisible ink, lie ready to
be evolved whenever the organism is disturbed by certain known
or unknown conditions." 5 Thus individuals derived from
domesticated breeds of pigeons or fowls may reproduce the
characters of extremely remote wild ancestors. In cross-breeding
between domesticated varieties the re-appearance of hitherto latent
ancestral characters is so common that Darwin declared " we must
conclude that a tendency to this peculiar form of transmission is
an integral part of the general law of inheritance."6

1 88. There is a good deal of evidence that latency is influenced
directly, in a measure at least, by the environment. Thus Ewart
rendered latent at will the male or female characters of rabbits.
Amongst bees the female characters develop fully only under
certain conditions of environment in which, apparently, nutriment

1 Animals and Plants, vol. ii. p. 26.

8 The Influence of the Testes upon the Secondary Sexual Characters of Fowls, 1908.

3 Fauna und Flora des Golfes von Neapel, Monograph, 29 ; Rhizocephala,
Geoffrey Smith, Berlin, 1906.

4 Proc. Roy. Soc., B., vol. Ixxxi. pp. 68-84.
6 Animals and Plants, vol. ii. pp. 35-6.

6 Loc. cit.t vol. ii. p. 31.

LATENCY AND RETROGRESSION 115

plays the chief part. The same is the case with aphides, which
produce males only when the weather grows cold and nutriment
less abundant. In true retrogression, on the other hand, there is
not mere latency, but absolute loss. A hereditary tendency is
eliminated from the germ-plasm. If the character which was lost
was a new variation, it can recur in the race only through another
variation, of like nature ; if it has arisen through evolution, through
the piling up of progressive variations during a succession of
generations, it can recur only through a similar process of selection.
It is conceivable, of course, that no characters are ever completely
lost, but that all apparently lost characters become latent. But
this implies that, though the germ-plasm may gain, it cannot lose ;
that the only true kind of variations are progressive variations ;
and that while it is possible for the individual to vary so that
he completes the parental development and adds a step, it is
impossible for him to vary so as not to complete it, except by
making a character latent. It implies that all the variations of
the two parents, the four grandparents, the eight great-grandparents,
of all the billions of ancestors, are represented in the germ-plasm ;
that nothing, not even a minute variation in a hair, that ever
appeared during the immensely long and varied life-history, has
ever been lost ; and therefore, that a human embryo, for instance,
has latent not only all the physical and mental characters
of the many types which preceded him, but all the variations of
these characters which occurred in all his ancestors. The germ-
plasm in a microscopical germ-cell is doubtless a very complex
entity, but this hypothesis would endow it with a greater number
of hereditary tendencies than it has chemical atoms. In truth we
have no choice but to believe that hereditary tendencies may not
only become latent, but that they may be entirely lost. Indeed,
when we remember how numerous have been the variations and
the ancestors of every individual, and how immense the changes
during the life-history, it is evident that the proportion of characters
which have persisted, either in a patent or in a latent condition,
must be infinitely small when compared to those which have been
altogether lost — which have retrogressed absolutely.

189. A complete discussion of latent characters may be
postponed with advantage. We need note only that when a
character, for example the gorgeous plumage of Gallus banktva,
the wild ancestor of our domestic poultry, becomes latent, then
(since retrogression and reversion are identical) subsequent
retrogression, which eliminates the more sober colours of the

u6 RETROGRESSION

domestic bird, and so permits the reappearance of the ancestral
traits, may present every appearance of progression. Obviously,
the domestic characters which were new to the race and which
rendered latent more ancient traits, result from progression, and
their disappearance and the consequent reappearance of the latent
wild characters is an act of retrogression as well as reversion. It
may happen, of course, as normally occurs in the case of the
sexual characters, that the traits of the domestic fowls are not
eliminated when the wild plumage reappears, but replace the latter
as dormant characters, and therefore that they may reappear in
descendants, and even alternate with the wild traits as the sexual
characters alternate with one another ; but the fact that it is
sometimes extremely difficult to breed out hitherto latent ancestral
characters when once they have reappeared, seems to indicate that
their recrudescence may occasionally be due to a loss of the newer
domestic characters, not merely to the latency of the latter.1

190. It will be worth the reader's time to try to imagine an act
of retrogression which is not also an act of reversion. To take an
extreme example : suppose a child is born lacking a limb. Experi-
ence shows that a deficiency so great occurring in a single genera-
tion usually indicates latency rather than loss. But suppose it is an
instance of real retrogression — i.e. of the total and permanent loss
of a complex hereditary tendency from the germ-plasm — then
clearly the child has reverted to that enormously remote ancestor
in whom the limb did not exist. It is not maintained of course
that there ever was a period during the life-history when three
perfect limbs were possessed by the race while the fourth was
lacking. But since every part is independently variable, it is
necessary in this connection to think of every part separately.

191. Not only is the limb independently variable, but each
smallest part of it possesses the same power. Suppose a child
comes into existence with a malformed limb. This variation may
be compounded of any number of smaller variations, some of which

1 " I may here add a remark made by Mr Wicking, who has had more experi-
ence than any other person in England in breeding pigeons of various colours,
namely, that when a blue, or a chequered bird, having black wing bars, once
appears in any race and is allowed to breed, these characters are so strongly
transmitted that it is extremely difficult to eradicate them " (Animals and Plants,
vol. i. p. 210). On the other hand if, for example, albino mice be crossed with
black-and-white Japanese waltzing mice, the ancestral grey colour appears, but
if the mongrels be inter-bred, the albino and the black-and-white types reappear.
In this case the albino and the black-and-white colour become merely dormant
when the grey reappears. Medelians will dispute the inference, but it can be
substantiated (see chapter vii.).

THE MASKING OF RETROGRESSION 117

are progressions and others retrogressions. If we think of each of
the component variations separately, and, if necessary, analyse
them, we see that every progression must be built on the develop-
ment as presented by the parent, must consist of an addition
after a complete recapitulation (as far as that character is concerned)
of the life-history as presented by the parent ; whereas every
retrogression must consist of a subtraction from the complete
recapitulation — a reversion. Think how we will, puzzle how we
may, we must always arrive at the conclusion that retrogression is
identical with reversion.

192. There are, then, two kinds of 'reversion.' (i) The
individual may revert ancestor-wards through retrogression —
through the total loss of a developmental potentiality from the
germ-plasm. (2) He may reproduce a dormant ancestral trait. The
latter, in appearence at least, is also reversion, even though nothing
is lost to the germ-plasm — even though the more modern trait
becomes in its turn merely dormant. Most biologists limit the
term reversion to the more or less glaring reproduction of a latent
ancestral trait, but only, I think, because they have not as yet
thought of retrogression in connection with reversion.

193. The reason why retrogression seldom JD resents the appear-
ance of reversion, and why, therefore, there has been a general
failure to recognize the relations between the two, arises from the
fact that, since the parts of the individual are independently
variable, retrogressive and progressive variations are usually closely
intermingled, with the result that the nature of the former is masked.
They cannot be clearly discerned as reversions. Moreover, in old-
established types especially, the majority of variations tend to be
of very small magnitude. Sometimes, however, retrogression is
extensive and affects some conspicuous character or a number of
characters together, and then, as when a prize breed loses its
special traits, we are able to recognize its nature. In by far
the great majority of instances, however, retrogression is not
obviously identical with reversion. Not sight, but thought, con-
vinces us of the identity. Thus, while the wing of a bird, whose
latest descendants have lost the power of flight, was evolving from
the reptilian fore-limb, much was lost as well as gained. Conse-
quently when the wing became useless, for example in the apteryx,
and retrogression en masse set in, there was no return to the
reptilian limb, for the major part of the latter had already under-
gone retrogression during its change to an organ of flight.

194. Every individual varies from his parent in an almost

1 1 8 RETROGRESSION

infinite number of ways. A proportion of his variations are pro-
gressive, and of them the great majority are useless, since they do
not make the child superior to, that is, more adapted to the environ-
ment, than the parent. They are small redundancies which do
not affect the survival of the individual, but which, if reproduced
by subsequent generations, would accumulate and ultimately over-
burden the race. We may note many of them in any human
being, but we cannot by mere observation form any conception of
their number ; for nearly all of them are too obscure and minute to
be recognizable as redundancies, and most of them are situated in-
ternally. But, when we are able to note one (e.g. a mole) clearly in a
parent, we are almost sure to find it lacking when we examine the
child. Natural Selection has played no direct part in its elimination ;
yet it has ceased to burden the race. To put the matter in another
way : no individual is absolutely perfect in every particular, and
many of his imperfections are due to progressive variations.
These redundancies are not as a rule reproduced, for though they
occur in every generation, the human race, for example, has not
altered appreciably in shape for thousands of years. That is, they
do not accumulate. They disappear, but, very obviously, not through
selection. Selection, indeed, could not reach them, for singly they
do not affect survival, and they never occur en masse in one
individual and not at all in another. The evident fact is that the
useless progressive variations of one generation tend to be planed
away by the retrogressive variations of the next. It is otherwise
with useful progressions. They tend to be preserved by selection,
even though, paradoxical as it may sound, they are in many cases,
when taken separately, beyond the reach of it. In a future chapter
we shall study the very admirable device by which the elimination
of useless and preservation of useful progressive variations is
achieved without a separate elimination of individuals for each
separate kind of variation.1 Meanwhile the point to be noted is
that selection plays no direct part in the retrogression of the
mass of progressive variations.

195. Every multicellular species has descended from unicellular
organisms. During the long course of evolution it has undergone
innumerable changes of form. Many structures, which once were
useful and for that reason underwent progression, subsequently
became useless and retrogressed utterly, or to such an extent that
hardly a trace of them remains in the abbreviated life-history that
is narrated in the development of the latest descendants. Other

1 See chapter ix.

THE ROLE OF RETROGRESSION IN EVOLUTION 119

parts, as their functions and anatomical relations changed, have been
so greatly and continually modified that, like a much-mended
garment, the original structures have nearly disappeared and have
been replaced or almost replaced by new material. Others again
have been so much less modified that the careful observer is able
to gather a good deal concerning the life-history. In yet others,
generally the more modern structures, for example the antlers of
the stag, the life-history is plain : only variations which were never
incorporated into the life-history of the race have vanished ; the
structures develop in the individual on much the same lines as they
were evolved in the race. In every species, therefore, we find
evidence of an immense amount of retrogression. Consider, for
example, how much man must have lost since he became a verte-
brate, and how much more in the even longer antecedent period.

196. Retrogression, then, has been as much a part of evolution,
of adaptation, as progression. It has planed away useless and
burdensome structures. It has straightened, simplified, and
abbreviated recapitulation ; the life-history is not told in all its
details ; the narrative is limited to particulars essential to its
development ; and thus development is rendered possible during
the brief lifetime of the individual. If a man, for example,
recapitulated all the changes undergone by his ancestors, he would
require, not'years, but ages for development. Lastly, retrogression,
combined with some progression, has rendered possible the exist-
ence of the developing individual in environments vastly different
from those inhabited by its prototypes of the ancestry. The
human embryo, for instance, dwells within its mother's uterus. Its
prototypes had an independent existence. Were they, with their
structures and faculties complete, placed in the uterus, they would
perish just as surely as the embryo would were it placed in the
ancestral environments.

197. Within the uterus the embryo leads a protected vegetative
life. It has no such active struggle for existence as the adult.
The now useless power, which depends on structures and faculties,
of fighting actively for itself, as did its prototypes, who lived in a
world where nutriment was scarce and enemies plentiful, has been
lost through retrogression. The sole business of the embryo is to fit
itself as quickly and as thoroughly by development as its nature per-
mits for the battle which occurs later. Quick development implies
quick recapitulation, which in turn implies abbreviated recapitula-
tion. In all the higher animals the length of the period of gestation
is always proportionate to, and therefore presumably dependent on,

120 RETROGRESSION

the amount and complexity of this intra-uterine preparation.
Even after birth the young of the higher animals are protected to
give time for still more development, still more recapitulation,
particularly that development which results physically from use
and mentally from that synonym for use, experience. Such young
animals, owing to the decay (precisely similar to that observable
in the embryo) of faculties, especially instincts, present in the
ancestry, are incapable of maintaining independent existence. In
brief, whenever the active struggle is abolished, the structures and
faculties by which it was maintained tend to disappear, except in
so far as they serve as foundations on which are reared characters
that are useful later in the battle of life.

198. Animals comparatively low in the scale of life, many
insects for instance, do not protect their young after birth. More-
over, birth occurs at an early period of development — that is,
when offspring have recapitulated nothing or comparatively little
of the life-history. But very complex and rapid development
occurs during the quiescent period in the egg-case. To take the
familiar example of the butterfly — the caterpillar when he emerges
has already undergone development in which he has recapitulated
a vast phase of the evolution of his race. Next, for a long period,
during which an active life is led, very few structural alterations,
except increase in size, occur. Probably during this active time
the environment, speaking relatively, very nearly resembles the
ancestral environments, and the caterpillar his remote ancestors
who developed no further. Doubtless he differs from them, but
not to the extent that the embryo in the egg-case differs from
the ancestors it represents. The structures and faculties have not
undergone the same amount of retrogression ; the life-history is
recapitulated in greater detail. The function of this active period
is the accumulation of nutriment which furnishes material both for
the growth of the caterpillar and for his subsequent developments.
Next comes another period of quiescence in the chrysalis, which
again affords opportunity for great retrogression and, therefore,
for the later phases of the life-history to be very rapidly retold.
In this period occur changes which swiftly recapitulate the evolu-
tion that added an aerial stage to the development of a hitherto
purely terrestrial insect. In the last, the active butterfly stage,
however long it may endure, there is again complete, or almost
complete cessation of structural alteration.

199. The quiescent periods of development in the egg-case and
the chrysalis are strictly homologous to the period of intra-uterine

RETROGRESSION IN THE EMBRYO 121

development in the higher animals. In them is achieved the same
end — the fore-shortening of long and changeful periods of the life-
history. All, or almost all rapid recapitulation occurs during
periods of quiescence when the individual is protected or con-
cealed, that is when he is least exposed to selection. Better than
anything else development indicates the extent to which the
organism is a bundle of adaptations. Thus the embryo of the
butterfly develops fast while it is stationary in its egg-case, where
it remains till food is abundant ; the active caterpillar, fitted to its
environment by all its structures and instincts, stores nutriment in
its tissues against a time when, did it continue active, it would be
very disadvantageously situated while changing into the adult
insect. The human infant is born to a mother who is fitted to tend
just such a developing being at just such a stage of its develop-
ment. Were its development different, did it recapitulate the life-
history in fuller detail, she could neither bear nor tend it. In both
the caterpillar and the human being the abbreviations of the life-
history, though happening at different periods of life, occur at
precisely the most useful periods. After the period of reproduc-
tion of offspring the fitness of the individual to the environment
declines — swiftly in the lower animals, more slowly in animals that
tend their young. For obvious reasons, Natural Selection can no
longer preserve it. There is no further recapitulation. There is
nothing to recapitulate.

200. Plants lead a life more quiescent than most animals.
Speaking generally, the seed drops to the ground, and the young
plant emerges from it into an environment which hardly changes
again during the lifetime of the individual, but which, since the higher
plants have evolved from lower forms, must have changed greatly
for the species. In them, therefore, retrogression has so abbreviated
a major portion of the life-history that no one merely examining
the embryo of an oak, for example, would gather more than a hint
of the immensely long and changeful process by which the species
underwent evolution.

20 1. We see then how great a part retrogression plays in
evolution and by what varied devices nature assists its operations.
It swiftly eliminates the useless progressive variations, the redund-
ancies, which occur in vast numbers in every individual. More
slowly, in proportion to their antiquity, it rids the species of
characters which have lost their utility. It abbreviates and
simplifies development. It wars against progression, but great
progression would be impossible without it It furnishes a half of

122 RETROGRESSION

the sum of adaptation, leaving only the other half to the direct
action of Natural Selection. Yet all these great effects result
solely because in every structure of every species the tendency to
vary retrogressively is so much stronger than the tendency to vary
progressively that retrogression is checked only by selection.
Obviously this tendency of retrogressive variations to preponderate
over progressive variations is highly adaptive — as adaptive as
spontaneous variability itself. The question then arises whether
it is an actual adaptation or merely something which has arisen
accidentally during the course of evolution. We saw that the
regulated variability which distinguishes all forms of life was,
beyond reasonable doubt, maintained, and controlled by Natural
Selection. The tendency to retrogression is only one of the ways
in which variability is regulated. We have, therefore, every reason
to suppose it is no chance accompaniment of life, but an adaptation
ranking in universality and importance with spontaneous varia-
bility, insusceptibility, and recapitulation. In other words, we
have reason to believe that it is a LAW that has resulted from the
selection of germ-plasms which, while tending to vary all round the
specific mean, yet tended, on the whole, to vary retrogressively.

202. The problem of retrogression cannot be approached by
any of the laboratory methods and therefore tends to be ranked
by some minds among the questions of ' philosophy.' Moreover,
the very simplicity of the device by which nature achieves such
great results is apt to awaken incredulity. I can only ask the
reader, while bearing in mind the facts of adaptation and also the
fact that both useless progressive variations and characters that
have become useless tend to disappear in the absence of direct
selection, to try here again to conceive interpretations other than
those I have suggested. Judging from my own experience, I
think he will fail.

203. We conclude, then, that the great mass of retrogression
we observe in nature is not due directly to Natural Selection — that
is to reversed selection. Since, as a rule, environments change
gradually, it occurs under conditions which afford no scope to
reversed selection. It is not to be supposed, for example, that the
apteryx suddenly abandoned habits of flight. While the struc-
tures and instincts which especially|fitted it for a terrestrial life were
undergoing progressive evolution, its wings were still helpful in
sustaining existence. But they became continuously less useful,
were less and less maintained by selection, and so at last
underwent retrogression. Sometimes, however, we may observe

THE ROLE OF REVERSED SELECTION 123

what appears to be clear evidence that reversed selection has
caused real retrogression. Thus certain blind crabs inhabiting
caverns have lost their eyes, but not the stalks on which the eyes
were carried ; since the eye is a more ancient organ than the stalk,
it should, on cessation of selection, have been more persistent ;
yet it disappeared first. Evidently something more than mere
cessation of selection was at work. In utter darkness the eye, a
prominent and vulnerable organ, would be not only useless, but
worse than useless ; and therefore reverted individuals would be
actively selected for survival, and the organ would be more rapidly
eliminated than could happen under cessation of selection. In
other cave-dwelling animals, which, as we suppose, are not
descended from stalk-eyed ancestors, the rudimentary eye is
covered by skin. Presumably in this case the partial retrogression
has resulted from mere cessation of selection, the eye being pro-
tected from injury and therefore from reversed selection by the
progression which resulted in the growth of the skin. Here, as
ever, nature has followed the line of least resistance.

204. But though reversed selection is seldom a cause of retro-
gression, it has nevertheless a very important function. Reversed
selection implies reversed progression of the race, which, in turn,
implies reversed development of the individual. When, therefore,
we see a structure better developed in the immature individual
than in the adult, we may be sure that the diminution in the adult
is due to reversed selection. Thus the remote ancestor of the
modern horse, the Hipparion, had three functional toes. The
embryo of the horse also has three toes of considerable size. But
the two outer toes in each limb, which in the embryo are nearly as
well developed as in the Hipparion, degenerate partially during
development, so that the horse is born with only one functional
toe. " Occasionally a foal is born with two hoofs on one or more
of its limbs ; at very long intervals a foal appears with three hoofs
on one or more of its limbs." Now, when the outer toe persists in
the individual, we have plainly, in a real sense, an arrest of
development. The toes remain in the embryonic, the ancestral
condition ; the whole life-history is not recapitulated. But in the
normal horse there is no arrest of development ; the recapitula-
tion is carried out to its fullest extent, though in the later stages
in a reversed direction. The toes, which were useful to the
ancestors, are harmless to the embryo, but would be harmful to
the adult, and, therefore, have been eliminated by reversed selec-
tion in the latter before retrogression has eliminated them in the

124 RETROGRESSION

former. Still better examples are seen in the disappearance in
later life of structures which are useful to the developing individual,
but which have no place in the scheme of adaptations of which the
adult is compacted. It is because of "selection which affects not
increase of an organ but decrease of it," that the human being
loses the placenta, the frog the special structures of the tadpole,
and many insects their larval organs. To sum up, cessation of
selection causes real retrogression, a real loss to the race (i.e. to
the germ-plasm) of ancestral characters ; reversed selection, on the
other hand, though it sometimes collaborates with cessation of
selection to produce real loss, causes, as a rule, like ordinary selec-
tion, not loss but gain to the germ-plasm, to which it adds a
hereditary tendency. It does not abbreviate ; on the contrary it
lengthens the life-history. Speaking generally, it causes the loss in
the later stages of development of characters which have developed
earlier. That is its special, its more common function.

205. In the present work we have accepted Weismann's theory
of the continuity of the germ-plasm. That theory fits the facts so
well that it has very few opponents at the present day. It
supposes that the germ-plasm is not formed afresh in every germ-
cell, but, by means of cell-divisions, is handed on by germ-cells
to descendant germ-cells. The process is a continuation of that
which occurred in the unicellular ancestors. The germ-plasm varies
and, since it is alive, its chemical constituents (carbon, oxygen,
nitrogen, etc.) change in a constant stream. Nevertheless from age
to age it is continuous in the same sense as the human body is
continuous from day to day.1 In addition we have supposed,

1 As far as I am able to judge, this, in essence, is the form in which Weismann
wishes us to accept his theory. He writes in his most recent work, " The
expression (ancestral plasm), however, has been very frequently misunderstood,
as if it were intended to mean that the ids retained unchanged for all time the
characters of their respective ancestors ; and I have even been credited with
supposing that our own ids still consist of the determinant-complexes of our
fish-like or amoeba-like ancestors. But in reality no id exactly or completely
corresponds to the type, that is to the whole being of any one of the ancestors
in whose germ -plasm it was formerly contained, for each of the ancestors had
many ids in his germ-plasm, and his entire constitution was not determined
by any one of them alone, but by the co-operation of them all. . . . Thus, accord-
ing to our view, the germ-plasm consists of ids, each of which contains all the
determinants of the whole ontogeny, but usually in individually different
quality " (The Evolution Theory, Eng. Trans., vol. ii. p. 38). Weismann's con-
ception of the germ-plasm, then, appears to be of a substance containing discrete
particles which he terms ids, any one of which is capable of directing development.
The ids differ from one another, but only in so far as is implied by the variations
of individuals. As noted by him, the term ' ancestral ' has resulted in con-
fusion ; it is inaccurate and misleading. The conception of the germ-plasm

THE REPRESENTATION OF ANCESTORS 125

what none will dispute, that the germ-plasm is the bearer of
hereditary tendencies or potentialities, and that according to the
nature of the latter is the nature of the individual which springs
from the germ-cell. Further, we have supposed, what very few
will dispute, and what indeed is implied in the theory of continuity,
that the germ-cell receives no living elements from the somatic
cells, but only shelter and nutrition. It is a unicellular organism
living in the midst of a community which is the multicellular
organism. From our point of view, therefore, individuals, for
example men, are nothing more than dwellings which the germ-
plasm builds about its germinal descendants. It follows — but
here we are contradicted by the language of all biological literature
— that the child inherits nothing from his parent. He resembles
his parent only because he mimics the development of the latter,
only because his development was directed by a split-off portion
of the germ-plasm that directed the development of his parent.
Yet again, we have insisted that it is quite inconceivable that the
development of the multicellular individual can be other than a re-
capitulation, more or less altered, of the life-history of his race.

206. If we are right, then, necessarily, such progressive
variations of the ancestors as have not been lost through retro-
gression, and therefore are reproduced in development, appear
in the order in which they occurred during evolution, the sole
exception being interpolated variations. In a general sense,
therefore, successive generations of ancestors are represented
(mimicked) during development in order, beginning with the
unicellular organism which is represented by the germ-cell, and
ending with such progressive variations of the preceding genera-
tions as are reproduced by the last generation. We must think
in terms of the germ-plasm, however, and bear in mind that, since
retrogression is constantly at work, even in characters that on the
whole are progressive ; since, while some characters have undergone

which I have endeavoured to place before the reader is that of a substance which
contains, or is, in some way, associated with the hereditary tendencies which direct
development. I suppose that the germ-plasms which direct the development of
any two individuals differ qualitatively somewhat. Whether or not the germ-
plasm consists of discrete units, each of^ which contains all the hereditary tendencies,
and one of which wholly or principally directs development, is a question I do not
discuss : I know of no facts bearing on the matter and no means of testing the
thinking. But, as will be seen, I do very strongly protest against the hypothesis
that the germ-plasm consists of discrete particles each of which represents a
particular ancestor. That hypothesis, I think, is not only not warranted by
valid evidence, but is negatived by the high probability that the germ-plasm is
continuous in a real sense from generation to generation.

126 RETROGRESSION

progression, others have undergone retrogression or have re-
mained stationary, and since variations have been interpolated,
no generation of ancestors is ever reproduced exactly by descen-
dants. Therefore the statement that ancestors are represented in
orderly succession (in the order in which they came into existence)
is true in a general and vague sense only.

207. Apparently, however, many biologists believe, not that
the germ-plasm undergoes such a change during evolution that
development is in a general sense a recapitulation of the life-
history, not that the successive generations of ancestors are vaguely
mimicked in turn during development, but that each ancestor
adds to the germ-plasm a * unit ' or ' contribution ' which may
control, or may assist in controlling, development from start to
finish, from germ-cell to adult.

208. The best known of the hypotheses which are founded on the
notion of ancestral contributions is Sir Francis Galton's ' Law of
Ancestral Inheritance.' This hypothesis, or modifications of it, which
differ in detail but are similar in principle, have been so widely
accepted that it is necessary to discuss it somewhat at length.
Galton analysed statistical data concerning stature, eye-colour,
artistic faculty, and health, collected from about one hundred and
fifty families of human beings, and extending over three or more
generations. Next, he analysed statistics concerning the colour
of Bassett hounds, a race of dwarf blood-hounds originated by
Sir Everett Millais some twenty years previously. He concluded,
" The two parents contribute between them on the average one-half
(or 0.5) of the total heritage of the offspring ; the four grandparents
one-fourth (or O-5)2; the eight great-grandparents one-eighth
(or o.5)3, and so on. Thus the sum of the ancestral contributions
is expressed by the series (0.5) + (o.5)2-f (o.5)3, etc., which, being
equal to unity, accounts for the whole heritage." l

209. Now obviously Galton's statistics do not furnish evidence
that ancestors contribute units to the germ-plasm. That deduction,
if it is in his mind, is drawn from the observation that offspring
may, in this or that character, resemble ancestors more than they
do parents. Probably it was reached before the statistics were
collected. Galton merely noted certain resemblances between the
individuals of three or four generations, and calculated that on the
average offspring resemble each parent to the extent of one-
quarter of their total characters, each grandparent to the extent

1 The Average Contribution of each Several Ancestor to the Total Heritage of the
Offspring, Proc. Roy. Soc. London, vol. Ixi. pp. 401-13.

THE LAW OF ANCESTRAL INHERITANCE 127

of one-sixteenth, and so on. He concluded further, that what was
true of the characters investigated was true of all characters, that
what was true of the generations investigated was true of all
generations, and seemingly also that the resemblances were due
to 'contributions' to the germ-plasm. The notion that ancestors
' contribute ' to the heritage of the child (i.e. add definite and
apparently discrete ' units ' to the germ-plasm) is founded on, but
not tested by his facts.

210. The principal difficulty in discussing the Law of Ancestral
Inheritance arises from the fact that since the nature of a
* contribution ' is not defined, the hypothesis is not ' definite in
conditions.' Conceivably, the word implies a variation which
occurred in the germ-plasm at the time that an ancestor existed — -
a variation which may or may not blend with other variations
occurring in the same and in preceding and succeeding generations.
Or * contributions ' may be regarded as discrete units which re-
present separate ancestors in the germ-plasm and have been added
to it by them. Since biometricians, as a rule, hold with Weismann
that the germ-plasm is continuous and that inheritance is usually
blended, it seems correct to conclude that what they mean by
their word ' contribution ' is a blend of the variations occurring in
a generation of ancestors. On the other hand the language used
appears to indicate clearly that what they mean is that the germ-
plasm is compounded of discrete units, each of which was somehow
contributed by a separate ancestor — contributed by the soma to
the germ-plasm, by the dwelling to the inhabitant. Probably such
an interpretation would be repudiated. Nevertheless, it would
certainly seem to be implied that discrete units representing
ancestors do in some way come into existence in the germ-plasm
and influence the development of the individual from start to finish.

211. "We seem to inherit bit by bit, this element from one
progenitor, that from another . . . while the separate bits are
themselves liable to some small change during the process of
transmission. Inheritance may therefore be described as largely
if not wholly ' particulate,' and as such it will be treated in these
pages. Though this word is good English and accurately ex-
presses its own meaning, the application now made of it will be
better understood through an illustration. Thus, many of the
modern buildings in Italy are historically known to have been
built out of the pillaged structures of older days. Here we may
observe a column or a lintel serving the same purpose for a second
time, and perhaps bearing an inscription that testifies to its origin,

128 RETROGRESSION

while as to the other stones, though the mason may have chipped
them here and there, and altered their shapes a little, few, if any,
came direct from the quarry. This simile gives a rude but true
idea of the exact meaning of Particulate Inheritance, namely, that
each piece of the new structure is derived from a corresponding
piece of some older one, as a lintel was derived from a lintel, a
column from a column, a piece of wall from a piece of wall.

212. "I will pursue this rough simile just one step further,
which is as much as it will bear. Suppose we were building a
house with second-hand materials carted from a dealer's yard, we
should often find considerable portions of the same old houses to
be still grouped together. Materials derived from various structures
might have been moved and much shuffled together in the yard,
yet pieces from the same source would frequently remain in
juxtaposition and it may be entangled. They would lie side by
side ready to be carted away at the same time and to be re-erected
together anew. So in the process of transmission by inheritance,
elements derived from the same ancestor are apt to appear in
large groups, just as they had clung together in the pre-embryonic
stage, as perhaps they did. They form what is expressed by the
words * traits ' — traits of feature and character — that is to say
continuous features and not isolated points.

213. u We appear, then, to be severally built up out of a host
of minute particles of whose nature we know nothing, any one
of which may be derived from any one progenitor, but which are
usually transmitted in aggregates, considerable groups being
derived from the same progenitor. It would seem that while the
embryo is developing itself, the particles more or less qualified for
each new post wait as it were in competition, to obtain it. Also
that the particle that succeeds, must owe its success partly to
accident of position and partly to being better qualified than any
equally well placed competitor to gain a lodgment. Thus the
step by step development of the embryo cannot fail to be influ-
enced by an incalculable number of small and mostly unknown
circumstances." l

214. Many biologists evidently do mean by 'contribution'
a unit added to the germ-plasm. For example, we are told, " The
Law of Ancestral Inheritance proves that all ancestors, however
remote, are able to leave the impress of their individuality upon
the sex-cells in diminishing proportion according to their remote-
ness. Such a fact can only be accounted for by assuming the

1 Galton, Natural Inheritance, pp. 7-9.

THE LAW OF ANCESTRAL INHERITANCE 129

existence in the germ-plasm of definite units carrying definite
characters, and the regular halving in the average strength or
amount of such characters during the reducing division of the
nuclear matter of the sex-cells which precedes each act of
reproduction." 1

215. Apparently, then, each ancestor is supposed to contribute
a unit to the germ-plasm, which, since the contributions taken
together amount to unity, is thus totally compounded of ancestral
units — two large units from the parents, four.units each a quarter as
large from the grandparents, and so on. But each ancestor's unit is
also totally compounded of units from his ancestors, whose units in
turn are totally compounded of units from their ancestors, and so on
in endless recession. Now, imagine a line of individuals, A,B, . . .
Y,Z. Then Z will have a unit from A. He will also have one
from B (which will contain a contribution from A). Likewise, he
will have one from C (which will contain a contribution from A
and one from B [which will contain one from A]). Yet again Z
will have a unit from D (which will contain a contribution from
A and one from B [which will contain one from A] and another
from C [which will contain a contribution from A and one from B
{which will contain a contribution from A}]) — and so on. Obviously
A's unit will be repeated many times over, in almost infinite sub-
division, in all the contributions of his descendants. So, also, as
regards B's unit and the units of the other ancestors, especially the
more remote. Really, however, ancestral contributions have not
this ideal simplicity of composition ; for every individual is of
almost infinitely long descent, and if of a sexually dimorphic species,
has two parents, four grandparents, eight great-grandparents, and
so on.

216. At first sight a law of ancestral contributions seems simple :
we suppose merely that each ancestor adds something representing
himself to the germ-plasm. If, however, we make the necessary
rigorous deductive inference of consequences, it becomes almost
unthinkable. It is opposed, in language at any rate, to the notion
that the ancestors of the germ-cells are, not ' individuals,' but the
cells of the germ-tract, which merely dwell within the individuals.
Notwithstanding all its appearance of mathematical precision, it is
so vaguely expressed that I doubt if any two people understand it
alike.2 I describe it as I understand it, or as far as I am able to

1 Vernon, Variations in Animals and Plants, pp. 134-5.

2 " This law, that the mean Characters of the offspring can be calculated with
the more exactness, the more extensive our knowledge of the corresponding characters

9

1 30 RETROGRESSION

understand it. Presumably a * contribution ' to the heritage of a
descendant means more than mere resemblance; otherwise it is
difficult to understand why a word so apt to mislead is used when
the unequivocal word ' resemblance,' which occurs readily to the
mind, is sufficient to describe the phenomenon. An ancestral con-
tribution which is halved and quartered and so forth would
certainly seem to imply a discrete unit representing an ancestor in
the germ-plasm ; and apparently since every ancestor's heritage is
compounded from those of his predecessors, it would appear also
that the contribution of every ancestor is represented in the
contribution of every successor. To say the least, it is hard
to believe that machinery for this perpetual and complicated
division can exist.1

of the ancestry ', may be termed the Law of Ancestral Heredity " (Mr Udney Yule,
" Mendel's Laws and their Probable Relations to Intra-racial Heredity," The
New Philologist, 1902, p. 202. " The degree to which a parental character affects
offspring depends not only upon its development in the individual parent, but on
its degree of development in the ancestors of that parent " (Prof. W. F. R. Wei don).
Mr Yule and Professor Weldon avoid the use of the word contribution. As
formulated by them the Law expresses what would appear an obvious truth ;
but it is then widely different from the Law as formulated by Galton and
accepted by Mr Vernon.

1 I have reasoned from what appears to me the plain meaning of Gal ton's
words. Here is another and apparently very similar interpretation : "A man
may receive a quarter of his hereditary characters from each parent, and a six-
teenth from each grandparent, but all except a] very minute portion of these
characters are common to all men, they being, in fact, the characters proper to
the species, Homo sapiens, as such. Instead of a quarter of a unit from each parent
a man receives only a hundredth or a thousandth of a unit of characters peculiar
to the parents as such, all the rest being the characters common to all the members
of the race. Even this minute fraction of a unit does not in any way represent
characters acquired by the parent during his lifetime, but is itself built up of
proportions of peculiar characters received from his parents, grandparents, and
other ancestors in accordance with the law of heredity " (Vernon, Variations in
Animals and Plants, pp. 146-7). Presumably Dr Vernon does not intend to imply
that a man receives a quarter of his bulk, his mass, from each parent. Extension
and weight are derived wholly from nutriment. We must go back, therefore,
as always in the study of heredity, to the germ-plasm, or rather to its hereditary
potentialities. If I understand Dr Vernon aright, he accepts the theory of discrete
ancestral units which are halved and quartered and so on in the germ-plasm, but
thinks that all ancestral units, at any rate all units that have come into existence
since man evolved, are much alike — i.e. he thinks that, apart from the potency
due to bulk, units differ only in comparatively^insignificant details ; just as men
are alike in being men, but differ inasmuch as they vary somewhat from one another.
The hand is a character " proper to the species, Homo Sapiens, as such." Is it
then contended that the child derives one-quarter of his tendency to develop
that organ under the stimuli of nutrition and use from each parent, one-sixteenth
from each grandparent, and so on ? The theory of Ancestral Inheritance assumes
that the influence of an ancestor eleven generations back is on the average more
than a billion times weaker than that of parent. But the character of a particular,

THE REDUCTION DIVISION 131

217. The hypothesis that ancestral contributions are halved in
every generation is a deduction from Galton's (and other) statistics,
and from the circumstance that a ' reduction ' division occurs in
the germ-tract. So much has been made of the reduction division
that it is necessary to consider it. It commonly happens that when
cells are about to multiply by self-division the ' chromatin ' of each
nucleus gathers into 'rods' or masses termed chromosomes, the
number of which is definite for each species. " Thus in man we
find 32, in a mouse 24, in a donkey 36, in a cockroach 32, in Ascaris
megalocephala^ var. univalens, 2 ; var. bivalens,4, and so on in different
organisms."! In ordinary cell division the chromosomes split, each
half from each chromosome forming a new chromosome which passes
to one of the daughter cells. The division of the cells thus extends
to a minute division of the structures within them. In this way the
normal number of the chromosomes is preserved. But when the
cells of the germ-tract are about to produce actual germs fit for
conjugation, the chromosomes do not split. In the case of sperms,
half of them pass as entire bodies to each daughter cell, which thus
receives only half the normal number of chromosomes. This is
the * reduction' division. A second division in which the chromo-
somes split, results in four cells, each of which, possessing half the
usual number of chromosomes, becomes a spermatozoon. In the
case of the ovum, four cells are not formed ; when the reduction
division occurs, one-half of the total number of chromosomes are
cast out of the cell in a ' polar ' body, leaving almost the whole of
the cell-body to the remaining chromosomes. At the next division
the reduced number of chromosomes split as in ordinary cell-
division ; but one-half of the product is again cast out of the cell
as a second polar body, leaving the ripened ovum, like the ripened
sperm, with only one-half of the normal number of chromosomes.
Therefore the divisions which result in four cells in the case of the
sperms, result only in one in the case of the ova.

218. An obvious interpretation of these phenomena is that
reduction implies nothing more than a preparation for conjugation ;
for, if the number of chromosomes were not reduced to half, they
would be doubled in each generation when sperm united with ovum,

for example albino, ancestor more remote than the eleventh may be reproduced
by offspring to the exclusion of the character of more recent ancestors. His
' unit,' therefore, must be strong enough to direct development. Must we
assume, therefore, that the germ-plasm is compounded of millions or billions of
units, the more modern of which are millions or billions of times more potent than
is necessary for the reproduction of a character ?
1 C. E. Walker, The Essentials of Cytology, p. 21.

1 3 2 RETROGRESSION

and this process would continue indefinitely. An obvious interpre-
tation of the occurrence of polar bodies is that they are abortive
cells — abortive because the ovum has retained almost the whole
of the cell-body and the contained food, for lack of which the
polar bodies perish. Neither of these interpretations can be tested ;
they are, from the nature of the case, merely working hypotheses.
In science guesses should be avoided if possible; but, at any
rate, the guess that the extension of the polar bodies is a
mere detail in the preparation of the ovum for conjugation is
at least as likely to be correct as the guess that reduction
implies a halving of ancestral contributions. Moreover, when uni-
cellular organisms unite, mixing their nuclei but not their cyto-
plasm, as happens in some cases, there is no extrusion and death
of polar bodies. The notion that polar bodies are merely cells
which perish from lack of cytoplasm and nutriment is supported,
besides, by the fact that, before disintegrating, their chromosomes
usually multiply by splitting as in ordinary cell-division. Probably,
therefore, extrusion and death are not essential parts of the process,
but only the means by which a double or quadruple supply of
nutriment is conferred on the ovum wherewith to start the new
cell-community. However, as we see, reduction has been held to
indicate a halving of ancestral contributions — an enormous but
untestable deduction.

219. On the other hand, suppose by an ' ancestral contribution'
is meant, not a unit representing an ancestor in the germ-plasm
and added to it by him, but a variation which has occurred in it
at the time he came into existence. Then, since each individual,
on the average, contributes a quarter of the heritage of his child,
we must suppose that he varied from his parents to the extent of one-
quarter of the sum of his characters. His parents did the same,
and so does the child. Therefore, on the average, the child varies
to the extent of three-quarters from its great-grandparents. But
were this true of all characters, so rapid would be the rate of racial
change, that a human being, for example, would become non-
human in three generations. If it be argued that the variations
of the individual from his parent do not imply variations from
remote progenitors, then how are the several 'contributions'
to be distinguished from one another ? How is it known that, on
the average, each parent contributes a quarter, each great-grand-
parent a sixteenth, and so on ?

220. The immense rate of change indicated by Galton's
statistics is due apparently to the fact that he investigated only

BIOMETRY 133

variable characters in very variable species. He himself terms the
chosen characters ' moderately exceptional.' l Bassett hounds
were established very recently, and display the variability of new
types. In many characters human beings display the variability
which follows cessation of selection. The reproduction of coat-
colour in the lower animals, and of eye-colour in men, tends to be
1 alternative.' 2 Probably human stature has never been very rigidly
fixed by Natural Selection, and variability has been influenced, in
England at any rate, by a great intermixture of races. Artistic
faculty and health are not only very variable, but develop under
the influence of an environment which, as regards these characters,
is very varied.3

221. Not until ancient, stable, non-exceptional characters, for
example heart, lungs, and the like, have been investigated shall we
be in a position to formulate or perceive the impossibility of
formulating a numerical Law of Ancestral Heredity (i.e. to indicate
the average rate of reversion). When that is done, I think it will
be admitted that variability, including the tendency to reversion,
is an adaptation regulated by Natural Selection, and, therefore,
that the degree of variability differs with the stringency of Natural
Selection in every species and character. I think, also, that it will
then be admitted that the true Law of Ancestral Heredity is
formulated when we declare that, In any character the tendency
to retrogression (i.e. reversion to ancestors} is proportionate^ on the
average^ to the speed of the antecedent progression.

222. The Law of Ancestral Inheritance is an example of the
biometric and statistical method of inquiry. As a method biometry
is, of course, like experiment, excellent. It enables the patient
worker to gather many obscured truths which, but for it, would
lie beyond our reach. But it is extraordinarily slow and laborious,
and, like experiment, has its limitations as a means of discovery
and as a test of thinking. So many biological facts are patent, and
so much biological thinking can be tested by reference to this patent
evidence that, apparently, it has been difficult to find subjects
suitable for biometric inquiry, except when the patent evidence
is ignored. Occasionally, therefore, such inquiry has been directed
to the discovery of matters already known, or which can be made
known at a thousandth part of the labour involved and with an
even greater degree of certainty. Inferences founded on materials
furnished by biometry require to be tested as carefully as any other ;
but, as in experiment, the two functions of discovery and testing

* Natural Inheritance, p. i. * See §§ 239, 277, 278. 3 See chapter xxii.

134 RETROGRESSION

are, apparently, frequently confused, and thoughts are claimed
as accurate merely because they are based on, not tested by,
statistical data.

223. In the Law of Ancestral Inheritance we have an instance
of an induction expanded, but not tested by a deduction, the latter
being regarded as the theory. Here the induction is that, on the
average, offspring resemble ancestors (at any rate in certain characters
and within three or four generations) in the stated degrees. The
deduction — the really tremendous expansion of the induction — is
that ancestors contribute in the stated degrees to the heritages of
descendants. Though the universe is a unity, the facts and ' laws '
of which are in harmony with one another, and it is the mission of
science not only to interpret the facts in terms of the laws but also
to demonstrate the relations between the latter, no appeal is made
to any conceived system of reality. The axiom that every induc-
tion must be used as a basis for a rigorous deductive inference of
consequences is disregarded. In other words the correctness of the
thinking, as distinguished from the facts, is left untested.

224. The law evidently bears on the theory of the Continuity
of the Germ-plasm, which supposes that the parents and ancestors
of the individual contribute nothing to the child, and on the theory
of Recapitulation, which supposes that ancestors are represented
during development, not en masse> but serially ; but no attempt is
made to show that it accords with these hypotheses, or, if it does
not, in what respects they are wrong. It remains as apart from
anything else that is known or that has been surmised by science
concerning living beings as a miracle.

225. The Law of Filial Regression furnishes another instance of
biometric work. It has been ascertained that when a group of
parents differs in any particular from the mean or average (medio-
crity) of their race, the offspring on the average differ less, grand-
children still less, and so on. In other words, if a group (or
individual) in any generation differs from the racial mean, its (or
his) predecessors and successors will, as a rule, be found less
different. "Thus take fathers of stature 72", the mean height
of their sons is /O'S", or we have a regression towards the mean
of the general population. . . . The father with a great excess of
the character contributes sons with an excess, but a less excess of
it ; the father with a great defect of the character contributes sons
with a defect, but less defect of it. The general result is a sensible
stability of type and variation from generation to generation. . . .
Now a man is not only the product of his father, but of all his

RETROGRESSION AND REGRESSION 135

past ancestry, and unless very careful selection has taken place,
the mean of that ancestry is probably not far from that of the
general population." 1 The induction here is that there exists a
tendency for exceptional groups to return towards mediocrity
unless Natural Selection interferes. The deduction is that on
cessation of selection the race or species tends to remain stable.
But when we appeal to reality the evidence is massive that cessa-
sion of selection results in retrogression. Here again no attempt
is made to demonstrate that the Laws of Regression and Retro-
gression are in accord, or, if not in accord, in what particular the
latter is wrong. The truth appears to be that, though regression
results in a levelling up to the specific mean as well as a levelling
down to it, yet, in a degree that varies in different species and
characters according to the rapidity of the antecedent progression,
the tendency to level down is somewhat greater than the tendency
to level up. The point aimed at is not the specific mean, but below
it. Consequently this point tends continually to fall unless
rendered stable or raised by selection. Therefore regression is but
the first phase of retrogression. As a rule, however, the latter
proceeds so slowly, by such imperceptible gradations, that its
detection is far beyond the reach of the laboratory, which can
examine, at most, only a few generations.

226. Formerly some men of science maintained that Natural
Selection had no real existence, or at least had not been de-
monstrated. Natural Selection implies a selective mortality, which
our acquaintance with the lives of wild plants and animals is not
sufficiently intimate to prove. It was shown, however, that
stringent and unmistakable selection occurs amongst all races of
human beings, the only * wild ' types which we are in a position to
observe with the requisite degree of thoroughness.2 In England, for
example, we are being selected by tuberculosis and other maladies ;
in Africa, malaria plays the same part ; in India dysentery, and so
forth. The immediate result is that individuals weak against any
lethal disease are weeded out wherever it is present. The remote
result is that every race is resistant to every disease in proportion to
the length and severity of its past experience of it. Therefore the
evidence of Natural Selection followed by evolution is plain and

1 Pearson, Grammar of Science (Ed. 1900), p. 456.

z See The Present Evolution of Man, 1896. The common notion that man is
not a ' wild ' or natural type is, of course, nonsense. He is not under the care
of and has not been artificially selected by any other type. Civilization has
altered the conditions under which he lives, and therefore the incidence of
selection and the direction of evolution, but that is all. It has not altered the
' laws ' of heredity for him.

136 RETROGRESSION

unmistakable. Besides the data which each person is able to verify
for himself, and which therefore is especially valuable scientifically
to him, a vast volume of very precise and detailed statistical infor-
mation relating to almost every human race and disease has been
published by all the Departments of Public Health in both hemi-
spheres. Presumably, if selection followed by evolution occurs
amongst men, it occurs amongst plants and lower animals. At
any rate, if it occurs amongst men, the inference that it occurs and
has occurred amongst other species is at least as likely to be true
as if drawn from a demonstration of its occurrence amongst some
other type of animal or plant.

227. Such, however, has been the passion for obscured facts
that this patent evidence has been ignored. Laborious laboratory
inquiries which extended over several years have been undertaken
to demonstrate the actual occurrence of Natural Selection.
Doubtless they satisfied the workers, but they were declared by
opponents to be invalid on the ground that natural conditions
were not accurately reproduced. Even by adherents of Natural
Selection they are declared to be "at present not absolutely
convincing." 1 Of all the statistical evidence, the best is thought
to be that collected by Bumpus in America.2 After a severe snow-
storm one hundred and thirty-six stricken sparrows were gathered,
of which seventy-two revived, while sixty-four perished. Bumpus,
after making careful measurements, concluded that "Natural
Selection is most destructive to those birds which have departed
most from the ideal type, and its activity raises the general standard
of excellence by favouring those birds which approach the structural
ideal." What precisely is the structural ideal is of course a matter
of opinion. It is at least possible that the birds which survived
possessed a superior power of resisting cold and hardship, and that
this power is not correlated to any of the dimensions — length of
head, beak, and so forth — that Bumpus was able to measure.
Compare the volume, precision, and relevancy of this evidence with
that concerning disease gathered by simple observation, and more
especially with that stored by Departments of Public Health.
Compare also the relative difficulty of demonstrating the connec-
tion between cause and effect in the two instances.

228. Biometricians have also sought to demonstrate that human
mental ' ability ' and powers of resisting disease are ' inheritable.'
They admit that the human species has arisen by evolution from

1 Vernon, Variations in Animals and Plants, p. 337.
8 Biological Lectures, p. 211.

NECESSARY TRUTHS 137

a lower type, and that the offspring of human beings are also
human ; that is to say, that human beings tend to reproduce
parental characteristics. It is likewise a patent truth that
man has more intellectual ' ability ' than any lower animal,
and another that some human races, those that have suffered most,
are more resistant to disease than others. At least, all these truths,
however ignored in the laboratory, are universally believed. Again,
it is a patent truth that a species or race is merely an aggregate of
related individuals, whence it follows that if one generation of a
species or race tends to transmit its characters to the next, then
individuals must tend to transmit their characters also. Conse-
quently it is inconceivable that human ability and powers of
resisting disease can have been evolved unless the paternal
characteristics, including variations, in these respects tended to be
inherited. Given the evolution, the general tendency to inherit
degrees of capacity is a necessary corollary which hardly needs
biometric confirmation. Here, as always, we create much better
science when we deduce one truth as a necessary corollary from
another (i.e. when we link the two truths together by a chain of
causation) than when we state them separately as isolated facts or
hypotheses.1 This unnecessary isolation of hypotheses is a principal
feature and fault of nearly all laboratory work. Science describes
nature ; and nature is a unity in which nothing is isolated. More-
over we have no means of estimating the ability of individuals
except by noting the degree of intelligence observable, and, as we
shall see later, intelligence depends largely on mental training, on
education, which differs greatly in different classes and races and
cannot be estimated in the laboratory. We have no means of
estimating resisting power to disease except by observing the degree
of resistance displayed under conditions of food, general health,
intensity of exposure to disease, and the like, all of which may vary
with time and place and are also outside the range of the
laboratory.

229. Similarly biometricians have sought to demonstrate that
individual degrees of fertility in men and horses tend to be
transmissible. But how, unless we presuppose some recent and
extraordinary change in nature, is the contrary conceivable ?
Manifestly the relative fertility of species (groups of related
individuals) is an adaptation, a product of evolution, which could
not have arisen unless the variations, the peculiarities, of individuals
had tended to be inherited by offspring. The degree of fertility
1 See §§75 (footnote), 352 (footnote).

138 RETROGRESSION

differs in different species, but always bears a close relation to
the number of offspring which it is possible to rear. Plants and
low animals, whose characters are developed wholly or almost
wholly under the stimulus of nutriment, do not protect nor train
their young, which are able to fend for themselves from the first.
Therefore their offspring may number millions. The physical and
mental characters of the higher animals are developed largely
under the stimulus of use ; the individual is born more or less
helpless, and must be protected and trained during development.
Therefore the number of offspring that can be reared is very small
compared to that in the lower types. Everywhere we find an
adaptation as regards fertility which would have been impossible
unless individual peculiarities in fertility had been transmissible
and had thus afforded materials for Natural Selection. It is said
sometimes that, throughout nature, intelligence and fertility are in
inverse ratio to each other. This is true ; but not for the reason
alleged — that they are fundamentally antagonistic to one another.
It is true only because intelligence has to be trained.1 The greater
the intelligence achievable by an animal, the more helpless it is at
birth and the more prolonged and strenuous must be its preliminary
training by its parents. Therefore, since intelligent animals are
able to protect and train only a few offspring, parsimonious nature
has rigorously limited the number of the latter. In the case of
man, as proved in the laboratory and more massively by Registrar-
Generals and the officials that correspond to them in foreign countries,
there are considerable differences in fecundity — in the number
of offspring actually produced as distinct from the number which
might be produced — between races and classes. This may indicate
differences in fertility ; but before the question can be decided, we
must pass, as in the cases of ' ability ' and resisting power to disease,
outside the laboratory and inquire into a multitude of circumstances,
such as the customs of the people, average age at marriage, religion,
morality, sanitation and general health, physiological knowledge,
desire for large or small families, and the like. Unless these are
considered, every deduction concerning human fertility which
expands an induction that was reached through a statistical con-
sideration of fecundity is illegitimate.

230. Numerous biometric studies of variability have been pub-
lished. In each case various characters in a number of individuals
(the more the better) of the same race have been measured and
the dimensions tabulated. In this way a very considerable

1 See § 624.

VARIABILITY 139

knowledge of the variability of certain characters in certain races
has been obtained — that is, a knowledge of the range within the
limits of which variations normally occur, the relative frequency of
each degree of deviation from the mode (the most common type),
and the degree in which the deviations of various characters tend
to be correlated with one another. Such knowledge is gathered
only at great expense of time and patience. It can, as a rule,
include only the variations of the fittest (the survivors), and never
more than a very few measurements in a very few animals and
plants. It may, of course, like knowledge of any other facts, prove
very useful. But curiously little effort has been made to use it,
to interpret it, to link it up with laws, with uniformities of causation.
Apparently the result, such as it is, of each inquiry has been held
to justify the labour. As far as I am able to judge, however, the
biometric evidence concerning variability is valuable chiefly for
the light it sheds on, and the support it affords to the hypothesis
that variations are both c spontaneous ' and under the control of
Natural Selection. It demonstrates that variations tend to occur
about equally about the specific mean, the plus and minus
variations of every dimension of a character being of nearly equal
frequency and magnitude ; material thus being afforded which
enables Natural Selection to meet every contingency. Again,
while all characters vary, large variations which tend to ruin the
co-adaptation of the parts of the organism are rarer than smaller
variations and most rare in the case of characters in which the
co-adaptation to the parts needs to^be very close ; thus the squirrel's
head and forefoot vary less widely in proportion as regards length
than the tail. Yet again, when characters are functionally corre-
lated, the variations tend to be correlated also ; thus if the length
of a bone in a man's arm is greater or less than the average, it is
more likely that the other bones in his arm will be correspondingly
long than that his teeth, nose, or beard will be so. If the Bathmic,
or the Lamarckian doctrine, or the hypotheses that variations are
commonly caused by the direct action of the germ's environment
were any of them true, variations would not be grouped about the
specific mean, but would all be in one direction or at least would
strongly preponderate in it. If variability were a * fundamental '
property of living beings, uncontrollable by Natural Selection, all
characters should be equally variable. At any rate small variations
should not so considerably and universally preponderate in closely,
as compared to less closely, co-adapted parts. This last hypothesis,
however, is even more decisively negatived by the fact that the

140 RETROGRESSION

lengthening of the germ-tract, the increase in the number of cell-
generations which occurs when plants are propagated by slips,
does not result in an appreciable difference in the number and
range of variations, as it would if variability were a fundamental
character beyond the control of natural selection, and occurring,
therefore, all along the germ-tract.

231. To sum up: the biometric method, as employed by many
of its exponents, suffers from the same defect as the experimental
method. Very often no facts other than those revealed by a
particular inquiry are taken into account, though many may be
available ; and, therefore, inferences from the evidence are left not
only isolated, but untested. The science created depends alto-
gether on a simple enumeration of instances, not on a knowledge
of causes. " But in estimating probabilities, it is not a matter of
indifference from which of these two sources we derive our
assurance. The probability of events as calculated from their
mere frequency in past experience affords a less secure basis for
practical guidance than their probability as deduced from an
equally accurate knowledge of the frequency of occurrence of
their causes."1 Not seldom in biometric inquiries — as in the
case of those inquiries about disease and fertility which we
have just examined — several scores or hundreds of observers
and thinkers are employed for years in ascertaining, with a
much lesser degree of certainty, that which a single thinker may
deduce in two minutes from known and admitted truths. " These
are but samples of the errors frequently committed by men who,
having made themselves familiar with the difficult formulae which
algebra affords for the estimation of chances under suppositions of
a complex character, like better to employ those formulae in
computing what are the probabilities to a person half informed
about a case, than to look out for means of being better informed.
Before applying the doctrine of chances to any scientific purpose,
the foundation must be laid for an evaluation of the chances, by
possessing ourselves of the utmost attainable amount of positive
knowledge." 2 Experimental observers, whose evidence we shall
consider next, have formulated hypotheses which have seemed
fundamentally wrong to biometricians. The latter, or some of
them, were induced to employ their method mainly, I believe, in
order to demonstrate the erroneousness of the conclusions reached
by their opponents. But, if these conclusions are mistaken, and
I think there are entirely conclusive grounds for believing that

1 Mill, Logic, III. xviii. 4 a Op. cit., III. xviii. 4.

BIOMETRY AND EXPERIMENT

141

they are mistaken, the truth would have been all the more
thoroughly proved had a completer use been made of the biometric
data — had the biometric conclusions (of which the principal is the
hypothesis that evolution is founded on small variations, * fluctua-
tions ' as they are called, not on mutations or sports) been linked
up with and tested by conclusions which are disputed by nobody
and are founded on facts, also undisputed, gathered by simple
observation.

CHAPTER VII
MENDEL'S LAWS

Sexual dimorphism — Cross-fertilization — Parthenogenesis — Self-fertilization —
The effect of conjugation — Sex an adaptation — Sexual characters — Alternative
and blended inheritance — Theories of the function of sex — The theory of continuous
evolution — The theory of discontinuous evolution — The Mendelian theory —
Dominance and recessiveness — Unit segregation and gametic purity — Exceptions
to the Mendelian doctrine — Latency, temporary and permanent — Compound
allelomorphs — Interpretations of Mendelian phenomena.

T

232. f | ^HE higher animals are all dimorphic, that is, each
species is divided into two groups which differ widely
in physical and mental characters. In the one group
are the males ; in the other, the females. Obviously, the sexual
differentiation is connected with reproduction. The mental
peculiarities of the two sexes are such as to impel to a series of
actions which eventually result in a union of sperm with ovum
under conditions advantageous to the development of the future
cell-community, to which end also the physical characteristics of
the parents are fitted. In all species the physical and mental
sexual characters furnish beautiful examples of co-adaptation.

233. Reproduction through the union of germs from two dis-
tinct individuals is so familiar that we are apt to accept it as
' natural ' and so dismiss it from our thoughts. Conjugation, how-
ever, is not a necessary antecedent of reproduction. Even in the
higher animals it occurs only once — when sperm and ovum con-
jugate— during the production of the millions or the billions of the
cell-community. The somatic cells never conjugate, and the
germ-cells only when a new cell-community is about to be pro-
duced, and then, in most cases, only with a cell from another body.
In the case of some plants and animals, for instance Cypris reptans
reproduction is apparently entirely parthenogenetic, no males
having ever been observed. Since these organisms retain their
sexual organs, they are, of course, descended from types in which
reproduction was, at least, sometimes preceded by conjugation.
In aphides reproduction is parthenogenetic during warm weather
when food is plentiful, but the winter eggs are fertilized, Queen

142

SPERMS AND OVA 143

and worker bees are derived from fertilized, drones from unfertil-
ized eggs. There are thus gradations between complete partheno-
genesis and conjugation occurring at the start of every cell-
community. The reproduction of unicellular forms has been
imperfectly studied. Possibly in some, or many, or most cases
conjugation never occurs. Even where it has been noted there are
always long intervals of asexual multiplication. In paramcecium,
for example, at lengthy but seemingly more or less fixed intervals,
conjugant individuals appear which differ somewhat from the rest
of the population in appearance. They correspond to the germ-
cells of multicellular organisms, and their descendants, which
intervene between one act of conjugation and the next, to the
generations of the cell-community.1

234. The ovum is usually a large and passive cell, more or less
laden with nutriment for the earliest needs of the new cell-com-
munity. The sperm is small and mobile, and is thus enabled to
reach and penetrate the ovum. But, as already noted,2 we have
every reason to believe that these differences of size, shape, and
function imply nothing as far as the germ-plasm is concerned.
Apparently the germ-plasm used in fertilization is situated wholly,
or almost wholly in the nuclei of the sex-cells, and the nuclei of
sperm and ovum seem equivalent as bearers of heredity. In most
cases, conjugating sperms and ova are derived from distinct cell-
communities of the same variety. Conjugation between the sex-
cells of distinct species, and in a lesser degree of distinct varieties,
is hindered or prevented by physical or physiological incapacity,3
and, in the case of the higher animals, by mental disinclination
as well. On the other hand, nature has elaborated many
devices to prevent conjugation between the germs of the same
individual.

235. In most animal species only sperms or ova are produced
by the same individual. Some low animals, however, for example
snails and earth-worms, and many plants are hermaphrodite,
possessing male and female organs of generation, and producing
both sperms and ova. In such cases, self-fertilization is prevented
by the ripening of the sperms and ova at different periods, or in
other ways. The prevention is usually less perfect in the case of
plants than of animals, so that in the former case self-fertiliza-

1 See § i. 2 See § 2.

3 Physical disability prevents, for example, a very large dog mating with a
very small one. Physiological disability renders mating sterile. In the latter
case the sperms do not fertilize the ova, or, as is probable in some cases, the
embryos do not develop beyond a very early stage.

144 MENDEL'S LAWS

tion may more often alternate with cross-fertilization. Some
plants, and some plant-like marine animals are normally self-
fertilized.1 Thus there are connecting links between constant
cross- and constant self-fertilization.

236. The normal effect of conjugation, then, is to mix, with
a degree of intimacy which is in dispute, two germ-plasms which
on the whole resemble one another somewhat closely, but which
differ in details. The difference is greatest when individuals of
different species cross, and least when there is self-fertilization.
Indeed, self-fertilization is an approach to parthenogenesis in
which there is no mixture. Another approach is the alternation
of parthenogenesis with conjugation as in aphides. Plainly, then,
conjugation is not an essential part of reproduction, which may
and does occur without it. Indeed it is precisely the partheno-
genetic types that reproduce most rapidly. But it is an accom-
paniment of reproduction so nearly universal that we have reason
to believe that it must possess some extremely important function.
Presumably it is an adaptation which, like other adaptations, has
been created and maintained by Natural Selection — an adaptation
so vastly useful that, to attain it, most multicellular species have
become dimorphic and have evolved all the manifold physical and
mental peculiarities of sex, including the keenest and fiercest of
instincts, so useful that to possess it the possible number of
offspring has been halved, since two individuals instead of one
are necessary to the production of each child.2 Thus great advan-
tages are lost for the sake of what is probably a greater.

237. The function of sex (of conjugation, of the mixing of
germ-plasms) has been, especially of recent years, one of the most
widely and acrimoniously debated of all the problems of heredity.
Too often in these discussions has the great probability that sex
is an adaptation, and, therefore, like other adaptations, a product
of Natural Selection, been ignored. Sex is so widespread and is
served by so many and such diverse physical and mental characters,
that to doubt that it has utility, to suppose it is a mere chance
accompaniment of life, is the very madness of scepticism. No
theory of sex is likely to be true that assigns to it a non-adaptive
function. What, then, is the function of sex ? In what way is it
useful? How does it serve to adapt species to their environ-
ments ? Moreover, how is it that some types are cross-fertilized,
others self-fertilized, and others parthenogenetic, while yet others
exhibit gradations between cross-fertilization, occurring regu-

1 Origin of Species, p. 123. * See § 336.

INHERITANCE AND REPRODUCTION 145

larly at the genesis of every cell-community, and complete
parthenogenesis ?

238. Before we attempt to solve the problem of sex we must
study for a space the phenomena of ' inheritance.' When repro-
duction is parthenogenetic, offspring reproduce parental characters
with variations. When two parents are concerned in reproduction
the process is more complicated. In sexually dimorphic species
the two parents resemble one another closely in some particulars,
for example in blood, muscles, glands, heart, lungs, liver, nerves,
and the like. In others, the sexual characters, they differ much
more widely. The child, being male or female, develops only one
set of the sexual characters. The other set, however, is not
wholly absent. Its items are merely rudimentary or latent. The
male breasts in man are examples of rudimentary organs. Of
latency there is unlimited evidence : for example, female birds
have been known in old age to develop the plumage of the
opposite sex ; elderly women occasionally develop to some extent
beards and moustaches ; haemophilia and colour-blindness, which
are usually male characters, are transmitted through daughters to
grandsons, and the good milking qualities of cows through sons to
granddaughters ; the female characters of bees are apparently
transmitted through the drones, and the male characters through
the queens ; doubtless, however, both sets of characters are
transmitted through both sexes. The male characters of aphides
are transmitted through a long series of pathenogenetic females.
This form of reproduction, in which one only of two possible
characters, or sets of characters, is developed, is termed
' alternative.'

239. The development (not inheritance, for both sets are
' inherited ' ) of the sexual characters, then, is alternative. But the
term * sexual ' must be given a wide meaning. It applies not only
to those primary differences of shape and function which are
directly concerned in reproduction, but also to those secondary
peculiarities of shape, colour, scent, and the like which, being
mostly on the surface of the body, and therefore observable, serve
as sexual attractions, as well as to the other physical and mental
peculiarities which distinguish the sexes. Most of the sexual
characters tend to hang together in sets, a male set and a female
set ; but some characters, which are sexual in the sense that their
function, in whole or part, is to attract the opposite sex, occur in both
sexes ; for example in human beings the mane on the scalp and the
coloration of the hair, skin, and eyes. But even in the case of those

10

146 MENDEL'S LAWS

characters which are common to both sexes and which may have
other functions besides sexual attraction, development tends to be
alternative. Thus the child of parents, one of whom has blue eyes
and the other hazel, usually has blue eyes or hazel eyes, never eyes
that are a blend between blue and hazel. So too, in a lesser degree,
children sometimes reproduce the colour and texture of hair of
one parent, and to a still lesser degree the colour of the skin.

240. Obviously the alternative development of the sexual
characters is an adaptation, a product of evolution. It is a device
by which cross-fertilization is secured. Though evolution has
caused most of the sexual characters to hang together in sets, yet
the separation of male and female characters is not always strictly
preserved. Occasionally a character, usually distinctive of one
sex, is found in an individual of the opposite sex. Thus, a man
may possess well-developed female breasts, or a woman a full
beard. Sometimes the male and female characters may be found so
intermixed, as for example in the so-called human hermaphrodites,1
that an individual of one sex may present every external appear-
ance of belonging to the other. Or the male and female characters,
instead of being inherited alternatively, may blend in varying
degrees — as when a woman is partially bearded or has a mascu-
line pelvis.

241. Selection, natural and sexual, however, must always have
tended to eliminate these abnormalities and so preserve the purity
of the sexual characters, their alternative development, and their
aggregation in distinct sets. Selection is, of course, more stringent
as regards the primary sexual characters, which are the more
essential part of the machinery of reproduction, than as regards
the secondary characters. Consequently blending or displacement
from the set in which they are normally found is rarer in the case
of the former than the latter. Thus men may have female breasts and
women beards, but never, as far as I am aware, have testes been
found associated with a uterus. By artificial selection man has
more than once succeeded in transferring secondary sexual char-
acters from one sex to the other. Thus formerly only the female
Polish fowl had the domed skull and cerebral hernia which now
characterizes both sexes,2 and the male Sebright bantam has the

1 A real hermaphrodite is an individual in whom both sets of sexual characters,
the male and the female, are patent; for example, snails and most flowering
plants. A ' so-called ' hermaphrodite is an individual in whom the male and
female characters have blended, or one in whom some male and some female
characters are patent.

2 Animals and Plants, vol. i. p. 269.

THE FUNCTION OF CONJUGATION 147

same hackles, saddle, and stickle feathers as the female. " Conse-
quently the tail is short and truncate as in a hen."

242. Manifestly the differentiation and the alternative develop-
ment of the sexual characters is not in itself an end. A male has
patent one set of characters and a female another, and males and
females are reproduced alternatively, not because the individual is
thereby brought into closer adaptation to the general environment
and his or her life more surely preserved, but to afford facilities for
mixing the germ-plasm, a process which, for some reason, we have
yet to discuss and if possible discover is of advantage to the
species. Therefore it is likely that the sexual characters have
come into existence because the non-sexual characters are, in some
way, beneficially affected by the intermixture of the parental
germ-plasms. When, therefore, we have discovered how the non-
sexual traits are thus usefully affected by conjugation, we shall
have discovered the function of sex.

243. Formerly, because, in the higher animals, young individuals
come into existence only after acts of conjugation, the 'obvious
inference' was drawn that the function of sex is to invigorate,
revitalize, or rejuvenate aged and debilitated germ-plasms. But,
as indicated by Weismann, it is difficult to understand how the
union of two outworn and enfeebled things can result in rejuve-
nescence. Moreover, parthenogenetic species, and plants which are
propagated by slips, retain their vitality perfectly.

244. Next Weismann, followed by the majority of biologists,
believed that the special function of the intermixture of somewhat
dissimilar germ-plasms which occurs in conjugation is to provide
the spontaneous variations which are the materials on which
Natural Selection works, He concluded consequently that
parthenogenetic species vary little if at all, and, therefore, are
incapable of adapting themselves to changes in the environment.
He supposed that they secured survival, not by close adaptation
but only by a very rapid rate of reproduction. But rapid repro-
duction is an adaptation which can have arisen only through the
Natural Selection of favourable variations. Therefore variations
must have occurred even after conjugation was abandoned. Besides,
it has been proved directly that he was mistaken. Variations
occur in abundance when reproduction is parthenogenetic. Thus
Weismann himself discovered evidence of variations occurring
in the absence of sexual reproduction,1 and as a result of a
biometric inquiry conducted on the parthenogenetic Daphnia

1 The Germ-Plasm, Eng. Trans., pp. 344-6.

148 MENDEL'S LAWS

magna, Dr E. Warren found " on measuring the offspring it was
obvious that the children of the same brood exhibited considerable
variability." 1 A more extended inquiry on Aphides led him to
suppose, however, that variability in asexual reproduction, though
considerable, is less than when offspring have two parents. We
shall see that this relative paucity of variations is due, probably,
to a comparative lack of retrogressive variations. Lastly, it is a
well-established fact that parthenogenetic species, for example
dandelions and hawkweeds, are particularly rich in varieties, a fact
implying abundant variations.2

245. Variability, then, can occur apart from conjugation. We
saw that the evidence is strong that spontaneous variability is an
adaptation controlled and maintained by Natural Selection, on
which account every species and organ tends to be variable in the
right degree.3 The least variable types and structures are those
which are closely adapted to the environment by stringent selection.
The more variable types and structures are those which are less
closely adapted and in which therefore variability is encouraged by
Natural Selection, or those which are not stringently selected for
the reason that very close adaptation is not necessary. Thus men
and garden plants are exceptionally variable because they are so
circumstanced that individuals that have varied largely, for
example in colour, have survived in considerable numbers and
have transmitted their increased variability to descendants. Thus
again the squirrel's tail is more variable than its head and forefoot
because there is a greater need for close adaptation in the latter.
Since, then, spontaneous variations occur in parthenogenetic
reproduction, the materials are present for the work of Natural
Selection, and that agency is able to increase or decrease the
variability of the species to any useful extent. Bi-parental repro-
duction is not necessary for the purpose ; and it is, at the very
least, most improbable that species can have been burdened with
sex to produce that which was already present, and which,
apparently, is kept within bounds only by selection. Undoubtedly,

1 Proc. Roy. Soc. London, 1899, vol. Ixii. p. 154.

8 See De Vries, Species and Varieties, pp. 59-61. " Thousands of forms (of
dandelion and hawkweed) may be cultivated side by side in the Botanical Gardens
and exhibit slight but undoubted differentiating features, and reproduce them-
selves truly." I follow De Vries in supposing that dandelions and hawkweeds
are parthenogenetic. I know nothing of the matter personally. There seems,
however, to be some doubt (see Bateson, Mendel's Principles of Heredity, p. 247).
At any rate it appears clear that these plants, if they do conjugate, do so com-
paratively rarely.

3 See § 163.

ALTERNATION AND BLENDING 149

therefore, Professer Karl Pearson is right in declaring that " Varia-
bility is not a product of bi-parental inheritance ; . . . whatever be
the physiological function of sex in evolution, it is not the
production of greater variability." 1

246. At the present day I think most biologists who have
given any thought to the question believe that the function of sex
is (through the mixing of germ-plasms) to mix the parental
qualities. There are, however, great differences of opinion as to the
nature and effect of this mixing, Suppose a man with black eyes
and six digits on each hand mates with a woman with blue eyes
and the normal number of digits ; then experience demonstrates that
each of the descendants of such a pair will have black eyes or blue
eyes (or perhaps grey or hazel eyes, as in some ancestor) : never,
or hardly ever, eyes that are intermediate ; and six digits or five
digits, not five and a half digits. But one or more of the children
may develop the father's eyes in combination with the mother's
hands, or the mother's eyes with the father's hands. In such a
child the parental characters are mixed ; but they are mixed as
black and blue marbles in a bag, not as black and blue colours
are blended on a painter's palate. On the other hand, the offspring
of a white man and a negress actually does blend the parental skin
colours ; the descendants are not black or white, but of a colour
that is more or less intermediate.

247. Here, then, we have two distinct types of ( inheritance,' the
alternative and the blended, both of which undoubtedly occur.
Since in the first type the father's or the mother's character is
reproduced, not a blend, and since the grandchild may have patent
the character which was latent in the parents, the resemblance to
the method by which the sexual characters are ' transmitted ' is
evident, the main difference being due to the fact that whereas the
various sexual characters tend strongly to hang together in distinct
patent or latent sets, the non-sexual characters, the reproduction
of which is alternative, tend to mix and so form new combinations.
Now the question we shall have to decide is whether the function

1 Grammar of Science, pp. 473-4, ed. 1900. In my work, The Principles of
Heredity (p. 49), I controverted Professor Pearson's statement, and pointed out
that a mulatto, for instance, the offspring of a white man and black woman,
varies from both parents in a definite way. I must now confess that I seem
to have mistaken Pearson's meaning. Conjugation is certainly a cause of some
variations, in that the offspring when they blend parental characters vary from
both .'parents. But variations and variability are different things. A partheno-
genetic species may be as variable or more variable than one the reproduction
of which is bi-parental.

ISO MENDEL'S LAWS

of sex is to mix non-sexual parental characters as colours are
blended, or to mix them as marbles are mixed. What, then, is the
rule in nature? Is blended ' inheritance' the normal for non-
sexual characters and alternative ' inheritance ' abnormal ? Or is
alternative ' inheritance ' the normal ? Or are they both normal in
the sense that nature has evolved both as adaptations — in the
sense that both have utility ? This question is being very sharply
debated at the present time. Formerly it was universally believed
— by Darwin for example — that offspring tend, as a rule, to blend
parental characters, and this view is now upheld by most biologists,
and in particular by the biometric or statistical school. The
experimental or ' Mendelian ' school, on the other hand, insist
that the non-sexual characters of parents are, as a rule, not blended
in offspring.1

248. Naturally these divergent views of heredity have led to,
or are associated with, equally divergent views of evolution.
Speaking generally, biometricians maintain that variation and
evolution are both continuous ; in other words, they suppose that
nature causes evolution by gradually and continuously raising the
specific mean through the selection of ' normal ' or ' fluctuating '
variations.

249. On the other hand, experimental workers, who are usually
c Mendelians ' and ' Mutationists,' insist that there are two distinct
kinds of variations, the continuous and the discontinuous. The
former, they maintain, fluctuate about a mean to which they tend
to return so strongly in succeeding generations, that they cannot
be made the foundation of permanent racial divergence by any
stringency of selection. In other words, they suppose that, owing

1 It is interesting to note how the different methods by which the rival schools
pursue their inquiries have tended to lead to divergent theories of heredity.
We shall see presently that blended ' inheritance ' is the rule when parents differ
comparatively little, that is, when their differences are of degree rather than
of kind ; and that alternative ' inheritance ' is the rule when parental differences
are greater, that is when they are of kind rather than of degree. The statis-
tician dealing with aggregates of individuals, and noting that even when parental
differences are great, offspring tend to ' regress ' towards the parental and specific
mean, is impressed by the fact that extreme plus and minus deviations from the
average type of the race are rare and are connected by lesser variations. He is
inclined, therefore, to lay stress on the truth that the vast majority of variations
are ' continuous,' and to believe that offspring tend, as a rule, to blend parental
characters. The experimental worker, on the other hand, deals with individuals
more than with aggregates, and naturally chooses as materials for study sharply
contrasted parental qualities, the inheritance of which can be more easily observed
in offspring than mere shades of difference. He tends, therefore, to lay stress on
' discontinuous ' variations, and to believe that alternative inheritance is the rule.

FLUCTUATIONS AND MUTATIONS 151

to the tendency to reversion, or rather regression, these fluctuating
variations cannot be accentuated or piled on one another by
selection continued through any number of generations. Accord-
ing to them evolution is founded solely on discontinuous variations
(' mutations '), which, though they may not always differ from con-
tinuous variations in magnitude, yet differ totally in kind and in
that they are absolutely stable.1 It is thought that, if an individual
in whom one of these discontinuous variations appears has mated
with an individual who has it not, then a proportion of the
descendants inherit it and a proportion do not ; there is rarely a
blend. If it is unfavourable, the descendants that are of the new
type are eliminated, and it disappears from the race ; if it is
favourable, the ancestral type may be eliminated in the struggle for
existence and the new type established in its place ; if the variation
is neither favourable nor unfavourable, the two types exist side by
side. According to the Mendelian and mutationist view, therefore,
evolution does not proceed continuously (along a smooth incline,
as it were), but by a series of steps of varying but usually con-
siderable magnitude. The theory of evolution by discontinuous
variations finds its strongest advocate in Professor Hugo de Vries,
the distinguished Dutch botanist. His opinions differ, however, in
some very important particulars from those of the more extreme
Mendelians.2

250. The theory of continuous evolution (that is, evolution
founded on ordinary ' fluctuating ' variations) is sometimes termed
the ' selection ' theory, that of discontinuous evolution the ' muta-
tion J theory. Both theories, however, are doctrines of evolution
by the selection of favourable variations. They differ in that they
attribute evolution to the piling up of different classes of variations.
It is true, however, that mutationists often lay much less stress
on selection and adaptation than selectionists.

251. Sir Francis Galton, who may be said to have founded the
biometric school, distinguishes three kinds of inheritance: (i)
Particulate, or inheritance " bit by bit, this element'from one pro-
genitor that from another," 3 as when black and white poultry are
crossed and the offspring have in varying degrees some feathers
black or barred, and others white. (2) Exclusive, when the
character of only one parent is reproduced to the total exclusion
of the other, as when the plumage of the offspring of black and

1 Doubtless the opinion that discontinuous variations are absolutely stable

is not held by all mutationists. Apparently, however, it is held by many of
them. See § 285.

8 See § 282. 3 Natural Inheritance, p. 7,

152 MENDEL'S LAWS

white fowls is wholly black or wholly white. Particulate inherit-
ance may be regarded as exclusive inheritance occurring in patches.
(3) Blended inheritance, as in the skin colour of a mulatto.
Blended inheritance! may be regarded as particulate inheritance
occurring in a very fine mosaic. Galton thinks, " There are pro-
bably no heritages that perfectly blend or that absolutely exclude
one another, but all heritages have a tendency in one or the other
direction, and the tendency is often a strong one."1 There can be
no doubt, however, that small progressive variations (fluctuations)
present in one parent, but absent in the other, tend to disappear
absolutely in the offspring. In such cases, therefore, there is no
blending.2

252. The greater part of modern experimental work follows
the lines laid down by Gregor Mendel, a monk who became Abbot
of Briinn, and who about the middle of the last century crossed
many varieties of the edible pea — Pisum sativum. Peas are
normally self-fertilized, the pollen-grains and ovules of the same
flower uniting. But the plants have conspicuous flowers, which,
presumably, underwent evolution because they attracted insects
and so secured cross-fertilization. We must suppose, therefore, that
peas have descended from ancestors that interbred. If the anthers
of a flower be amputated before the pollen is ripe, and pollen from
another plant be conveyed to the pistil, it is still possible to secure
cross-fertilization.

253. Mendel worked with a number of strongly contrasted
varieties — 'tall' and 'dwarf plants, for example. From the
mongrel seeds, thus obtained, only tall plants developed. They
were allowed to self-fertilize themselves, as were their descendants.
About one-quarter of the offspring — the grandchildren of the
original cross — developed as dwarfs and three-quarters as tall plants.
No plants were intermediate. Thereafter the dwarfs continued to
breed ' true ' as long as the experiments were continued, producing
no tall plants in succeeding generations. It seemed evident that
the race was purged of the influence of the tall variety. On the
average, a similar number of tall plants behaved in like manner,
producing only tall descendants. Their race, also, had become
1 pure.' But the remaining plants (fifty per cent, of the whole)
behaved like their cross-bred parents, producing tall and dwarf
offspring in the old proportion, the dwarfs being all pure, and the
tall plants pure and impure. This process, also, continued until
the experiments ceased.

lQp. fit,, p. 12. 2See§ 194.

DOMINANTS AND RECESSIVES 153

254. Mendel supposed that the ' tall' and 'dwarf characters
were represented by units in the substance we now call germ-
plasm. He thought that each pollen grain and unfertilized ovule
(gamete, or germ-cell) contained one unit for stature, and therefore
that each fertilized ovule (zygote) contained two.1 One only of
these units directed development, and the character which resulted
from its influence he termed the ( dominant.' The latent character
was termed the ' recessive.'

255. He supposed further that before the development of the
germ-cells of the mongrel plant which sprang from the zygote, the
units multiplied and separated, so that in each of its pollen grains
and ovules only one unit was present, a dominant unit or a reces-
sive unit. When the plant flowered and self-fertilization again
took place, it was a matter of chance whether these units paired
with their own kind in the zygote, or with units of the opposite
type. If a dominant unit met another dominant the result was a
' pure ' dominant plant, which never had, nor-could have a recessive
descendant so long as self-fertilization continued. In like manner,
if a recessive unit met another recessive the line became exclusively
recessive. But, if a dominant met a recessive, the resulting plant
was an ''impure' dominant, which looked like the pure dominant, but
was really different in that it was a hybrid having descendants of
the three types, pure dominants, recessives, and impure dominants.
Every plant which displayed the recessive character was pure of
course, for otherwise the dominant element would have been patent.

256. If the reader will shake together in a bag a hundred
black and a hundred white buttons, representing dominant and
recessive units respectively, and then withdraw them at hazard in
pairs, he will find that, on the average, half the buttons will be
paired with their own kind and half with the opposite kind. He
will then have approximately twenty-five black pairs representing
pure dominants, twenty - five white pairs representing recessives,
and fifty black-and-white pairs representing impure dominants.
The proportion of pure dominants, recessives, and impure domi-
nants, therefore, is supposed to be regulated by the law of chance.

257. It was found that peas possessed several Mendelian
characters besides length of stem, for example colour of cotyle-
dons (yellow or green), colour of seed skins (brownish or white),
colour of flowers (purple or white), shape of ripe pods( inflated or
constricted), colour of unripe pods (green or yellow), position of
flowers (axial or terminal), and shape of seeds (round or wrinkled).

1 See Bateson, Mendel's Principles of Heredity, pp. 338-9.

154 MENDEL'S LAWS

One of each of these characters is always dominant over its
alternative, for example yellow in the cotyledons is dominant over
green, purple in flowers over white, round shape over wrinkled
shape in seeds.

258. But, if a variety has one character which is dominant over
its alternative in another variety, it does not follow that the rest
of its characters are also dominant. One or more characters in the
second variety may be dominant. Consequently, if two varieties
are crossed, the first mongrel generation (all impure dominants] may
exhibit some of the characters of one variety and some of the other.

259. Moreover, if a variety having a certain set of Mendelian
characters is crossed with a variety having another set, then the
descendants are apt to exhibit the characters in new combinations
even after they have become * pure.' Thus, if a variety with
inflated pods, wrinkled seeds, and green cotyledons be crossed
with one having constricted pods, round seeds, and yellow
cotyledons, the ' pure ' descendants may exhibit every combination
of the alternative characters, for example contracted pods with
round seeds and yellow cotyledons, or inflated pods with wrinkled
seeds and yellow cotyledons. It appears, therefore, that unlike
sexual characters, the alternative or Mendelian characters do not
necessarily hang together in sets, but are * inherited ' independently
of one another. When, therefore, we study heredity in terms of
the Mendelian theory, we must think, as always, not of the in-
dividual as a whole, but of his characters separately. Obviously,
the hypothesis that characters are represented in the germ-plasm
by units, which pair in the fertilized ovum but separate in its
germinal descendants, is an inference, not an observed fact. These
units cannot be seen in the germ-plasm, or, if seen, recognized.
It is this inference which is especially the Mendelian hypothesis
and on which stress is laid.1

260. The points to be especially noted when studying the
Mendelian theory are (i) the alternative units are supposed not to
blend or unite in the fertilized ovum (zygote) with their ' opposite
numbers,' but to remain distinct and ultimately to segregate, so that
the germ-cells (gametes) of the individual that arises from the
zygote contain each only one unit for each character ; hence the
terms ' unit segregation ' and ' gametic purity.' (2) The different

1 " This purity of the germ-cells and their inability to transmit both of the
antagonistic characters is the central fact proved by Mendel's work. We thus
reach the conception of unit characters existing in antagonistic pairs." (First
Report to the Evolution Committee of the Royal Society, by Miss Sanders and Mr
Bateson, p. 126, 1902.)

QUALIFICATIONS OF MENDEL'S LAWS 155

units of a set are supposed not to hang together but to be inherited
independently of one another so that new combinations may be
formed. They have been termed * allelomorphs,' alternative
inheritable units, each of which in one set of allelomorphs is
capable of displacing its opposite number in another set. (3) One
unit of every pair tends to be dominant over its alternative, so
that when both are present in a zygote the individual which springs
from it displays the dominant character only. Such, at any rate,
were the chief points of the Mendelian theory as originally pro-
pounded, and as held very recently.

261. More extended study, however, has rendered it evident
that in all points the Mendelian doctrine needs more or less qualifica-
tion. Dominance is seldom if ever complete. As regards any
Mendelian character, the hybrids of the first generation (all impure
dominants) usually resemble the dominant parent more nearly than
the recessive ; but the influence of the latter may be observed, at
least very often. " Even in the pea it is not the case that the
heterozygote [mongrel] always shows the dominant allelomorph as
clearly and in the same intensity as the pure dominant, and, speak-
ing generally heterozygotes, though in numerous instances readily
referable to one or other of the allelomorphic types, exhibit these
types in a more or less modified form."1 Frequently indeed a
combination of parental qualities amounting to particulate, mosaic,
or even blended inheritance is observable in offspring. Thus a
cross between black and white plumage in poultry may result in
barred offspring, as often happens when the white Leghorn fowl
is crossed with the black Cochin ; 2 or in a minute patchwork, as
in the case of the blue Andalusian fowl which results from crossing
a black bird with a ' splashed ' white ; or there may be complete
blending, as in the offspring of a white man and negress.3

262. Sometimes the usually recessive character may be
dominant.4 Again, instead of one type being dominant over the
other, the character of neither parent is reproduced, but a common
ancestral form reappears. For example, when albino mice are
crossed with black-and-white Japanese waltzing mice "a grey

1 First Report to Evolution Committee, p. 129.

2 Davenport, Inheritance in Poultry, p. 40.

3 Adherents of the Mendelian doctrine sometimes maintain that blended
inheritance is nothing other than a fine mosaic. Doubtless they are right ; but
I imagine their opponents mean nothing more by blended inheritance than that
it is a very fine mosaic — a mosaic as fine, perhaps, as the mixture of colours in a
painter's brush. All blending, for example a mixture of alcohol and water, is a
mosaic, even if one of chemical molecules.

4 First Report to Evolution Committee, p. 120.

i$6 MENDEL'S LAWS

house-mouse resembling in size, colour, and wildness the wild
house-mouse " 1 is produced ; when yellow-grey Belgian rabbits are
crossed with white (albino) Angoras the offspring have " wild-grey
coats indistinguishable from those of the wild-grey." 2 When Mr
Hurst crossed Black Hamburgh with Buff Cochin poultry, " in the
first plumage the two sexes are quite distinct. The cockerels had
golden-brown hackles, red-brown saddles, black and brown tails and
wings, and buff-brown breasts regularly spangled with black. The
pullets were as dull and sober in colour as the cockerels were
brilliant, being black intermixed with light and dark brown, with
darker tails and heads and spangled breasts. It seems rather
curious that a cross between two breeds, each of which has normally
similar plumage in both sexes, should produce offspring in
which the two sexes are so distinctly differentiated."3 Among
domesticated pigeons the plumage of the wild blue-rock, and
among poultry that of the ancestral Gallus bankiva may reappear
when domesticated breeds are crossed. When the horse is crossed
with the Burchell zebra, which has a few broad stripes, the offspring
present the narrower and more numerous stripes of a remote
ancestor.4 Similar instances of 'reversion' are common amongst
plants ; for example, if a jonquil be crossed with a daffodil, Narcissus
odorus results.5

263. Dominance may be influenced by the environment, as in
the case of Ewart's pigeons, whose offspring reproduced the
characters of the English parent when the Indian parent was ill,
but those of the latter when its health was good.6

264. Dominance may be affected by the sex of the parent.
Thus, when white Leghorn and Indian Game poultry are crossed,
" all male cross-breds and female cross-breds from Indian Game
mother almost always have the ground colour white, but female
cross-breds from white Leghorn mothers have the ground colour
more or less dingy-brownish white." 7 " Booting (feathered foot) is
always dominant when the feathered form is the mother, no matter
what the race." 8 " The canary has two forms which are both in a
sense albino, the yellow and the cinnamon. When green (viz. non-

1 First Report to Evolution Committee, p. 145.

2 C. C. Hurst, Experimental Studies on Heredity in Rabbits, p. 301.

3 Second Report to Evolution Committee, p. 135.
Ewart, The Penicuick Experiments, p. 92.
Vernon, Variations in Animals and Plants, p. 169.
See § 132.

First Report of Evolution Committee, p. 99.
Davenport, Inheritance in Poultry, p. 86.

GAMETIC PURITY 157

albino) females are crossed with cinnamon males, both greens and
cinnamons are invariably female. When cinnamon females are
crossed with green males the young are always green." 1 The
instance " most familiar amongst animals is perhaps that of the
Mule (Mare and Jackass) and the Hinny (She-ass and Stallion)
and amongst plants the hybrids of Digitalis." 2

265. Dominance may be influenced by race. " While long tail
and crest feathers are dominant in poultry, long hair (equally due
to the prolonged life of the follicle) is recessive in mammals (Castle,
J903, 1905; pp. 64-7, 73-4; Hurst, 1904). White is usually
recessive to pigment in flowers and mammals, but is usually
dominant to pigment in poultry." 3 " Yellow (beak and foot colour)
of the white Leghorn dominates over black of the Minorca, but
yellow of the dark Brahma is dominated by the Minorca." 4

266. Dominance may be affected by the idiosyncrasies of the
parent. " In all cases as yet investigated (in poultry) individuals
differ greatly in the results they give, and we can only suppose that
these differences represent different proportions in the number of
effective dominant and recessive germs which they produce." 5

267. Lastly, in some cases it is difficult to say which of a pair
of characters is dominant, since both are patent in about equal
numbers in the first mongrel generation, as in the case of a sixth
digit in man or a fifth toe in poultry. Even when a character is
usually strongly dominant over its alternative, recessive individuals
sometimes appear in the first mongrel generation.6

268. To sum up : it is very evident that " Dominance is a
matter of degree, not of kind ; " 7 " Dominance is a phenomenon
presenting various degrees of intensity." 8

269. We have next to consider the hypothesis of gametic purity
— a hypothesis which implies that the pure dominants and recessives
which spring from impure dominants of the first and succeeding
mongrel generations, extracted pure dominants and recessives as
they are called, inherit only one kind of unit out of each pair of
alternative units, and therefore (as regards each separate character)
are in effect derived from only one of the crossed ancestral lines.

1 Second Report to Evolution Committee, p. 128.

2 First Report to Evolution Committee, p. 132.

3 Davenport, Inheritance in Poultry, p. 132.

4 Ibid., p. g/.

5 First Report to Evolution Committee, p. 106.

6 First Report to Evolution Committee, pp. 1 19 et seq.

7 Inheritance in Poultry, p. 85.

8 First Report to Evolution Committee, p. 126.

158 MENDEL'S LAWS

In order to understand the ensuing discussion with ease the reader
is advised to familiarize himself with the following : (i) According
to the Mendelian hypothesis from a cross-bred individual, if self-
fertilized or mated with another impure dominant, should arise
pure dominants, recessives, and impure dominants in the average
proportion of one pure dominant and one recessive to two impure
dominants, this proportion being due to the circumstance that the
dominant and recessive units should be present in the germ-cells of
the cross-bred in about equal numbers. If the three kinds of
offspring depart much from the stated proportions, it is evident that
something besides pure chance is at work. The impure dominants
of the next and succeeding generations should behave in a similar
manner. (2) Since an impure dominant produces an equal number
of dominant and recessive gametes, therefore, if such an individual
of any generation be crossed with, a pure dominant (which produces
only dominant gametes), half the offspring, on the average, should
be pure, and half impure dominants. If crossed with a recessive
half the offspring should be impure dominants and half recessives.
(3) Pure extracted dominants, mated together, should produce only
pure dominants, extracted recessives only recessives, and extracted
recessives crossed with pure extracted dominants only impure
dominants in the first cross. (4) With respect to each separate
character, then, pure extracted dominants and recessives are not,
from the Mendelian point of view, hybrids at all ; they are believed
to be gametically pure, having reverted wholly to one or other of
the types that were crossed, the other type being quite eliminated
from them. They should exhibit, therefore, no tincture of the
alternative characters.

270. In all points, however, the doctrine of unit segregation and
gametic purity needs qualification. Thus, when Mendel crossed
round with wrinkled peas, he obtained in the second mongrel
generation — when the proportion of dominants (pure and impure)
to recessives should have been as three to one — in one case forty-
three dominants to two recessives, and in another fourteen domi-
nants to fifteen recessives ; and, when he crossed yellow with green
peas, he got in one case twenty dominants to nineteen recessives,
and in another thirty-two dominants to one recessive.1 In some
cases extracted recessives (presumably pure) when crossed with
pure recessives gave dominant offspring instead of only recessives.
In one such case ninety-four dominants and a single recessive
resulted.2 In other cases only pure dominants producing only

1 First Report to Evolution Committee) p. 128. . a Op. cit.y p. 79.

PATENCY AND LATENCY 159

pure dominant offspring resulted in the first hybrid generation.1
Millardet's ' false hybrids ' are celebrated. He " found that when
certain varieties, especially of strawberry, are crossed together,
(i) the cross-breds may precisely reproduce the maternal type,
without any indication of the paternal characters ; (2) in other cases
the cross-bred individuals may show either the maternal characters
pure (save in one case the colour of fruits) or the paternal characters
pure. Seeds from plants thus exclusively reproducing one parental
type themselves gave plants again exclusively of that type. To
such forms he gives the name lfaux hybrides* or ' hybrides sans
croisement? " 2 Other similar cases might be mentioned.3

271. All these facts are inconsistent with the Mendelian
doctrine. For example, if unit segregation and gametic purity are
realities, how is it possible (i) that only pure dominants, having
only dominant descendants, can occur in the first hybrid genera-
tion, or (2) that recessives can ever produce dominant offspring and
descendants ? We may indeed adopt the far-fetched hypothesis
that in the first case recessive units or gametes were not produced,
or perished, leaving only dominants to continue the race, and in
the second the more probable conjecture that the recessives were
in reality impure dominants in which the recessive units had
temporarily become dominants.

272. But another explanation not only inherently more pro-
bable, but supported by evidence that appears massive and
conclusive, is possible. We saw that the development, not
inheritance, of the sexual characters is alternative. In every
individual, for example man or woman, one of each pair of sexual
characters is as a rule entirely dominant over its alternative. The
alternative, however, is present in a latent condition, that is
every individual is an impure dominant. Thus, in man bearded-
face is dominant over smooth-face, whereas the latter is dominant
in a woman ; but the man transmits the latent female character to
his daughters and the woman the latent male character to her
sons. Here the inheritance, so-called, is alternative in a completer
sense than in the case of Mendelian characters ; for each character
is in turn dominant over its alternative. But in some cases male
characters may become latent for prolonged periods, as in aphides
during the summer. Female characters are seemingly, permanently
recessive in the ova of the queen bee, for unfertilized eggs produce

1 Op. cit., p. 80. 2 Op. cit., p. 154.

*Op.cit.,p. 8 1. See also Bateson, Mendel's Principles of Heredity, chapter
xiv.

160 MENDEL'S LAWS

only drones ; while, presumably, male characters are permanently
latent in such species as propagate only by parthenogenesis.

273. Now the presumption is that the inheritance of the Men-
delian characters is of the same type as that of the sexual characters,
and therefore that, instead of segregation and gametic purity, what
really occurs is patency and latency)- If that be the case the
recessive character, which is temporarily latent in the ' impure '
dominant, is permanently latent in a line of 'pure' dominants,
whereas, on the other hand, the dominant is permanently latent in
the recessives — permanently latent, that is, until the conditions
which bring about such latency are disturbed in much the same
way as when the conditions of latency of the female characters in
the ova of the bee are disturbed by fertilization, or those which
bring about the latency of the male characters in the summer ova
of aphides are disturbed by the advent of winter. If this be true,
the independent inheritance of characters on which Mendelians
insist is a myth. There is only independent development, inde-
pendent patency and latency. When, therefore, one variety is
crossed with another and the descendants show the varietal
characters in new combinations, all the alternative characters of
both varieties are present, but only a half of them are patent, and
this half includes characters from both species.

274. Evidence more direct than that furnished by analogy is
not lacking. Contrary to what was formerly believed, the 'ex-
tracted ' pure dominants and recessives of the second and succeeding
generations are rarely without traces of the alternative characters.
They are in truth real mongrels (not only as regards the whole
individual, but as regards each separate character) in which one or
more of the characters of one of the crossed varieties predominates
more or less, the degree of this predominance varying from an
absolute, or almost absolute completeness that approaches the
commonly complete dominance of the sexual characters, to a
blend intermediate between the crossed varieties. Thus in the
case of poultry, " very frequently, if not always, the character that
has once been crossed has been affected by its opposite with which
it was mated and whose place it has taken in the hybrid. It may
be extracted, therefrom, to use in a new combination, but it will be
found altered. This we have seen to be true for almost every
character sufficiently studied — for the comb form, the nostril form,

1 1 made this suggestion in the second edition of The Principles of Heredity
(Appendix B) ; I find, however, I was anticipated by Professor T. H. Morgan
(Science, xxii., 1905).

COMPOUND ALLELOMORPHS 161

cerebral hernia, crest, muff, tail length, vulture hock, foot- feathering,
foot-colour, earlobe, and both general and special plumage colour.
Everywhere unit characters are changed by hybridizing." 1 Clearly,
then, as is sometimes the case with the sexual characters, especially
the less stringently selected secondary sexual characters (e.g. in
human ' hermaphrodites '), the allelomorph, which is supposed by
Mendelians to be absent, very often, indeed almost always makes
its presence felt. We must assume, therefore, that before separat-
ing— if they do separate — the alternative units — if there are any
units — infect one another (z.^blend) so as to form hybrid units ; or
else we must assume that they do not blend, but remain together,
and that one (but not always the same one) dominates more or
less completely over the other. In any case, " construed in the
strictestsense the doctrine of gametic purity is untenable."2

275. Now ample evidence exists that allelomorphs sometimes
combine to form compound allelomorphs. When two varieties
are crossed, one or other form may dominate, or the type may
blend, or the ancestral type may appear. When this, the first
mongrel generation, is self-fertilized or bred together, it sometimes
happens that there is no return in the offspring to the grandparents
(the types that were crossed). On the contrary the descendants
break up into two or more forms distinct from the grandparents,
one or more of which may breed true. For example, if the Stanley
sweet-pea, which has dark maroon petals (standards and wings),
be crossed with the Giant White, the offspring are Giant Purple
Invincibles with maroon standards and blue wings. " These first-
crosses, self-fertilized, gave Giant White, Giant Purple (without
blue wings), Mars (a well-known red variety), Her Majesty (a full
magenta, well-known), and a form like Her Majesty, but flaked
with white. One plant of each was saved and its self-fertilized seed
sown. Mars and Her Majesty came true. The Giant White was
tested, and it came true also. The Her Majesty flaked with white,
however, gave Whites, Her Majesty, and Her Majesty flaked white
again. The Giant Purple gave Giant White, Her Majesty, Giant
Purples, and two plants of a streaky cream colour. . . . We are
then led to the conclusion that the allelomorph transmitting the
coloration of Stanley is compound, and that it can be broken up
into simpler and possibly component elements." 3

1 Inheritance in Poultry, p. 80.

2 Castle and Allen, The Heredity of Albinism. Proceedings of the American
Academy of Arts and Sciences, vol. xxxviii. No. 21, p. 615.

3 First Report to Evolution Committee, pp. 142-3. See also Bateson, Mendel's
Principles of Heredity ,fpp. 60 et seq.

II

1 62 MENDEL'S LAWS

276. It is admitted, then, that two or more dissimilar
allelomorphs sometimes unite permanently to form compound
allelomorphs which are transmitted to descendants as units. In
the case quoted above, the component characters are, I believe,
supposed to have been more or less patent, and therefore the
Stanley presented an appearance different from any of the types
from which it was obtained by cross-breeding. But, if compound
allelomorphs in which each component unit is patent may occur,
it is not unreasonable to suppose that allelomorphs, supposing
they exist, may sometimes combine to form more or less permanent
compounds in which one (or more) of the components is patent
and the other (or others) latent. That this has happened at
least very frequently there can be no possible doubt. We see it
in aphides, in which the allelomorphs for the male characters are
latent all the summer. Every case of the reappearance of a latent
ancestral character (at any rate in a pure-bred race) l is an instance
of it.

277. If we cross a Japanese waltzing mouse with an albino
mouse, then the ancestral wild-grey colour reappears in a large
proportion of the offspring. It is supposed, doubtless correctly, by
Mendelians, that the special characters of the two domestic breeds
arose originally as mutations from the wild type. Since it is very
improbable that two animals varied discontinuously in the same
way and at the same time and place, the mutants (as the individuals
that underwent mutation are termed) were crossed with the wild
type.2 The reproduction was Mendelian, and artificial selection
established a race of ' pure ' recessives amongst the descendants
— Japanese waltzing mice in the one case and albinos in the other.
According to the Mendelian doctrine of unit segregation and
gametic purity the grey colour should have been quite absent
(not latent) from both varieties.3 It was only latent, however.
It follows that in this case there was no unit segregation nor
gametic purity. What really occurred was, not the elimination
of the ' grey allelomorph ' but the formation of a compound

1 See § 280.

z " Mendel's discovery, it will be understood, applies only to the manner of trans-
mission of a character already existing. It makes no suggestion as to the manner
in which such a character came into existence. The facts, however, leave no room
for doubt that at least one character of each pair of simple allelomorphs has arisen
discontinuously. The fact that the gametes of the cross transmit each member
of the pair pure, is as strong an indication as can be desired of the discontinuity
between them." First Report to Evolution Committee, p. 151. See § 290.

8 See §255.

LATENT ANCESTRAL CHARACTERS 163

allelomorph in which the grey was permanently latent. It
would appear, therefore, that the essential features of Mendelian
inheritance are, not segregration and gatnetic purity, but the perma-
nent dominance of one alternative character and the permanent latency
of the other.

278. Any number of similar instances might be quoted. Thus
when Mr A. D. Darbishire crossed fawn-and-white Japanese
waltzing mice v/ith albinos, the descendants exhibited a number
of colours which he classified as yellow, fawn colour, grey (pale
and dark, the colours of the wild mouse), black, lilac (pale and blue-
grey), and chocolate.1 In this as in many other instances (e.g.
Stanley sweet-pea, quoted above) the allelomorphs from both the
crossed varieties were evidently highly compound, several latent
characters being revealed. The appearance of the black coloration
is particularly interesting. It has appeared also when pigmented
guinea-pigs and rabbits were crossed with an albino variety.
Thus Mr C. C. Hurst crossed Belgian rabbits which have yellow-
grey fur with angoras which are albinos.2 Both varieties had
been pure-bred for at least eight and probably many more genera-
tions. The offspring all displayed " grey coats like that of the
common wild rabbit." Bred together the mongrels produced
wild greys, albinos, Dutch-marked, and black offspring. The
three latter types bred true when mated with their own kind.
They were pure recessives. The greys were pure and impure
dominants, with albino, black, or Dutch markings as the latent
element. There was never a return to the yellow-grey Belgian
coloration. A further series of experiments proved that the
black coloration as well as the grey and Dutch markings had
been introduced by the various albinos of the original cross. Now
albinism is a typical recessive character which, according to the
doctrine of unit segregration, should always be pure. Yet we see
that in mice, rabbits, and guinea-pigs it may be associated with
latent grey, black, or Dutch coloration. Plants furnish evidence
similar in kind, and even greater in quantity. Thus if two white-
flowered varieties of garden plants be crossed the offspring may
have coloured flowers.

279. The reproduction of ancestral traits seems to afford
evidence that is decisive in favour of the hypothesis of alternate

1 " On the Result of Crossing Japanese Waltzing with Albino Mice." Biometrika,
Jan. 1904.

2 ," Experimental Studies on Heredity." Linnean Society's Journal, Zoology,
vol. xxix.

1 64 MENDEL'S LAWS

latency and patency, and fatal to the hypothesis of segregation.
Nevertheless, Professor Cuenot has attempted to surmount the
difficulty.1 He supposes that colour depends, not on a single
unit or hereditary tendency, but on two, a colour factor and a
colour determiner. According to him, if the one or the other be
absent, the individual is an albino. As a fact, it is the factor
that is supposed to be absent from the albino, which, it appears,
usually carries one determiner and may carry more. According
to the latest views the factor is always the same for all the colours
of a species, but the determiners (which Bateson has surmised
are ferments 2) may be as many as there are differently coloured
varieties.3 Colours (i.e. ferments) vary in dominance, the ancestral
colour, for example ' wild-grey ' in rabbits and mice, often being the
most dominant of all. Consequently, if an albino rabbit or mouse
be crossed with some coloured domestic variety (e.g. Belgian
rabbit or Japanese waltzing mouse), then, since the albino races
seem always to carry -the grey determiner, and the coloured variety
carries the factor, the offspring are all grey. If more determiners
are carried by the albino, the descendants are not only grey and
white, but other colours as well. In this way the reappearance
of ancestral traits when varieties are crossed is accounted for in
terms, not of latency, but of segregation.

280. Cuenot's hypothesis of factors and determiners has been
used to interpret, not only the reproduction of ancestral colours but
also that of all other ancestral peculiarities, for example shape and
instinct. Presumably these, also, are due to ferments. But, since
both Cuenot's hypothesis and the hypothesis of segregation, which
it is intended to support, are merely founded on, not tested by
experiment, the repetition of the explanation in any number of
instances does not prove them to be true. Apparently, however,
mere repetition is all their adherents consider necessary. The facts
fit the hypothesis of simple latency and patency at least equally well.
Indeed they fit the latter better ; for, if we hold it, we have no ex-
ceptions, such as those I have summarized in paragraphs 271 and
284, to explain away. Here then we have two rival hypotheses,
two interpretations of the same facts. Both of them remain simple
guesses, utterly valueless to science, unless they can be tested. " In
such a case it is necessary to look for some instance which can be

1 La loi de Mendel et Vhfrtditt de la pigmentation chez Us souris (2me note).
Arch, de ZooL, exp. et gen (4), Notes et revue, pp. xxxiii.-xli.

2 Mendel's Principles of Heredity, pp. 226-9.

3 The Progress of Genetics since the Rediscovery of Mendel's Papers, by W.
Bateson.

CRUCIAL INSTANCES 165

explained on one only of these rival hypotheses ; . . . such a test
case is called a Crucial Instance" ] " One single circumstance,
which admits of one explanation only, is more decisive than a
hundred others which agree in all points with one's own hypo-
thesis, but are equally well explained on an opposite hypothesis." 2
Now, as regards the rival hypotheses of segregation and latency,
any number of cases have been recorded which furnish quite
decisive crucial instances ; but, though the experimental school
has piled one untested interpretation on another, though they have
explained alternative reproduction by segregation, segregation by
factors and determiners, and determiners by ferments, never yet
has any appeal been made to them. Ancestral traits may be
awakened experimentally by crossing domesticated varieties ; but
these are not the only occasions when they appear. Their reproduc-
tion by pure-bred individuals is far from uncommon. "Thus we
see that, in purely bred races [of pigeons] of every kind known in
Europe, blue birds occasionally appear having all the marks which
characterize C. livia" 3 The following is a very striking instance
of the reappearance of long latent ancestral characters in an
individual which not only reproduced them, but had previously
reproduced those of her own variety as well. Several like instances
have been recorded. " Mr Hewitt possessed an excellent Sebright
gold-laced bantam hen, which, as she became old, grew diseased in
her ovaria, and assumed male characters. In this breed the males
resemble females in all respects except in their combs, wattles,
spurs, and instincts ; hence it might have been expected that the
diseased hen would have assumed only those masculine characters
which are proper to the breed ; but she acquired, in addition, well-
arched tail sickle-feathers quite a foot in length, saddle-feathers on
the loins, and hackles on the neck — ornaments which, as Mr Hewitt
remarks, ' would be held as abominable in this breed.' The
Sebright bantam is known to have originated about the year 1800
from a cross between a common bantam and a Polish fowl,
recrossed by a hen-tailed bantam, and carefully selected ; hence
there can hardly be a doubt that the sickle feathers and hackles
which appeared in the old hen were derived from the Polish fowl
or common bantam ; and we thus see that not only certain masculine
characters proper to the Sebright bantam, but other masculine
characters derived from the first progenitors of the breed, removed

1 Welton, Manual of Logic, vol. ii. p. 102.
1 Ueberweg, Logic, Eng. Trans., p. 513.
8 Animals and Plants, vol. i. p. 206.

166 MENDEL'S LAWS

by a period of above sixty years, were lying latent in this hen-bird,
ready to be evolved as soon as her ovaria became diseased."1
Here there can have occurred no reunion of previously divorced
factors and determiners. The only conceivable interpretation of the
facts is that the ancestral characters were latent', and if they are
latent in the pure-bred varieties, we have no right to assume that
they segregate in the mongrel. " Entia non sunt multiplicanda
prceter necessitate™"

281. Very obviously Cudnot and his followers have not taken
all the evidence into account. His hypothesis merely complicates
the problem and confuses the issues by introducing the entirely
gratuitous assumption that the production of characters depends,
not on a single unit or hereditary tendency in the germ-plasm, but
on two, a factor and a determiner. It must be understood that
there is no real evidence in favour of this hypothesis. It was
invented only because without some such supposition the reproduc-
tion of ancestral traits rendered the hypothesis of segregation
untenable. It is unnecessary, therefore, to consider what have
been euphoniously termed the ' later refinements ' of the Men-
delian hypothesis, such as negative ' elements ' in which apparently
* absence ' constitutes the alternative allelomorph. As I say the
reproduction of ancestral traits by pure-bred races constitutes
decisive proof that the Mendelian phenomena are due to alternate
patency and latency, not to segregation.

282. De Vries offers yet another explanation of Mendelian
phenomena.2 According to him a new species differs from the
parent stock by the addition of a fresh progressive character (a
mutation) to the sum-total of ancestral characters. A new variety,
on the other hand, differs from the parent stock in that it has
latent or patent a character which is in the opposite condition in
the parent stock. When, therefore, species cross they tend to be
more or less sterile, for the character is unpaired ; or if the union
is fertile there tends to be more or less of blending. When
varieties cross with the parent type the patent character is dominant
over the latent character, and there is Mendelian inheritance, with
segregation of patent and latent units in succeeding generations.
But, if this theory be correct, the albino rabbit must have been
latent in the yellow-grey, the yellow-grey in the albino, and the
black, wild-grey, and Dutch colorations in both. The ancestors
of both races, therefore^ must have been all these colours in turn

1 Animals and, Plants, vol. ii. p. 29.

1 Species and Varieties, Their Origin by Mutation. Lectures IX and X.

SUMMARY 167

at one time or another, which is very improbable. Again, since
the inheritance of polydactylism in man and the lower animals is
alternative, Professor de Vries' theory involves the corollary that
mammals have descended from ancestors which possessed six
digits, one of which has become latent, which also, to say the least,
is very improbable.

283. Taking all the facts into consideration, I think there can
be no doubt that reproduction of at least many mutations is alter-
native from the first. The only matter open to doubt (and even
that, as we see, is not open) is whether the alternation involves
alternative inheritance (unit segregation and gametic purity) or
merely alternative development (alternative patency and latency).
Great stress is often laid on the frequency with which alternative
characters are reproduced in the second mongrel generation in what
are known as the Mendelian proportions. Thus, if round and
wrinkled peas are crossed, the average proportions in the second
mongrel generation are three round peas to one wrinkled ; if rose
comb is crossed with pea comb, the proportions are nine walnut
combs, three rose, three pea, and one single. These proportions
are certainly very interesting and remarkable. Beyond doubt
they suggest segregation rather than patency and latency. But
suggestion is not the same thing as demonstration. The latter
must depend on surer evidence, such as that furnished by pure-
bred varieties. Here, as I say, we have positive testimony that the
Mendelian phenomena do not indicate segregation.

284. To sum up : we have a choice between two possible
explanations of Mendelian phenomena. On the one hand is the
orthodox Mendelian doctrine of dominance (patency and latency) in
the first hybrid generation, and segregation and gametic purity in
the pure dominants and recessives of succeeding generations ; on
the other hand is the theory of temporary patency and latency in
the first generation and more perfect and permanent patency and
latency in the pure dominants and recessives of succeeding genera-
tions. I am not aware of any fact in the whole range of Mendelian
literature that contradicts the second theory. But the first is
contradicted by the facts (i) that pure dominants and recessives
may occur in the first hybrid generation ; (2) that apparently pure
dominant races may produce recessives, and recessive races domi-
nants ; (3) that dominants and recessives may occur in altogether
disproportionate numbers in any generation succeeding the first ;
(4) that extracted* dominants and recessives nearly always
bear traces of their hybrid origin (i.e. display some degree of

1 68 MENDEL'S LAWS

patency of the latent allelomorph) ; and (5) that in a very
great number of cases (i.e. in pure-bred varieties) it has been
actually proved that pure dominants and recessives carry the
alternative unit in a latent condition. Moreover, the analogy of
the sexual characters points clearly to latency rather than to
segregation.

CHAPTER VIII
THE MUTATION THEORY

The nature of mutations — The impossibility of distinguishing between
fluctuations and mutations by means of experiment — The alleged immutability
of mutations — Our power of studying smaller variations — Human inter-varietal
crossings — Latent characters are common when domestic varieties cross ; they are
rare when natural varieties cross — The effects of Natural and Artificial selection
are not identical — Objections to the mutation theory — The distinction between
inheritance and reproduction — The modes in which mutations are inherited and
reproduced.

w

285. "^^ T'HETHER due to unit segregation and gametic
purity, or to patency and latency of the components
of compound allelomorphs, there can be no doubt
of the actual occurrence of the Mendelian phenomena. We must
endeavour, therefore, to estimate the part played by them in nature.
The more extreme section of the experimental school insists that
all those differences (even minute differences) between parents and
children which we have defined as variations (innate or germinal
differences, differences in hereditary tendencies) are mutations,
that the inheritance of all mutations is Mendelian, and that muta-
tions are permanent changes which" selection alone can eliminate,"
whereas ' continuous,' * normal,' or ' fluctuating ' variations are mere
modifications due to changes in the action of the environment. Con-
sequently, according to them, all evolution, at any rate all permanent
and considerable evolution, is founded solely on mutations. It
follows if this hypothesis be true, that the stability of racial
characters is due, not to their long-continued selection, but to the
circumstance that they have arisen through the accumulation of
mutations, all of which were stable from the first.1

1 " Doubtless some of the so-called fluctuations are in reality small mutations,
whilst others are due to environmental influence. The difficulty of distinguishing
between the two is very great. The simultaneous existence of small mutations
and large fluctuations leads to the disguising of the former by the latter. Only
careful and laborious analysis will avail us here, and such analysis is precisely
what is at present lacking. The position is roughly as follows. Of the inheritance
of mutations there is no doubt. Of the transmission of fluctuations there is no
very strong evidence. It is therefore reasonable to regard the mutation as the
main, if not the only basis of evolution. And the great service which Mendel has

1 70 THE MUTATION THEORY

286. The word mutation is one of the loose, ill-defined terms
so common in biology and the bane of it. Thus, to Mr Punnett
it implies a variation, large or small, which is stable because the
inheritance of it is Mendelian. To Professor de Vries it implies
a 'sport,' 1 a change " of wide amplitude," 2 the inheritance of which

rendered to this branch of philosophy is the demonstration of the fact that the
mutation when once it has arisen is not likely to be swamped by interbreeding
with the normal form, provided that it is not injurious to the species. We now
recognize discontinuity in inheritance as well as in variation. The new character
which arises as a mutation has its representative in the gamete. Once it has
arisen selection alone can eliminate it. Mendel's discovery then has led us to
materially alter our ideas of the evolutionary process. The small fluctuating
variations are not the materials on which selection works. Such fluctuations are
often due to conditions of the environment, to nutrition, correlation of organs,
and the like. There is no indisputable evidence that they can be worked up and
fixed as a specific character" (Mr R. C. Punnett, Mendelism, ed. ii., pp. 72-3).
" Modification of characters by selection, when sharply alternative conditions (i.e.
mutations) are not present in the stock, is an exceedingly difficult and slow process,
and its results of questionable permanency. Even in so-called ' improved '
breeds, which are supposed to have been produced by this process, it is more
probable that the result obtained represents the summation of a series of mutations
rather than that of ordinary fluctuating variations. For mutations are per-
manent ; variations are transitory. A moment's reflection will indicate the
probable reason. Variations which are distributed symmetrically about a modal
condition, so as to produce when graphically expressed a frequency of error curve,
represent the result of a number of causes acting independently of each other.
These causes are principally external, consisting in varying conditions of food
supply, temperature, density, moisture, light, etc. These conditions alter from
generation to generation, and so do effects dependent upon them. Mutations,
on the other hand, have an internal origin, in the hereditary substance itself.
They are relatively independent of the environment, being affected only by such
causes as affect the nature of the hereditary substance itself, one of which ap-
parently is cross breeding " (Professor M. E. Castle, " The Mutation Theory of
Organic Evolution, from the Standpoint of Animal Breeding." Science, April 7,
1905). " Lop-eared rabbits have ears two or three times as long and as wide
as those of ordinary rabbits. A cross between lop-eared rabbits and ordinary
ones produces offspring with ears of intermediate size, which sometimes stand erect
and sometimes lop. The ear characters which were so distinct in the parents have
in this case lost their identity in the offspring, and apparently cannot be recovered
again in the original condition, for the offspring transmit to their young the blended
character rather than the extreme conditions found in then* respective parents "
(Castle, " Recent Discoveries in Heredity." Popular Science Monthly, pp. 194-5).
Professor Castle refutes himself in a very interesting way. Probably no one will
deny that the lop-eared condition has an " internal origin in the hereditary
substance itself." Certainly it is quite permanent in the race and has no appear-
ance of depending on " varying conditions of food-supply, temperature, density,
moisture, light," etc. But it blends with the ordinary ear. Therefore it cannot
have resulted from a mutation the inheritance of which was Mendelian ; for
if it blends now, it must have blended formerly. Therefore it must have resulted
from the selection of fluctuations the inheritance of which was blended.

1 Species and Varieties, p. 191.

*0p.cit.,p. 715.

THE INADEQUACY OF EXPERIMENT 171

is not alternative, which tends to be stable because it involves
the acquisition of a new unit1 by the germ-plasm, but which is
necessarily stable only when the individual possessing it mates
with a similar individual.2

287. A little thought renders it evident that none of the
problems raised by the Mendelian and Mutation hypotheses can
be solved on the data furnished by experiment alone. Experi-
mental evidence lacks minuteness and precision. It is, besides, far
too fragmentary. Thus experiments which cover only a few
generations are absurdly inadequate to decide the questions
whether or not mutations are permanent and whether evolution
can or cannot be founded on the continued selection of fluctuations.
If, however, we turn to the more ample and conclusive evidence
afforded by the life-history of species, we see at once that of the
two deductions that evolution is founded on mutations and that
mutations are permanent, one must be wrong, for, with mere
cessation of selection, every character (e.g. eyes and limbs) tends
to retrogress till it disappears. The statement that mutations are
immutable is a very good example of the mistaken judgments
which tend to follow too exclusive a reliance on the meagre results
obtainable by a single method of inquiry. The observer is con-
stantly under the temptation to draw inferences larger than are
warranted by the scanty data at his command. It is interesting
to note that, since mutations may be small, what Darwin and his
followers call variations (changes " which have an internal origin
in the hereditary substance itself"), some members of the experi-
mental school term mutations ; and what the former call acquire-
ments (due to "varying conditions of food-supply, temperature,
density, moisture, light," etc.), the latter term variations. Except
that we are told that mutations do not blend or retrogress, nothing
more is done than to change the names and conduct the argument
on that basis.

288. Again, the question as to whether the larger variations
(i.e. the mutations of de Vries) are more permanent than smaller
variations (i.e. fluctuations and the small mutations of Punnett),
and whether the inheritance of small mutations tends to be
alternative, cannot be decided by the mere experimental observer.
He has no special knowledge of the lesser variations, for the study

1 " We may assume that these units are represented in the hereditary substance
of the cell-nucleus by definite bodies of too small a size to be seen, but constituting
together the chromosomes." Op. cit., p. 306.

8 Op. cit., Lecture IX.

172 THE MUTATION THEORY

of which his method is unsuited. The whole literature of experi-
mental inquiry may be ransacked and not a single observation
on the smaller variations will be found. " For almost always
the points which tell are too fine to be dealt with in our analysis." l
Probably domesticated poultry, owing to the number and diversity
of the varieties and the ease with which they may be bred, and
the offspring compared with the parents and with one another,
have been the subject of more exhaustive experimental study than
any other type. The method of study in this case, as in all others,
has always been to cross the more dissimilar varieties — a rumpless
fowl with one possessing a rump, a long-tailed fowl with a short-
tailed one, a white individual with a black, and so on. The
following is a fairly complete list of the characters studied : —

Comb form. Uropygium. Ear-lobe colour.

Nostril form. Tail length. General plumage

colour.

Cerebral hernia. Vulture hock. Colour of hackles.

Crest. Booting. Wing bars.

Muff. Extra toe. Shafting.

Beard. Colour of mandible and Body lacing.

foot.

Frizzling. Iris colour. Pencilling.2

Obviously we do not study the smaller variations, the ' fluctuations,'
when we cross any one of these characters with its opposite.
They are great differences which have arisen as sports or been
established by generations of careful selection, not those small
variations which commonly distinguish mating individuals when
the breeding is intra- varietal.

289. Our power of observing small differences is proportionate
to our familiarity with the object of study. Thus the shepherd is
able to distinguish between the individuals of his flock and even
to note a good deal when he sees a strange flock ; but the ordinary
observer can hardly distinguish one variety of sheep from another
unless they display some glaring differences of size, shape, or colour.
To the Englishman landing in China the natives seem as much
alike as peas — as in fact they are. He becomes trained in time to
distinguish Chinamen, but not peas. But from earliest infancy we
are forced to observe very closely the human beings among whom
we are reared. Indeed it is a main business of our lives to do so.

1 Bateson, Mendel's Principles of Heredity, p. vii.

2 Quoted from Inheritance in Poultry, by Mr C. B. Davenport, p. 81.

THE INADEQUACY OF EXPERIMENT 173

So acute does our observation become that when we have once seen
and noted a face we are usually able to distinguish it again even after
the passage of months or years. Here our power of discrimination
far surpasses our power of expression in words. Nevertheless, so
confusing is the effect of modifications and spontaneous variations
that, even in the members of our own families, we are unable to
note clearly the effect produced by the crossing of parental
differences, though these are often considerable. No experimental
observer, no matter to what an extent a recluse and a student, is as
familiar with any type of animal or plant as he is with human
beings, for, at least, he is always more intimate with himself, a
human being, than with anything else. Much less, therefore, is
his power of observing the inheritance of small differences in other
types. When, therefore, relying on experimental evidence, he
states that the inheritance of the smaller mutations, like that of
' sports,5 is alternative, or when he declares that all true variations
are mutations, and therefore extremely stable, he is guessing. He
has, as I say, no data on which to found a judgment. Unless we,
also, are content merely to guess, we must test his hypotheses by
the ordinary scientific procedure of making a rigorous deductive
inference of consequences followed by an appeal to nature, to
ascertain whether these consequences accord with reality. The
reader must bear in mind that the experimental evidence is not
neglected when more is added to it, and the thinking not the
less likely to be correct because we use our best endeavours to
ensure its accuracy. I do not think it will be possible to contest a
single fact of this added evidence which I shall adduce ; and, if it
is incontestible, then, as far as I am able to judge, the conclusions
we shall reach follow as necessary consequences.

290. When we cross two varieties of fowls or any other
domestic animals or plants, then, as regards the differences we are
able to note — the larger differences — the development is often
alternative. There is usually some blending observable both in
the first and in the succeeding hybrid generations ; but it is not
the conspicuous feature. The conspicuous feature is alternative
reproduction ; the resemblance to one parent type is much closer
than to the other; there is seldom such blending that both the
opposing parental characters are equally, or nearly equally repre-
sented. Now races of men differ among themselves in size,
shape, colour, and so on, almost as much as do varieties of poultry.
If human varieties cross, and almost every human variety has
crossed repeatedly with almost every other, the inheritance of

174 THE MUTATION THEORY

parental differences is never alternative. As regards a few
features — I can think only of eye-colour — the characters of a dark
race may dominate over those of a light-coloured one; but the
dominance is permanent ; it is transmitted to all the members of
all succeeding generations that breed together. Therefore the
reproduction is not Mendelian. But as regards the great majority
of characters the blending is perfect and often nearly equal, and
as such is transmitted to the latest descendants. A race of per-
manent and patent mongrels is formed. If three or four races are
crossed together, as has happened in South America, each
contributes its quota in perpetuity to the blend. It is a common
belief amongst experimental workers that " a fusion of characters
is rather a rare phenomenon. Human skin-colour is the one
striking case." But really that is very wrong. Fusion is very
much the general rule, not the exception.1 The fact that the
gametes of the cross blend " is as strong an indication as can be
desired of the * continuity ' between them." 2 When the negro, for
example, crosses with a white race, the offspring, the mulatto, is
conspicuously a blend in all except eye-colour. His hair, it is true,
more closely resembles in texture the African than the Caucasian

1 Strange as it may appear to people who have travelled in Asia, Africa,
America, Australasia, or Polynesia, experimental workers, or some of them,
express doubts as to whether human races really blend. " It would be extremely
interesting to students of genetics to learn upon what evidence Dr Archdall Reid
bases his positive statement that there is no segregation in the case of the Mulatto "
(Mr R. H. Lock, Nature, Oct. I7th 1907; see also Bateson, Mendel's Principles of
Heredity, pp. 208-9). " The evidence on which I base my assertion that there is
no segregation in the mulatto is that of my own eyes. Mulattos vary amongst
themselves, but the blend is usually very obvious and is reproduced in subsequent
generations when the breeding is inter se. With every infusion of European blood
the negro type — skin colour, hair texture, shape of features, and^the like — grows
fainter until at length the ' touch of the tar brush ' is hardly, if at all, perceptible ;
and this blending, as far as I am aware, occurs not only in all crossed human
varieties, but in other natural varieties as well. There may be exceptions, in
fact I believe there are ; but blending appears to be the rule in the vast majority
of instances " (G. Archdall Reid, Nature, Oct. 3ist 1907). " If Dr Archdall Reid
will produce authenticated pedigrees showing the repeated crossing of the mulatto
with pure white blood and pure black blood respectively, together with a detailed
account of all the offspring produced, he will make a very substantial contribution
to our knowledge of heredity in the human race, and one which will be examined
with very great interest by Mendelians" (Mr R. H. Lock, Nature, Nov. I4th).
" Since Mr Lock is probably the only human being who doubts the blending of the
black and white races in Mulattos and their descendants, it would be well if he,
rather than I, undertook the collection of pedigrees. He would feel himself on
the track of a great discovery which would enlighten even Mulattos, whereas I
should feel I was wasting time " (G. Archdall Reid, Nature, Nov. 2ist).

* See footnote, § 277.

WHERE DORMANT TRAITS ARE ABSENT 175

type, but proof of blending is furnished by the fact that continued
infusion of white blood in succeeding generations results in a
gradual change of type till at last the hair loses all traces of
woolliness. In these later generations also the colour of the
eye may suddenly be changed to a lighter hue. This last fact
affords another crucial instance which demonstrates that Mendelian
inheritance implies, not segregation, but latency. The inheritance
of eye-colour is alternative in ordinary intra-varietal breeding.
But when a white race is crossed with a black the eye-colour of
the former becomes permanently latent, or, at least, as long as
the mongrels breed together. But the latency is weakened by
successive infusions of white blood, till at length the descendants
may have blue or hazel eyes. If there were segregation of units
accompanied by the destruction or the non-reproduction of those
for light colour, the latter could never reappear, no matter how
often the infusion of white blood were repeated.

291. In addition to manifesting nearly complete general blend-
ing, human races when crossed differ from crossed varieties of
domestic plants and animals in another, an equally remarkable,
and a very important way. Never in human crossings is a latent
ancestral character brought to light, whereas the reappearance of such
characters, dormant perhaps for many generations, is one of the
most conspicuous results of the crossing of domestic varieties.
Now what is the significance of these very remarkable differences
of inheritance ? How is it that in the one case blended inheritance
is the rule, whilst in the other alternative reproduction combined
with a frequent development of hitherto latent characters is
general ? If we are able to unravel this mystery, I think we shall be
able to solve those problems of heredity which, of recent years, have
especially occupied the attention of experimental workers, and indeed
of most biologists.

292. The majority of experimental observers claim that the
inheritance of mutations is alternative. If we substitute 'develop-
ment ' for ' inheritance,' the evidence that they are right seems
clear, at least as regards many mutations. In man occur polydacty-
lism, hypophylangia, alkaptonuria (a dark-coloured condition of

I the urine), haemophilia, colour-blindness, deaf-mutism, and other
large variations,1 all of which may be classed as mutations,
and the development of which is alternative. Again, the majority
of experimental observers declare that a mutation is properly
defined as a large discontinuous variation, one which is not
1 See §§ 769-71-

i;6 THE MUTATION THEORY

connected by intermediate links with smaller variations. Doubt-
less in this also they are right. The mutations which have been
discovered in man all display this peculiarity. Yet again they
claim that domestic varieties of plants and animals have arisen, not
through the fixation of fluctuating variations by continued selection,
but through the artificial selection of mutations. Here, also, there
is good reason to believe that they are right, at least in large
measure. Breeders of plants and animals are no more able than
experimental workers to distinguish the smaller differences between
mating individuals. Moreover, they are in haste to get good
results. Of necessity they have selected large mutations rather
than small fluctuations.1 This, however, has not always been the
case. For example, when evolving speed in the American
trotting horse, a favourable mutation, involving as it would a
co-adaptive change in a thousand structures — that is a thousand
co-ordinated mutations — would be an exceedingly rare, indeed, an
almost impossible occurrence. Therefore the breeder must depend
on fluctuations, which in this case, though imperceptible to the
eye, can be measured by the test of speed. It is admitted that the
inheritance of fluctuations is blended, and that, as regards them,
offspring display a strong tendency to return to the ancestral
type. For this reason, according to Mendelians, do trotting horses
tend to retrogress unless carefully selected, and when crossed with
inferior types to transmit blended characters to descendants.

293. Experiments in crossing have been limited in great
measure to domestic plants and animals. Wild types are less
accessible, more difficult to manipulate, and often more or less
sterile when crossed. When, however, the cross is fertile, the
hybrid, like man, usually blends the parental characters and
transmits the blend to its descendants. In hardly a single instance
has the crossing of natural varieties revealed a latent ancestral
character? Darwin noted long ago that " Gartner further states
that reversions rarely occur with hybrid plants raised from species
which have not long been cultivated, whilst, with those which have

1 " He [Man] often begins his selection by some half-monstrous form, or at
least by some modification prominent enough to catch the eye or to be plainly
useful to him." Origin of Species, 6th ed., p. 60.

2 1 know of only one to which my attention was called by Sir William Thiselton-
Dyer. When Kalanchce flammed was crossed at Kew with K. Benin, the hybrid
displayed characters which can hardly have been other than ancestral traits
which have remained latent in one or other species (see Morphological Notes, by
William Thiselton-Dyer, K.C.M.G., F.R.S., Annals of Botany, vol. xvii. No. Ixvi.,
March 1903, pp. 435-41-

NATURAL AND ARTIFICIAL VARIETIES 177

been long cultivated, they are of frequent occurrence. This con-
clusion explains a curious discrepancy : Max Wichura, who worked
exclusively on willows which had not been subjected to culture,
never saw an instance of reversion ; and he goes so far as to
suspect the careful Gartner had not sufficiently protected his
hybrids from the pollen of the parent species. Naudin, on the other
hand, who chiefly experimented on cucurbitaceous and other culti-
vated plants, insists more strenuously than any other author on the
tendency to reversion in all hybrids. The conclusion that the
condition of the parent-species, as affected by culture, is one of the
proximate causes leading to reversion, agrees well with the converse
case of domesticated animals and cultivated plants being liable to
reversion when they become feral ; for in both cases the organiza-
tion or constitution must be disturbed, though in a very different
way."1

294. We are driven then to the conclusion that Natural and
Artificial selection are essentially unlike. Nature and man do not
select the same class of characters. Man, perforce, chooses
mutations. Nature, with finer powers of discrimination and with
unlimited time and material at her disposal, chooses, perhaps with
very rare exceptions, fluctuating variations. In no other way is it
possible to account for the striking differences revealed when natural
and artificial varieties are crossed. It is known that man tends to
select mutations, and that the reproduction of mutations tends to
be alternative. It is clear that when reproduction is alternative,
characters tend to become latent, and when latent to become patent
in cross-breeding. If, then, as experimental workers suppose, nature
chooses mutations, how does it happen thatnaturalvarieties, when crossed,
not only blend very often, but hardly ever reveal latent characters ? 2

295. The fact that natural varieties often blend their characters

1 Animals and Plants, vol. ii. pp. 24-5.

8 Since latent characters are in effect found only in domesticated varieties, it
follows that Darwin, who drew the materials on which his conclusion was founded
wholly from artificial varieties, formulated too wide an inference when he declared
that, " besides the visible changes which it [the germ] undergoes, we must believe
that it is crowded with invisible characters, proper to both sexes, and to both the
right and left side of the body, and to a long line of male and female ancestors
separated by hundreds or even thousands of generations from the present time ; and
that these characters, like those written on paper with invisible ink, lie ready to be
evolved whenever the organization is disturbed by certain known or unknown
conditions " (Animals and Plants, vol ii. pp. 35-6). It follows, also, that Professor
de Vries is mistaken in denning a variety as a type which has patent or latent a
character which is in the opposite condition in the parent species. A type which
carries a latent character is always a mongrel ; for it is only when varieties possess-
ing alternative characters cross, that latency occurs. Thus, all sexually dimorphic

12

i ;8 THE MUTATION THEORY

when crossed is decisive proof that they have not arisen by muta-
tions, the reproduction of which is alternative, for had they so
arisen the cross-breds would also display alternative reproduction.
As we see, artificial varieties, which, admittedly, have arisen by
mutations, display, not only alternative reproduction, but latent
characters in abundance. It does not follow, however, that all
characters which alternate in cross-breeding have arisen by
mutation. So far as has been observed, reproduction is alternative
only when characters are sharply contrasted ; and sharp contrasts
may arise as well by the piling up of fluctuations occurring during
many generations as by single mutations. It would seem, however,
that alternative reproduction is much more the rule when the
contrast has been reached by mutation than when it has resulted
from the accentuation of fluctuations.

296. On the other hand, if it be contended that mutations
occurring in wild nature have been preserved, not because their
reproduction was alternative, but because the mutants were sterile
with the parent type but fertile inter se, then it must be shown
that mutations, not only useful but similar in kind, occur in such
numbers that physiological isolation 1 without extinction is possible.
The fact that human races are fertile when crossed is proof that
physiological isolation can have played no part in their differentia-
tion. Unless, then, heredity is different in plants and lower
animals from what it is in man, we must believe that the natural
varieties of the former were similarly inter-fertile at their origin,
but that, in many of the cases which have been examined, differen-
tiation is now physiologically greater than in the case of human
races. Doubtless most natural varieties are more ancient than
those of man ; for few species can have so quickly invaded diverse
environments, where selection differed, as the human being, who
is omnivorous, and therefore not dependent for nutriment on

types are mongrels (in a real sense) between male and female. Again, the human
races of North- Western Europe, where travel and interbreeding have been so
common, and which in the past has been so often invaded by alien conquerors,
are mongrels between several races, as is shown by the fact that, unlike all other
animal races, they have variously coloured eyes. Yet, again, the albino rabbit
and mouse are mongrels between the white and the ancestral grey types. In
this connexion it matters not, of course, wrhether a variety is composed of many
individuals, or of only a single individual who has mutated from the parent
type. De Vries states that latency is of universal occurrence (Species and
Varieties, p. 222), but he gives no evidence. He mentions instances of retrogres-
sion in plants, and assumes (p. 631) without further proof that it implies, not total
loss, but latency. He assumes, in effect, that while the germ-plasm may gain
characters, it cannot lose them, see § 188.
1 See § 332.

INUTILITY OF MUTATIONS 179

special plants and animals, or on soil or climate, and who, owing to
his mental powers, is otherwise very adaptable.

297. The sole warrant for the belief that fluctuating variations
cannot be made more stable by continued selection is furnished
by the fact that recently evolved domestic varieties, such as the
American trotting-horse, tend to retrogress rapidly when no longer
selected. We have already discussed this question in part ; 1
presently we shall see how sex is instrumental in determining the
rapid retrogression of characters of recent origin. The sole warrant
for the hypothesis that the organic world has arisen by the selection
of mutations is furnished by the fact that some mutations have
been observed in wild nature, and that mutations appear excep-
tionally stable. Doubtless, however, they are common enough.
In man, the only natural species with which we are at all intimately
acquainted, they are very common, and often the same mutation
is repeated in many individuals. The medical profession owes its
prosperity largely to them : they fill our hospitals ; surgeons are
busy every day rectifying such mutations as hare-lip and club-
foot. But never yet has a mutation been recorded — neither in man,
nor in lower animals, nor in plants — that gave its possessors an
advantage in the struggle for existence so overpowering that
it enabled them to supplant the ancestral type. And hardly a
mutation has been recorded which enabled its possessors to persist
alongside the parent variety, at any rate when the reproduction
was bi-parental.2

298. Mutationists declare that the general failure to detect

1 See § 182.

2 The most widely discussed mutations are those of CEnothera lamarckiana, an
evening primrose, investigated by de Vries. Several species of evening primroses
were brought to Europe from America during the seventeenth and eighteenth
centuries. It is not known when, if ever, O. lamarckiana was introduced. It
was first observed by Lamarck at the beginning of the last century in a garden at
Paris, and at once recognized as a type new to science. The fact that this ' stately,'
' beautiful,' and noticeable plant was previously unknown to botanists, the
circumstances under which it was discovered, and the fact that it is not known
to grow wild anywhere in America, render it likely that it originated as a garden
variety in Europe, possibly in the very garden in which Lamarck found it. Most
probably, like so many other cultivated varieties, it is a mongrel, possessing an
unknown number of latent characters. At any rate it is a descendant of a wild
American plant, which, for more than a century, had been cultivated in Europe,
and which, presumably owing to changes in selection due to the great changes in
its environment and possibly to crossing, had become highly variable. The
patch of plants in which de Vries discovered his mutants from O. lamarckiana
had escaped from cultivation and was growing wild in a disused potato field.
More mutations occurred after he had altered the environment yet again by re-
moving specimens to his garden, where he cultivated the plants on a large scale.

i8o THE MUTATION THEORY

favourable discontinuous variations in wild nature is due solely to
difficulties of observation. But there are no such difficulties in
observing the neglected human species which we are so very capable
of observing. It is not really beneath the dignity of science to utilize
familiar facts. Mankind has spread over the whole habitable
globe ; it inhabits very diverse environments ; it is numbered in
millions, and has hundreds, if not thousands of stable varieties.
Some races such as the Esquimaux and the Tierra-del-Fuegians,
are apparently as ' pure ' as natural races of lower animals ; others
are simple mongrels ; yet others are compound mongrels.
Some mongrel human races are very ancient ; others are com-
paratively new.1 Racial changes of a permanent sort there have

The mutants, which were of at least seven different types, were comparatively
few in number in the field. Most of the types were weakly and perished. In the
field two types " have held their own during the last sixteen years, and probably
more, without, however, being able to increase their numbers to any noticeable
extent. Others perish as soon as they make their appearance, or a few individuals
are allowed to bloom, and probably leave no progeny. But perhaps the cir-
cumstances may change, or the whole strain may be dispersed and spread to new
localities with different conditions. Some of the latter may be found favourable
to the robust gigas or rubrinervis, which requires a dryer air, with rainfall in the
spring-time and sunshine during summer " (Species and Varieties, p. 574). Muta-
tions are comparatively few, changes of climate rare, and the dispersal of most
plants, except by human agency, slow. The chance of these mutations surviving
in nature seems, therefore, somewhat remote. It is significant that de Vries
" made experiments with some hundred species that grow wild in Holland. . . .
No real mutability could be discovered " (p. 520) in the native plants growing
in their ancestral environment. Or, to express the fact in other and probably
more correct terms, these natural varieties revealed no latent characters. To
account for the fact that O. lamarckiana mutated frequently while the native
Dutch plants mutated not at all, the hypothesis was formulated that in the life-
histories of species periods of great mutability alternate with periods of stability.
" Of course this mutable state must have had a beginning, as it must sometimes
come to an end. It is to be considered as a period within the lifetime of the
species, and probably it is only a small part of it " (p. 29). Manifestly this de-
duction, like that of colour-factors, is a pure guess, invented to bolster up another
hypothesis which was found not to agree with reality. We may predict
with entire confidence that every variety which has evolved under artificial
selection and has been frequently crossed is an ' eversporting variety,' whereas
every species which has evolved under Natural Selection is stable.

1 " In the case of a problem like that of man, complicated as it is by the fact
that he has ' crossed more often than any other animal,' and further rendered
intractable by the circumstance that he is not amenable to experiment, a great
difficulty arises in discovering which are the actual allelomorphs concerned "
(Mr R. H. Lock, Nature, iyth Oct. 1907). " How can the fact that human races
have crossed more often than any other animal complicate the problem ? My
statement implied, not that every race is a chaotic mixture of types, nor even that
there are no pure types, but only that we have here a very large and varied mass
of material on which to found our judgments " (G. Archdall Reid, Nature, Oct.
3ist 1907).

HUMAN RACIAL DIFFERENTIATION 181

been in plenty. In some places, as in parts of New Guinea, where
war is nearly perpetual and inter-marriages between tribes
comparatively rare, the inhabitants of almost every district, like
the land shells of Samoa l display stable characters which clearly
differentiate them from their neighbours. Even in Great Britain
we have still these local races, as in the Yorkshire dales and High-
land glens. So surely as a human race separates into two or more
sections between which interbreeding is restricted, just so surely
does differentiation set in. The section that remains in the
ancestral environment continues comparatively stable ; the section
that migrates undergoes swifter but always continuous and steady
adaptive change. Evidently there has been no lack of such varia-
tions as contribute to stable differentiation.

299. If, then, evolution is due solely to mutations, how does it
happen that no favourable human mutations have been noted —
neither large observable mutations, nor those which render mating
physiologically sterile ? The latter certainly have not occurred, for
differentiated human races are perfectly fertile when crossed.
The former as certainly have not occurred ; for written human
history stretches into thousands of years, and men are fond of
recording wonders, and none of this kind have been recorded.
I think no mutationist, in face of this massive evidence, will
venture to uphold the thesis that human differentiation has resulted
from mutations. And, if not human differentiation, why the
differentiation of other natural species and varieties ? As I say, we
have no reason to suppose that heredity in the animal man
differs from heredity in lower animals and in plants.

300. In a few — speaking comparatively, a very few — instances,
mutations, occurring chiefly in self-fertilized plants, have been
known to persist without artificial aid for several generations.2 In
every such case the mutation has been comparatively unimportant
as regards the function of the part that has undergone change. A
leaf or a flower has altered its shape or colour or texture, a flower-
stem has grown longer or shorter, the wing of a butterfly has
grown darker, and so forth. But all organs are not on the surface
of the body ; their co-adaptations, therefore, are not always so few
and simple as those of leaves and flowers. Consider a mutation

1 See § 332.

2 The only mutation, human or other, if mutation it can be called, known to
have been persistent under natural conditions for a considerable length of time,
of which I am aware, is the Hapsburg lip, an ungainly feature of the reigning
house of Austria. I imagine it would have disappeared long ago if the faces it
marred had not belonged to an inbred imperial family*

1 82 THE MUTATION THEORY

occurring within that immensely complex and delicately adjusted
machine, a higher animal. To be useful the mutation must
not only be an improvement in itself, but it must be correlated to
a thousand readjustments — a thousand co-adapted mutations in
other parts of the machine. Otherwise it will be positively harm-
ful.1 Indeed, the principal difficulty to be surmounted by the
supporters of the mutation hypothesis is not adaptation to the
environment but co-adaptation within the organism. Suppose,
however, we cede the point, and agree that the miracle may happen
and a thousand co-adapted mutations may occur in a single indi-
vidual. Then, either the reproduction will be blended, or it will be
alternative. If it be blended, the mutation will be swamped unless
more miracles happen and many other individuals mutate in the
same way and at the same time and place. If it be alternative,
the co-adaptation will be lost in succeeding generations through
mixture with the characters of individuals who have not mutated ;
for Mendelian observers insist, and very rightly, that the alternative
characters are reproduced independently of one another, and
that all the characters of the same individual are not necessarily
patent or dormant together.

301. It must be noted, morever, that, not only are the parts of
a living being co-adapted, but that different species of animals
and plants are also co-adapted to one another. Thus the plants
which herbivorous animals are capable of using as food possess
great powers of multiplying themselves and of reacting to the
stimulus of injury, of regenerating lost parts. Thus also the
powers of pursuit possessed by carnivora are closely related to
the powers of escape possessed by their prey. If evolution were
by mutation, then a mutation, increasing the speed of one species,
could only be met by a mutation occurring at the same time and
place, increasing the speed of the other. For example, if wild
dogs suddenly mutated in this way, and the various animals they
hunt did not, the inevitable extinction of the latter would soon
be followed by that of the former.

302. It is possible to account for the co-adaptation of parts
and species to one another on the theory that evolution results
from the continued selection of constantly occurring small fluc-
tuations— from the constant and steady change of species in
adaptation to changes in their surroundings ; but how is it possible
to account for it on the theory of large and, speaking comparatively,

1 De Vries (Darwin and Modern Science, p. 68) insists that correlated mutations
are common. But correlation is not the same thing as co-adaptation.

THE ARRIVAL OF THE FITTEST 183

very rare mutations ? No real attempt has been made to sur-
mount all these difficulties. Merely because some mutations have
been observed it has been assumed that all evolution proceeds
by steps and not up a smooth incline. Merely because some
mutations, the inheritance of which is alternative, are comparatively
stable, it has been assumed that all mutations are absolutely stable.
Merely because fluctuations cannot be fixed by a short course of
experimental selection, it is assumed that they cannot be fixed by
the age-long selection of nature. Merely because varieties which
have been evolved under artificial selection display when crossed
alternative reproduction in widely divergent characters, it has been
thought that all inheritance is alternative. All these inferences are
illegitimate expansions of single inductions — illegitimate, because
there has been no rigorous deductive inference of consequences,
and no appeal to reality for confirmation.

303. It is not to be maintained, of course, that no mutation has
ever been selected by nature. It is maintained merely that species
are so accurately adapted to their environments, including one
another, and that their structures — nervous, circulatory, alimentary,
bony, muscular, glandular, etc. — are so closely co-adapted that a
favourable mutation must be an extraordinarily rare thing — so rare
that as factors in evolution mutations are negligible. We are
told sometimes that, whilst Natural Selection may account for the
survival of the fittest, it does not account for the arrival of the
fittest. This jingle of words implies, of course, that fluctuations are'
too small to have selection value.1 But we shall see in later
chapters, when we study the recent evolution of man, who, as I
say, is the wild type we are best able to observe, that fluctuations
have so real a survival value that, according as men fluctuate favour-
ably or unfavourably — solely on that account — they survive and see
their grandchildren, or perish in youth. The arrival of the fittest,
owing to the necessary co-adaption of parts and species, is an im-
mensely greater difficulty for the mutationist than for the selectionist

304. We have noted that living beings are bundles of adapta-
tions. No phenomenon of life is more universal than the occurrence
of fluctuations. Presumably, therefore, fluctuating variability is
an adaptation, and a highly useful character. It has a function.
Mutationists — at any rate many of them — admit, for example in
the case of trotting-horses, that fluctuations are transmissible to
some extent, and may be the sources of some temporary evolution.
But we are asked to believe that opulent but parsimonious nature,

1 See § 826 (footnote).

1 84 THE MUTATION THEORY

that prolific creator of wonderful adaptations, has so contrived that
directly this evolution becomes of importance as a factor in survival
it is brought to a standstill ; the species must wait for that rarest
of phenomena, an adaptive mutation.

305. To sum up, the Mendelian doctrine — the notion that
inheritance is alternative, that allelomorphs meet in the zygote but
separate in the descendant gametes — is founded on experiment.
It has not been tested by experiment. Experimental tests reveal
the existence of blending when natural varieties are crossed, and
of latent characters when artificial varieties are crossed, and, there-
fore, in both cases negative the hypothesis of segregation. The
attempt to explain away latent traits by the hypothesis of factors
and determiners is founded on a pure guess which is negatived by
their occurrence in pure-bred varieties. The mutation hypothesis
can hardly even be said to be founded on experiment ; for most
mutations have been simply observed. In any case the notion that
evolution depends solely or mainly on mutations neither has, nor can
be tested experimentally ; for we can never be sure that we have
correctly reproduced ' natural ' conditions, nor can we continue our
experiments long enough. But both the Mendelian and Mutation
hypotheses may be tested by the ordinary and necessary scientific
procedure of making a rigorous deductive inference of consequences
and appealing to reality for confirmation. In neither case have
their supporters applied the test. Both hypotheses, therefore, are
" awful examples " of all that scientific thinking should not be.

306. The reader perceives that the traits which mainly dis-
tinguish the experimental biological school from all other schools
in all other branches of science are its self-imposed restrictions in
observing and thinking — restrictions which render it impossible for
the experimental worker to prove his hypotheses to the satisfaction
of other people, or for others to disprove them to his satisfaction.
With the exception of data furnished by some few human abnor-
malities and the like, almost the whole of the facts used have been
drawn from experiment, and none of them have been used to test
the thinking. We read occasionally in the literature of that school
such pronouncements as, " Evolution became the exercising ground
of essayists. . . . Genetic experiment was first undertaken, as we
have seen, in the hope that it would elucidate the problem of
species. . . . The time has now come when appeals for the vigorous
prosecution of this method should rather be based on other
grounds." x " The time is not ripe for the discussion of the origin

1 Bateson, Mendel's Principles of Heredity, pp. 3-4.

THE ESSAYISTS 185

of species. With faith in evolution unshaken — if indeed the word
faith can be used in application to that which is certain — we look
on the manner and causation of adapted differentiation as still
wholly mysterious."1 The "essayists" were such men as Darwin,
Wallace, Huxley, Ray Lankester, and Thiselton-Dyer in England,
Weismann and Osborn abroad. Some of them did not them-
selves experiment ; but it is possible to think correctly, even about
experiments, without first having personally controlled the
breeding operations of rabbits and guinea-pigs. Moreover, the
quantity of data already in hand to which Darwin's work called
attention was so large as to occupy more than sufficiently the time
of the most industrious thinker who was capable of dealing with
complex material. The method of the essayists was not, as might
be gathered from the words I have quoted, to neglect experimental
work. Some of them constantly experimented. On the contrary,
their method was to use, not only the experimental, but all the
materials at their command, and to test their thinking in every
way possible. Therefore their writings necessarily took the form
of "essays." It is only when we use isolated fragments of evidence
and guess about it that we are able in biology to avoid — if that be
a merit — even the appearance of reasoning.

307. The writings in which the Mendelian and mutation
hypotheses are formulated are as much essays as those which are
denounced as such. They are distinguished from the latter only
by very novel conceptions concerning the nature of science and of
logical proof. It would not be surprising were a section of the
general public, which has only the vaguest ideas as to what science
is and how it has been created, deluded into the belief that
experiment is an invariable accompaniment of special accuracy
in scientific observation and thought. For experiment is an
instrument which has been employed almost solely by men of
science. But that a whole school of biologists should entertain
that notion, apparently in complete unawareness that the question
as to what constitutes evidence and what proof has been elabo-
rately discussed by some of the greatest thinkers of the past, is
certainly very remarkable. It is, perhaps, conceivable that
experimental workers are right in neglecting patent facts and tests
for thinking; but I do not think I can be wrong or prejudiced
when I insist that so great a departure from established scientific
usage should be vindicated by at least some formal attempt at
justification. But never yet has this been done. As matters
1 Bateson, Darwin and Modern Science, p. 99.

1 86 THE MUTATION THEORY

stand, appeals that we shall vigorously prosecute the experimental
method and abstain from controversy mean little more than that
we shall ignore all material gathered otherwise than by experiment,
and abstain from testing the correctness of guesses — that we shall
permit biology to become a tumbling-ground for irresponsible
whimsies. Declarations that the time is not ripe for the discussion
of the origin of species, and that the manner and causation of
adapted differentiation are still wholly mysterious, imply nothing
more than that it has been found impossible to bring the Mendelian
and mutation hypotheses into accord with the fact that living beings
exist and are fitted to their surroundings. The denial (based on
the supposed inutility of structures, the uses of which have not
been ascertained) that living beings are, in a wonderfully complete
degree, adaptational forms, has precisely the same origin.

CHAPTER IX
THE FUNCTION OF SEX

Most Mendelian characters are sexual characters — The parallel between
Mendelian and sexual characters — It has been said that the inheritance of sexual
characters is Mendelian — The truth is that the inheritance of Mendelian char-
acters is sexual — The function of sex if (i) the Mendelian hypothesis is true,
(2) if the mutation hypothesis is true, (3) if evolution is founded on fluctuations and
inheritance is blended.

M

308. -|\ /fUTATIONS and Mendelian reproduction are
realities. If, then, the organism is a bundle of
adaptations, and evolution builds on fluctuating
variations which blend, how is their presence to be accounted for ?
We have considered several great problems of heredity and
evolution, for example the nature of the distinction between
classes of characters, the mode in which the individual develops,
the mode in which species evolve, the causation of variations,
and the like. Obviously the mutation hypothesis is concerned
with none of these except evolution. But evolution is merely
another name for the adaptation which results from progression
and retrogression ; and, as we have seen, it is not believable that
mutations, which occur only rarely and which, speaking practically,
are never adaptive, can have furnished the materials for the
multitudinous, the perpetually changing, the infinitely complex
and delicate adjustments of living beings. We are driven, then,
to the conclusion that they are nothing other than abnormalities,
extreme variations which arise only because evolution (and there-
fore the regulation of variations) is never perfect — just that class of
variations which nature checks by the weeding out of the exception-
ally variable individuals, but which human breeders encourage and
preserve, that class on which surgeons expend the resources of their
art to eliminate in the individual but to perpetuate in the race.

309. We have to delve deeper before we can account for the
Mendelian phenomena. Experimental workers assume that in
Mendel's laws they have acquired a master-key to all or most of
the problems of heredity. But, if we consider the question closely,
it becomes evident that Mendel's laws are concerned with nothing

187

1 88 THE FUNCTION OF SEX

more than the effect or function of conjugation)- Manifestly they
have no bearing on such problems as progression, retrogression,
recapitulation, variability, the causation of variations, the dis-
tinction between characters, and the rest we have discussed.
They merely attempt to describe the way in which parental
characters are distributed amongst offspring and descendants
under conditions of conjugation. To parthenogenesis they do not
apply ; for here, since no allelomorphs meet, none can be dominant
or recessive, none can segregate. In fact, they apply to no
problem that is presented in common by parthenogenetic and
conjugating species. At any rate I can think of none ; and though
I have inquired industriously amongst the adherents of " the new
science of genetics," I have quite failed to secure enlightenment.2

310. It has been said, indeed, that since "the rule that all
organisms pass through a sexual cycle at some period of their
existence has extremely few exceptions," 3 all problems of biology
are problems of conjugation. It would be as reasonable to declare
that, since all organisms die, therefore all problems of biology are
problems of death. Such a statement is merely equivalent to a
declaration that the universe is a unity, the facts and laws of
which are related. Again, it has been said, " It is the claim of the
Mendelians that they have discovered in certain cases some of the
fundamental characters of an organism — the units of hereditary
transmission, which are represented in the reproductive cells by
definite entities known as allelomorphs.' 4 But, obviously, if there
is no segregation, but merely patency and latency, the discovery
has not been made. In this instance, also, it would be well if the
reader paused and asked himself, not whether Mendelism solves
any problems, but whether it has a conceivable bearing on any
problem save that of conjugation — of sex.

311. We saw that individuals of sexually dimorphic species
have two sets of sexual characters, one of which is patent
and the other latent, one of which is dominant and the other

1 Of course every effect is not necessarily a function. A function is that which
bestows utility. One effect of sex is to halve the possible number of offspring.
But no one will believe that this halving is the function of sex. Besides, nature
is able by the selection of fertility to increase the number of offspring produced by
a pair up to any useful limit, and so obviate this effect. On the other hand, if,
as Mendelians suppose, bi-parental reproduction mixes parental characters as
marbles are mixed, but leaves them otherwise unchanged, it would seem we have
no alternative but to suppose that such mixing is both the effect and the actual
function of sex. I think it is impossible to imagine any other function.

2 See, for example, Nature, 3rd Oct. 1907 to Jan. 23rd 1908.

8 R, H. Lock, Nature, Nov. I4th, 1907. * Op. cit., Nov. I4th, 1907.

SEXUAL AND MENDELIAN REPRODUCTION 189

recessive. Every individual is in fact an 'impure dominant.'
The non-sexual characters, on the other hand, are all patent.
When the breeding is intra-varietal, as it normally is in nature,
mating individuals (apart from their sexual characters) differ,
with rare exceptions, only to the extent of fluctuations, the in-
heritance of which, admittedly, is blended. The exceptions are
mutations which, like the sexual characters, tend not to blend, but
to become patent or latent in descendants. We saw also that
when natural varieties, which have arisen through the selection of
fluctuations, cross, they tend to blend their characters ; but when
artificial varieties, which have arisen through the selection of muta-
tions, cross, the reproduction of the characters in which they differ
tends to be alternative. Evidently, then, the mode in which muta-
tions are reproduced by offspring and descendants presents a close
parallel to the mode in which the sexual characters are reproduced.
312. The parallelism between the two sets of phenomena, the
sexual and the Mendelian, grows clearer the more we study it.
We have already noted many of the likenesses, but it will be useful
to bring them together, (a) Of necessity some of the sexual char-
acters, especially the primary characters, are developed in distinct
sets — a male set and a female set — which are kept separate by
selection. Most of the Mendelian characters, on the other hand,
are developed indifferently by both sexes. But many characters
the functions of which are sexual (in that they serve as attractions),
though not exclusively sexual, are reproduced in the latter way ;
for example, colour of eyes, and, to some extent, colour of skin and
hair in the intra-varietal matings of man, and colour of plumage
and hair in the inter-varietal matings of many birds and mammals.
(b) Sometimes characters peculiar to one sex are transferred to the
other, as in the cases of the bony cranial protuberance of the Polish
fowl 1 and the plumage of the Sebright bantam. Some Mendelian
characters are transmitted sexually, as colour-blindness and haemo-
philia in man. They would be termed sexual, not Mendelian, were
they more common. Deaf-mutism appears to furnish a further
connecting link, for the condition tends to affect the males in some
families and the females in others.2 Moreover, the dominance and
recessiveness, the patency and latency of Mendelian characters
is sometimes affected by the sex of the parents, the offspring of
reciprocal crosses being unlike.3

1 Animals and Plants, vol. i., p. 269.

8 C. J. Bond, British Medical Journal, Oct. 28th 1905.

3 See § 264; see also Bateson, Mendel's Laws of Heredity, chapter x.

190 THE FUNCTION OF SEX

313. (c) The alternative development — the alternative patency
and latency — of sexual characters is more perfect than that of most
Mendelian characters, but this is only what might have been
expected ; for it has been secured by selection, just as the less
perfect, or rather the different alternation in aphides, and bees has
been similarly secured, (d) When Mendelian characters are crossed,
one of each pair is usually the dominant in the first hybrid genera-
tion. Thus colour is usually dominant over white in mammals
and flowers, whereas the contrary is the case in poultry. In the
case of sexual characters one or other alternative dominates in any
individual. But sometimes the offspring of a single pair are
wholly of one sex, a phenomenon not very rare in human families ;
whilst, on the other hand, in the case of some Mendelian alterna-
tives, both types tend to appear in the first hybrid generation — for
example, normal and extra toes in poultry, (e) As might have
been expected also, the sexual characters show a lesser tendency to
blend than Mendelian characters ; but some degree of blending is
not uncommon in the former, as when women have masculine pelves
and partially bearded faces. (/) The crossing of varieties may
bring to light long dormant Mendelian characters — for example,
wild-grey in mice and rabbits ; it may also reveal strictly sexual
characters which have long been latent ; for example, broodiness
and sexual peculiarities of plumage in fowls ; and sometimes the
lost sexual characters may reappear in connection with traits
properly belonging to the opposite sex.1 (g) As Ewart2 and
others have shown, the dominance of both sexual and non-sexual
alternative characters is capable of being influenced by the
environment.

314. (ti) If the characters of crossed varieties blend or are lost,
there is a very general tendency to sterility, as is the case when
natural varieties interbreed ; but if they alternate so that the char-
acters are unchanged, as when artificial varieties cross, fertility is
perfect. " We know no Mendelian case in which fertility is im-
paired." 3 We have here a very clear indication of the parallelism
between sexual and Mendelian characters, for under such conditions,
as in mules, sexual characters also tend to blend or be lost with con-
sequent sterility, (i) Mendelian characters which segregate in later
generations are sometimes blended in the first hybrid generation —
for example, in the case of Andalusian fowls ; or there may be
particulate inheritance in the first generation and more complete

iSee § 280. 2See § 132.

3 First Report of Evolution Committee, p. 148.

SEXUAL AND MENDELIAN TRAITS 191

separation subsequently.1 In like manner, when varieties are
crossed, a pseudo-hermaphroditism is not uncommon, that is, the
inheritance of male and female characters is then particulate, the
separation into male and female sets is not preserved ; there is on
the contrary Mendelian independence of characters. (/) As we
have seen, there is no real segregation of Mendelian any more
than of sexual characters. There is only patency and latency.
(k) Sometimes both alternative Mendelian characters, for example,
extra toe and normal foot in poultry, appear, like the sexual
characters, in the different individuals of the first hybrid genera-
tion, and would continue to appear in each succeeding generation
were they like the sexual characters crossed in each generation.
(/) In other instances, the Mendelian traits are long latent, like the
sexual characters in aphides ; but like them reappear at length, as
in cases of reversion in pure-bred varieties.2 (m) In another pecu-
liarity, and that a very striking and important one, Mendelian
and sexual characters display a suggestive resemblance. Both
are traits in which, unlike fluctuations, the mating individuals are
strongly contrasted ; for the Mendelian characters are usually
mutations or characters which originated by mutation in ancestors.

315. Plainly, the parallel between sexual and Mendelian
reproduction is very close. It is so close that experimental
workers, though they have not by any means perceived all the
likenesses, have surmised that the inheritance of sexual characters
accords, in many instances at least, with Mendel's laws.3 Indeed,
they have supposed that the inheritance of sex is merely an
example of Mendelian inheritance,4 and that continued investi-
gation will eliminate any apparent contradictions and anomalies.
But another interpretation of the facts is conceivable. Examine any
list of Mendelian characters, for example those of poultry 5 or peas.* A
glance shows that, as a rule, the majority of the items in such a list are
sexual in the sense that, as attractions or otherwise, they are concerned
with reproduction. It is possible, then, that, so far from it being
a fact that the reproduction of sexual characters is an example of
reproduction of Mendelian characters, the reverse may be the case.

316. The question we are now in a position to ask ourselves
is, Which mode of reproduction, the sexual or the Mendelian,
contains the other ? Which is a variety of the other ? In deciding

1 Inheritance in Poultry, p. 85. 2 See § 280.

3 See Bateson, Mendel's Laws of Heredity, chapter x.

4 See Castle, Heredity oj Sex.

5 See § 288. 6 See § 257.

I92 THE FUNCTION OF SEX

this problem, we must bear in mind that sexual reproduction is
almost universal ; whereas, to judge by facts that have been
actually observed, not merely imagined, Mendelian reproduction
is one of the rarest things in nature. Speaking practically, it
occurs only when mutations are reproduced ; and all the evidence
indicates that mutations occur relatively seldom, and, even then,
are very seldom preserved, except when the selection is artificial.
Mendelian reproduction, therefore, is, in effect, unknown in
normal — that is, zVz/ra-varietal — breeding. Natural varieties very
rarely cross, and only rarely display Mendelian traits when man
crosses them. Such traits are common only when artificial
varieties, in which mutations have been accumulated by man, are
crossed by man. They seem common to experimental workers
only because the materials for thought to which they have limited
themselves have been obtained almost exclusively in this latter
way. I think, therefore, that no one who has been accustomed
to found his judgments, not on the exception but the rule, will
hesitate to conclude that Mendelian reproduction is a variety of
sexual reproduction, and that the converse is as absolutely untrue
as if we had declared that mammals are a variety of dogs.

317. If we found our judgments on verified evidence alone,
the conclusion seems irresistible that Mendelian * inheritance ' is
a human creation, and that the right interpretation of the facts
appears to be, that nature treats mutations, when man interferes
and presents them to her, as sexual characters. She is not a
conscious selecting agency, and they resemble the sexual characters
and differ from the fluctuations which she normally meets, in that
they constitute wide differences between mating individuals. But
her treatment of them is more or less uncertain ; hence, as
compared to sexual traits, their imperfect alternation and their
tendency to blend in greater or. lesser degree. It appears, then,
that Mendelian characters are nothing other than non-sexual or
semi-sexual characters abnormally reproduced in the mode that
sexual characters are normally reproduced. It follows that experi-
mental workers have been engaged in investigating, not heredity
in general, not even the function of sex, but only certain anomalies
of sexual reproduction which occur under conditions of artificial
selection and crossing. They are the unhappy victims of a vast
practical joke unconsciously played by the human breeder.

" The earth hath bubbles, as the water has,
And these are of them." *

^'Macbeth," i. 3.

MENDELISM AND SEX 193

They furnish examples of the disasters which tend to befall us
when we limit the area whence we draw the materials for thought,
and fail to test our thinking in every way possible, when, in fact,
our attitude is sectarian, not scientific.

318. The question of the relation between sexual and
Mendelian characters cannot, however, be disposed of in this
summary fashion. At any rate, since the reader may still consider
it a matter of opinion whether the inheritance of sexual characters
is Mendelian or the reproduction of Mendelian characters sexual,
it ought not to be so disposed of. It is necessary to make the
usual deductive inference of consequences, and then to compare
these consequences with reality. It is an indisputable truth that
living beings exist and have undergone evolution. Does the
hypothesis that the inheritance of characters, including the sexual,
is Mendelian accord with this truth, or is it incompatible with it?
Or, on the contrary, does the hypothesis that inheritance tends
to be blended, and that Mendelian traits are abnormalities of
sexual reproduction introduced by man, accord with it? In
brief, we have now to investigate the function of conjugation,
of sex.

319. If the Mendelian theory is true, the effect and, therefore,
presumably, the function of conjugation is to mix parental
characters as marbles are mixed, not to blend them as colours
are blended. Now suppose, for example, that a tall man mates
with a short woman and offspring are born to them. This means
that both parents have been so well adapted to the environment,
and their characters so well co-adapted to one another, that they
have been enabled to survive till they were mature. But if
characters are transmitted independently of one another, the ' tall '
and ' short ' characters of the parents will be mixed in the
offspring. This is not what happens in nature. It is not even
what happens when artificial varieties are crossed by man ; for
only a very few of the characters (e.g. colour of plumage and extra
toe) of such varieties have been established by him through the
selection of mutations. But it is what is implied in the Mendelian
doctrine. It must be remembered that tallness and shortness in
human beings and other animals depend, not on a single character
like internodal length in the pea, but on a multitude of structures,
all of which are supposed to be inherited independently of one
another.1 Moreover, relative tallness and shortness are not neces-
sarily fluctuations, for there are stable tall and short human races

1 Bateson, Mendel's Principles of Heredity, p. 209.

194 THE FUNCTION OF SEX

which, as it happens, are able to cross successfully. On the
Mendelian theory, however, the effect of bi-parental reproduction
should be calamitous ; and one is left to wonder how it happened
that this form of reproduction replaced parthenogenesis, in which
such a disastrous mingling of incongruous elements would, at
least, not occur. Moreover, self-fertilization is not uncommon, and
is a product of evolution. Here, since, almost invariably, only
like characters meet, there can be, speaking practically, no mixing
of unlike allelomorphs, and we must suppose that conjugation
— that sex, which has burdened living beings with so many
characters — has no function whatever. It is surely not surprising,
then, that Mendelians, conscious of the tangle, should feel moved
to declare that they "look on the manner and causation of adapted
differentiation as still wholly mysterious," and that "we can
profitably reject, as I believe, much of the theory of Natural
Selection, and more especially the idea that adaptations have
arisen because of their usefulness."1

320. On the other hand, if the mutation theory as conceived
by Professor de Vries is true, that is, if the variations on which
progressive evolution is founded are large discontinuous mutations,
and if mutants tend to be sterile when crossed with the parent
type, or if fertile, to have offspring which blend the parental char-
acters, then, again, one is left to wonder at the extraordinary
function assigned by implication to sex. When reproduction is
parthenogenetic, useful mutations, if they occur, have an excellent
chance of surviving. But when reproduction is bi-parental, they
can very rarely, if ever, escape being lost through sterility, or
swamped through blending. According to this hypothesis, there-
fore, it would appear that the function of sex is to render nature
powerless to produce adaptive changes. And yet we must suppose
sex to have been evolved by nature. In this case also how shall
we account for the occurrence of self-fertilization ?

321. Examine now the theory that evolution proceeds through
the constant selection of 'continuous,' 'normal,' or 'fluctuating'
variations, the inheritance of which is blended.2 As we have seen,

1 See § 306.

* The term ' blended,' with the meaning given it in the present work, is not
altogether correct ; but it is convenient. It is used in contradistinction to
1 alternative ' and includes all shades of blending from an equal mixture of parental
characters to an exclusive reproduction of the character of one parent with total
loss of the character Of the other. Exclusive inheritance in this sense differs
from dominance in that the former implies the complete loss of the character of
one parent, whereas the latter implies only its latency. To the Mendelian

THE BLENDING OF PARENTAL TRAITS 195

every species which is sexually dimorphic, possesses two kinds of
characters. In some characters parents resemble one another
closely ; that is, they differ normally only to the extent of fluctua-
tions. The inheritance of these characters is blended. In other
characters parents differ so widely that, did we not know them to
be male and female, we should suppose them to belong to different
species. The inheritance of these larger differences is apparently
alternative. Really it is blended ; only the reproduction is alterna-
tive ; for since parents transmit their characters through children
of the opposite sex to grandchildren of the same sex, we know
that, though every individual possesses only one set of non-sexual
characters, he possesses two sets of sexual characters, one of which
is patent and the other latent. If, then, similar characters blend
(e.g. the ears of one parent with the ears of the other, and so on),
there can be no doubt, in the case of the sexual traits, that the
patent male characters of the father blend with the latent male
characters of the mother, while the patent female characters of the
latter blend with the latent female characters of the former. The
child, however, presents a deceptive appearance of inheriting only
one set of characters in which there is no blending. Abnormally,
the patent sexual traits of the one sex blend with those of the
other as in many of the so-called hermaphrodites of sexually di-
morphic species. Except in the case of mutants, which in nature
only very rarely survive and have offspring, all the larger differ-
ences between mating individuals are sexual. But in some
characters mating individuals do not differ widely. Thus the
coloration of the male and female may be similar. The inherit-
ance of such characters is admittedly blended. In parthenogenesis
there is neither latency nor, of course, blending. Latency and
blending are phenomena of bi-parental reproduction only.

322. The only real exception to blended inheritance that I can
think of occurs when a mutation first arises, If the mutant (the
individual that has mutated) be crossed with a normal individual
the mutation may be diminished, in which case the inheritance is
blended ; or it may be quite eliminated, leaving no representative
in the germ-plasm, in which case there occurs that extreme form
of ' blended ' inheritance which we have termed exclusive ; or the
mutation may be present in the offspring unchanged by conjuga-
exclusive inheritance is identical with gametic purity, but, as we have seen, it is
certain that gametic purity does not occur when ' inheritance ' is alternative. In
such cases we have only alternative development. The term prepotent as applied to
a parent, implies that his or her character predominates in the blend in any degree
up to an exclusive inheritance. To the Mendelian prepotence implies dominance.

196 THE FUNCTION OF SEX

tion in a patent or latent condition, in which case there is no
blending in that generation. In subsequent generations there is
blending if descendants of the mutants interbreed, for they will
have the character in a patent (dominant) or latent (recessive)
condition. It is not to be supposed, however, that mutations are
reproduced unaltered in offspring and descendants. Presumably,
like other characters, they are subject to fluctuating variations, of
which the general trend is retrogressive. They disappear, there-
fore, in time by sudden mutation, or probably more usually by
gradual retrogression, unless preserved by selection. We have no
reason to suppose that they are less liable to retrogression when
latent than when patent. No doubt, numbers of latent characters
have persisted through many generations in domestic species ; but,
speaking comparatively, all domestic species are of recent origin,
and the retrogression of some useless patent characters (e.g. limbs
when they have become useless) is very slow. Nature is parsi-
monious of her materials ; it is improbable, therefore, that the
germ-plasm is burdened for ever with useless dormant characters.
At any rate, there is not an iota of evidence that it is so burdened.
An interesting point in connection with latent traits is the reap-
pearance in offspring of numerous narrow, rather faint stripes when
the horse, which has no patent stripes, is crossed with the Burchell
zebra, which has a few broad ones. This is the most ancient
latent character known to me. It is commonly believed that the
narrow stripes are due to reversion to a common ancestor. This
may or may not be true ; but it does not follow that the dormant
trait is carried by both species. Dormant traits are practically
unknown in natural varieties such as the zebra ; and horses, even
when pure bred, sometimes display traces of stripes. It is pro-
bable, therefore, that the horse is the carrier of them, that they
were rendered dormant in the ancestry by the artificial selection of
mutations, and that they have grown faint through retrogression.

323. Offspring vary ' spontaneously ' from their parents in two
ways. First, they blend parental characters, and so differ from
both parents ; or, if there is exclusive inheritance, they differ from
one parent. Second, they differ from both parents otherwise
than by blending. With this latter sort of spontaneous variations
we have already dealt.1 We have to consider the variations
which result from blending. Suppose, now, to choose a homely
example, a man with an exceptionally broad nose mates with a
woman with an exceptionally high nose. Then, if the result be

1 See chapter'v.

BLENDING IMPLIES RETROGRESSION 197

a blend, the offspring approach the ordinary specific type more
nearly than either parent ; that is, there is retrogression or
'regression ' as regards the progressive variations of both parents
— a retrogression towards the specific mean. Again, suppose
there is exclusive inheritance, so that the peculiarity of one parent
is entirely lost. We noted that this very often happened in the
case of those numerous small redundancies, those small progressive
variations which offspring invariably display.1 Here, again, there
is return to the specific type and retrogression. When offspring
inherit exclusively from the progressive parent, there is, of course,
no retrogression ; but this, as proved by the general tendency to
retrogression, happens comparatively infrequently, and, in any
case, there is no progression.

324. Blended inheritance, therefore, nearly always implies
retrogression when parents differ. The characters in which they
differ tend to be lost, wholly or partially, within the limits of the
difference. It never implies progression. When progression
occurs, it is due, not to blending, not to the intermixture of
parental germ-plasms, but to that spontaneous variability which
is present in all forms of life, including parthenogenetic types.
Notwithstanding all that has been written on the subject, there is
absolutely no evidence that sex is ever a source of progressive
variations. Whenever we are able to trace its influence clearly,
blending (i.e. retrogression) is what we observe. It is true that
cross-breeding may reveal latent characters in a domestic species.
But this apparent progression is never real. Indeed, it frequently
implies retrogression.2 Again, when varieties are crossed and
their constitution 'broken/ as it has been termed, the increased
variability which has been said to occur in descendants may well
be due to alteration, through retrogression, of that tendency to
vary only within narrow limits, which was imposed by Natural
Selection on both varieties after they became adapted to their
surroundings — to a return to that condition of wider variability
which was imposed on them while they were becoming adapted.
Varietal crossing, however, is a rare phenomenon in nature. It is
one of the abnormalities which especially distinguish artificial
breeding.

325. The function of sex, therefore, is to bring about
retrogression. But this retrogression does not occur at hap-
hazard. On the contrary, sex, a principal source of retrogression,
does its work with as much discrimination as Natural Selection,

1 See § 194. a See § 189.

198 THE FUNCTION OF SEX

the sole source of progression. For example, to choose another
homely instance, suppose a human race inhabits a region where
malaria is prevalent, but where tuberculosis and measles are
absent. Then offspring will vary from their parents, favourably
and unfavourably, with respect to all three diseases. In other
words, they will, as compared to the parents, be more resistant
or less resistant to each disease — more or less able to survive if
exposed to it. It does not follow, however, that an individual
who has varied favourably as regards malaria, will also have
varied favourably as regards tuberculosis, measles, or any other
disease. Since malaria is present, those who have varied un-
favourably in relation to it will be eliminated, while those that
have varied favourably will be preserved. Like will mate with
like, and therefore little or no retrogression caused by blending
will occur to check progression caused by Natural Selection. On
the other hand, the progressive variations with respect to tuber-
culosis and measles will be mere useless redundancies. Since
there will be no elimination of those that vary unfavourably,
unlike individuals will mate. The result will be retrogression.1
Apply this reasoning to all the characters of the individual, and
the function of sex becomes apparent. Natural Selection preserves
or causes progression in useful characters by eliminating the
individuals that do not possess them in sufficient degree. On the
other hand, sex, a product of evolution through Natural Selection,
automatically eliminates useless characters, but without eliminating
the individuals that possess them.

326. The fact that races undergo protective evolution only

1 When two dwarf breeds of dogs are crossed the offspring tend to be larger
than either parent. This would seem to indicate progression as a result of crossing.
But such breeds have resulted from the artificial selection of mutations. In them,
presumably, the larger size is latent. Again, inbred artificial varieties tend to be
delicate ; and Darwin noted that, when two such varieties are crossed, the result
is often an increase of health and vigour. It seems not unreasonable to suppose
that the apparent progression is really due to retrogression. Nature eliminates
unfavourable variations in all directions in evolving varieties. But man, devoting
his attention exclusively to one or two points (e.g. speed in race-horses, size,
shape, and colour in flowers), neglects or cannot perceive others which, though
unfavourable, are not eliminated by selection because the individuals are pro-
tected, nor by conjugation because the individuals, being inbred, are much alike.
Crossing unites unlike individuals and so eliminates the unfavourable redund-
ancies ; for example, it tends to remove the traits that cause ' delicacy ' and so to
restore the pristine vigour. It performs that which it is the function of conjugation
to perform. If this interpretation be mistaken we have no alternative but the
hypothesis of rejuvenescence. It should be noted that the traits that man con-
sciously selects are usually mutations. But those which he unconsciously selects
(e.g. 'delicacy') are usually fluctuations.

THE EVOLUTION AGAINST DISEASE 199

against the diseases to which they are exposed is, I conceive,
clear proof that the organic world has not arisen by mutations
which are permanent and which therefore nothing but selection
can eliminate. We shall see in the next section of the present
volume how great that evolution has been, how closely it adjusts
each variety to its special environment, and how laden it is with
momentous consequences. Now, since all races evolve against all
the diseases to which they are exposed, it is evident that favour-
able variations against every disease occur in every race. Unless
disease miraculously evokes these variations, they are spontaneous,
and therefore, unlike the evolution which results from their selec-
tion, not dependent on the presence of the disease. Either they
are fluctuations which retrogress in the absence of selection, or
they are mutations which, it is said, only selection can eliminate.
If experimental workers are right and they are mutations, then,
when a variation which increases the power of resisting a disease
occurs in a country in which the disease is not present, it will not
be eliminated by selection, for it will be a harmless character.
Since such variations are spontaneous they will occur as abundantly
when the disease is absent as when it is present. If, then, evolu-
tion is by mutation, how does it happen that only races long exposed
to a disease are resistant to it, so that whole races tend to die out
when exposed to new diseases under stringent conditions — for
example, the inhabitants of all the Western world when exposed
to tuberculosis ? The mutation theory is not complete as it stands.
The fact that races do not evolve against diseases to which they
are not exposed demands the corollary that every useless mutation
(e.g. capacity to resist measles) is also so harmful that nature
eliminates the individual possessing it. Otherwise it is impossible
to account for the fact — which we shall be in a position to perceive
more clearly later — that races evolve only in useful directions.1

327. " It was said even at the time of Drelincourt that no
less than two hundred and sixty-two groundless theories of sex
had been suggested ; and it may be added that since that time
there has been no falling off of interest in the sex question if the
number of new theories proposed is a criterion." The latest theory,
that which I venture to formulate, is sure, therefore, to meet
with scepticism. Nevertheless, the evidence supporting it when
gathered together appears strong. Whether I am right or wrong,
the correct interpretation in this case, as in other instances,
probably lies obvious on the surface, provided we do not allow
1 See chapter xiii. and especially § 435.

200 THE FUNCTION OF SEX

ourselves to be blinded by that veil of familiarity which is so apt
to obscure the significance of common facts. To me it seems
likely that the failure to discover the function of sex is due
largely to the circumstance that the attention of biologists has
been concentrated, on the one hand, on progressive evolution, and
on the other hand, on striking abnormalities. Retrogressive
evolution, which is every wit as important, every wit as adaptive
as progressive evolution, has received scant attention ; and
biologists, with hardly a recent exception, have attributed it to
the same agency (direct selection) as produces progression. The
fact that it occurs in the total absence of direct selection has not
received due weight. Presumably, sex has some function. The
two theories most in favour with biologists at preseut are, on the one
hand, the hypothesis that it renders species variable and so
provides materials for Natural Selection, and on the other, that it
mixes parental qualities as marbles are mixed. We have already
dealt with the Mendelian hypothesis. No one not a Mendelian
doubts the swamping effect of sex on progressive variations. The
function of sex, therefore, cannot be the provision of progressive
variations as materials for the work of Natural Selection. Sex itself
must have been evolved by the prolonged selection of pre-existing
progressive variations.1 Moreover, it has been proved that par-
thenogenetic species display such variations in plenty. Indeed, a
principal part of the work of Natural Selection seems to be to
confine variations within useful bounds.

328. Before we can be in position to understand the effect and
the function of conjugation, we must study normal intra-varietal
breeding. We are quite incapable of observing its effects in plants
and lower animals. Even in human beings, with which we are so
familiar, our task is rendered very difficult by the constant presence
of spontaneous variations arising independently of sex. Modi-
fications, due to the action of the environment on the germ-cell
as well as on the soma, also complicate matters. However, we
have no reason to suppose that amongst human beings,
members of a natural ' wild ' species, the effects of conjugation
differ greatly, if at all, when the breeding is inter-racial from what
it is when it is intra-racial. Many human varieties differ so widely
that when they cross we are easily able to note the effect of con-

1 Possibly it originated in attempted cannibalism amongst unicellular organ-
isms, an attempt which resulted in beneficial fusion. Thence, perhaps, during the
evolution which adapted species for conjugation, arose gradually those multi-
tudinous sexual differentiations which we find in multicellular animals and plants.

STABILITY OF PARTHENOGENETIC TYPES 201

jugation. In every instance the result is a blend which persists
in subsequent generations, not a Mendelian mixture. Here,
very clearly, the effect of blending is retrogression towards the
parental and varietal mean. If many races interbred it would
imply retrogression, within the limits of their differences, towards
the specific mean, consequently towards the ancestral type. Thus,
if races which have undergone evolution against different diseases
cross, the resisting powers of those races which have undergone
progression are diminished in the descendants.1

329. We have used the term blending as including all degrees
of prepotency up to the exclusive inheritance of the character of
the one parent and the permanent loss of that of the other. Old
established characters tend always to be prepotent over newer
characters, as is proved by the fact that when parents differ the
progressive variations of one generation tend not to be reproduced
by the next. It is also proved by another set of facts, namely,
that retrogression of even old-established parts is a constant ac-
companiment of cessation of selection. We have no reason to
doubt that, apart from the effects of blending, offspring tend to
vary from their parents retrogressively as well as progressively.
Evidently these retrogressions which imply reversions to an old
type, tend to be prepotent over the type which has become the
normal of the race ; hence, in part at least, retrogression in the
absence of selection.

330. The little evidence we possess concerning parthenoge-
netic species points in the same direction. Their useless characters
(e.g. receptacula seminis in Cypris reptans) are very persistent.
Parthenogenetic types are exceptionally prolific of progressive
varieties, a fact which clearly indicates comparative lack of regres-
sion and, therefore, of retrogression.

331. The fact that under conditions of parthenogenesis (complete
or partial) " thousands of forms may be cultivated side by side
. . . and exhibit slight but undoubted differentiating features, and
reproduce themselves truly by seed " 2 is very significant. It affords
evidence (i) that progressive variations are then plentiful, and
therefore that bi-parental reproduction is not the cause of them ;
(2) that such variations are then especially persistent, and therefore
that conjugation tends to plane them away, and (3) that fluctuations
are unstable, not because they are due to " varying conditions of
food supply, temperature, density, moisture, light," etc., but because
they blend with one another in bi-parental reproduction. Otherwise,

1 See § 464. 2 See § 244 (footnote).

202 THE FUNCTION OF SEX

since persistent variations are so many in parthenogenesis, we must
suppose that mutations are a thousandfold more numerous under
that condition than when reproduction is bi-parental, which is, to
say the least, unlikely.

332. Speaking generally, among animals that reproduce bi-
parentally, varieties are few when the powers of locomotion are
great — that is when mating between individuals derived from
widely separated districts is common. Thus, avian species have
few varieties except when spread over a very wide area or an area
that is interrupted by natural barriers, and often, unlike partheno-
genetic types, only a single variety inhabits a whole region.
When there are effective barriers, varietal differentiation is usually
noticeable. When the powers of locomotion are less, the number
of varieties is greater. Thus, as Gulick noted, every valley in
Samoa has its local species of land-shells, the differentiation
between the varieties, species, and genera being proportionate to
the distances which separate them.1 All this indicates strongly
that the effect of sex is to blend characters. If the theory of unit
segregation and gametic purity were true, and, as a consequence,
that of blended inheritance untrue, species which reproduce sexually
should possess at least as many varieties as those the reproduction
of which is parthenogenetic, and those which range widely as many
as those with poorer powers of locomotion. In that case there
would be, not only no approach to uniformity through conjugation,
but such a shuffling of characters that almost every individual
would form a variety by itself.

333. The fact that, apart from the sexual traits, all the individuals
of the same variety differ, with rare exceptions, only to the extent
of fluctuations, is presumptive evidence that the function of sex is
to blend parental characters. In that case the average experience
of the whole race, rather than the, perhaps, exceptional experience of
single individuals, becomes the determining factor in evolution. The
advantage of this is obvious); for most individuals are more likely
to have an average than an exceptional experience. Moreover, as
I say, blending when combined with Natural Selection is a selecting
agency. Selection eliminates harmful progressive and retrogressive
variations, and, on rare occasions, old-established characters that
have become harmful. Blending, with its swamping effects, its
general tendency to produce retrogression, eliminates useless char-
acters and variations — characters and variations which are merely
useless to the individual, but which, if accumulated, would become

1 See Darwinism, by Alfred Russel Wallace, p. 43.

THE SPEED OF RETROGRESSION 203

harmful to the race. Selection may be compared to a sculptor
who designs and rough hews a statue ; sex to a colleague, more
skilful mechanically, who chisels out the finer lines.

334. We never see racial progression except when selection,
natural or artificial, is at work. The evidence is, that given
sufficient time, retrogression invariably occurs when there is
cessation of selection, its speed being proportionate to the recency
of the antecedent progression. Now, when a character (e.g. limb)
has been long established, constant interbreeding has so blended
together all the strains of a race, that mating individuals differ
comparatively little. At any rate, apart from mutations, which
are comparatively rare and tend to be eliminated, individuals,
exhibiting every gradation between the extremes of ' normal '
variations, occur — the most numerous type and therefore the most
influential as regards inheritance being those which approximate
most closely to the specific mean. In such cases, therefore, the
retrogression which follows the cessation of selection depends
wholly on the prepotency of new retrogressive variations, and is
a very gradual process. But when the character (e.g. any of the
special points of prize breeds) has been newly established, mating
individuals differ more, for the blending will have been less
thorough, and retrogression, therefore, is more rapid. It is possible,
indeed I think it is probable, that retrogression follows mere
cessation of selection even in parthenogenetic species. But the
prolonged persistence of useless structures in such rapidly repro-
ducing types as Cypris reptans, as well as the fact that partheno-
genetic species tend to break into a multitude of progressive
' varieties,' indicates that retrogression on cessation of selection
is a slower process than when blending is present.

335. The higher animals are the most complex products of
evolution. The multitude and differentiation of their structures is
very great, and the fact that they are active moving machines renders
necessary a very delicate co-adaptation of all their parts. A tree
may differ, always does differ, greatly in shape from other members
of the species ; but, if a higher animal diverges much from his type
in shape, he is a monster and cannot persist. But this very com-
plexity of structure and closeness of adjustment increases the area
of variability and the chance that variations will throw the whole
machine out of gear. It is significant that the reproduction of all
these animals is bi-parental. The blending of useful characters,
combined with the automatic planing away of redundancies, relieves
Natural Selection of half its task of adapting them to the environ-

204 THE FUNCTION OF SEX

ment. When considering Natural Selection, we are apt to think
of the progressive variations of the individual as passing unchanged
to his descendants. As a fact, apart from his variations, the
descendant is, so to speak, a composite photograph of ancestors
from which useless characters are, more or less, excluded. It is
largely because conjugation has planed away redundancies and
blended into a congruous whole much that enabled the survivors in
past generations to persist till they had offspring that the individual
is so closely adapted to the average environment of his race.

336. Self-fertilization is not uncommon in plants, and it occurs
also amongst vegetative marine animals. Doubtless it has arisen
as a substitute for cross-fertilization, owing to the uncertain
occurrence of the latter amongst the individuals of stationary and
scattered types. The germ-cells of an individual differ amongst
themselves, but not, on the average, to the same extent as germ-
cells derived from different individuals. In self-fertilization,
therefore, the influence of conjugation, though still potent, is less
than in cross-fertilization. Presumably, however, it is sufficient
for the needs of the comparatively simple types among which
it is found. Parthenogenesis is comparatively rare, and occurs
as a rule among simple forms, the multiplication of which is very
rapid, and which thus provide very abundant materials for Natural
Selection. The theory that the function of sex is to bring about
the retrogression of useless characters by the blending of paren-
tal traits, therefore, accords well, not only with the facts of
bi-parental reproduction, but also with those of self-fertilization
and parthenogenesis.

337. The problem of sex occupies at present a disproportionate
share of biological attention. The study of it, under the name of
Mendelism, is very fashionable. Nevertheless, from a practical
point of view, indeed from every point of view, it is of lesser im-
portance than many other biological problems. A complex and
difficult question, it cannot be solved except by examining it from
all points of view, by utilizing all the evidence available, and testing
our thinking carefully. It cannot be too often or too forcibly
reiterated that the only extensive body of evidence in our possession
relating to normal intra-varietal breeding and the crossing of natural
varieties is that drawn from human races. That evidence indicates
decisively that offspring blend parental characters. To restrict our
data to the scanty and imperfect material obtainable by crossing
domestic varieties for a few generations, and even then by observ-
ing only the inheritance of glaring parental differences, is to court

SCIENTIFIC METHOD 205

failure. It would be as reasonable to isolate a party of English
people, rear them for three or four generations under conditions as
foreign as they could possibly be made, and then, while excluding
all other evidence as non-experimental and therefore fit only for
essayists, attempt from the data thus obtained to write an account
of the mode of development of English society. I think a
historian who adopted such a method would not be deemed wise,
even if he were deemed a historian ; but the illustration does not
greatly exaggerate the method and claims of some experimental
workers who esteem themselves austerely scientific. " Experiments
on crossing can give nothing but laws of crossing; it may be
possible that some of these laws may be applicable to the breeding
of pure races, but this cannot be decided without definite trial." 1
A full appreciation of the importance of experimental work need
not blind us to the value of evidence differently obtained, nor to
the fact that there are problems of heredity other than the effect
of conjugation. In truth, heredity is a subject much wider, much
more important practically, much more fascinating intellectually
than is implied in a good deal of recent work.

1 Mr Udney Yule.

CHAPTER X
SUMMARY

Adaptation — Stimuli to growth — The confusion as to what is innate and
what is acquired — Variations — Spontaneous variability and insusceptibility of
the germ -plasm — Recapitulation — The function of conjugation — Blending —
Alternative recapitulation — Fluctuations and mutations — The difficulties pre-
sented by the different sciences — Methods of inquiry — The method of comparing
races — Materials supplied by human beings — The greater problems of Heredity.

w

338. "W"lt 7"E see then that the great outstanding feature of living
beings is that, in part and whole, they are adapta-
tions. For example, in man, the being we know
best, very few characters exist the utility of which in past or present
has not already been ascertained. Doubtless a proportion of his
characters — for instance susceptibility to the charm of alcohol —
may be mere by-products of evolution, accidental accompaniments
of useful characters ; but, speaking comparatively, they are rare.
His nervous, circulatory, muscular, glandular, digestive, and other
systems, the mass of his characters, his specific and varietal
traits as distinguished from his personal variations, are nearly
all demonstrably useful. We shall see that what is true of his body
is true also of his mind. The variations of the individual are, of
course, not all useful, but the spontaneous variability to which they
are due and which supplies the materials for selection is an
immensely useful trait which has been evolved through Natural
Selection into an adaptation. Presumably adaptation is not less
perfect in plants and lower animals than in man. Apparently they
have been just as much subjected to selection. In all probability,
therefore, if we are less able to trace the utility of all their
characters, it is only because here our knowledge is less complete.
It must be borne in mind, however, that nature can do no more
than choose from the variations or combinations of variations that
happen to be presented to her for selection. If, therefore, two
sections of a species separated, but continued to exist under
conditions which (were it possible) were identical, they would still
be sure to differentiate ; for neither the variations presented to
nature for selection nor the accidents of survival would be quite

206

THE STIMULI TO DEVELOPMENT 207

the same. If, then, two varieties (e.g. of man) arise in different
localities, it does not follow necessarily that in each locality they
have diverged progressively in the most useful direction conceivable,
but only that each has diverged in a useful direction.

339. Except actual injuries, as distinguished from vital re-
actions to injury, all the characters of living beings result from an
interaction between the hereditary tendencies or potentialities of
the individual and stimuli which awaken them to activity. In
essence, all evolution consists in the evolution of these hereditary
tendencies — that is, in the evolution of the germ-plasm.

340. There are many such stimuli to development. Amongst
the principal are nutriment, use, and injury. In order to avoid
unnecessary complications in the argument, I have ignored all
stimuli save the three named, or rather I have roughly grouped
under the head of nutriment all stimuli save use and injury.
Here I have merely followed established biological custom, which
distinguishes characters as inborn and acquired, and separates the
latter into those resulting, on the one hand, from use, and on the
other, from injury. Nutriment supplies, not only a stimulus to
development, but the materials for all growth. All the ' normal '
structures of many species appear to develop wholly under the
influence of this stimulus, and many of the structures of all species
so develop. In every case the beginnings of all growth are
attributable to it, for, of necessity, it is the first stimulus to which
each organism and structure responds. The capacity to develop
under the influence of use or injury is present only in structures
where it is useful, at a time when it is useful, and only to an
extent which is useful. The power of responding by growth to
injury (regeneration, healing) has been closely studied by biolo-
gists. That of responding to the stimulus of use has been more
neglected. The utmost confusion prevails, for example, as to
which characters in each species develop under the influence of
nutrition, and which (if any) under that of use. When, however,
we study mind we shall see that this question is the most interest-
ing and practically important of all the problems of biology.
Probably the great Lamarckian controversy, which still lingers,
would have ended as soon as it began, if biologists had carefully
defined their terms and noted in what species, in what characters,
and to what extent the power of responding to the stimulus of
use was developed : in other words, if they had studied this power
as what it really is, an adaptation, a product of evolution, not a
chance or necessary property of living protoplasm.

208 SUMMARY

341. Modern biologists are accustomed to divide the characters
of multicellular living beings into those which are inborn or
innate and those which are acquired, and to declare that only the
former can be inherited by offspring. They are mistaken. No
character, in any real sense, is more innate than any other. The
child inherits nothing from his parents. These terms are convenient,
inasmuch as they enable us to avoid circumlocution, but they are
inaccurate. The true distinction between characters results from
the stimuli under which they arise. The so-called acquirements
arise under the stimulus of use or injury ; the so-called inborn
characters under other stimuli, especially that of nutriment. The
true meaning of the statement, that acquirements are not trans-
missible, is that the characters which arise under the stimulus of
use or injury in the parent are not reproduced in the child under
the stimulus of nutriment. This sudden transference of characters
from one category in the parent to another in the child certainly
never occurs. In the first category they are products of evolution ;
if they were reproduced in the second they would be products of
miracle.

342. Offspring resemble their parents, but with minor differ-
ences. These differences are due either to differences in the play
of stimuli on individuals, or to germinal differences. The latter
are termed variations, and on them all evolution is founded.
Massive evidence indicates that immensely the greater number of
variations are spontaneous. This, in turn, implies that the
germ-plasm is highly insusceptible to the direct action of the
environment. A close examination of the evidence renders it
clear that living beings could not have persisted on earth unless
their variations had been spontaneous and their germ-plasm
resistant.

343. Variations are either progressive or retrogressive. Since
the general resemblance between parents and offspring is due to
the fact that the latter in their own development closely recapitu-
late the development of the former, a progressive variation implies
a prolongation of the parental development, a complete recapitu-
lation with an additional step. On the other hand a retrogressive
variation implies an incomplete recapitulation, an abbreviation.
Since offspring recapitulate (with variations) the parental develop-
ment, they necessarily recapitulate (with interpolated additions
and subtractions due to innumerable interpolated progressive and
retrogressive variations that occurred in the ancestry) the evolution
of the species. It follows that retrogression implies a reversion to

DIRECT AND INDIRECT SELECTION 209

the ancestral type. It further follows that (as regards each char-
acter) ancestors are represented by the individual, not en masse>
but in orderly succession. The so-called contributions of ancestors
are nothing other than reversions, that is to say, failures to
recapitulate the life-history beyond the points reached by the
ancestors, or else the reappearance of hitherto dormant characters.
The truth of recapitulation, though admitted by the majority of
biologists, is universally ignored when theories of heredity are
formulated. Biologists found their belief in recapitulation solely
on very uncertain and fragmentary embryological evidence. They
have not realized that, given facts which are admitted to be true,
any method of development other than by a recapitulation of the
life-history is unthinkable. This failure, together with the failure
to distinguish the true nature of, the true distinction between,
innate and acquired characters, has been in the past a principal
obstacle to a scientific systematization of the facts of heredity, a
main source of error, confusion, wild speculation, and endless
controversy.

344. Evolution (i.e. adaptation) depends as much on retro-
gression as on progression. Direct Natural Selection is concerned
almost exclusively with progression. Only seldom is it a cause of
retrogression, which, with rare exceptions, occurs only on cessation
of selection, and is due to the general tendency to reversion — i.e.
the general tendency to abbreviate rather than to prolong the life-
history. In the last analysis, however, this tendency is itself due
to the Natural Selection of strains that possess it in the right
degree. Retrogression planes away all redundancies, all useless
variations and structures that have lost their utility.

345. The function of conjugation is to blend parental char-
acters. The average experience of the race is thus substituted
for the special experience of the individual. Moreover, in each
blend retrogressive (i.e. the more ancient) characters tend to be
prepotent over progressive (i.e. less ancient) characters. The
effect of this blending, therefore, is to bring about the more or less
rapid retrogression of useless characters — a retrogression which is
only checked or reversed by selection. Sex, therefore, is as much
a selecting agency as Natural Selection. Since every gradation
occurs between equal blending of parental characters and the
exclusive inheritance of the character of one parent only, it is
convenient to class even exclusive inheritance under the head of
blended inheritance. There is no such thing as alternative
inheritance ; there is only alternative patency and latency. When

14

210 SUMMARY

this occurs the child inherits the characters of both parents but
develops those of only one. Blending then occurs between the
patent traits of one parent and the latent traits of the other.
Therefore, speaking practically,1 all inheritance is blended in bi-
parental reproduction. Unit segregation, gametic purity, and
independent inheritance of characters (in the Mendelian sense) are
all myths that have been founded on experiment but have not
been tested by it or in any other way. They are mere guesses.
The evidence from which they have been inferred is very restricted
and fragmentary, and, especially when considered in connection
with other larger bodies of fact, really points to quite other
conclusions.

346. In sexually dimorphic species every individual possesses
one set of non-sexual characters, all of which are patent, and two
sets of sexual characters of which only one set is patent. But
if parents differ greatly in any non-sexual character, the reproduc-
tion of it tends to follow the sexual mode. This rarely happens
in the normal intra-varietal breeding of natural varieties, for under
such conditions individuals who differ greatly from the norm
seldom survive and have offspring, but it is quite a common
occurrence under artificial selection, which is distinguished from
natural selection by the choosing of mutations rather than of
fluctuations, the crowding together of newly formed varieties in
the same locality, and their constant intercrossing through design
or accident. All the evidence indicates that in nature varieties
arise solely or almost solely under conditions of geographical
separation. Artificial Selection and artificial varieties there-
fore differ profoundly from Natural Selection and natural
varieties. In artificial varieties are found dormant traits which
are practically unknown in natural varieties. Judging from the
analogy of patent characters, it is an error to suppose that dormant
traits persist for ever. Having no utility, they are not maintained
by Natural Selection, and therefore tend to disappear in time.
Thus when the horse is crossed with the Burchell zebra the repro-
duction of the long dormant ancestral stripes is very faint as
compared to the vivid reproductions of ancestral coloration which
may appear in offspring when two dull-plumaged breeds of poultry
or two white varieties of garden flowers are crossed.

347. The progress of science depends first on the collection of
verified facts, and second on their systematic arrangement. The
facts must be verifiable or we cannot know them to be true. They

1 See § 322.

THE DATA OF THE SCIENCES 211

must be systematized, or they are of no greater scientific value
than the amorphous mass of data with which casual experience
stores our minds. The methods by which facts are collected and
arranged differ according to circumstances.

348. In some sciences, for example systematic botany, zoology,
and anatomy, the facts are nearly all patent and, once ascertained,
fall so naturally and easily into the right categories that the
difficulty of systematization, of discovering the relationships
between the facts, is reduced to a minimum. In others, the ex-
perimental sciences, for example physics and chemistry, very few
facts are patent to our senses : the main difficulty lies in ascertain-
ing them. Therefore special methods of investigation have been
devised. In yet other sciences, for example heredity, though
many facts are patent, others are obscured, and the relationships of
nearly all are hard to ascertain. Consequently we have difficulties
both in discovering information and in arranging it. The patent
facts can be simply observed. The obscured facts must be rendered
patent by means that clear away the obscuring conditions. The
difficulties in arranging the facts must be met by testing our think-
ing with especial care. In this way only is it possible to achieve
an approach to exactness.

349. Very remarkable notions as to what constitutes science
are prevalent amongst sections of biologists. Thus medical men,
who are biologists in the sense that they are students of a living
being, frequently denounce deduction. Apparently they are un-
aware that the correctness of, inductive thinking can be tested
efficiently only by means of it, and that mathematics, the purest
and most accurate of sciences, the model for the rest, is almost
purely deductive. Again, systematic zoologists and botanists
sometimes denounce 'speculation.' That is they denounce all
thinking which is not very easy, all attempts to ascertain relations
that are not very obvious. Yet, again, some experimental observers,
appealing to physics and chemistry, sciences that are both accurate
and experimental, often insist that biology must be made accurate
by being made experimental. But physics and chemistry are not
accurate because they are experimental, but because the data
on which they are founded are capable of being as precisely
measured as it is possible to measure anything, and because
the students of them test their thinking with great care. In
biology, we must, of course, when necessary, use experiment as
well as every other means of ascertaining truth. But that is one
thing. Quite a different thing is what has actually happened in

212 SUMMARY

practice — the limitation of thought to data provided by experi-
ment, and the abandonment, from lack of material, of all attempts
to ascertain the correctness of hypotheses. The experimental
method can do no more than fill some lacunae in our already wide
knowledge of living beings. In the past men have sometimes
filled these gaps with imaginary facts and have speculated wildly.
But such lapses from scientific caution afford no excuse for treat-
ing the gaps when filled by experiment with authentic facts as the
whole of knowledge and then speculating still more wildly.

350. Splendid examples of scientific method, of combined
induction and deduction, are the hypotheses of evolution and
Natural Selection. The actuality of evolution was suspected even
by the Greeks, but modern conviction, founded as it is on authenti-
cated facts and carefully tested thinking, is more surely based.
By linking together particular facts we infer (i) that it is possible
to create new varieties of animals and plants by careful artificial
selection, (2) that varieties, species, orders, and genera tend to
shade into one another, (3) that species inhabiting the same or adja-
cent areas tend to have features more alike than those more widely
separated, (4) that the remains of animals and plants preserved
in geological strata indicate that related species, which were
widely separated in time, were as a rule more unlike than those
that were more nearly contemporary, and (5) that the structures of
embryos are often more suggestive of lower types than of their
own adult progenitors. Linking together all these inductions, as
in reaching them we linked together particular facts, we are able
to infer the hypothesis of evolution. In this way, not only is a
deeper knowledge and a larger synthesis achieved, but we are
able to perceive a new and very valuable aspect of truth which
induction could never have established unaided by deduction, and
which suggests many fresh inductions and deductions which, again,
not only reveal still newer truths, but tend to test the aspect of
reality, which was reached in part by deduction.

351. Darwin accepted the theory of evolution and linked it
with the inductions — which had previously been more or less
familiar to all men — (i) that offspring tend to vary from their
parents, (2) that some of them are better adapted to achieve
survival than others, (3) that they tend to outnumber their parents,
(4) that, nevertheless, the number of individuals in a species
does not, as a rule, increase, and (5) that species are adaptational
forms. Noting that all these inductions were in harmony and
testing them rigorously, he linked them together in the hypothesis

DARWIN'S WORK 213

of Natural Selection. His reasoning was largely deductive, for, apart
from the tests to which he subjected his thinking, his attention was
not attracted by human disease and, consequently, he never observed
Natural Selection actually at work. He was unable, therefore, to
reach his wider synthesis through an actual observation of parti-
cular facts or test it by an appeal to them, but his work was fertile
in suggestions — hence, for example, Poulton's attempt to demon-
strate Natural Selection amongst chrysalises, and Weldon's
attempt to prove its occurrence amongst crabs. Hence also many
biometric inquiries.

352. Starting from the point at which Darwin stopped, accept-
ing his theory of evolution by Natural Selection, and combining
with it the hypotheses which we reach by induction, that species
tend to retrogress on cessation of selection, and that offspring
recapitulate the main features of the parental development, we are
able to infer (i) that retrogressive variations tend to predominate
over progressive variations, (2) that, with rare exceptions, variations
are spontaneous, and that spontaneous variations tend to occur all
round the specific mean, (3) that, therefore, the germ-plasm is
highly insusceptible to change through the direct action of the en-
vironment, (4) that, apart from his own progressive variations, the
development of the individual is an abbreviated and inaccurate
recapitulation of the evolution of the race, and (5) that, therefore,
every retrogressive variation is, in effect, a reversion. Here we
formulate laws or generalizations of heredity which are probably
as nearly fundamental as it is possible to reach in the present state
of our knowledge. As in the case of Natural Selection, the process
of reasoning, since we endeavour to ascertain whether our laws are
in harmony with one another and with reality, is largely deductive.
But, granting the premises from which we started, and none of
them are seriously disputed, I believe we must not think at all, or
we must think in terms of miracle, or we must accept the laws as
true. And, very obviously, if they are true, if they are real laws,
we have made a step towards rendering biology (or at least the
study of heredity and evolution) a deductive science — towards
establishing it on the basis of a few generalizations, to which a vast
mass of data, already discovered or yet to be discovered, may be
linked by chains of causation, that is to say, towards attaining
that goal which is the aim of all science.1

1 " It will be seen hereafter that there are weighty scientific reasons for giving
to every science as much of the character of a Deductive Science as possible ;
for endeavouring to construct the science from the fewest and the simplest possible

214 SUMMARY

353. The method of inquiry on which Darwin principally relied,
and which enabled him to affect so great a revolution in modern
thought, was to compare varieties and races living under one set
of conditions with those living under another. Having noted the

inductions, and 'to make these, by any combinations, however complicated, suffice
for proving even such truths, relating to complex cases, as could be proved, if
we chose, by inductions from specific experience. Every branch of natural
philosophy was originally experimental ; each generalization rested on a special
induction, and was derived from its own distinct set of observations and experi-
ments. From being sciences of pure experiment, as the phrase is, or, to speak
more correctly, sciences in which the reasonings mostly consist of no more than
one step, and are expressed by single syllogisms, all these sciences have become
to some extent, and some of them in nearly the whole of their extent, sciences of
pure reasoning ; whereby multitudes of truths, already known by induction from
as many different sets of experiments, have come to be exhibited as deductions
or corollaries from inductive propositions of a simpler and more universal
character. Thus mechanics, hydrostatics, optics, acoustics, thermology, have
successively been rendered mathematical ; and astronomy was brought by Newton
within the laws of general mechanics. Why it is that the substitution of this
circuitous mode of proceeding for a process apparently much easier and more
natural, is held, and justly, to be the greatest triumph of the investigation of
nature, we are not, in this stage of our inquiry, prepared to examine. But it is
necessary to remark, that although, by this progressive transformation, all sciences
tend to become more and more Deductive, they are not, therefore, the less Induc-
tive; every step in the Deduction is still an Induction. The opposition is not
between the terms Deductive and Inductive, but between Deductive and Experi-
mental. A science is experimental in proportion as every new case, which presents
any peculiar features, stands in need of a new set of observations and experiments
— a fresh induction. It is deductive in proportion as it can draw conclusions,
respecting cases of a new kind, by processes which bring those cases under old
inductions "(J. S. Mill, Logic, Bk. II. chap. iv. § 5). " The discoveries which change
the method of a science from experimental to deductive mostly consist in
establishing, either by deduction or by direct experiment, that the varieties of
a particular phenomenon uniformly accompany the varieties of some other
phenomenon better known. Thus the science of sound, which previously stood
in the lowest rank of merely experimental science, became deductive when it
was proved by experiment that every variety of sound was consequent on, and
therefore a mark of, a distinct and definable variety of oscillatory motion among
the particles of the transmitting medium. When this was ascertained it followed
that every relation of succession or co - existence which obtained between
phenomena of the more known class, obtained also between the phenomena which
correspond to them in the other class. Every sound being the mark of a particular
oscillatory motion, became a mark of everything which, by the laws of dynamics,
was known to be inferable from that motion ; and everything which by those
same laws was a mark of any oscillatory motion among the particles of an elastic
medium, became a mark of the corresponding sound. And thus many truths,
not before suspected, concerning sound, become deducible from the known laws
of the propagation of motion through an elastic medium ; while facts already
empirically known respecting sound become an indication of corresponding
properties of vibrating bodies, previously undiscovered " (op. cit., II. iv. 7). " We
have thus already come within sight of a conclusion which the progress of the
inquiry will, I think, bring before us with the clearest evidence, namely, that in the

DARWIN'S METHOD 215

differences between races and between conditions, he sought to ac-
count for the former by the latter.1 His very learning and the skill
with which he used it contributed, through exhaustion of materials,
to render the task of his successors difficult. The actuality of
evolution was proved and the method of evolution demonstrated,
but many problems of heredity remained. A great deal of splendid
work was done subsequently, but it was felt that our knowledge of
wild plants and animals was very vague, and an impression spread
that laboratory methods alone were capable of supplying information
sufficiently exact.

354. But, clearly, if we are able to trace precisely the changes
a race undergoes as a reaction to the conditions under which it
dwells, if we are able to establish clearly the connections between
causes and effects, we observe nothing less than an actual, a very
perfect experiment. Such an experiment, since it is conducted by

sciences which deal with phenomena in which artificial experiments are impossible
(as in the case of astronomy), or in which they have a very limited range (as in
mental philosophy, social science, and even in physiology), induction from direct
experience is practised at a disadvantage in most cases equivalent to impracti-
cability ; from which it follows that the methods of those sciences, in order to
accomplish anything worthy of attainment, must be to a great extent, if not
principally, deductive. This is already known to be the case with the first of
the sciences we have mentioned, astronomy ; that it is not generally recognized
as true of the others is probably one of the reasons why they are not in a more
advanced state " (op. cit., III. vii. 3).

1 " If what is called observation is at so great a disadvantage, compared with
artificial experimentation, in one department of the direct exploration of pheno-
mena, there is another branch in which the advantage is all on the side of the
former.

" Inductive inquiry, having for its object to ascertain what causes are connected
with what effects, we may begin this search at either end of the road which leads
from one point to the other ; we may either inquire into the effects of a given cause
or into the causes of a given effect. The fact that light blackens chloride of silver
might have been discovered either by experiments on light, trying what effect
it would produce on various substances, or by observing that portions of the
chloride had repeatedly become black, and inquiring into the circumstances.
The effect of the urali poison might have become known either by administering
it to animals, or by examining how it happened that the wounds that the Indians
of Guiana inflict with their arrows prove so uniformly mortal. Now it is manifest
from the mere statement of the examples, without any theoretical discussion,
that artificial experimentation is applicable only to the former of these modes of
investigation. We can take a cause and try what it will produce ; but we cannot
take an effect and try what it will be produced by. We can only watch till we see
it produced, or are enabled to produce it by accident.

" This would be of little importance, if it always depended on our choice from
which of the two ends of the sequence we would undertake our inquiries. But
we seldom have any option. As we can only travel from the known to the
unknown, we are obliged to commence at whichever end we arc best acquainted
with." (Op. cit., III. vii. 4.)

216 SUMMARY

nature under natural conditions, spreads over a great number of
generations, includes the largest possible number of families and
individuals, and results eventually in definite and unmistakable
changes of considerable magnitude, is superior to any inquiry that
can be devised in the laboratory, where only a very few generations
can be studied, and where, since our power of observing and
measuring the lesser variations is very limited, it is impossible to
observe gradual but cumulative change. Provided the conditions
of accurate observation are present, I think no thoughtful biologist
would maintain that the method of comparing races is scientifically
unsound. He might insist, however, that such conditions are never
met. Undoubtedly they are difficult or impossible to find when
we study natural species of plants and lower animals, and the
study of domestic varieties is misleading. But one vast field of
research has been left practically untilled by students of heredity —
the human species. Here, if only because we are very familiar
with the subjects of observation and, therefore, able to note small
differences, our knowledge is more definite and precise than in the
case of any other species. In certain particulars at least we are
able to watch, under conditions insuring great accuracy, the
tremendous and crucial experiments made by nature.1 We may
see the differentiation of races occurring in such a way as enables
us to trace the connexion between cause and effect. In a real sense
we may extend our observations over hundreds of generations and
thousands of years, for, in many instances, by comparing con-
temporary races, we are able to ascertain exactly the ancestral
type of a race that has changed under the influence of a precisely
known agent.

355. Occasionally I have expressed myself very positively in
the preceding pages, and this will be displeasing to some readers.
But the evidence on which my conclusions are founded is given in
detail, and certitude is not necessarily dogmatic nor unscientific. I
have tried, as best I am able, to test my thinking. I can only ask
my readers, while bearing the evidence in mind, to think out the
greater problems of heredity for themselves — to ask themselves
whether evolution is ever anything but adaptation, whether it is
possible for any class of characters to be in any true sense more
innate or inheritable than any other, whether it is conceivable that
the development of the individual can occur otherwise than by
recapitulation, and therefore, whether retrogression can ever be
other than reversion, whether the main mass of retrogression is

1 See footnote, § 53.

THE GREATER PROBLEMS OF HEREDITY 217

due directly to Natural Selection, and, if not, whether it is not
possible to formulate a rational theory to account for its occurrence,
whether under the conditions in which life exists variations can be
other than spontaneous, whether the power of growing under the
stimulus of use is not just as much an adaptation as the power of
repairing damaged parts under the stimulus of injury, whether the
effect of conjugation is to mix parental characters as marbles are
mixed or to blend them as colours are 'blended, and what in the
one case or the other is the function, the utility, of the mixing, and
above all to ask themselves whether adaptation is due wholly to
the direct action of Natural Selection or in large part also to
retrogression occurring in the complete absence of selection.

356. These are the greater problems of heredity. It is very
possible that the solutions I have ventured to suggest are
erroneous, but I am very sure that evidence exists which should
enable us, if only we think clearly, closely, and comprehensively
enough, to solve them, and that very much of this evidence may
be obtained from a study of human beings. To that study we
will now proceed.

CHAPTER XI
HUMAN DISEASES

Neglect of the human species by modern students of heredity — The meaning
of racial change — Progression and retrogression — The present evolution of man —
Microbic disease — Air, water, earth, and insect-borne diseases — Toxins — Species
that produce abundant extra-cellular toxins, and species that produce little or
none — Phagocytes — The duration of disease and its cause — Acquired immunity.

357. "• FORMERLY man, considered as a whole, as a bundle
PI of useful and related characters, occupied a good deal
of scientific attention. Darwin traced his descent.
Huxley sought to fix his place in nature. Spencer, Romanes, and
Lewes dealt with his mental evolution — mainly from the stand-
point of Lamarckism. But of late years the turn given by fashion
to biological work has been unfavourable to an adequate study of
him. He cannot be dealt with experimentally, at any rate not by
inter-varietal crossings arranged by the worker. The results of
crossings arranged by nature have not to my knowledge attracted
much attention except in so far as is indicated by the surprising
statement that human skin-colour is the only feature which crossed
varieties blend perfectly. The alternative inheritance of various
human abnormalities has been noted. Biometricians have devoted
rather more attention to man than Mendelians and mutationists.
They have endeavoured, on the one hand, to ascertain the degree
of correlation between certain of his parts, and on the other to
discover the extent to which some of his variations tend to be
inherited. Only a very small portion of the total field has been
covered, however, and some biometric work is vitiated by a
failure to distinguish adequately between * innate ' and ' acquired '
characters.1 The importance of drawing this distinction will
become manifest as we proceed.

358. While studying heredity in connection with human beings
we shall have to depend largely on patent facts — quite indisput-
able facts, however— collected by simple observation, and largely
also on the special method of comparing races. The data left

1tSee §§ 706 et seq.

118

THE UTILITY OF HUMAN CHARACTERS 219

unused hitherto are extremely rich and suggestive, and will furnish,
not only materials from which may be drawn some conclusions,
which to me seem indisputable, but also the means of testing the
thinking by which they are reached. We shall be embarrassed,
however, by the mass of error which has collected around the
subject. In all ages the thoughts of men have been concentrated
on themselves, their parents, children, and fellows, and traditions
have arisen which, though far from the truth, are yet — owing to a
human mental characteristic of the highest general utility l — very
hard to break down.

359. The reader must bear in mind certain conclusions which
we have already reached. Like other living beings, man is mani-
festly a bundle of adaptations. Indeed, since he is better known,
he is more manifestly a bundle of adaptations than any other
type. Beyond doubt some human characters have no utility.
Of these a few may be by-products of evolution correlated to more
useful traits, the only one of the kind of any importance known
to me being susceptibility to the charm of alcohol and other
narcotics. Others, such as the colour of blood and bone, are
chance qualities of useful characters — chance in the sense that in
all probability they have not arisen through selection. These,
however, do not enter into the account ; of necessity blood and
bone must have some colour.2 Yet others have lost their utility,
and have become or are becoming vestigial. Speaking generally,
in only a few instances has the past or present utility of a character
not been ascertained. There can be no doubt, therefore, that the
immense majority of human characters, whether in the trunk,
limbs, or head, are adaptations. The growth of modern physio-
logy implies merely an increased power of interpreting human traits
in terms of their utilities.

360. We also reached the conclusion that all adaptation has
resulted from the combined action of progression and retrogression,
the former being a product of selection, the latter usually following
cessation of selection. Given progression as an accompaniment
of selection, and retrogression as a correlate of cessation of selec-
tion, close adaptation is obviously inevitable. We concluded,
further, that this theory of evolution has for its necessary corollary
a theory of heredity which supposes (i) that the great mass of
variations are spontaneous, and, therefore, (2) that the germ-plasm,
so far as its hereditary tendencies are concerned, is highly in-
susceptible to the direct action of the environment ; (3) that

1 See § 663. » See § 649.

220 HUMAN DISEASES

retrogressive variations tend to predominate over progressive
variations; and (4) that these three fundamental characters of
living beings are themselves adaptations which have resulted from
Natural Selection.

361. Nearly all biologists at the present day accept the theory
of Natural Selection; but some accept it with considerable
reservations, and none, as far as I am aware, accept it in the form
I have suggested. For example, the elimination of useless
characters (variations and old-established parts) is still generally
attributed to reversed selection. Sometimes progression is
thought to result from an inherent growth-force that is only kept
in check by Natural Selection, which therefore moulds the race
by planing away superfluities. In other words, progression is
thought to result, not from selection, but from a natural tendency
for progressive variations to predominate over retrogressive varia-
tions. According to this theory, therefore, all species would
progress were it not for Natural Selection. There is massive
evidence, however, that this view, which appears to be especi-
ally popular amongst the supporters of the mutation theory,
is mistaken. All parts, for example vestigial parts and the
special features of prize domestic breeds (e.g. race-horses), which
have no survival value, tend to disappear on cessation of selection,
and we have only to observe Natural Selection in actual opera-
tion to perceive plainly that its special role is the causation of
progression.1

362. My excuse for the positive attitude I assume must be
that I offer, in the chapters that now follow, easily verified and,
I think, very conclusive evidence of Natural Selection in actual
operation ; whereas the opinions I controvert are founded on a
consideration of lower animals and plants, amongst which,

1 As a rule the idea that one or the other kind of variations tends to predominate
is implied rather than expressly stated in the theories of biologists. The problem
has not often been especially formulated. I think most students of evolution
believe, more or less vaguely, that progressive and retrogressive variations about
balance one another. This view, however, leaves unexplained the retrogression
of parts that have no selection value. Weismann's theory of Panmixia implies
that retrogressive variations predominate, and he has attempted to account for
the fact by his hypothesis of Germinal Selection. The view I have ventured to
set before the reader differs from his merely in that I attribute the predominance
to a tendency evolved by Natural Selection, and do not speculate on the
mechanism of processes in the germ-plasm concerning which I have no data.
Mutationists and Mendelians ignore retrogression. At any rate, the subject is
not to my knowledge mentioned in their works. Indeed the fact that retro-
gression constantly occurs on cessation of selection is not only quite ignored,
but also is by implication controverted by many of them. See § 285.

EVOLUTION AND RACIAL CHANGE 221

admittedly, when wild, the operation of Natural Selection cannot
be observed, and amongst which, when domesticated, it is largely
in abeyance. Very many, if not all, biologists believe, also, that
variations commonly result from the direct action of the environ-
ment on the germ-plasm, and found this opinion mainly on
experimental evidence — that is, on evidence obtained from plants
and animals which have been placed under conditions abnormal
to the race and to the individual. But, as already noted, such
experiments prove merely that it is sometimes possible to devise
conditions in which the germ-plasm, like other living structures,
is injured and yet not killed. They do not demonstrate that the
variations of a species in its normal environment commonly arise
in this way. It is impossible to prove a universal negative, and
therefore, if only for that reason, we cannot demonstrate that
variations are not so caused. Indeed, I do not maintain anything
of the kind. I insist merely, on grounds which I believe are quite
unassailable, that the conditions of life are such that it could not
persist on earth unless the vast majority of variations were spon-
taneous— unless the germ-plasm were highly insusceptible to the
direct action of the environment. We have already dealt with
some of the evidence. But it will be well worth while to consider
it more at length, especially as we shall thereby gain an insight
into man's recent evolution, and be brought in contact with some
practical problems of great importance.

363. We reached one other conclusion which bears on our
present task, namely, that the predominance of retrogressive
variations is less marked in the case of old-established than of
more recently evolved characters. This, also, is an adaptation.
The circumstance that continued selection tends to render
characters more stable carries the advantage that ultimately a
minimum of selection suffices to maintain a useful trait. The
mortality resulting from selection is thus diminished, and the
selection (and therefore the progression) of other useful characters is
rendered possible without the death-rate exceeding the birth-rate.

364. Before discussing human heredity, it is necessary to
define carefully the meanings we attach to such terms as ' evolu-
tion,' 'racial change,' and the like. They have both been used,
especially by popular writers, to indicate two quite separate sets
of phenomena, which, if we wish to avoid endless confusion, must
be clearly distinguished. On the one hand are germinal or truly
innate changes; on the other are changes due to a differential
play of stimuli. Thus the colour difference between Scandinavians

222 HUMAN DISEASES

and negroes has a germinal origin, whereas that between English-
men at home and in India is merely acquired. So, also, the mental
difference between a naturally intelligent race and a naturally
dull one is not the same as that between two races, one of which
has been rendered more intelligent than the other by a better
system of mental training. By such terms as evolution, racial
change, progression, and retrogression we shall always in the
present work imply germinal change. By so doing we shall
follow an established biological custom, which, as a rule, is in-
fringed only when the writer mistakes acquirements for germinal
changes. It is often very difficult to disentangle the two, and the
attempt to do so will form a main part of our future task.

365. Accepting for the moment, then, the hypothesis that racial
progression is invariably due to selection, whereas retrogression
results, as a rule, from cessation of selection, it is evident that, if
we seek to ascertain the direction in which a human race is under-
going germinal change, we must study the causes of death. If we
find that inferiority in any character results in a considerable
mortality, or in a diminution of the average number of offspring,
we may assume that in all probability the trait in question is
undergoing progression ; for here we have evidence that the
race is not yet well adapted to the environment. On the other
hand, total loss of utility, implying as it does cessation of selection,
implies also a tendency to retrogression.

366. During the last few thousands of years man has altered his
environment in one very important way and in that one way only.
He has become increasingly civilized. Civilization implies, on the
one hand, protection from most of the dangers which beset wild
animals, and, therefore, cessation or diminished stringency of
selection along those lines of evolution which raised man in the
animal scale and ultimately made him human. On the other hand,
it implies a fuller command over the resources of nature, which in
turn implies a more abundant and regular supply of food, and that
again implies a more crowded and settled population. The problem
before us is whether this vast alteration of environment has resulted
in appreciable germinal change — in appreciable progression or
retrogression. Civilized man differs in many striking ways from
the modern savage, and probably, therefore, from his remote
ancestors. Our task is to ascertain how much of this difference is
innate and how much due merely to a differential play of stimuli.
We shall study first man's physical characters, reserving mind
for a later section of this book.

HUMAN PROGRESSION AND RETROGRESSION 223

367. Popularly, and even by most scientific men, the human
race is supposed to be undergoing progression in all sorts of
directions. Others suppose that cessation of selection is resulting
in general retrogression. But clearly, as in other species, the great
majority of human physical characters are merely stationary.
They are selected, but only to an extent which maintains an
efficiency previously established. They fit the race sufficiently
well to the environment, and only marked defect usually results in
a failure to rear offspring. Judging from ancient remains and
from a comparison with modern savages, civilized man differs
little, if at all, from his remote ancestors in hands, feet, blood, bones,
heart, lungs, and the like. Doubtless, owing to accidents of
survival, to sexual selection, or to migration which brings different
sets of selecting agencies into play, all races have undergone
some structural changes ; but these are comparatively unimportant.
In obvious physical features, the features by which biologists are
accustomed to measure physical change, humanity as a whole has
undergone little innate alteration during the few thousands of
years of civilisation. We are said to be more bulky than our
ancestors of six or seven centuries ago, but there is no evidence
that during the interval big individuals have been specially
selected for survival. Probably, therefore, the increase in size is
due merely to environmental changes, such as improved nutrition
and treatment of the young, which permits better individual
development. An analogous case is that the modern girl of the
higher classes is taller on the average than her grandmother, and
the modern field labourer than the factory hand. Some modern
savages are taller on the average than the members of any
civilized race, and some skeletons of the Stone Age are those of
large men with well developed crania.

368. Of retrogression, also, there is little positive evidence.
Thus, when suitably trained, civilized men appear to be, on the
whole, just as keen of sight and hearing and as capable of enduring
fatigue as savages. The Boers and Australian whites are cases
in point. It is only when we compare man to the nearest lower
animals that we seem to obtain positive evidence. Some of his
senses, his hearing and sense of smell, for example, appear
weaker. His jaws and teeth certainly, and probably his digestive
apparatus, have undergone retrogression. He is less able to
masticate and assimilate the raw coarse food on which his
ancestors subsisted. But, even here, it is probable that much is
attributable to the direct action of the environment on the developing

224 HUMAN DISEASES

structures. The senses of hearing and touch and possibly of smell
become very acute in the blind, and civilized children are supplied
with such soft food that their jaws are not stimulated to the
utmost possible development. Their teeth, which owe nothing to
the stimulus of use, and therefore attain their full size, are crowded
irregularly together in the small jaws, and while retaining fragments
of fermentable food in their interstices, are not cleansed by the
tough fibrous substances which form a prominent part of the diet
of savages.1 They are therefore particularly exposed to decay.
African negroes have magnificent teeth ; their relatives in America
suffer much from caries ; yet only a few generations separates the
American black from a savage ancestry.

369. It follows that though man has not now so strenuous
nor so active a struggle for mere existence as formerly, though
exceptional strength, activity, endurance, beauty, or cleverness do
not at the present day imply as a rule more than an average
number of offspring ; though men perish so very rarely and in such
a haphazard manner from wild beasts and enemies and from priva-
tion that there is no real selection, though modern/weapons of war
do not discriminate between the fit and the unfit in battle, yet since
man's ancient characters are firmly established and since con-
spicuous defect still acts, on the average, as a bar to offspring, he
has undergone little retrogression. Of progression on lines of
ancient characters there is no valid evidence.

370. Nevertheless, since men still perish in great numbers
before contributing their full quota of offspring to the race, some
sort of selection is occurring. Ourfacilitiesfor ascertainingits precise
nature are particularly good. Indeed, this is the only instance in
nature in which the operations of Natural Selection may be
observed, not merely guessed at. In every civilized country tables
of mortality are compiled from which we may learn exactly the
causes which eliminate the inhabitants of civilized states, the number
of deaths due to each cause, and the ages of those who perish. In
the vast majority of instances civilized men die of disease? Disease

1 J. Sims Wallace, Decay in Teeth (London, Churchill).

8 In England and Wales 520,031 people died during the year 1905. Of these
19,437 perished of violence, mainly the result of accident in flood or field or in
mines. Among the violent deaths, however, were 133 from homicide, 17 from
execution, and 3 from battle; 21 persons died from starvation, 2638 committed
suicide, but probably many of these suffered from physical or mental diseases ;
8 1 3 are said to have died of plague. The remaining half million perished almost
exclusively from disease, including from tuberculosis 55,759, pneumonia 44,367,
bronchitis 38,915, cancer 30,221, diarrhoea 20,534, measles 1 1,076, whooping-cough
8709, influenza 6953, diphtheria 5459, scarlet fever 3834, cirrhosis of liver 4008,

HUMAN EVOLUTION 225

then is the only stringently selective agent amongst civilized
men. The types it weeds out are those that are weak against disease,
the survivors are those that are resistant to disease : it follows that
the only racial progression, certainly the only considerable racial
progression, that civilized human races undergo is one against
disease.

371. This conclusion is likely to be controverted, and by none
more strenuously than by students of evolution, most of whom have
devoted attention exclusively to such peculiarities of shape, colour,
size, and the like, as mark obvious differences between species and
varieties, and who have not taken into account the actual causes
which eliminate human beings under conditions of civilization.
But, either heredity is of the same nature in man as in other species,
or it is not If it is not, how shall we account for the miracle of
adaptation, and for the constant retrogression of useless parts ?
Man, while supplying indubitable evidence of progression when
under selection, affords no clear instance of real progression in
the lack of it. If retrogression constantly accompanies cessation
or diminishing stringency of selection, it follows that only selec-
tion, which is sufficiently stringent, can be a cause of progression.
Amongst civilized men, then, what are the causes of stringent
selection other than disease? What types of men are being
eliminated ? In what direction precisely is progression occurring ?
I have known men who have attempted to answer these questions,
but I have never known one who succeeded. At best they have
merely guessed vaguely at lines of elimination the existence of
which they were unable to demonstrate, or indicated lines of progres-
sion which they could not show were other than acquirements
due to the better development (through improved conditions) of
the descendants as compared with the ancestors.

372. The reader has only to refer to his own experience of life
to perceive that not a single character save power of resisting
disease is stringently selected. Except in extreme cases such traits
as, for example, shortness of stature, muscular weakness, or lack
of beauty or intellect, are not serious bars to offspring. But great
susceptibility to disease is an absolute bar, for the individual
perishes in early life. Relative susceptibility is a lesser obstacle,
but individuals characterized by it are seriously handicapped,
and 22 1 1 of alcoholism. Of the total number of deaths 280,302 were of people
under 45 years of age, and 239,729 of older people; 18,871 infants died because
prematurely born, 2343 of teething, and 12,933 of convulsions. Doubtless in
the last three categories, disease, parental (through causing injury in utero) or filial,
was a potent factor.

226 HUMAN DISEASES

and frequently perish without leaving offspring. It is conceivable,
of course, that insusceptibility to this or that disease may be
correlated to some other and apparently unrelated character such
as height or colour or peculiarity of disposition, which therefore
would undergo concurrent evolution as the race grew resistant to
the disease. But, speaking comparatively, correlated characters of
this sort are very rare, and the study of disease has revealed none,
though the opportunities for observation are excellent ; for we are
able to compare races which are very susceptible to this or that
disease with races which are highly resistant. Very certainly the
comparison of such races reveals no such correlations.

373. Some biometric investigations, it is true, seem to indicate
lines of progression and retrogression other than that related to
disease ; but the data on which they are founded are very scanty
as compared with the evidence that can be gleaned from tables of
mortality ; they cover only a few generations, and make no very
serious attempt to distinguish real variations from acquirements.
In the case of disease we are able not only to obtain precise
numerical information on a large scale as to the causes of death, but
it is in our power to test such theories of evolution as we may found
on that information in a very decisive way, by comparing races
which have long and severely suffered from any disease with races
that have been newly introduced to it. By this means we may
discover, for example, whether the selective elimination which
we suspect to be a cause of progression is a true cause, and
whether the progression, if any, has correlated to it the growth of
some other trait.

374. Of deaths due to disease by far the greater number are
caused by microbic maladies, or by the abuse of such narcotics as
alcohol and opium. Probably, with the exception of violent death,
which is non-selective, and cancer, which occurs mainly during
advanced life, and therefore exercises little or no selection, there
are no other very important causes of elimination. Thus of the
76,844 deaths which occurred in England and Wales during the
year 1905 from diseases of the heart and blood-vessels, it is pro-
bable that the great majority had a microbic or alcoholic origin,
especially in the case of people who died before the end of the
reproductive period. Doubtless, also, the deaths of very many of
the 18,871 infants who perished because prematurely born, or who
died of 'convulsions '(12,53 3), or of teething (2343), were due to the
same causes acting directly on the children or through the parents.

375. Half a century ago the nature of microbic diseases was

MICROBIC DISEASES 227

unknown. Thus when I was a boy in India, troops were marched
across the wind to new camps in the endeavour to avoid cholera. At
the present day even school children have some idea of the agencies
which cause them. Sanitary authorities work with a knowledge
of cause and effect, which is daily growing more exact, and hardly
a year passes but some disease hitherto mysterious is traced to a
microbic origin. As a consequence, both the prevention and treat-
ment of disease are becoming more rational. Men hope with good
reason to utterly abolish such terrible maladies as malaria, the
treatment of which was formerly limited to attempts to cure, and
which were supposed to be as irremovable a part of the natural
features of a country as its mountains and rivers.

376. Human zymotic, infectious, or microbic diseases — tuber-
culosis, scrofula, lupus, influenza, measles, common cold, bronchitis,1
chicken-pox, smallpox, syphilis (great pox), and other venereal
diseases, whooping-cough, diphtheria, pneumonia, rabies (hydro-
phobia), tetanus (lock-jaw), enteric fever (typhoid), scarlet fever
(scarlatina), typhus, leprosy, septicaemia, peritonitis, malaria,
dysentery, epidemic diarrhoea, cholera, yellow fever, plague, sleep-
ing-sickness, erysipelas, rheumatic fever, puerperal fever, abscess,
meningitis, cerebro-spinal (spotted) fever, mumps, opthalmia,
phlebitis, tonsilitis (quinsy), beriberi, dengue, blackwater fever,
Malta fever, and a host of others — are caused by the invasion of
the body of man, and the multiplication within his blood or
tissues of various species of microbes, minute unicellular plants
or animals, which find their nutriment in him. Very many of
these parasitic disease-producing (pathogenic) organisms have
been seen under the microscope. In many cases the causal con-
nexion of a species with the disease to which it gives rise has
been demonstrated by an experimental inoculation of non-infected
animals, and at the present day the doubts of a medical man as to
the nature of the disease he is treating are often solved by the
bacteriologist with his test-tube and microscope.

377. Some zymotic diseases are comparatively rare. The
microbes may be uncommon, as those of spotted fever ; or they may
not easily find entrance into the living body, as those of lock-jaw,
or they do not readily establish themselves in the healthy tissues of
the normal individual, as those of septicaemia. Others are so
prevalent in some countries, and gain entrance to the body so
readily that no man escapes infection unless he is "by nature"

1 See The Sixty-eighth Report of the Registrar General of Births, Deaths and
Marriages, p. cxiii.

228 HUMAN DISEASES

immune, or death, unless he possesses a high degree of resisting
power — for example, the microbes of measles, common cold,
whooping-cough, and tuberculosis in England, malaria in West
Africa, and dysentery in India.

378. The species of microbes that cause disease in man,
numerous as they are, form but a fractional part of the total
number of parasitic species which afflict animals and plants, and
these again are few as compared to the multitudes of unicellular
organisms which find their nutriment in non-living matter. Some
of the latter, the saprophytes, exist on the dead bodies of animals
and plants, which but for them would cumber the earth unchanged.
Each species fits its own particular niche in nature. All are
capable of extremely rapid multiplication, a circumstance which
not only secures the persistence of the species, but provides
material for selection, and, therefore, facilities for quick adaptation
to changing environments.

379. Of the microbes which cause human disease, some, for
example those of typhoid, cholera, dysentery, and diarrhoea, enter
the body in water or other nutritive substances. Since infected water
is a very common vehicle, they are usually termed water-borne.
The microbes of other species are commonly inhaled. The types
which use this latter method of entrance are usually very minute ;
they float in the air like fine dust, and therefore are termed air-
borne. Such are the microbes of influenza, smallpox, common
cold, and many other maladies. Few of these types, owing
doubtless in part to their small size, have been seen. While,
seemingly, the microbes of all air-borne species are very minute,
small size is of course not their only means of adaptation to their
method of infection. For example, it appears likely that their
mode of existence in the body is such that they are exhaled
directly into the atmosphere by the breath of the sufferer,1 where-
as the microbes of the water-borne maladies pass from him mainly
in solid or liquid excreta. The air-borne microbes, owing to their
mode of conveyance and their enormously rapid rate of multiplica-

1 There is evidence that the microbes of such diseases as scarlet fever may be
carried into the atmosphere, or may infect the clothes through dried particles
from the surface, especially in the later stages of the disease. In the latter case,
the microbes are beyond the reach of the phagocytes or the enzymes (see §§ 385-6).
This is probably the explanation of the well-known fact that a person recovered
from scarlet fever is often infective to his fellows for a period which is long com-
pared to that which is the rule with common cold or influenza. In its earlier
stages it is practically certain that scarlet fever infects through the breath.
Certainly^it is very infective before there is any desquamation of the skin.

MODES OF INFECTION 229

tion, are exceedingly infective. Consequently, the immediate
neighbourhood of a person attacked by them is dangerous to
susceptible people. On the other hand, a person suffering from a
water-borne malady may be approached with safety, the danger
lying in the source, the nutriment (water or food) whence the
disease was acquired, or in the solids or liquids he may excrete.
Some species of microbes which enter by the breath, for example,
those of tuberculosis, are comparatively large and heavy. They
fall to the ground, whence, the sputum in which they are contained,
having dried, they are swept up with particles of dust by currents
of air. They are, therefore, termed earth-borne. As compared to
the air-borne types they are in lesser multitudes in the air sur-
rounding a sufferer whose neighbourhood, therefore, especially
in well-ventilated spaces, is not so charged with infection. The
microbes of other earth-borne diseases, for example those of
tetanus, gain entrance through abrasions in the skin.

380. Yet other species, for example those of malaria and
sleeping-sickness, are insect-borne ; that is, they are conveyed
from an infected to a susceptible person by blood-sucking insects.
Lastly, some species, for example those which cause the venereal
diseases, pass by direct contact from one person to another.
Rabies, which is one of these ' contagious ' maladies, is hardly
ever, if ever, communicated by one human being to another, but
is acquired through the bite of an infected individual belonging
to some lower type of mammal.

381. The terms contagious, earth, air, water, and insect-borne
are convenient as indicating common modes of infection, but
they do not necessarily imply that each of the various diseases
infects in only one way. For instance, scarlet fever is usually
air-borne and tuberculosis earth-borne; but it is probable that
both are sometimes conveyed by milk. During the war in South
Africa, enteric fever seems to have been spread by dust storms,
or by flies which had been feeding on excreta. In England
also flies are common vehicles for infantile diarrhoea during the
summer months.

382. The bodies of the higher animals consist mainly of
nutritive substances, and would be happy hunting-grounds for
microbic types if they possessed no means of defence. Though the
skin and food and air passages of the higher animals swarm with
unicellular organisms, these are absent from the tissues of a healthy
individual. The fact that the microbes of disease are often able
to break down the defence and enter the tissues, whereas the

230 HUMAN DISEASES

harmless types are unable to do so, points to the fact that the
former have special means of offence. When studying heredity
in relation to disease, it is necessary to know something of these
means of offence and defence, otherwise we are liable to fall into
the error, which vitiates so much speculation on the subject, of
mistaking somatic modifications for germinal changes.

383. Just as the different species of microbes have different
means of entering the body, so. when once the entrance is affected,
they tend to select different parts or tissues of the body for their
habitation. Some, as those of malaria and probably of all
'general' diseases such as influenza, smallpox, measles, and
scarlet fever, inhabit the blood or lymph. They multiply with
great rapidity, and penetrate to every region. On the other hand,
tuberculosis especially affects the lungs and lymphatic glands,
more rarely the membranes of the brain, the joints, and the skin.
The microbes of diphtheria are usually limited to the mucous
membrane of the upper air passages, those of pneumonia multiply
in the lungs, those of cholera, enteric fever, dysentery, and epidemic
diarrhoea in the bowels. The microbes of tetanus are limited
to the small area surrounding the wound by which they have
gained entrance.

384. Though the area of body invaded by the microbes of a
disease may be very small, yet in many cases the sufferer becomes
extremely ill. Thus in tetanus he is thrown into convulsions,
which resemble those produced by strychnine, and which indicate
that his spinal column is in some way poisoned. We may search
the cord in vain for bacilli. Again, it is possible to grow several
species of pathogenic microbes in broth or other nutrient fluid
outside the body. If this medium is filtered so that it is entirely
free from living organisms, and then injected into the body, the
symptoms of the disease may follow. It is evident, therefore, that
at least some species of microbes elaborate poisons, or toxins as
they are technically termed, which they set free in the medium
surrounding them. In tetanus and diphtheria the toxins enter the
blood stream at the small area affected, and so produce the
symptoms of poisoning. Toxins, like pepsin and trypsin, which
are digestive secretions from the cells of the alimentary tract of
the higher animals, are evidently ferments; that is, substances
which in some unknown way bring about chemical changes in
certain other substances when the latter are exposed to their
action.

385. The cells of the multicellular organisms are specialized

PHAGOCYTES 231

for the performance of various functions that adapt the individual
to his environment. The function of certain classes of cells is
secretion. Thus the cells of the alimentary tract secrete the
digestive ferments which prepare the food for assimilation, while
such glands as the thyroid and the super-renal capsules manufac-
ture * internal ' secretions which pass into the blood, and are
essential to the well-being of the cell-community. Very important
members of the cell-community are certain colourless cells, the
white blood corpuscles or leucocytes, which float in the blood
stream or wander in the tissue spaces. In a sense not altogether
metaphorical, these cells are the sanitary inspectors, the police, the
scavengers of the community. They may be seen to approach
intrusive microbes, enclose them within their own substance, and
destroy them, apparently by digestion, or else perish themselves,
apparently by poisoning. On account of this function of ingesting
microbes they have been termed phagocytes.

386. The fluid part of the blood as distinguished from the
corpuscles is termed serum. Several species of microbes, for
example those of diphtheria, flourish in serum which has been
withdrawn from the body and freed from blood -cells. It is, there-
fore, for them a nutritive, not a poisonous substance. But if
microbes are introduced into the body enclosed in a capillary
glass tube, the ends of which are plugged by a substance that
permits the free diffusion of fluids, but prevents the escape of the
micro-organisms or the entrance of the phagocytes, the latter
collect about the tube in numbers, especially at the open ends
where they form clusters. Presumably, as sanitary officials, they
are attracted by the secretions (toxins) of the microbes. Presently
the micro-organisms perish and disintegrate, apparently in much
the same way as when actually enclosed in the substance of the
phagocytes. Similarly during recovery from diphtheria the bacilli
may be found perishing on the surface of the throat, even when not
in contact with phagocytes. It appears, then, that the phagocytes,
and possibly other cells of the body, secrete substances, as harmless
to themselves as pepsin to the stomach cells, which act as counter-
toxins and poison the microbes, and that they are stimulated to
this act by the presence of the microbes and their toxins. Pre-
sumably these counter-toxins are identical with or similar to the
digestive ferments that destroy bacilli which are actually ingested
by the phagocytes.

387. The toxins of the various species of microbes are not
identical, as is proved by the fact that the symptoms of the

232 HUMAN DISEASES

different diseases are unlike ; for example, the symptoms of the
poisoning occasioned by diphtheria are different in type from
those which occur in tetanus. Judging again by the symptoms,
the virulence of the toxins of some diseases is much greater than
that of others. Possibly there is not in nature a more deadly
poison than the tetanus toxin. The microbes, few in number and
located in a single small area, can produce only an exceedingly
minute quantity, yet the sufferer is thrown into violent convulsions,
and is often killed. On the other hand, even when large areas of
the body are affected by leprosy, the person afflicted feels compara-
tively well. In measles, smallpox, influenza, and the other acute
diseases, the infected person falls suddenly and violently ill.
Evidently he is suffering from intense poisoning ; but he may be in-
fected for months by tuberculosis before he is even aware of illness ;
and, even when he is dying, his symptoms are traceable to nutritive
changes, and to the irritation and destruction of tissues caused by
the microbes themselves, or to toxins and waste products produced
by the microbes of normally saprophytic species, which have
established themselves in the perishing areas of tissue, rather
than to toxins secreted into the surrounding medium by the bacilli
tuberculosis. Therefore, we may reasonably infer that, whereas
some species of microbes produce virulent toxins which pass into
the surrounding medium, the toxins of others are weak or are
retained within the microbes.

388. This hypothesis is confirmed by another set of facts
In acute diseases, such as diphtheria and tetanus, though the
phagocytes crowd towards the infected area till the red and in-
flamed tissue surrounding it is full of them, yet, killed or paralysed
by the concentrated toxins, they do not ingest the microbes, at
any rate at first. If the sufferer dies they are unable to the end to
cope with the invaders ; but in cases of recovery they gradually
gain the upper hand, and in the later stages of disease the dis-
integrating microbes may be seen within them. On the other
hand, in such diseases as tuberculosis and leprosy, the phagocytes
ingest the microbes from the first. The struggle is then, in a way,
physical, not one conducted at long range like that fought out with
the microbes that produce virulent toxins. Victory depends, so to
speak, on personal prowess. If the microbes are victorious, they
spread and multiply, and the sufferer eventually dies ; if the
phagocytes are victorious, the microbes are exterminated and the
sufferer recovers.

389. Microbic diseases differ greatly in the suddenness of their

ACUTE AND CHRONIC DISEASES 233

onset, and in their duration. As a rule, the more sudden and violent
the onset of a disease the shorter is its duration. Thus influenza,
common cold, pneumonia, diphtheria, smallpox, and many others,
develop and end quickly. After an illness of a few days the sufferer
dies or recovers — at least he recovers from the actual disease, though
injuries (sequelae) inflicted by it may persist, for example deafness
from scarlet fever. Before his illness he is free from microbes, as
is proved by the fact that he does not infect his fellows ; during it
he swarms with them, for he is then very liable to convey infection ;
after recovery, since he is no longer infective, he is free from them
again. Something has banished the microbes. His body has
undergone a profound and remarkable change. From being a soil
in which the parasites were able to flourish and multiply, it has be-
come impossible as an abiding-place to them. He has acquired
immunity. He has developed, not under the stimulus of nutriment,
but under that of experience (use). This kind of immunity, which
follows recovery from disease, is obviously quite distinct from that
power of resisting infection which develops under the stimulus of
nutriment, and is termed inborn immunity, and is often seen in
Englishmen, for example in relation to tuberculosis. In the case
of some diseases, smallpox, measles and others, acquired immunity
is usually permanent, but in the case of others, for example common
cold, influenza, and diphtheria, it is generally temporary.

390. In strong contrast to the acute diseases are such chronic
maladies as tuberculosis and leprosy. Here the onset of illness
is marked by no sudden symptoms of deep poisoning ; the complaint
pursues a prolonged indefinite course ; recovery, if it occurs, is as
gradual as the onset, and is commonly accompanied by exacerba-
tions and remissions of disease. The microbes are banished, not
because that particular bodily change which is termed * acquired
immunity ' supervenes, but because an improvement in general
health, due to better nutrition, or surroundings, or some such cause,
strengthens the individual, and with him his phagocytes, and enables
them to destroy their enemies. Often, in spite of apparent recovery,
the microbes may linger in the system for years ; and if the health
be lowered, the disease, uninfluenced by the past experience of the
individual, may be started afresh by surviving microbes, or by a
secondary infection from without, and so ultimately prove fatal.
Recovery from such chronic maladies of indefinite length, there-
fore, is precarious ; it affords no protection, no increase of resisting
power, no 'acquired immunity.' Unlike a man who has recovered
from smallpox, one who has experienced tuberculosis is always in

234 HUMAN DISEASES

peril — in deadly peril, if exposed to reinfection under unfortunate
conditions. The fact that he has experienced the disease is evi-
dence that he is susceptible to it, not that he has acquired increased
resisting power.

391. Between such diseases as smallpox which run a short,
sharp, definite course during which acute poisoning occurs, and
such maladies as tuberculosis which are unmarked by acute
poisoning, and run a course of quite uncertain but always relatively
prolonged duration, lie such complaints as enteric fever and
syphilis. The onset, course, and recovery from enteric fever,
unlike that from smallpox, is comparatively slow, but not so slow
as in the case of tuberculosis ; nevertheless, there are very distinct
symptoms of poisoning, and the duration of the disease is pretty
definite. In syphilis, the onset of the disease is even more delayed,
the symptoms of systemic poisoning as indicated by fever and a
feeling of illness are, as a rule, hardly observable,1 and the microbes
may persist in the system for two or more years. Nevertheless, the
disease ultimately confers an immunity which is usually permanent.

392. Malaria occupies a curious position. Its toxins are
abundant and virulent, and the reaction to them is sharp and
rapid. The individual develops high fever and other symptoms
of poisoning ; but presently the symptoms abate ; apparently the
microbes cease to produce toxins ; the individual appears to
acquire immunity. But this phase is of very short duration. After
an interval, which may be measured by hours or days, the signs
of poisoning recur. During the period of intermission the microbes
seem in a resting stage, when, like the tubercle bacilli, they are
highly resistant to the phagocytes. In individuals belonging to
races which have had much experience of malaria a more per-
manent immunity slowly arises. Thus all, or nearly all, negro
children on the West coast of Africa suffer long from malaria, and
many perish of it, but the adults are more or less free of it. At
any rate, they are much more resistant. Blacks from the American
Islands, many of whom enter the country as soldiers in West
India regiments, suffer severely, and it may be fatally at first, a fact
which has led Koch and others to the highly erroneous conclusion
that no race is more resistant than any other to malaria. But
West Indian blacks, comparatively few of whom perish, suffer
much less than the white officers. If they survive for some months

1 In syphilis the development of the rash is sometimes marked, as in measles,
by a rise of temperature indicative of poisoning. Indeed, the evidence of the
presence of toxins in syphilis is clear. See §§ 416-418.

IMMUNITY 235

they acquire immunity ; whereas the whites continue to suffer —
if anything more and more severely as they become weakened-
The latter cannot acquire permanent immunity. They cannot
rear families, and a white settlement in African swamps or forests
would soon become as extinct as the British colony in Darien.
The following from Miss Mary Kingsley is very much to the
point : —

393. " Yet remember, before you elect to cast your lot with the
West Coasters, that 85 per cent, of them die of fever, or return
home with their health permanently wrecked. Also remember
that there is no getting acclimatized to the Coast. There are, it
is true, a few men out there, who, although they have been resident
in West Africa for years, have never had fever, but you [can count
them on the fingers of one hand. There is another class who
have been out twelve months at a time, and have not had a touch
of fever ; these you want the fingers of your two hands to count,
but no more. By far the largest class is the third, which is made
up of those who have had a slight dose of fever once a fortnight,
and some day, apparently for no extra reason, get a heavy dose,
and die of it. A very considerable class is the fourth — those who
die within a month or a fortnight of going ashore.

" The fate of a man depends solely on his power of resisting
the so-called malaria, not in his system becoming immuned to it.
The first class of men I have cited have some unknown element in
their constitutions that renders them immune. With the second
class the power of resistance is great, and can be renewed from time
to time by a spell home in a European climate. In the third
class the state is that of cumulative poisoning ; in the fourth of
acute poisoning." 1

394. Now since acquired immunity arises most rapidly in acute
diseases in which virulent toxins are most abundantly and quickly
produced, since it arises slowly when toxins are less abundant or
more gradually developed, and since it never arises when the
evidence indicates that poisoning by toxins plays a minor part or
no part at all in the disease, it is clear that acquired immunity is
due directly to the presence of the toxins, not to the presence of
the microbes. This hypothesis is confirmed by the fact just
mentioned, that in acute diseases the phagocytes are able to
approach and destroy the microbes as soon as the symptoms ot
acute poisoning are mitigated, whereas in the more chronic
maladies, though from the first undeterred by toxins, they are

1 Travels in West Africa, pp. 526-7. Macmillan & Co.

236 HUMAN DISEASES

unable to overcome the microbes except after a prolonged struggle
from which no acquired immunity results.

395. It is a noticeable and very important fact that immunity
acquired against any acute disease does not confer immunity
against any other. Thus experience of smallpox or scarlatina
affords no protection against measles and whooping-cough. The
toxins differ, and therefore immunity to each disease must be
acquired separately.

396. Obviously, the various species of microbes are adapted
by different means to the environment. In the search for nutri-
ment they enter the body in different ways. Some species defend
themselves from the phagocytes by means of toxins which they
secrete into the surrounding medium ; others have evolved great
powers of resistance which doubtless depend in part at least on
toxins retained within themselves. In no case is the death of the
host they inhabit of advantage to the microbes. They are adapted
for the temperature, nutriment, and other conditions met in the
living body. The dead body becomes the prey of the bacteria of
putrefaction. The death of the individual, the cell-community
attacked by them, is comparable to the destruction of a hive by
the bee-keeper in an attempt to secure the honey. Continued
multiplication of the microbes within the system, however, insures
the death of the host, if only by interference with the functions of
life. The preservation of their species, therefore, demands that
the microbes shall pass through an unending succession of living
individuals. In acute diseases this is secured by rapid multiplica-
tion and migration to fresh and susceptible persons during the
short interval of safety afforded by the toxins before acquired
immunity or death supervenes. In the more chronic maladies there
is less need for rapid multiplication and migration. The host is
not poisoned. His continued existence is an advantage as afford-
ing a continuous supply of nutriment and prolonged opportunities
for infecting other individuals. However quickly the microbes may
multiply, they never increase at the tremendously rapid rate which
characterizes the organisms of the acute diseases. Thus, in a few
days or weeks, measles, influenza, or smallpox may spread over
a vast area of country, and infect millions of people. The progress
of tuberculosis and leprosy is always much slower.

CHAPTER XII

ACQUIRED IMMUNITY

Intra- and extra-cellular toxins — Susceptibility to disease — Methods of altering
virulence — Parasites and saprophytes — Smallpox — Rabies — Anthrax — Diptheria
— Active and passive immunity — Antitoxin — Syphilis — Snake venom, and
vegetable poisons — Yeast — The nature of acquired immunity — Pasteur's theory —
Chauveau's theory — The theory of neutralization — The theory of habituation —
Ehrlich's side-chain theory — Inborn and acquired immunity.

T

397. f | ^HE nature of acquired immunity and the means by
which it is acquired have long been subjects of debate.
Many hypotheses have been formulated. Since the
mass of facts is enormous, and the difficulty of tracking their
relations very great, the subject is an exceedingly difficult and
complex one. Probably a workable idea of it will be most easily
conveyed to the reader if we begin by setting down an array of
facts, all of which I believe have been verified ; or, at any rate, few,
if any, of which are disputed.

398. (a) Acquired immunity is evidently a reaction against toxins.
The toxins of the acute and sub-acute diseases, against which
alone immunity is acquired, are set free in the medium surrounding
the microbes much as snake venom is set free in the blood-stream
of the victim. Other toxins, intm-cellular toxins, are more or less
retained within the microbes. Thus, if the bacilli of tuberculosis,
the extra-cellular poisons of which are non-existent or very
feeble, be triturated in a mortar and treated with water, a poison,
tuberculin, may be obtained, which, when injected, produces
symptoms markedly different from those which occur in the actual
disease. (£) Some species of microbes can be cultivated in blood-
serum outside the body — not only in the serum of susceptible
individuals, but also in the serum of those who have acquired
immunity. (V) Immunity is influenced by individual peculiarity,
race, and age. Thus many Englishmen are under ordinary con-
ditions immune to tuberculosis; "white rats, adult dogs, many
kinds of birds, and frogs are naturally immune to the bacillus of
anthrax, which is very fatal to cattle, common rats, field-mice,

237

238 ACQUIRED IMMUNITY

and man. Algerian sheep resist the organism, whereas other
breeds of sheep readily succumb. Dogs are practically immune
to tuberculosis, while guinea-pigs are killed by the most minute
dose of the bacillus. Rats and mice are not susceptible to diph-
theria. In none of these cases, however, is the immunity absolute.
By altering the circumstances of the animal it is generally possible
to render it susceptible to the disease. Thus, by keeping frogs at
a raised temperature, it is possible to infect them with anthrax ; and
by overtiring animals by excessive work they may be made suscep-
tible to infection with organisms to which they otherwise possess
almost complete immunity." 1

399. (d) As a general rule parasites flourish best in the species of
animal which they normally inhabit, doubtless because they have
evolved adaptation to that particular habitat; for this reason
human diseases more readily afflict allied species (mammals in
general and monkeys in particular) than types less akin, (e) Mic-
robic species, if removed from their normal habitat (e.g. from
one species of animal to another, or from the living body to non-
living media), are apt to alter their degree of virulence. The
longer they inhabit a species of animal the more virulent, as a
rule, do they grow for that species till a degree of virulence,
sufficient to enable the microbes to persist, is reached. Thus the
microbes of rabies taken from dogs and passed through a series of
rabbits have their virulence immensely exalted for rabbits, though
it is said to be lessened for human beings.2 When transferred to
non-living media microbes tend to lose their virulence and become
saprophytes. The only rational explanation appears to be that
in the former case selection of the microbes that are most virulent
to the new type of host, and therefore best able to defend them-
selves from his phagocytes, causes progression ; whereas in the
latter cessation of selection leads to the loss of the now useless
virulence. On the other hand, normally saprophytic organisms
may be rendered virulent by placing them in the living body, first
in situations where they are least exposed to the phagocytes, and
then in situations where they are more exposed. Some organisms,
normally saprophytic (e.g. the tetanus bacilli and those which cause
putrefaction) are intensely poisonous. Apparently their toxins
have been evolved, not through a struggle with phagocytes, but
probably with other lowly organisms.

400. (/) It has been conclusively proved experimentally that if
smallpox be passed through a series of calves it becomes cowpox ;

1 Bosanquet, Serums, Vaccines and Toxines, p. 13. 2 Op. cit., p. 153.

SMALLPOX 239

in the horse it becomes horse-pox ; transferred back to man
it is vaccinia. By then the nature of the microbes has been
profoundly altered. Owing probably to a loss of virulence
(i.e. offensive and defensive power), they are unable to spread over
the body, but are restricted to the spot of inoculation, where they
and their toxins are most concentrated. The toxins, however,
permeate the body, and induce a general change, from which
results recovery from vaccinia and immunity to smallpox. The
absence of the microbes from the blood-serum, and therefore from
the lungs, prevents their diffusion by the breath. Probably it is
for this reason that vaccinia, unlike smallpox, is not air-borne.
Consequently, it does not infect people in the vicinity. It has
become like rabies and syphilis, a disease which is communicated
only by direct contact and under particular circumstances.1 It
does not, during its passage through a series of human hosts, again
evolve the ancient characteristics of smallpox because, on the one
hand, the failure of its microbes to pass naturally from a sufferer
to his fellows results in the extermination of all that are not
artificially removed, so that there is no survival of the fittest as re-
gards the power to migrate, while, on the other hand, man artificially
enables the more and the less fit to migrate alike. Human races
which have had no ancestral experience of smallpox, which have
not been weeded out by it, have comparatively low powers of
resistance. A party of Esquimaux, who visited Berlin and were
vaccinated there, developed a general disease resembling or identi-
cal with smallpox, and perished of it.2 The microbes, therefore,
were able to spread over the entire body. Doubtless if vaccinia
were passed through a series of such people, and then through
more resistant types, it would again become smallpox — just as
harmless saprophytic organisms become virulent parasites if passed,
under favourable circumstances, through a series of living hosts.

401. (g) Rabies in dogs is a very deadly disease. If passed
through a series of rabbits, it becomes still more virulent, at any rate,
for rabbits. If passed through a series of monkeys it becomes milder.
Pasteur secured complete immunity from virulent rabies by inocu-
lation first with the mildest type (from monkeys), then with
more virulent types, and lastly, with the most virulent type (from
rabbits). Subsequently he discovered an even better method, that

1 Not all ' general ' diseases, malaria for example, are air-borne. To be air-
borne it is necessary not only that the microbes shall find their way to the air
passages, but also that they shall be adapted for transmission through the air.

2 The Scottish Medical and Surgical Journal, April 1900, p. 330.

240 ACQUIRED IMMUNITY

now in use. Rabies develops slowly in an infected person. The
microbes inhabit especially the great nervous centres, the brain and
spinal cord. Pasteur dried a series of cords from infected rabbits,
made emulsions from them, and injected the emulsions into in-
dividuals who had acquired the disease, but had not as yet
developed the symptoms. He began with a cord which had been
artificially dried for fourteen days. Next he used in succession
fresher cords, till he injected material from one which was abso-
lutely fresh, and which would have infallibly communicated the
disease had the previous treatment not been undergone. As a
result the individual, so far from acquiring the disease, developed
immunity.

402. (h) Pasteur subjected the bacilli of anthrax, for a longer
or shorter time, to an abnormal degree of heat. He found they
became * attenuated' (i.e. lost their virulence) in proportion. If,
now, sheep were inoculated, first with bacilli of little virulence,
and then in succession with those of greater virulence, they could
eventually be rendered immune to those of the greatest virulence.
Attempts to pass directly from weak to strong bacilli led to the
death of the infected sheep, (z) A few microbes are not, as a rule,
sufficient to infect even a very susceptible individual. They are
destroyed by the phagocytes, and tend merely to induce an in-
crease of resisting power. Rabbits are susceptible to anthrax, and
young animals more susceptible than older individuals. It has
been found that not less than 16,000 bacilli must be injected into
a young rabbit to induce the disease.

403. (/) If diphtheria bacilli be cultivated in broth, outside the
body, they render the broth intensely poisonous with their toxins.
If the broth be injected, at first in small but afterwards in larger
doses, into a horse, the animal acquires immunity, and remains in
good health during the rest of the treatment. But immediately
after a large dose his blood-serum is poisonous to other animals
which have not been similarly treated. If, however, the serum be
withdrawn from him after a fit period, it is not only harmless, but
helps another animal (e.g. man), who is suffering from the actual
disease, to recover ; or, if not suffering, it renders him, for a time
at least, insusceptible. This is the celebrated antitoxin treatment
which has greatly reduced the mortality from diphtheria, and is
yearly being extended to other diseases, the medical treatment of
which was formerly of little value. (/£) Roux found it possible to
obtain at different times two lots of serum of equal value from a
prepared horse, though no intermediate injection of toxin had

ACTIVE AND PASSIVE IMMUNITY 241

been made. (/) An injection of a right quantity of antitoxin
confers a ' passive ' immunity which is less enduring than the
'active' immunity which results from actual experience of the
disease. Some authorities suppose that the former is due merely
to the presence of neutralizing substances introduced with the
injection of antitoxin, or afterwards produced under its influence
by the individual, and that it persists only so long as these remain
within the system ; whereas active immunity is thought to be a
vital reaction to the microbes themselves. But probably the truth
is, that active and passive immunity are merely degrees of the
same thing, and that in any disease the duration of immunity
depends more on the severity of the illness, and on the consequent
completeness of the reaction, than on the presence or absence of
the microbes. A kind of passive immunity may be induced by
the repeated injection of small quantities of microbes. Workmen
in sewers acquire a passive immunity to enteric fever, doubtless
through constant experience of small doses of bacilli. Dwellers in
malarious countries, or in places where yellow fever is prevalent,
live immune till after a sojourn in a more healthy climate. One
vaccination mark confers an immunity which is more passive than
that conferred by two, that conferred by two is less enduring than
that conferred by more, and still less lasting than that acquired
through experience of actual smallpox. Judged by its duration,
immunity against such diseases as diphtheria, influenza, and
common cold is always passive.

404. (m) Just as immunity acquired against any disease does not
confer immunity against any other, just as vaccinia confers im-
munity only against smallpox, so the antitoxin of any one disease
confers no resisting power against any other, (ri) Within limits, a
dose of toxin large enough to be poisonous may be rendered
harmless by previous intermixture with the corresponding anti-
toxin. This * neutralization ' is somewhat less marked if the two
be simultaneously injected into separate parts of the body, and
still less marked if the antitoxin be injected some time after the
toxin — which, in effect, is what is done when disease is treated by
means of appropriate serum. A mixture of toxin and antitoxin,
for example that of tetanus, in a proportion just harmless to a
rather resistant animal of a susceptible species, for example a
mouse, is poisonous to a more susceptible animal of the same
species, or to an animal of a more susceptible species, for example
a guinea pig. An animal which has acquired immunity to a
disease (i.e. which has acquired the power of resisting infection)
16

242 ACQUIRED IMMUNITY

does not necessarily retain its power of tolerating large doses of
toxin when these are injected.

405. (o) Syphilis is a disease of such long duration that it may
cover several pregnancies in a woman. As a rule, the infants that
are born during her illness suffer less and less as the disease pro-
gresses. Thus, speaking generally, if she have rapidly recurring
pregnancies, at first she miscarries early in the pregnancy, then a
dead but fully developed child is born, then a child which appears
healthy, but soon wastes and dies, then one who survives but ex-
hibits signs of disease, and lastly one which shows no signs of it.
Even if both parents be diseased the successive children tend to suffer
less and less. If a diseased woman bears children to successive men,
then, whether the male parents be diseased or not, her successive
children tend to suffer less and less as time goes on till they do not
suffer at all. But, if a diseased man has infected children by a suc-
cession of women who were not previously diseased, the last child
tends to suffer as severely as the first. Evidently, then, while a woman
may mitigate the disease for her offspring, a man cannot. Though
a woman suffering from the disease tends to confer immunity on
her surviving children, yet a woman recovered from it confers none
on children that are not infected — at least, judging from the
analogy of other diseases, so we must suppose, for a mother who
has suffered from and acquired immunity against measles, scarla-
tina, smallpox, or any other malady, confers no immunity on her
offspring. A woman who has recovered from syphilis has never
been known to bear a diseased child to an infected father. But a
woman who has not, and never has had the disease, may bear an
infected child to such a mate. The bearing of the infected child
confers immunity on her, for she never contracts syphilis when
suckling it, though healthy wet nurses may. A diseased woman
may bear a healthy child which, presumably, is immune, since it
does not acquire the disease when suckled by her. The proof that
it is not infected is afforded by the fact that it does not convey the
disease to a healthy wet nurse.

406. (/) Snake poison (a toxin) may be swallowed in doses a
thousand times larger than would suffice to cause death if injected
under the skin. Immunity instead of death results. The Bushmen
of South Africa are declared on good authority to seek and obtain
safety from snake-bite by swallowing poison glands. Snake venom
artificially attenuated is now successfully used as an antitoxin for
the cure of snake poisoning, (q) Nicotine, opium, strychnine, and
other vegetable poisons, many of which are used as medicines, are,

PASTEUR AND CHAUVEAU 243

in effect, toxins — that is, they are defensive poisons which have
been evolved as means of protection against animal enemies, insects
or herbivora. Usually such toxins, besides being poisonous, have
an unpleasant taste. As is well known, use enables the individual
to tolerate immensely increased doses of some vegetable poisons,
such as nicotine and opium ; in other words, a high degree of
immunity may be acquired. The vegetable toxins abrin, ricin, and
crotin are probably of a proteid nature, resembling the toxins of
disease in having a very complex chemical composition. In the
case of each of them it is possible to manufacture an antitoxin
protective against the corresponding toxin, (r) If the yeast fungus
be placed in a solution of sugar it consumes the latter and excretes
alcohol. Alcohol is not a toxin, a defensive weapon, but a waste
product, comparable to the urine of man not to the venom of
snakes. When it attains a certain strength (about 14 per cent.) in
the solution the fungus perishes — just as the cells of a man's body
perish if his excreta be retained as in kidney or liver disease.

407. Here we have a confused mass of data, culled from many
sources. Our task is to ascertain the relations of the facts and so
link them together, so systematize them, as to discover, if possible,
how immunity is acquired. Pasteur supposed that each species of
microbe finds in the body of its host a special pabulum, the ex-
haustion of which results in the starvation of the microbes, and
therefore in immunity — permanent if the pabulum be not renewed,
temporarily if it be renewed. But Nature has evolved both man
and microbes as bundles of adaptations. It would be strange if
man possessed a series of pabula which are not necessary to his
well-being — for he lives very well after recovery — but which render
him liable to disease. Chauveau supposed that the microbes like
yeast, are killed by the concentration of their own excreta, and
that immunity is permanent or temporary accordingly as these
waste products are permanently bottled up within the body, or
eliminated. But waste products are usually less inimical to the
organism producing them than to most organisms to which they
are strange. Thus yeast fungi are able to live in a solution in
which the percentage of alcohol is as high as thirteen or fourteen ;
but no man could live if alcohol formed anything like that propor-
tion of his total body weight. Both Pasteur's and Chauveau's
hypotheses are decisively negatived by the fact that microbes may
flourish in sera taken from immune individuals.

408. Highly popular is, or was, the hypothesis that microbes or
their hosts produce substances (the antitoxins) which chemically

244 ACQUIRED IMMUNITY

neutralize and render harmless the toxins — much as an acid
neutralizes a base — and so enable the phagocytes to overcome
their enemies. The supporters of this hypothesis point to the
suggestive facts that, within limits, toxins are rendered harmless
to an animal if the corresponding antitoxins are first injected in
sufficient quantities, and that, if mixed with the antitoxins before
injection, they are neutralized more thoroughly, and therefore are
less poisonous than when injected simultaneously but separately,
and, further, that when mixed outside the host a definite amount of
antitoxin will render inert a definite amount of toxin. But a
number of additional facts indicate that the neutralization theory
is untenable. If a fatal dose of toxin be rendered harmless by a
minimum quantity of antitoxin, and then another lethal dose
of toxin be added to the mixture, the latter should become lethal
once more. But it does not, it merely causes a very slight illness.
It needs the addition of quite a number of lethal doses to make
the mixture deadly. Again a mixture of toxin and antitoxin may
be made which is harmless for one animal (e.g. mouse) but
poisonous to another (e.g. guinea pig), a fact which proves that the
reaction that results in immunity is, not merely a chemical, but a
vital one. Yet again, if a mixture of diphtheria toxin and antitoxin
which is harmless to a mouse be made, it is rendered poisonous by
heating it to the boiling point of water. Similarly if the mixture
be placed in a porcelain filter the toxin passes through, but the anti-
toxin remains, a fact which is decisive that the interaction between
the two substances is not of the nature of a chemical combination.
409. Both toxins and antitoxins are substances of highly
complex chemical composition ; each toxin is ' neutralized ' only by
the corresponding antitoxin ; the power of producing its particular
toxin has been evolved by every species of microbe ; but antitoxins
as shown by the acquirement of immunity may be produced by
races which have had no previous experience of the corresponding
diseases ; antitoxins have been found in the blood of animals a few
minutes after the injection of the corresponding toxins. Therefore
the hypothesis of the chemical neutralization of toxins by antitoxins
elaborated by the individual attacked involves the assumption that
the animal body is a species of magic bottle which instantly
produces, under conditions never perhaps experienced by the race,
elaborate substances exactly suited to the needs of the moment.
It is, in fact, a hypothesis of immunization by miracle. Equally
founded on an appeal to the supernatural is the hypothesis, which
is or was popular, that the microbes after producing toxins which

THE HYPOTHESIS OF NEUTRALIZATION 245

defend their lives are good enough to produce antitoxins which
compass their own destruction.

410. The theory of neutralization, so simple at first sight but
so incredible when examined closely, is one that would naturally
occur to students of chemistry which to some extent all medical
men, and more especially all bacteriologists are by training. A
theory hardly less obvious and certainly more probable, is more
likely to find favour with students of evolution which no medical
men are as yet, at least by formal training. Men get ' used ' to
opium and nicotine just as they get used to exertion or heat or
anything else. Opium and nicotine are toxins in a real sense.
No one has suggested that the power of tolerating increased doses
of them is due to the production of neutralizing substances, any
more than they have suggested that the power of tolerating heat
or fatigue is due to the formation of substances which chemically
neutralize heat or fatigue. In each case the growth of toleration,
like the growth of the limbs after birth, is plainly one of that large
class of acquired characters by means of which the higher animals
achieve part of their development and by which they are made so
adaptive. There does not seem to be any very valid reason why
we should place acquired immunity to disease in another category
and ascribe to it a miraculous origin. Certainly, antitoxins seem
to neutralize toxins, but it is possible to find an explanation which
savours less of the supernatural.

411. The spinal cord of a rabbit in the later stages of virulent
rabies contains microbes and their toxins, but, presumably, little or
no antitoxin, for the animal, if not killed, invariably perishes.
But, if we kill the rabbit and dry the cord, antitoxins soon begin to
appear. Evidently, moreover, the quantity, or quality, or both, of
this substance alters in a peculiar way from day to day ; for, if we
inject an emulsion from a cord of a freshly killed rabbit into an
infected man, we do not cure his disease. Nor do we cure it if
we make the emulsion from a cord which has been dried a fort-
night. To achieve the desired result we must follow a certain
routine ; we must begin with a cord that has been thoroughly
desiccated and then proceed by fresher and fresher cords till at
last we inject one that is absolutely fresh and virulent. Here the
theory of neutralization clearly breaks down. The cells of the cord
are dead and dried and cannot produce a neutralizing substance ; the
microbes are dead or dying and are wildly unlikely to produce it ;
most decisive of all, the immunizing agent is not found in any
particular cord, but only in a succession of cords when these are used

246 ACQUIRED IMMUNITY

in a certain order. Again, if we pass smallpox microbes through
a succession of calves, we attenuate the disease. Presumably, we
so weaken the toxins that the microbes are unable to spread
through the body. Vaccinia, with its weakened toxins confers
immunity against smallpox, for, if a man has recovered from the
former, his phagocytes are able to destroy the microbes of the
latter when brought in contact with them; hence his acquired
immunity. In the same way it is possible to immunize against
rabies by passing the microbes through a series of animals
(monkeys) which 'attenuate' it. Again by subjecting anthrax
microbes to an abnormal degree of heat we are able to attenuate
them. By inoculating first with much attenuated microbes, and
then in succession with less attenuated microbes, we are able to
bring about immunity against the most virulent form of the
malady. Since in these cases, we introduce directly, not anti-
toxins but attenuated microbes, then if the theory of chemical
neutralization be correct we must make the incredible hypotheses
that the passage of rabies through monkeys, of smallpox through
calves, and the subjection of anthrax to heat so alters the microbes
that they produce substances which exactly neutralize the toxins
which their ancestors produced.

412. It is very significant that microbes, attenuated to the
right degree, will confer immunity on animals of a species some-
what resistant to the disease, but cause death with symptoms of
the virulent disease in animals of a species that is less resistant.
A parallel fact is that, while smallpox, measles and many other
diseases destroy the less resistant, they confer immunity on the
more resistant individuals of the same species. Obviously, there-
fore, the toxins of attenuated disease tstill remain toxins — but
weakened toxins. Consequently we are driven to the conclusion
that in rabies, smallpox, and anthrax experience of a mild variety
of a disease helps to the acquirement of resisting power against
the more virulent variety — not by introducing substances which
chemically neutralize the toxins but by supplying weakened toxins,
reactions against which act as stepping stones towards reaction
against strong toxins.1 In other words, when the individual has

1 The alteration in the toxin of rabies in drying cords may arise in one of
two ways : (i) the virulent toxin may be directly altered by the drying process,
or (2) the microbes may be so altered that they produce attenuated toxins. Some
authorities have surmized that as drying proceeds the microbes perish, first at
the surface of the cord, and then progressively towards the centre, and, therefore,
that the efficacy of Pasteur's treatment depends on the injection of small but
progressively increasing^quantities of microbes. But the microbes are already

THE RATIONALE OF ACQUIRED IMMUNITY 247

acquired the power of resisting weak toxins, he is in a position of
advantage from which he can react to the stronger toxins and so
acquire immunity. In these instances, then, acquired immunity is
nothing other than a * use-acquirement,' resulting from progressive
habituation. The antitoxins educate the phagocytes till they are
able to tolerate the strongest toxins and destroy the microbes
producing them.

413. That habituation plays a great part in the acquirement
of immunity is evident from the fact that, if we begin with small
but increasing doses, we may eventually inject very large doses
of diphtheria toxin into a horse, without making him ill, though his
serum becomes poisonous to other animals, which, of course, it
would not be were his immunity due to chemical neutralization.
So also, by beginning with small doses a certain degree of
immunity against morphia, nicotine, and arsenic may be achieved.
It is evident, therefore, that immunity may be secured with com-
parative ease in two ways, by giving weakened toxins, or by giving
small but increasing doses of unaltered toxins. The chemical
composition of morphia and nicotine is comparatively simple.
These substances, therefore, cannot be altered without destroying
them as poisons. Arsenic is a still more simple substance. But
the composition of the microbic toxins, that of such proteid
vegetable poisons as abrin and ricin, and that of such animal
poisons as snake venom is very complex. Therefore they may
be altered in such ways as to leave them still poisonous but
weakened in various degrees. If food be swallowed, it is digested
by the pepsin and the other ferments secreted by the alimentary
tract and passes into the system in a somewhat altered condition.
Similarly if snake poison be swallowed, it is digested and some-
what altered so that it enters the blood in an attenuated state and
educates the system against virulent venom injected under the
skin.1 If the poison gland be swallowed, it is also digested.
Now microbes, during recovery from disease or if enclosed in a
capillary tube, perish though not in contact with phagocytes.

present in the infected person in numbers sufficient to cause disease, that is, they
are present in such numbers that the phagocytes cannot overcome them ;
and their numbers continually increase. According to this hypothesis, then, if
we wish to cure a disease due to an increasing number of microbes, we must add
to the multitude from extraneous sources.

1 Digestion in gastric juice of spinal cords infected with rabies, has also been
practised, especially in Italy as a means of attenuating the virus of that disease.
If a series of injections of this digested material be made into sheep an antitoxic
serum may be obtained.

248 ACQUIRED IMMUNITY

Presumably the same digestive substance which destroys them
when enclosed within the phagocytes is secreted into the surround-
ing medium and destroys them there — just as pepsin, which is
harmless to the stomach cells which produce it, digests food at a
distance from them. Moreover, just as pepsin digests both snake
venom and the gland which secretes the venom, so, presumably,
the ferments secreted by the phagocytes digest both the microbes
and their toxins. Of the existence* of these digestive ferments
there can be no doubt. Thus, if we add blood from a person
recovering from enteric fever to a medium in which typhoid bacilli
are contained, the behaviour of the latter indicates injury.

414. If, then, this theory be correct, and I am not aware of
anything known to us which contradicts it, antitoxic serum from
a horse contains substances — ferments and enzymes — which are
engaged in digesting the toxins and so attenuating them ; for
which reason a fatal dose of toxin is rendered harmless when
mixed before injection with its equivalent of antitoxin while the
effect of even larger doses is mitigated. But, what is even more
important, it contains more or less attenuated toxins which form a
scale up which the cells of the individual into whom it is injected
react until he achieves the power of tolerating the strongest toxins.

415. Given suitably attenuated toxins and time for reaction,
immunity against acute disease may almost always be secured.
Thus, if an individual be infected with rabies, which develops
slowly, there is usually ample time if treatment be begun early.
In diphtheria, which develops quickly, days and hours may be
of vital importance ; but since we are able to pour in an ample
supply of antitoxin, our treatment may be very successful. The
vaccine treatment of smallpox, on the other hand, is preventive
not curative. It is useless to vaccinate after the disease has
manifested itself, for before the weaker toxin is elaborated, the
sufferer is on the high road to recovery, or is past help.1 Pre-
sumably the normal process of acquiring immunity is in essence
similar to that which occurs when antitoxins are artificially intro-
duced. The severity of the disease depends in part on the resisting
power of the individual attacked, and in part on the virulence of

1 It is remarkable that subcutaneous injections of considerable quantities of
vaccine lymph does not appear to have been tried in smallpox. Theoretically
such treatment should be excellent. It is probable, however, that the majority
of deaths amongst sufferers from smallpox are caused not by that disease, but by
subsequent septic infection and the absorption of the toxins of putrefaction.
Even so, however, if the injection of vaccine lymph caused the vesicles to abort,
the effect wouM be curative.

SYPHILIS 249

the microbes. If the phagocytes are resistant they are able to
produce enzymes which attenuate the toxins, thus providing
antitoxins, and recovery follows. If their resisting power is low,
they are paralysed or killed, enzymes are not produced, a scale of
attenuated toxins is not provided, and the individual does not
react, but perishes. The tobacco smoker does not acquire increased
resisting power against any other toxin, for example, he is not
rendered more resistant to opium. Similarly, since the toxins of
every disease differ from those of every other, immunity (i.e.
habituation) acquired against any one disease confers no increase
of resisting power against any other.

416. Syphilis, which has been curiously neglected by students
of acquired immunity but which is often quoted by medical
supporters of the Lamarckian doctrine, affords very instructive and
illustrative data. The disease is caused by a microbe, the spirochete
pallidum. It has been said that offspring may be infected by
either parent, but certainly infection is much more common through
the mother. If it be true that healthy mothers sometimes bear
infected children, then, in such cases, the microbes must have been
travelling with the fertilizing spermatozoon, or in some other way
which I cannot imagine have entered the ovum without invading
the maternal tissues. The microbe of Texas fever, a disease of
cattle, is known to travel with the germ-cells of the tick with
which the cattle are infested. The child in utero, is, rightly
speaking, merely a parasite on the mother. It adheres to her
by the placenta, through which it receives nutriment, and in which
the thin-walled maternal and foetal vessels lie in close contact so
that fluids with dissolved solids and gases pass from one to the
other, whereas solids such as blood corpuscles and microbes do not.
In some diseases of which syphilis affords by far the greater
number of examples, injury to the placental vessels may occur and
result in the passage of solids, for example microbes. Apparently
the toxins of syphilis are but slowly elaborated and are not very
virulent. Consequently the disease is of gradual development and
of long duration. It would appear that the microbes, while they
are yet few in number, are at first confined to the place of entry,
where they are protected by their concentrated toxins. Later
when they have multiplied and the resistance of the phagocytes
has been, for the time, overcome by the increased abundance of
toxins, they spread over the whole system. The mother, then,
gradually acquires immunity. Her phagocytes become tolerant
of the toxins and produce enzymes which attenuate them, A

250 ACQUIRED IMMUNITY

scale is thus provided up which she reacts. Her fcetus receiving
enzymes and attenuated toxins from her tends to acquire immunity
at the same time.

417. But young individuals are usually less tolerant of disease,
less capable of acquiring immunity, more liable to be poisoned
even by attenuated toxins than older individuals.1 Consequently
in the earlier stages of the mother's illness the fcetus tends to
perish. In the later stages, protected by the mother's enzymes,
and little injured by the much attenuated toxins, the child may be
born with every appearance of health ; but after birth, when both
the enzymes and the attenuated toxins from the mother have
disappeared, the microbes may reassert themselves, and the child
may perish, or waste and sicken for a time till its own immunity is
thoroughly established. If the placental vessels are uninjured, so
that only the mother or the child is infected, the non-infected
individual tends to acquire immunity more easily and quickly than
when microbes with their concentrated toxins are present. It
undergoes, in fact, a serum treatment strictly analogous to that
which has proved so successful in diphtheria — or rather strictly
analogous to that by which we secure immunity to a person in
imminent danger of infection by diphtheria. Consequently a non-
infected child, born to an infected mother, tends to acquire im-
munity and survive, though it is possible that its immunity, being
1 passive,' may not be permanent. Doubtless if a mother, who has
recovered, becomes pregnant of healthy children, she confers no
immunity on them, for no toxins or antitoxins are present to cause
reaction. So also a mother who has recovered from measles or
smallpox confers no immunity on her children subsequently con-
ceived. But doubtless, also, if she becomes pregnant of an infected
child, she confers immunity ; for toxins elaborated in the child pass
to her, and returning as antitoxins induce a reaction similar to that
which arises in the children she bears in the later stages of her
own disease. At any rate, as far as I am aware, no instance is

1 Doubtless this is because they represent a stage in the life-history at which
powers of making resistance had not been evolved, or so much evolved. Young
embryos represent a stage when the very power of making use-acquirements did not
exist. Probably, therefore, the survival even of foetuses is determined less by their
own resisting powers than by those of their mothers. It must be noted, however,
that since variations occur in all stages of development, and since children as
well as adults are selected by most diseases, they are usually more resistant than
their remote ancestors to diseases of which the race has had experience — as is
proved, for example, by the fact that English children are more resistant to
tuberculosis than American Indians, who therein resemble the ancestors of the
English (see § 442).

EHRLICH'S HYPOTHESIS 251

known of a mother who had suffered from syphilis bearing infected
children to a diseased father, though probably the union of such
mothers with such fathers is not very rare. Obviously, a father
can never confer immunity, for immunity is a reaction made by
phagocytes and perhaps some other cells functionally concerned,
not by the germ-cell, the function of which is reproduction.

418. It is clear, then, that in syphilis there is no transmission
of acquirements in the Lamarckian sense — that is, the child does
not develop under the stimulus of nutrition characters which the
parent developed under the stimuli of injury and use. The child
acquires the disease and, if it survives, immunity, as the parent did,
through infection with a microbe which has previously lived in
another person. Therefore the expression ' hereditary syphilis ' is
erroneous. It would be as reasonable to speak of a bullet which
passed through the mother and lodged in the child as a hereditary
bullet.

419. An explanation of immunity at present very popular
amongst bacteriologists, is Ehrlich's 'side-chain' hypothesis,
a chemico-physiological attempt to interpret the facts. This
hypothesis resembles Darwin's theory of pangenesis, Weismann's
theory of germinal selection, Mendel's theory of segregation, and
many others, in that it is not founded on actual evidence. It seeks
to account for facts believed to be true by assuming conditions not
yet ascertained to exist. Ehrlich supposes that the cells of the
body possess side-chains composed of molecules, receptors as
they are termed, the primary function of which is to attach to the
cells various kinds of food molecules, fats, carbohydrates, oxygen
and the like. The receptors, therefore, are of different kinds.
In addition to having an affinity for this or that kind of food-
molecule, this or that kind of receptor may have an accidental
affinity for this or that kind of toxin — an affinity which is a
positive and fatal disadvantage, for the cell is thereby rendered
susceptible to poison. If much toxin be present, many
receptors combine with its molecules and the cell perishes. If
little is present, some of the side-chains alone perish and are shed,
combined with the now inert toxin, and undergo subsequent
disintegration in the blood serum. This may be termed the
chemical part of the theory. The physiological part is the
supposition that the loss of side-chains stimulates the cells to
excessive production of them. The appropriate receptors are
thus set free in the blood which consequently becomes antitoxic.
Immunity is thus acquired. It is not stated whether this excessive

252 ACQUIRED IMMUNITY

production and shedding of receptors occurs normally in the
presence of over much nutriment. Presumably, it does not, since
the free receptors would render the food incapable of being taken
up by the cells and thus over much nutriment would eventually
be equivalent to too little, and starvation would result. In any
case, the power of acquiring immunity is, according to Ehrlich's
theory, an accidental accompaniment of the power of assimilating
nutriment.

420. On the other hand, inborn immunity — the kind which
prevents an animal ever acquiring a disease — is thought to depend
(i) on a lack of receptors which have an affinity for the toxins of
that particular disease, or (2) on the normal presence of free
receptors in the blood — that is, on receptors which for some
reason are free in the serum, though disease has not stimulated
their super-production. Such non-bacterial poisons as morphia,
nicotine, arsenic and the like — which are not of very complex
composition, are supposed to affect not the side-chains especially,
but the whole cell, which is thus poisoned or else acquires resisting
power against them in ways that differ from that in which it
acquires immunity against the proteid poisons.

421. Obviously, the physiological part of Ehrlich's theory
attributes immunity to use-acquirement. It attempts to explain
up to a certain point how toleration of toxins arises ; that is,
Ehrlich supposes that toxins stimulate cells to the production of
receptors. But the central mystery of how it happens that the
stimulation has the effect alleged, remains unsolved. Instead of
direct digestion by enzymes, neutralization and subsequent dis-
integration (which must be due to some form of digestion), are
imagined. But, since it is admitted that toleration of poisons of
simple composition, such as morphine and nicotine, is not due to
an increased production of receptors but merely to increased
toleration by the cell itself, the necessity of postulating the
existence of the receptors is not very evident. No account is
taken of the evolution of the power of attack in bacteria nor of
resisting power in the species attacked. In fact the whole in-
dubitable truth of evolution is ignored. Disease is treated, not as
part of the normal environment as it really is, but as an accident
which is resisted by accident. Immunity, inborn and acquired,
is regarded, not as a product of protective evolution, but as a
fortunate ' fluke.1

422. Some varieties of animals (e.g. white rats) are normally
immune to certain diseases to which allied varieties or species

ACQUIRED IMMUNITY AN ADAPTATION 253

that use similar food are liable. Some individuals of a species
(e.g. man) are immune to disease (e.g. scarlatina), to which other
individuals are liable. Many species of animals normally immune
to this or that disease, are liable to infection, if the health be
lowered as by abnormal heat or cold. Antitoxins ('receptors')
may be obtained from the dead or dying cord of a rabbit which
was suffering from rabies and would infallibly have perished if
it had not been killed ; that is, though receptors are not produced
in the living animal in sufficient abundance to neutralize the toxins,
and though they cannot, of course, be produced by the dead cells
of the drying cord, yet in the latter they are thought to be in
abundance. Snake venom, in doses lethal a thousand times over
if injected under the skin, confers immunity if swallowed. Whence
the receptors in the latter case ? All these facts are inconsistent
with the side-chain theory, which with many other bacteriological
hypotheses would, I think, never have been formulated had their
authors taken the whole of the facts into account — had they
paused to consider that living nature is a product of evolution, not
of miracle.

423. If the reader bears in mind the facts of adaptation, if he
remembers that almost every important character is an adaptation,
I think that he must conclude that acquired immunity is not an
isolated phenomenon nor a ' fluke,' but essentially a use-acquire-
ment entirely comparable to other use-acquirements in the sense
that the power of acquiring it has been evolved. I think, also, he
will find the strongest reasons for believing that the process by
which this habituation is achieved, is, in the case of virulent
complex toxins at least, one of reaction from weak to stronger
toxins, the weak toxins, the so-called anti-toxins, being nothing
other than stronger toxins that have been more or less digested,
and in this way chemically altered by enzymes secreted by the cells.1

1 All the evidence points to the fact that acquired immunity is especially a
reaction to the extra-cellular toxins (exotoxines) — those that are secreted by the
microbes into the surrounding medium, not retained within themselves. Thus,
while an experience of a few days confers immunity to such diseases as smallpox
and measles in which symptoms of toxin poison are much in evidence, life-long
experience confers no increase of resisting power against tuberculosis or leprosy —
even when the sufferer is but slightly infected and his natural powers of resistance
are but little lowered. Effective antitoxic treatment, therefore, would seem
impossible in such cases. Very scanty success, or no success has attended all
attempts to deal thus with maladies which, being experienced, do not naturally
give rise to acquired immunity in resistant individuals. The celebrated tuberculin
treatment of phthisis is a case in point. Tuberculin is prepared from dried tubercle
bacilli and contains therefore an intra-cellular toxin (endotoxine). It seems to

254 ACQUIRED IMMUNITY

424. The outline I have attempted to give of the process of
digestion is, of course, even if correct in all its facts and inferences
a mere sketch. Each species of bacteria may secrete not only one
but two or more toxins complementary to one another. Thus
there is ample evidence of the existence in acute diseases of toxins
which are retained within the microbes, in addition to those which
are passed into the surrounding medium. Probably the organisms
of the chronic diseases (e.g. tuberculosis) are protected more especi-
ally by the former, those of the acute diseases (e.g. small-pox) by the
latter, whereas those of the sub-acute diseases (e.g. syphilis) depend
in a more equal degree on both. It is significant that an extract
obtained from dead tubercle bacilli is very poisonous, while one simi-
larly obtained from diphtheria bacilli is not. Again, there is some
evidence that one kind of enzyme acts directly against the microbes
and another against their toxins. The cells, therefore, may secrete,
not one kind of enzyme, but perhaps several. The same enzyme
may not protect against every disease. The process of digestion
may not be continuous, but may proceed by well marked steps in
which various cell products, globulins, lysins, alexines, opsonins,
and the like successively take part. As far as I am able to judge,
however, no matter how complicated the process, it is somewhat of
the nature I have attempted to describe.

425. Inborn immunity on the other hand must in each case be

have some curative properties, which depend apparently on an increase of in-
flammation round the foci of infection which leads to necrosis and sloughing of
the diseased tissues ; but there is no evidence that it conduces to that toleration,
that acquired immunity, to the attainment of which the antitoxic treatment of
acute disease is so great a help. The antitoxic treatment of such troubles as
alcoholism and morphomania has also been tried — with declared success by the
originators of the treatment, with ill-success by all who followed them. Doubt-
less serum treatment of a tendency to fatigue by means of an antitoxin obtained
from very tired animals will one day be attempted, and will meet with the same
unsatisfactory sort of success. Some of the hypotheses formulated and acclaimed
by bacteriologists are of a kind to fully justify the endeavour. The speed with
which immunity is acquired bears an evident relation to the abundance of the
extra-cellular toxins and the rapidity with which they are produced by the
microbes. All the cells of the body are affected by them and all those which are
functionally concerned in the acquirement of immunity tend to react. In the
case of the intra-cellular toxins only those cells which ingest the microbes are
affected. Possibly this is the reason why immunity is acquired in the one case
and not in the other. The duration of immunity, which is usually life-long in
some diseases and of short duration in others, depends on factors which are quite
unrecognized. It is sometimes said that one attack of certain diseases (e.g.
diphtheria) in which the period of immunity is short, predisposes to subsequent
attacks ; but the truth of this surmise is very doubtful. An attack of such a
malady indicates that the individual is susceptible ; subsequent attacks probably
indicate no more than a recrudescence of this susceptibility.

INBORN AND ACQUIRED IMMUNITY 255

due to one of two very different causes ; a very high resisting power
on the part of the individual attacked, or to a low attacking power
on the part of the microbes. The high resisting power is due to
stringency of selection affecting the species possessing it ; the low
attacking power is due to lack of selection amongst the microbes.
Thus human races that have been much afflicted by tuberculosis
are, as compared to other human races, especially resistant. Dogs
on the other hand are almost quite immune. Since we have no
reason to suppose that these animals have ever suffered from the
disease, we are driven to the conclusion that the environment they
offer is unsuitable to the tubercle bacilli. It is one to which their
evolution has not adapted them. It must be noted, however, that
an evolution, which fits a race for a particular environment, does
not necessarily unfit it for existence in another, and, within limits,
a different one. Thus many European plants and animals, in-
cluding man himself, flourish exceedingly in New Zealand and
elsewhere. So also the bacillus tuberculosis, which, so far as we
know, has never afflicted wild guinea pigs, is very deadly to them
in captivity. In rare cases inborn immunity appears to be a
correlate of other and apparently quite unrelated characters.
Thus, unlike coloured varieties, white rats are immune to anthrax.
426. The main purpose of the present chapter is to establish
a clear distinction between inborn and acquired immunity —
between the kind of immunity which arises under the stimulus of
nutrition and that kind which develops through individual experi-
ence of disease. To achieve this object we have been forced to
discuss the rationale of acquired immunity. The two kinds are
constantly confused. Thus in medical discussions, one has only
to maintain that parental diseases and acquired immunity are not
* hereditary,3 and some one is sure to retort that in both instances
the contrary is constantly observed in syphilis. Many doctors are
still convinced that ' common sense ' demands a belief in the
Lamarckian doctrine. Certainly nearly all doctors are convinced
on grounds of common sense that ill-health tends to so affect the
germ-plasm that, in consequence, offspring of unhealthy people
are commonly born degenerate. In other words they believe that
parental disease is a frequent cause of variations in offspring. We
have already discussed this problem somewhat in detail, but it is
of great practical as well as theoretical importance and will repay
further study. The ground is now cleared of possible misconcep-
tions and we may proceed to discuss it in comfort.

CHAPTER XIII
THE PRESENT EVOLUTION OF MAN

The conditions under which infection occurs — Inborn immunity develops in
the individual under the stimulus of nutriment — Acquired immunity under that
of use — Theories of the causation of variations and the facts of disease — The
decisive nature of the evidence furnished by disease — Malaria — Tuberculosis —
The air-borne diseases.

W1

427. ~^"^ 7"E saw *n *ke eleventn chapter that, with the excep-
tion of alcohol, opium, and perhaps one or two
other narcotics, microbic disease is the only agency
which is stringently selective amongst civilized men. Speaking
generally, in England, for example, the people who survive and
leave offspring are not those who escape contact with the microbes
of such prevalent diseases as measles and whooping-cough, but
those who are resistant to them. Selection implies, of course,
variations in resisting power, and no one will deny that men differ
naturally in this particular as in all others. Again, no one will
deny that resisting power against one disease does not necessarily
imply resisting power against any other. The selection is, in fact,
' specific.' Each disease chooses its own special victims, and is the
cause of an evolution only against itself. On the other hand, no
one who has studied diseases doubts that, owing to fluctuations in
vitality and environment, individuals tend to alter from time to
time in their powers of resisting it. The man who is very resistant,
may become less resistant through the operation of some cause
which lowers his vitality, while he who is very susceptible may be
rendered more or less so through changes in health and sur-
roundings. Nevertheless, the truth holds that the naturally more
resistant tend always, under any condition, to survive in greater
numbers than the more susceptible. Lastly, selection is not
equally stringent in all environments, nor at all times in the same
environments. It has been ascertained, experimentally, that the
dosage of microbes plays a large part in the causation of infec-
tion, and, therefore, in the causation of acquired immunity or
death. The microbes of disease are much more numerous in some

256

ACUTE AND CHRONIC DISEASES 257

situations than in others. We, in England, contract almost all
our diseases in dwelling-houses or in places of popular assembly,
such as schools and churches. In the slums of cities where over-
crowding is greatest, the separation between the sick and the
healthy most imperfect, the dilution of the dosage with fresh
incoming air most incomplete, and the general nutritive and
sanitary conditions worse, selection is more stringent than in better
houses and in rural districts. Such very common diseases as
measles, chicken-pox, and whooping-cough are usually always
present (endemic) in towns, whereas in the country and even more
in remote islands, such as the Hebrides, they tend to be more
distinctly epidemic. That is, in towns the exposure of susceptible
people to large doses is very frequent, while in the country it is
more exceptional.

428. We saw also that all microbic diseases may be placed in
one or other of two categories. On the one hand are those
diseases against which immunity cannot be acquired, and, on the
other, those against which it may be acquired — acquired immunity
being an entirely specific reaction which follows individual experi-
ence of disease, and which in every case is of avail only against the
particular disease which has been experienced. It is quite distinct
from ' innate ' immunity, which (though it is also specific) does not
follow but precedes experience of the microbes, and which arises
therefore like eyes, ears, hair, and teeth, as a nutritional character.
Tuberculosis and leprosy are typical examples of diseases against
which immunity cannot be acquired. No doubt, in a sense,
immunity may be acquired against some of them ; that is, owing to
improved health and vitality, an infected person may recover and
live immune; but this is not what is meant by the technical expres-
sion * acquired immunity.' On the other hand, a person may be
' innately ' immune against such typically acute diseases as measles
and influenza. That is, he resists infection though exposed to
doses which would give rise to disease in the ordinary individual
who has not acquired immunity. But in the case of such diseases, in
the vast majority of instances, people differ, not so much because they
resist infection, for nearly all contract each disease if sufficiently
exposed to infection, as because they recover more or less easily.1

1 Inborn immunity, though rare in measles and so rare in smallpox that
formerly when the disease was prevalent an unmarked skin was in itself regarded
as an exceptional beauty, is common enough in some acute diseases. Thus,
though constantly exposed to infection, I have never contracted diphtheria nor
scarlatina. Probably, in the case of such diseases, the two forms of immunity
are evolved concurrently.

258 THE PRESENT EVOLUTION OF MAN

It follows, if there is any truth in the theory of evolution
through Natural Selection, that a race much afflicted by a chronic
disease — for example, tuberculosis — should evolve inborn immunity
against it ; whereas, if afflicted by an acute disease — for example,
measles — it should tend to develop an inborn power of acquiring
immunity. Both inborn immunity and the power of acquiring
immunity arise in the individual through the experience his race
has had of disease. They are nutritional characters. But actual
acquired immunity arises in the individual through his own
personal experience of disease. So also a man's hand and his
power of acquiring callosities on it are due to an evolution in
his race which enables him to develop those characters under the
influence of nutrition ; but the actual callosities are due to his own
experience of rough work.

429. Again, we have seen that there are several theories of
evolution, each with its corresponding theory of heredity. First,
there is the theory of an internal adaptive growth-force, which
supposes that variations tend, on the whole, to be adaptive. This
hypothesis, which is founded purely on an appeal to miracle,
need not be considered further. Science ought not to appeal to
the supernatural until, at least, it has been demonstrated that
natural interpretations are impossible. Second, there is the
Lamarckian doctrine, which supposes that characters acquired by
parents under the influence of use or injury, tend to be reproduced
by offspring under the stimulus of nutriment. Third, there is that
very popular theory of heredity which supposes that variations
commonly arise through the direct action of the environment on
the germ-plasm. This hypothesis of the causation of variations
is usually associated with the doctrine of Natural Selection, but
is clearly incompatible with it. Examined closely, we find that
it implies a theory of racial change, but not adaptive change. It
implies, in fact, that species drift helplessly under the influence of
the environment in directions which may or not be adaptive, but
which can very rarely be adaptive. Lastly, there is the theory
that the mass of variations are spontaneous, and that they occur
all round the specific mean, and, therefore, that the germ-plasm
(in so far as its hereditary tendencies are concerned) is highly
insusceptible to the direct action of the environment. This
theory, and this alone, is compatible with the doctrine of Natural
Selection. If only we think closely and clearly, we find also that
it is the only theory which fits in with the facts of adaptation.

430. Now, which theory of heredity is borne out by human

THE RACIAL EFFECTS OF DISEASE 259

experience of diseases? If the Lamarckian doctrine be true, all
races exposed to such chronic maladies as tuberculosis should
steadily deteriorate ; for by such maladies the individual is never
strengthened in any known way, but, on the contrary, always
injured. His resisting power is lowered. Therefore, no matter
how slight and partial, how fitful and faint the inheritance of
parental injury, yet the effects accumulating during many genera-
tions should at last cause the race to trend towards extinction.
Is it, then, the fact that races afflicted by tuberculosis, or any
other agency which causes chronic ill-health, are steadily deterio-
rating, steadily becoming less and less capable of existence? On
the other hand, acute maladies confer a great measure of resisting
power on individuals who have experienced them and survived.
If this be inherited, no matter how faintly and fitfully, the race
should in time develop absolute inborn immunity, absolute in-
capacity to acquire disease. Is it, then, the fact, that races which
have long been afflicted by such acute maladies as measles,
chicken-pox, whooping-cough, and the like, have become quite
immune to infection ? Evidently the Lamarckian doctrine implies
racial effects due to disease which are very remarkable. Each
chronic disease must weaken the race till it perishes, each
acute disease must strengthen it till it is quite immune to that
disease.

431. The hypothesis that variations are caused by the direct
action of the environment, though often confused with the
Lamarckian doctrine, is quite distinct from it.1 It supposes, not
that the characters which arise in the parent through use or injury
are reproduced by the child under the influence of nutrition, but
merely that nutritive substances, waste products, toxins, and the
like, circulating in the blood, or otherwise acting on the germ-
cells, tend to alter the hereditary tendencies in the germ-plasm in
some definite way — in such a way that the individual who
springs from the germ-cell is injured or benefited, weakened or
strengthened. At first sight this hypothesis is much more probable
than the Lamarckian theory. But it is only reasonable to suppose
that if the germ-plasm is altered at all by the direct action of the
environment, it is injured and devitalized, not benefited by ex-
posure to the toxins of acute diseases or by the general inter-
ference with nutrition which accompanies the chronic maladies,
At any rate, while it has often been held that parental ill-health
is a cause of filial degeneration, no one has suggested that syphilis,

1 See § 98.

260 THE PRESENT EVOLUTION OF MAN

tuberculosis, malaria, measles, or any other disease or ill-condition
suffered by parents increases the vitality of their offspring. If,
then, this theory is correct, all races afflicted by any sort of disease
should steadily drift towards extinction.

432. Lastly, if the theory that the vast majority of variations
are spontaneous, be true, and, therefore, if the doctrine of Natural
Selection be correct, then every prevalent and lethal disease should
be the cause of protective evolution against itself. Diseases which
are not prevalent or not lethal should cause no racial change.
Prevalent and lethal chronic diseases, since the survivors from
them are people who resist infection, or who, if they recover from
infection, do so only because their vitality is improved, not because
they undergo that peculiar reaction known as acquired immunity,
should cause an evolution of inborn immunity — an evolution of an
inborn power of resisting infection. Prevalent and lethal acute
diseases, since the survivors from them do not, as a rule, resist
infection, but merely when infected tend to recover within a
definite time, should cause an evolution of the power of acquiring
immunity under the experience of disease. In other words, the
evolution should be such that, in the case of chronic maladies,
immunity should develop in the individual under the stimulus of
nutrition, whereas in the case of acute maladies it should develop
in him under the stimulus of use. Thus, if the theory of spon-
taneous variations and of Natural Selection be true, the individuals
of a race that has been long and severely afflicted by tuberculosis
should, as a rule, display a greater innate power of resisting infec-
tion, or, if infected, of withstanding the malady, than individuals
of races that have been less or not at all afflicted. A race afflicted
by measles should display no greater power of resisting infection
than any other race, but a much greater faculty of recovering by
the acquirement of immunity than races that have had less experi-
ence of the disease. On the other hand, races that have been
afflicted by such non-lethal diseases as chicken - pox x should
possess a power of resistance no greater than that displayed by
races that have had no previous experience. Moreover, in all
cases the resisting power, whether inborn immunity or the inborn
power of acquiring immunity, should be specific. That is, the
effect of each disease on human races should be an increased

1 In 1905 " chicken-pox is said to have claimed ninety- three victims, but it
is at least probable that some of the latter were unrecognized cases of the graver
malady " (smallpox). — Sixty -eighth Annual Report of the Registrar-General of Births,
Deaths, and Marriages in England and Wales, p. Ixxix.

MATERIALS FOR STUDY 261

power of resisting it and nothing more. The race should not gain
in beauty or muscular strength or size or anything of the sort.1
Of course, it is possible that this or that character may in the
future be found to be correlated to susceptibility to, or to power of
resisting this or that disease, but, to the best of my knowledge,
nothing of the kind has yet been discovered.2

433. Very plainly, disease furnishes ideal material for investi-
gation of that most important problem of heredity, the causation
of variations. The acquirements made under the influence of
injury (e.g. in such chronic maladies as tuberculosis), or of use
(e.g. in such acute complaints as measles), are very striking and
peculiar, and in the case of many diseases and many races have
been made by every generation for unnumbered generations. The
germ-cells are often literally bathed in toxins, it may be for pro-
longed periods, as in syphilis and malaria. Their nutrition is
interfered with for even longer periods in such complaints as
tuberculosis and leprosy. Our opportunities for observation are
particularly good, for every one of us has had personal experience
of illness, and is acquainted with numerous cases of it. Any
amount of precise statistical evidence, furnished by Departments
of Public Health, concerning the different effects of disease on
different races, is available. Every instance of the birth of a child
to a parent who is or has been diseased constitutes an experiment
which is as stringent as any that can be consciously devised, but
which possesses in addition the advantage that it is made under
conditions that are normal to the species. Like many other
experiments, this experiment has the disadvantage that the effect
produced on the offspring, if any," may be so small as not to be
observable, or it may be so confused with spontaneous variations
as not to be detectable ; but in the case of every disease we are
able to compare many races which have suffered much and long

1 It seems hardly necessary to insist on this, but various critics have thought
it necessary to declare that there is no evidence that much experience of disease
produces the ' finest race.'

2 The dark colour of negroes has been thought to be correlated to their high
powers of resisting malaria. But many black races, for example some Polynesians,
are highly susceptible, and some white races are relatively resistant. Thus malaria,
which destroyed an invading British army as a fighting force, left the inhabi-
tants of the island of Walcheren able to pursue their ordinary avocations.
Biometric attempts have been made to discover correlations between physical
and mental traits and disease by comparing individuals of the same race, but if we
compare individuals of different races, in whom contrasts in resisting power, colour,
and the like are so much more marked as to be easily observable, we find no
such correlations.

262 THE PRESENT EVOLUTION OF MAN

with many others which have suffered less or not at all. If disease
produces any germinal change, then, no matter how small and im-
perceptible the difference between one generation and the next, or
how confused with spontaneous variations, the constant accentua-
tion of the alteration during hundreds, perhaps thousands, of
generations, must make it at last manifest and unmistakable.
The multitude of races and their diseases is so great that we are
able to make endless comparisons and so reduce the chance of
error to a minimum. The materials are so familiar that every man
may verify them for himself; whereby that grave source of error
and doubt, the ' personal equation ' of the observer, is eliminated.

434. Manifestly, we are dealing now with a problem of the first
importance, the question of the causation of variations, which,
both from a theoretical and a practical standpoint, is the central
problem of heredity. All theories of racial adaptation and
degeneration, of the influence of environment, of likenesses and
differences between parents and offspring, of plant and animal
breeding, of far-reaching social effort depend on it. Disease affords
material for solving the problem more conclusively than anything
else to be met with in nature. The reader must, therefore, consider
carefully what theory of the causation of variations fits in with the
known changes undergone by races that have been in contact with
disease. In other words, he must make a rigorous deductive infer-
ence of consequences, and then carefully compare these con-
sequences to reality.

435. The facts are decisive. Nearly all human races have been
exposed to disease for thousands of years, and in no instance is
there to be found an iota of evidence that any race has, as a con-
sequence, become degenerate, or that any race has transmuted
acquired into inborn immunity. On the contrary, not only is
every race resistant to every prevalent and lethal disease precisely
in proportion to its past experience of it, but the resisting power is
such that it can have been evolved only through the Natural
Selection of the spontaneous variations of a germ-plasm that was
insusceptible to the direct action of the environment, and did not
transmute acquirements into innate characters. Without excep-
tion, those races which have been exposed to diseases (e.g. tuber-
culosis), against which immunity cannot be acquired by the
individual, have tended to become, not enfeebled, but innately
capable of resisting infection ; whereas, races which have been
exposed to diseases against which immunity may be acquired
(e.g. measles), have evolved nothing other than an increased

ACCLIMATIZATION 263

capacity of making the acquirement, of recovering from infection.
On the other hand, races that have been exposed to non-lethal
diseases (e.g. chicken-pox), are neither more nor less resistant,
neither more nor less degenerate than races that have had no
previous experience of them. Apparently they are in no way
changed. The sufferings of races have not altered them at all.
Only the elimination of the un fittest has altered them.

436. Clearly both the Lamarckian doctrine of the transmission
of acquirements and the doctrine that variations are normally
caused by the direct action of the environment on the germ-plasm
are erroneous. The theory that the mass of variations are spon-
taneous is just as clearly correct. Only in that case can Natural
Selection, the actuality of which as regards disease is obvious to
every observer, have produced the particular racial changes that
have resulted. We constantly speak of the acclimatization of an
individual or a race. As applied to individuals, the term is a
synonym for use-acquirement, for protective development, for a
becoming accustomed or habituated to the new conditions — a
habitation which may be ' active ' (i.e. due to recovery from actual
disease), or ' passive ' (i.e. due to experience of microbes and toxins
in doses too small to cause disease). As applied to races, it is a
synonym for protective evolution, which, in the case of diseases
against which immunity cannot be acquired, implies the increase of
a power of resisting infection, and in the case of diseases against
which immunity can be acquired, implies the increase of a power
of recovering from infection and resisting it subsequently. When
we talk of the deadly climate of West Africa and the healthy climate
of England, we think only of ourselves. Not less deadly to the
African negro, to whom the West Coast is healthy, is the climate
of London with its prevalent tuberculosis. To the Polynesian or
Red Indian, whose race has had even less experience of this disease,
a residence in any one of our great cities is usually equivalent to a
sentence of death.

437. All educated men know more or less clearly that every
race that has long dwelt in any environment is especially well
adapted to the conditions of that environment, including its
diseases. Medical men share this knowledge. But most doctors
believe a/so that races tend to deteriorate when exposed to injurious
conditions. The two beliefs are utterly incompatible, and afford a
good example of the confusion of thought that arises when the
duty of making a rigorous deductive inference of consequences
is neglected. The latter belief (that variations are commonly

264 THE PRESENT EVOLUTION OF MAN

caused by the direct action of the environment) is based in part,
apparently, on a tradition ultimately derived from popular notions
and first acquired by us all in the nursery, and in part on experi-
ments and statistics which as a rule have no bearing on the point
at issue. The problem, as we have already noted, is not whether
it is possible to devise conditions in which the germ-plasm is
injured beyond recovery, but not destroyed, but whether under
conditions more or less normal to the race variations are commonly
caused by the direct influence of the environment.1 Disease,
which at one time or another affects practically every individual
in England and Africa, has for thousands of years been almost
as normal an occurrence as birth itself.

438. The experiments on which medical men rely are such as
are afforded by Clayton's beans,2 transplanted Alpine plants,
Fere's alcoholized eggs,3 and the like. The experiments they
ignore are those of nature which every day's professional work
brings under their notice, but over which hangs the veil of famili-
arity. The statistics they rely on are such as alienists collect.4

1 See § 1 60. 2 See §§ 134, 156.

3 I think it would puzzle anyone who tries to think clearly to explain how
Fere's perpetually quoted experiments bear on the problem of the causation of
variations. Fere exposed eggs to the vapour of alcohol and got some remarkably
miserable chickens. This indicates that alcohol is bad for developing chickens.
It does not indicate that the ill-effects are germinal and therefore ' innate ' and
' transmissible ' to descendants — any more than a plucked chicken indicates that
the effects of plucking are ' inheritable.' Fere should have bred from his de-
debauched chickens. The attitude of some medical men, who are interested in
philanthropy, especially temperance reform, and who have been accustomed to
insist on the ' degeneracy ' which results from insanitation and drink, is instructive
from the point of view of scientific education (see § 1 16, footnote). The statement
that ill-conditions cause protective evolution, not racial deterioration, is often
declared by them to be too ' philosophical ' or ' academic ' or ' logical.' ' Honest
facts ' are demanded. It is hard to say what is meant exactly — possibly nothing
more than that the masses of fact on which the statement is founded are large
and complex, and the thinking necessary before the relations can be ascertained
somewhat difficult. The fact that diseases cause evolution, not deterioration, if
not honest, is at least indisputable. I imagine by honest is meant experimental.
The statement that " we know very little about heredity " has no doubt very
often an element of truth ; but the version that " very little is known about
heredity " is distinctly inaccurate. Sometimes it is said that " the proposition
that germ-cells are inviolable is sheer nonsense. They are just as liable to injury
as other cells, and we have daily experience that somatic cells may be injured."
But no one has maintained that germ-cells are inviolable. It has only been
maintained that all kinds of cells, including the germ-cells of all species, have
been so dealt with by Natural Selection that they hold to their hereditary
tendencies almost as firmly as they hold to life.

*See §§ 131, 135.

THE MIGRATIONS OF NEGROES 265

The statistics unused are those published by Departments of
Public Health, which, especially in the conquests and colonies of
Europeans, show clearly the real effects which have flowed from
racial experience of disease.

439. It is hardly necessary to quote evidence that races are
resistant to diseases in proportion to their past experience of
them.1 The evolution of negroes against tuberculosis, however, is
so very illuminating and typical that it is worth while to devote a
paragraph to it. There are no accounts of negro conquests outside
the limits of Africa, but from very ancient times a constant stream,
of slaves has passed to Southern Europe and Asia, where they
have been employed mainly in domestic service, and in more
recent times to America, where their principal occupation has been
agriculture. The invasion of Asia has continued to our own day ;
but, notwithstanding the great antiquity and volume of the stream,
one may search from Spain to the Malay Peninsula, and, except in
recent importations, find no trace of a negro ancestry. Yet slaves
like cattle are valuable property, more cheaply bred than imported.
In Eastern countries they have often been kindly treated, and
many have achieved wealth and power. Yet they all perished in
a few generations, the elimination of the unfit being so stringent
as to cause extinction, not evolution. A permanent, colony of
native Africans in the midst of an ancient tuberculosis-infested
civilization is impossible. The fate of negro migration into
America has been different. The race had undergone some
evolution against tuberculosis in Africa, and therefore was more
resistant than the vanishing aborigines. In its new home,
employed in agriculture in a hot climate where white men and
tubercle bacilli, also recent importations, were yet few in number, it
was placed under the best conditions possible. Gradually, as the
stringency of selection waxed, it evolved increasing resisting power.
To-day the descendants of the migrants have undergone such an
extent of protective evolution that they are able to dwell even in
North American and European cities, though it is still said of
them that "every other adult negro dies of consumption."

1 The reader who requires evidence will find it in convincing quantities in my
work, The Principles of Heredity, chapter xi.

CHAPTER XIV
EPIDEMIC AND ENDEMIC DISEASE

The conditions of parasitic life — Probably every disease originated from a
single centre — No new diseases are known — Disease in ancient and modern times
— Contagious diseases — Insect-borne diseases — Air-borne diseases — Water-borne
diseases — Earth-borne diseases — The antiquity of diseases — Pestilence — The
invasion of the Western Hemisphere by disease — Diseases as empire-builders.

w

440. "^""^f 7"E mav safely assume that the micro-organisms of
disease evolved from saprophytic forms of life, the
only alternative being the impossible hypothesis
that these highly specialized types arose by spontaneous generation
after the evolution of the higher animals and plants. Precisely
how the passage from a saprophytic to a parasitic mode of life
occurred is a matter of conjecture. We know only that there is per-
petual war in nature, and that the bodies of the higher animal types
contain nutritious material of which the lower types must always
have tended to avail themselves. From the beginning, therefore,
there must have been some sort of a struggle. The evolution of
the parasite had two concurrent phases. First, the saprophytic
species must have become capable of persisting for a longer or
shorter period in living bodies in spite of their defences. Second,
it must have evolved means of passing from infected to healthy
but susceptible individuals. Some saprophytic species are very
virulent, for example those of putrefaction. Apparently the
toxins they manufacture are either digestive ferments or means of
offence or defence against other lowly organisms. Under favour-
able circumstances they readily adopt a parasitic mode of life,
causing disease ; but, since they are unable to pass easily from one
individual to another, they cannot maintain themselves as parasites.
Thus, also, the microbes of vaccinia are unable to persist unless
artificially propagated. The main difficulty to be overcome by an
evolving microbic species, then, is not the development of virulence,
but the evolution of faculties for passing from one individual to
another. Possibly each species of pathogenic organism first estab-
lished itself as a regular parasite during times when hardship, famine,

THE ORIGINS OF MICROBIC DISEASES 267

or other causes had lowered the resisting power of a community of
its present hosts.

441. The microbes of the different diseases differ so sharply in
the effects they produce, in their methods of protecting themselves
when in the body, and in their modes of passage from one in-
dividual to another, that it seems more probable that each patho-
genic species was derived direct from a separate saprophytic type
than that any two species were derived from a common parasitic
stock — an ancient disease ancestral to two modern diseases. Very
possibly the air-borne species arose from saprophytic types that
were originally air-borne, the water-borne species from water-borne
saprophytes, and the contagious types from saprophytes that
normally and harmlessly inhabited cavities of the body, and so on.
Again, since the constant tendency in nature is towards differentia-
tion, not approximation, in type, since the microbes of disease are
highly specialized, and since the passage from saprophytic to
parasitic ways of life is very difficult, whereas, when once the
parasitic habit is established, the passage from one host to another,
and so from one country to another, is comparatively easy, it seems
probable that no disease had multiple origins in different parts of
the world, but that every disease spread from a single centre.1
However, as to all this we have no direct evidence on which to base
speculation.

1 At least we must consider it improbable that diseases had multiple origins
if we accept the selectionist theory of evolution. Doubtless, however, supporters
of the mutation theory, who insist that the same mutation tends constantly to
occur in the same species, would hold a contrary opinion. But probably recur-
rent mutations are in most, if not all cases, reversions (see footnote, § 297).
None of them have been known to be adaptive, and a mutation which adapted
a saprophytic species in all its structures to a parasitic mode of life would be a
very wonderful thing. It would involve, not only the sudden development of
great virulence and all that that implies, including a capacity to resist the enzymes
of the host, but, at the same time, a power and a tendency to pass from the
infected person to others in the neighbourhood. Moreover, this amazing con-
glomeration of correlated mutations would have to occur, not in one or a few
microbes but simultaneously in thousands ; for if only a few microbes invade
the body they perish. Disease results from the invasion of very many (see
§ 402). Thus the microbes of vaccinia are unable to persist naturally because
as a variety they lack means of passing from one host to another. It follows, if
evolution is by mutation, then only the simultaneous mutation of thousands of
vaccinia or other microbes could render them independent of artificial propagation.
On the other hand, if evolution proceeds by the selection of fluctuations, a passage
through a few weakly (e.g. non-resistant or starving) persons might create the
necessary virulence (see § 400). It must be borne in mind that it has been ex-
perimentally demonstrated that microbes gain in virulence only slowly after the
passage of many generations, and unless greatly injured, as by heat, lose their
virulence as slowly.

268 EPIDEMIC AND ENDEMIC DISEASE

442. Somewhat better than mere guessing is the assumption
that mankind, under the influence of constant persecution, has
gradually grown more resistant, not only to particular diseases, but
to microbic infection in general. Owing to the increase of popu-
lation, and to the crowded, insanitary, wretched conditions under
which many communities live, the facilities for the evolution of
parasitic types are now greater than ever they were. Yet, though
we have the whole world under survey, we never hear of a new
disease. The so-called new diseases are merely maladies newly
observed in their ancient habitats, or complaints which have
invaded fresh territories. Presumably, therefore, the alteration of
saprophytes into parasites (i.e. the evolution of a new disease) is
now a more difficult and unlikely occurrence than it was anciently.
This conjecture (that mankind has evolved against microbic infec-
tion in general as well as against particular diseases) is confirmed
by the fact that children, who recapitulate the life-history, are, as
a rule, less resistant to microbic disease than adults, even when the
disease is one of which the race has had little or no experience.
For example, English children succumb much more readily than
older persons of their own race to malaria and dysentery. It
must be remembered, however, that since variations occur during
all stages of development, the race evolves in the stage of develop-
ment reached by the child as well as in the adult stage. On this
account African and Indian children succumb much less readily
to malaria and dysentery than English children, though more
readily than adults of their own race.1

443. On the other hand, we have no certain evidence that any
disease has ever completely died out. The chances are all against
such occurrences in the past. When once established as parasites,
the microbes, owing to the continual growth of human populations,
found a constantly augmented food-supply as well as increased
opportunities of reaching fresh fields of conquest. Sanitary
science is still in its infancy, and as yet has accomplished compara-
tively little. Under skilled direction it has done something towards
diminishing earth-, water-, and insect-borne diseases. Tuberculosis,
enteric and yellow fever, and malaria have diminished somewhat
in a few parts of the world. Leprosy has disappeared from some
countries. But air-borne diseases, which are propagated through
a medium the flow of which is too swift and the volume too vast
for control, are as common as ever. Almost every child acquires
measles, whooping-cough, chicken-pox, mumps, common cold,

1 See § 417.

THE ANTIQUITY OF DISEASES 269

bronchitis, and, in its modified form, smallpox. All are more or
less exposed to scarlet fever, diphtheria, pneumonia, and influenza.

444. We have historical evidence of the antiquity of many
diseases. Leprosy is mentioned in the Book of Exodus as pre-
valent in Egypt. By other accounts it was prevalent in India,
China, and Japan about the same time. Contagious diseases (e.g.
syphilis) were well known to the Greek and Roman writers.1 We
have few accounts of them from the Middle Ages, when physicians
regarded their treatment as degrading to professional dignity ; but
at the Renaissance the ' great pox ' was a terrible scourge. " A
pox on you " was a common Elizabethan malediction. " Consump-
tion of the lungs may be traced with certainty in the writings of
every period as far back as the earliest attempts of the ancient
world to deal with medicine according to a method."2 Granting
that diseases had not multiple origins, their wide prevalence in the
ancient world, when communities dwelt in far greater isolation
than at present, argues extreme antiquity.

445. It seems probable that both man and his diseases arose
in the Eastern Hemisphere, where " behind dim empires ghosts of
dimmer empires loom." Still more ancient than the oldest
empires are the traces of the early agriculturists, who in turn were
preceded by the hunters and cave-men of the long Stone Ages.
Amongst savages of the lowest types the problem of the food-
supply is always acute. Population, as till lately amongst the
natives of Australia, tends always to exceed the available supply
and is limited by recurrent famine. Man is naturally a gregarious
animal, delighting in large communities, but the difficulty of pro-
curing sufficient food forces a race of hunters, not only to scatter,
but to assert rights of ownership over large areas of country,
intrusion into which by strangers is strongly resented. Hence
tribal jealousy, perpetual warfare, and frequently an isolation so
profound and stringent that the inhabitants of near valleys may be
of distinct types and speak a language unintelligible to their
neighbours. Civilization implies a dense and settled community,
which in turn implies a more abundant and secure supply of food,
and that, again, implies comparative peace, combined with regular
communications over great areas of land and even of water, where-
by the deficiencies of one part are supplied from the super-

1 Hirsch's Handbook of Geographical and Historical Pathology, vol. ii. p. 2
(New Sydenham Society). The notion is general that the venereal diseases were
imported from America, but this would appear to be an error.

2 Op. cit., vol. iii. p. 170.

2;o EPIDEMIC AND ENDEMIC DISEASE

abundance of others. Our many and vast English cities are
possible only because our peace is more profound and our means
of communication more perfect than ever before in the history of
man. On our tables may be found fruit and spices from the
tropics, wheat from Canada, Australia, and Russia, mutton from
New Zealand, beef from the Argentine, rice from India and China,
bacon from the United States, and fish from half the world.
To-day we may eat cheese or drink wine that has been stored for
years. So widely do we travel that there is on earth scarcely a
distinct language but some Englishman is able to express himself
in it.

446. The pressure of population, therefore, is usually greatest
amongst the lowest types of mankind, and this results, not in
intercommunication, but in isolation ; in wars the object of which
is extermination not subjugation ; in a search for food, not for
slaves, whom a stone or pointed stick would arm as well as their
masters. Doubtless it was during this time of great pressure and
desperate struggle that man, spreading slowly from a common
centre, populated the Eastern and ultimately the Western
Hemisphere.

447. The era of the early hunters, who subsisted solely on
wild animals and vegetables, was followed by that of the primitive
shepherds and husbandmen, who made provision, not only for the
immediate present by hunting, but for the future by labour. The
supply of food became more abundant and secure. Property in
land tended to become personal instead of tribal. Men began to
gather for mutual protection into communities, which differed
from one another in their stored productions. Barter, and there-
fore intercommunication, become more general and widespread.
Since the labour of a man now produced more food than sufficed
for his own existence, warfare underwent gradual change. The
conquerors sought slaves and tributaries rather than mere elbow-
room. They subjugated rather than exterminated their enemies.
Population increased immensely, and with it the microbes of
disease, which, spreading'.from their centre of origin, ranged to and
fro with travellers and raiders.

448. The microbes of contagious diseases pass directly from
one individual to another. The living body furnishes their entire
environment, and, therefore, they are able to exist in all climates
and under all conditions. The long duration in the individual of
syphilis, the chief of them, makes itespecially capable of infecting and
maintaining its hold on new communities. But the method by which

THE MIGRATIONS OF MALARIA 271

contagious maladies pass from one individual to another renders
their diffusion through a population comparatively slow. They
are endemic from the first. They rarely cause great epidemics ;
but, once established, are never again absent from their new habitat.

449. The microbes of all other diseases alternate between the
human body and the world outside, in which, on the way to fresh
'hosts,' they pass a longer or a shorter time. They are depen-
dent, therefore, to a greater or lesser extent on this outer environ-
ment. The insect-borne maladies are found only in localities
where the insect host is able to maintain existence. Malaria was
once common in England, but the conditions became unfavourable
to the mosquito, and the disease disappeared. Though many
infected people from the tropics land on our shores, it cannot re-
establish itself. In historic times it is said to have invaded
Greece and Italy, and by some medical writers is supposed to
have contributed to the downfall of the classic empires. In more
modern times it invaded Mauritius. The fact that before the
historical era malaria had spread to most parts of the globe where
its intermediate host, the Anopheles mosquito, is capable of per-
sisting, is evidence of its vast antiquity. Of all the host of
maladies which now infest the Western Hemisphere it is apparently
the only one of any importance which was not introduced by
Columbus and his successors. Possibly it is the most ancient of
all human diseases. The path by which it journeyed to America
is quite unknown. Under present conditions of climate it can
hardly have travelled by the Arctic circle. Before the era of
European discovery man had crossed the Pacific, all the large
islands of which are thickly populated. But, except near
Asia, malaria is unknown in them. The difficulties of crossing the
practically uubroken expanse of the Atlantic are obvious. The
antiquity of the disease is evidently so great that the surmise that
it may have reached America during a warm inter-glacial period is
perhaps not altogether extravagant.

450. Plague, sleeping sickness, and yellow fever are other very
important insect-borne maladies. Plague is a disease of rats, the
intermediate host being a species of flea which is parasitic on these
animals, but which will on occasion attack human beings. During
an epidemic the rats tend to be exterminated and the disease to
die out. It is endemic in India, but several great pandemics in
which it spread widely are recorded in history. It was known in
Europe before the Christian era.1 In the sixth century after

1 Hirsch, vol. i. p. 494.

272 EPIDEMIC AND ENDEMIC DISEASE

Christ it " spread over the whole Roman Empire of the East and
West and even far beyond the limits of the empire ; . . . and
wrought the most frightful devastation wherever it appeared ; . . .
it depopulated towns, turned the country into a desert, and made
the habitations of men to become the haunts of wild beasts."1
Another great pandemic, " known everywhere under the name of
the Black Death as one of the great events in the world's history,"
" reached over the whole of the known world " and destroyed a
third or a quarter of the inhabitants of Europe. The Great Plague
of London furnishes an additional example.

451. Yellow fever, like malaria, has the mosquito for its inter-
mediate host. Its original habitat appears to have been the West
Coast of Africa, but it is now endemic in the tropical parts of
Eastern America. Till very recently sleeping sickness appears to
have been confined to the West Coast of Africa. It was often
carried by slaves to Brazil and the West Indies, where, however, in
the absence of its intermediate host the tsetse fly (Glossina
palpalis\ it did not spread. The infected slaves were supposed
to be suffering from nostalgia or home-sickness.2 Owing to the
improvements of communications consequent on European con-
quest, it has spread very widely and has now almost reached the
East Coast near Zanzibar, where it is likely to prove a scourge as
terrible as it is already in Uganda. Doubtless the tsetse fly
preceded the disease in Central Africa, but did no great harm till
infected human beings arrived. The insect-borne diseases are the
only complaints which, on the whole, afflict sparse populations
more than they do denser communities of men.

452. Air-borne maladies are immensely infective but of short
duration in the individual. After a brief illness the sufferer dies or
acquires an immunity which may or may not be permanent. Con-
sequently, in small and isolated communities, they can occur only
in epidemic form, at any rate when the immunity they confer is at
all lasting. Owing to the large number of susceptible persons,
such a disease, when it reaches a new country, spreads like fire.
If it has long been absent, it strikes down the whole population.
So many are infected, so abundant do the microbes become, that
no one escapes the chance of infection. As a consequence, the
food-supply of the microbes is swiftly exhausted, and the malady
disappears till re-introduced from foreign sources. On the other

1 Hirsch, vol. i. pp. 495-6.

* The Kingdom of Man, by Sir E. Ray Lankester, p. 159 (London : Constable
& Co., 1907).

EPIDEMIC AND ENDEMIC DISEASE 273

hand, when a community is large, and especially when it enjoys
constant intercourse with other considerable centres of population,
air-borne disease prevails in endemic form, mild exacerbations of
which are termed epidemics. Nearly every one suffers during
youth. The non-resistant perish, the resistant acquire immunity.
New births supply materials sufficient to secure the persistence of
the disease, and provide for the so-called epidemics; but the
microbes never become so abundant as when they invade a new
country and infect the whole population. Therefore children may
not be infected until several years after birth.

453. Disease, when endemic, is far less terrible than when
epidemic. In the former case the sick are tended, the treatment
is understood, and the business of the community is not impeded.
In the latter, so great may be the number of adult sufferers
that the sick receive scant attention, and so considerable the dis-
location of business that famine may follow. Disease, when
endemic, does the work of selection much more 'cleanly' and
thoroughly than when epidemic. Practically every non-resistant
person is eliminated, but few people perish from neglect or starva-
tion. Epidemic disease, on the other hand, causes the death of
numbers of people whose powers of resistance are considerable,
while it spares during its intervals of absence many others whose
resisting powers are low. It selects in a much less discriminating
fashion.1

454. Formerly smallpox was endemic in Europe in the same
way as measles is to-day. At present vaccinia is endemic. The
disappearance of smallpox coincided with the prevalence of
vaccinia. A considerable portion of the community, including
some men distinguished in science or of great intellectual activity,
insist that the two events had no causal connection, and therefore
that vaccinia is not a preventive of smallpox. But, if they are
right, it is difficult to conceive what can have banished the latter.
It cannot have been sanitation, for smallpox is an air-borne

1 We noted that sanitary science has absolutely no control over air-borne
disease. In England it is customary to close the schools during an epidemic of
measles, chicken-pox, mumps, or whooping-cough. It is a question whether
" the game is worth the candle," at any rate as a preventive measure. Speaking
practically, every susceptible child — and innately unsusceptible children are
rare — is sure to acquire the disease sooner or later. The danger from chicken-
pox and mumps is negligible. Measles and whooping-cough are more dangerous
to infants than to older people, but not appreciably more dangerous to school
children than to adults. If these diseases are inevitable, it is perhaps better that
they should be done with early in life, when time is less valuable and the incon-
venience not so great as later.
18

274 EPIDEMIC AND ENDEMIC DISEASE

disease, and no other disease of this kind has been so affected. It
cannot have been isolation, for, if vaccinia is no protection, almost
the whole community is susceptible, and doctors and nurses should
contract and spread the disease. Isolation is possible only when
susceptible individuals are comparatively rare. It has been denied,
even, that there is such a thing as acquired immunity against any
disease. But the fact that the microbes of acute disease, which at
first swarm in an infected person, disappear within a definite time,
so that the sufferer no longer conveys infection after recovery, is
decisive proof. The fact that a vaccinated person cannot be made
to contract vaccinia again soon after recovery is proof that it con-
fers immunity against itself. The fact that he can be successfully
vaccinated after an interval of years is proof that the immunity is
not perpetual. The fact that smallpox, if experimentally trans-
ferred to the calf, becomes cow-pox, and if transferred back to man
becomes vaccinia, is proof that the latter is a modified form of
smallpox. The fact that recently vaccinated persons are able,
with almost complete safety, to nurse people ill of smallpox,
whereas unvaccinated persons are almost sure to contract the
disease, is proof that experience of the attenuated malady affords
protection from the more virulent type. The fact that in England
most people who contract smallpox have been vaccinated, but not
recently, is proof that the protection afforded by vaccinia is only
transient — so transient, owing to the mildness of the disease, as to
be midway between ' acute ' and * passive ' immunity. Probably
the agitation against vaccination would never have arisen in this
country had the power of conferring permanent immunity from
smallpox not been claimed for vaccinia by the medical men of
a past generation. Reaction followed the discovery that most
sufferers from smallpox had undergone vaccination. The public
learns very slowly, but forgets no faster.

455. Water-borne diseases are almost as infective as the air-
borne type. They prevail as epidemics more rarely in isolated
communities, but as such are not uncommon in densely populated
centres. The microbes are very dependent on the environment
outside the body of the host, therefore they are less able to
travel than air-borne species, and seasonable changes may for
a time purify the water-supply, even where they are most
prevalent.

456. Earth-borne diseases, of which the only one that greatly
affects human beings is tuberculosis, are always endemic. Direct
sunlight is fatal to the microbes of tuberculosis. In effect, it can-

THE DISEASES OF THE LOWER ANIMALS 275

not be contracted in the open air. Its microbes are found especi-
ally in such dark, ill-ventilated, and crowded dwellings as are
built by the civilized inhabitants of cold and temperate regions.
More especially it affects the larger towns and cities, and yet
more the slums of these. Beyond all other complaints it is the
disease of civilization. As in the case of syphilis, its long
duration confers considerable powers of journeying to distant
lands.

457. For all we know or can surmise to the contrary, distinctively
human contagious and insect-borne maladies may have prevailed
during the early Stone Age. Air-borne maladies can hardly have
come into being till large continental tracts had been relatively
densely peopled by hunters and nomads. The advent of water- and
earth-borne diseases must have occurred later. Their existence
implies large and settled populations. In the one case the water-
supply, and in the other stationary dwellings must have been
constantly used and infected. Probably, of all animals, human
beings suffer most, or at least from the greatest number of microbic
diseases. More than any other animal, man now dwells in large
and settled communities, between which there is constant inter-
course. Many insect-borne diseases of the lower animals, however,
are known to be endemic in certain regions, as for example the
Texas fever of cattle, which is carried by ticks, and the fly-disease
in South Africa, which is borne by the tsetse fly. Races long
afflicted by them tend to evolve resisting power, whilst, as in the
case of man, immigrants suffer severely. Air-borne diseases, such
as are perhaps the rabbit plague of Canada and rinderpest which
lately more than decimated the herbivora of Africa, are the causes
of the great murrains or pestilences which tend to appear whenever
animal populations become dense. The distemper of dogs appears
to have become endemic amongst the large and settled canine
population supported by man, but amongst wild animals air-borne
diseases appear always to be epidemic. Earth-borne diseases occur
especially amongst browsing animals, which acquire them through
herbage that has been tainted by infected individuals. Probably
the disease which destroys hive - bees is earth - borne. Since
recovery within definite time from microbic diseases implies
immunity, and since the vast destruction of life greatly diminishes
the available supply of nutriment for the microbes, epidemics
amongst lower animals are usually very transient. Probably the
starting-point of every great pandemic of earth-borne disease is
some area where the animal hosts, having undergone evolution, are

2;6 EPIDEMIC AND ENDEMIC DISEASE

numerous but resistant, and where, therefore, the disease is endemic.
Rinderpest is said always to start from Southern or Central Asia.1

458. In histories and poems dealing with recent times, and in
the works of modern philosophers or people who attempt to found
new religious sects, we rarely meet any mention of endemic diseases.
These are accepted as part of the normal environment, and claim
allusion only when some prominent person dies of a ' decline '
(consumption) or the like. But should a great pestilence occur, it
is eagerly noted, described, and made the basis of endless disserta-
tions and exhortations. Yet among modern civilised people
endemic disease claims by far the greater number of victims. So
also ancient records, which were written not for us but for the
contemporaries of the writers, tell as little of the endemic diseases
prevalent at the time as they do of the everyday life of the people,
but much of such great and striking disasters as epidemics and
wars. We may be sure, however, that some endemic diseases, for
example leprosy, the contagious maladies, and malaria, did exist
very anciently.

459. A notable contrast between ancient and modern times is
furnished by the fact that pestilence (i.e. epidemic disease) was

1 The microbic or other diseases of plants and lower animals, considered from
the standpoint of the student of evolution, constitute a vast subject of great
intellectual fascination and practical importance, which, it is to be hoped, some
worker with more time and knowledge than I am able to claim will investigate.
Like me, he will find his materials scattered through books of travel, histories,
and technical works, but will have to surmount even greater difficulties than I
have encountered in my very imperfect and fragmentary study of human disease.
Many profitable industries have been ruined or are being checked in various
parts of the world by plant or animal disease. Thus Phylloxera vastatrix (a species
of Aphides) caused great damage to the vines of France, and coffee-growing had
to be abandoned in Ceylon. Pig and poultry farming on a large scale are un-
profitable, because as surely as many animals are gathered in one place they are
swept by epidemic disease. Wild animals are delicate in captivity, mainly because
they perish of microbic diseases against which domesticated animals have under-
gone some evolution. The difficulties of the farmer illustrate very vividly the
dangers which beset the human race in its earliest struggles towards settlement
and civilization. Human selective breeding is at present outside the range
of practical politics. Selective plant and animal breeding is practised all the world
over ; but I am not aware that plants and animals, especially animals, have ever
been bred to any considerable extent with the view of increasing their powers of
resisting disease. Some horses and cattle, for example, are able to acquire im-
munity to the fly disease of Africa. Artificial selection achieves results much more
rapidly than Natural Selection. It should not be difficult to establish a resistant
race by continued breeding from animals that had shown themselves capable of
recovery from infection. Since plants are almost incapable of making use-
acquirements, and since their diseases are usually caused by muticellular organisms,
only ' inborn ' immunity could be evolved amongst them.

ANCIENT EPIDEMICS 277

formerly much more common and severe. The Great Plague of
1666 was the last very destructive epidemic in England, but it was
not nearly so destructive as the Black Death, which occurred some
centuries previously. Both these pestilences had spread from
regions in the East, where they were endemic, where the inhabitants
were so resistant that the victims were comparatively few, and
where they caused no more comment in histories, poems, and ex-
hortations than malaria in Africa or tuberculosis in England. As
has always been customary, preachers in Europe attributed them to
the anger of the Deity, and called the peoples to repentance for
sins committed against this or that religion, and to a more
strenuous support of this or that sect. Similarly, while no great
epidemic of our domestic diseases is recorded in history, they have
occasioned some terrible pestilences amongst peoples to whom they
were previously unknown, to whom we conveyed them, and by whom
they were regarded as evidence of divine or diabolical anger.

460. The inference is irresistible that historians are mistaken
when they attribute ancient epidemics to diseases which, owing to
war, bad sanitation, or similar causes, came suddenly into being,
but have since died out of the world. In each case in which the
accounts are sufficiently ample and clear, every ancient pest may
be identified with an air, water, or insect-borne malady now, as then,,
endemic in some part of the world, whence it has spread periodically
whenever the conditions, such as a hot, dry summer and much inter-
course between neighbouring nations, have become favourable.
Bad sanitation tends, of course, to render a strange water- or insect-
borne disease epidemic when once it has arrived, but, other things
equal, it tends also to perpetuate it afterwards in the endemic
form. Yet, though sanitation did not noticeably improve, the Black
Death, the Great Plague, and other exotic diseases retreated to
their normal habitats in India or farther east. Both the former
were evidently the same bubonic plague which is now ravaging
India. They " spent their force," they disappeared from Europe
because they were epidemic — because the disease became so pre-
valent that it exhausted its nutrient supply of susceptible rats or
human beings so effectually that it could not persist. Very
modern sanitation has rendered its return to Europe difficult.
Rats are less numerous. Probably all our earth- and air-borne
diseases, which are much better able to travel than insect and
water-borne complaints and therefore sooner become permanently
established, were endemic amongst our ancestors before the dawn
of established history. But from remote periods, from myth and

278 EPIDEMIC AND ENDEMIC DISEASE

legend, we seem to gleam dim accounts of air-borne pestilences.
Thus the disaster which befell the Assyrian host before Jerusalem
and that which afflicted the Greeks before Troy had that appalling
suddenness which characterizes an air-borne epidemic occurring in
a population entirely susceptible.

461. To sum up, human microbic diseases seem to have origi-
nated in the Eastern Hemisphere, which has long been thickly
populated, each disease from a single centre, whence it spread —
facts which appear to be confirmed by the apparently total lack of
all microbic diseases, except malaria, in the various parts of the
West before the invasion by Europeans and their subsequent
establishment there. Earth-borne and contagious diseases must
have been endemic from their origins, as also must have been some
insect-borne maladies. Doubtless water-borne diseases early
became endemic wherever the conditions, including a dense and
settled human population, were favourable. Air-borne disease was
probably epidemic at first, passing with great rapidity and fear-
ful results from one region to another, but gradually became
endemic in all thickly populated localities that were in frequent
communication with surrounding areas. There can be no doubt
that all our familiar maladies were rife in Europe at the time when
Columbus set out on his fateful voyage, and initiated the greatest
tragedy, the most tremendous event in human history.

462. On the one side of the Atlantic were peoples who for
thousands or tens of thousands of years had been slowly evolving
resisting power against a multitude of maladies — peoples whose
increase had been very slow, largely because of the numbers of the
unfit that had perished from disease, maladies that had gradually
passed from the epidemic form in which the selection of their
victims was haphazard and imperfect, to the endemic form, when
selection was more thorough and clean. These Eastern peoples
now dwelt under conditions that would have been fatal to their
remote ancestors. Their civilization, with its dense communities
and constant communication between distant parts, was absolutely
conditioned by their power to resist many diseases. Their houses,
especially in their great cities, were dark, ill-ventilated, and
crowded both with men and microbes. Their clothes, which their
climate necessitated and custom and religion ordained even in
warmer regions, were vehicles almost ideally adapted for the con-
veyance of disease. On the other side of the Atlantic were peoples
who had undergone no evolution against any zymotic malady except
malaria, and against the latter only in the wooded tropical parts.

DISEASE IN THE NEW WORLD 279

To them came Eastern civilization, not by slow degrees, as it had
dawned on the inhabitants of the Old World, but suddenly, and,
in its consequences, fearfully. The aborigines could not in a few
generations achieve an evolution which the Europeans had accom-
plished only during the lapse of thousands of years and at a cost of
millions of lives.

463. At once the very ancient conditions of the Old World
were reproduced. Air- and water-borne diseases began to sweep in
great waves of pestilence over the whole vast regions of the West.
The entire population was susceptible ; and, therefore, almost
every individual was stricken down. Each disease took its toll of
victims, and then, its nutritive supply exhausted, passed, but only
to return after intervals of years in the same epidemic form.
Towns and cities of the European type, foci of endemic disease,
arose on the seaboard, extended into the interior, and provided
the starting-point of fresh epidemics. Measles, cholera, and
especially smallpox, penetrated into remote prairies and forests,
and piled the earth with the dead. Since the invasion by
Europeans was rapid, and the aborigines had achieved no ante-
cedent evolution, the epidemics were more frequent than anciently
in the Eastern Hemisphere, and more deadly in their effects.
Whole tribes and nations were exterminated.1

464. The part played by tuberculosis, though less striking and
obvious, and therefore less noticed by historians, was even greater.
Prevailing mainly in the North and South, in the neighbourhood
of European settlements and missionary establishments, it spread
with their extension into the interior and swept the land quite
bare of its native inhabitants. It completed the destruction, begun
by air- and water-borne diseases, of the natives even of the tropical
West Indian Islands and parts of the adjacent mainland, especially
in the neighbourhood of mines, in which aborigines were forced to
labour and where the malady prevailed to a terrible extent. But
in the mainland of tropical America, where the great forests were
defended by malaria which prevented white settlement, and by
heat which necessitated the building of airy dwellings, it did com-
paratively little harm. Moreover, the whites intermarried with the
aborigines, and the mixed race which resulted, inheriting in half
measure powers of resisting both malaria and tuberculosis, seems,
as in Mexico, destined to survive. In North America and in the
open pampas about the river Plate, the work of extermination was
more thorough. Many unions occurred between the whites and

1 Hirsch, vol. i. p. 136.

280 EPIDEMIC AND ENDEMIC DISEASE

the aborigines. But except on the distant frontiers the native
women perished or were sterile through ill-health, and even the
half-caste children could not survive under the conditions that
were created.1 The natives melted away, and now are found almost
solely in remote and thinly populated wilds, where a nomadic life
affords some protection. The white colonization of Australasia
is having similar results. In Polynesia, as soon as the trader
brings his clothes and the missionary insists on his converts wear-
ing them and attending crowded churches and schools, the work of
extermination begins.

465. In Asia and Africa, where Europeans have made many
conquests and native wars have been as many and as bloody
as in the West, every European settlement has a flourishing
native suburb. But throughout America and Australasia no con-
siderable European town has a native quarter. This one fact
brings into startling prominence the difference between the in-
habitants of the East and West. The latter were able to
found settled communities and even cities before the advent of
tuberculosis. Since its arrival even nomadic life is hardly possible
to them.

466. Writing of the Spanish occupation of the West Indies, the
historian Froude declares, " The Carib races whom the Spaniards
found in Cuba and St Domingo had withered before them as if
struck by a blight. Many died under the lash of the Spanish over-
seers. Many, perhaps the most, from the mysterious causes which
have made the presence of civilization so fatal to the Red Indians,
the Australians, and Maoris. It is with man as it is with animals.
The races that consent to be domesticated, prosper and multiply ;
those that cannot live without freedom, pine like caged eagles, or
disappear like the buffaloes of the. prairies. Anyway, the natives
perished out of the islands of the Caribbean Sea with a rapidity

1 The fact that half-castes abound in tropical America but are comparatively
rare in the North has an interesting bearing on the Mendelian hypothesis. It
has been surmised that the inheritance of susceptibility and resisting power to
disease is alternative. But if that were true, and if the independent inheritance
of characters be also a fact, half-castes should abound in the North as much as
in the South, and be as capable of dwelling in tubercle-infested cities as Europeans-
A proportion, while displaying a Mendelian mixture of Indian and European
characteristics, should inherit fully the powers of resisting consumption possessed
by their white ancestors. Obviously, since they persist in the tropics, where
selection by tuberculosis is less stringent, but perish in the temperate regions,
where it is more severe, the ' inheritance ' of resisting power is blended, not
alternative ; wherein it accords with all other human racial traits except eye
colour.

CAUSES OF DEATH 281

which startled the conquerors. The famous Bishop Las Casas
pitied and tried to save the remnant that was left. The Spanish
settlers required labourers for the plantations. On the continent
of Africa were another race, savage in their natural state, which
would domesticate like sheep and oxen, and learnt and improved
in the white man's company."

467. These sentences are typical of much that has been written
concerning the decay of the New World races. Almost all writers
unite in speaking of it as mysterious, and yet the facts are patent
to all observers on the spot. There is no more mystery connected
with their decay than with the extinction of the dodo and the
bison. It cannot be doubted that the races of the New World
have suffered or are suffering extinction in consequence of
the introduction amongst them of Old World microbic diseases,
and because of one other cause, also an importation, of which
more hereafter.1

468. Like the imported African slaves that suffered from
sleeping sickness, and perhaps also Swiss mountaineers who are
said to die of nostalgia, but probably fall victims to microbic
disease, they perish of physical, not mental decline. Their in-
capacity to achieve European civilization is mainly corporal, not
psychical. That much is quite beyond dispute and may be verified
by reference to the reports of all the Departments of Public Health
in America, Australasia, and Polynesia. These show quite deci-
sively that the proportionate mortality of the natives is very high,
that they perish on the average at an exceptionally early age, and
that the causes of their deaths are our imported diseases. Their
families are abnormally small ; but we need not, as so many
writers have done, seek a mystical explanation. Presumably, in
the New World as in the Old, amongst natives as amongst
Europeans, ill-health is one of the causes of sterility.

469. Anciently the inhabitants of conquered territories were
put to the sword, and thus were never again a menace to the
invaders. In this manner the Jews established themselves in
Palestine, and, apparently, the Saxons in England. Zengis Khan
is said to have destroyed eighteen millions of people in China
alone. Red Indians and Maoris sought to exterminate their
enemies, as do African and Polynesian savages at the present day.
Civilized peoples fight to conquer, not to destroy. Rome extended
her sway over many lands, the inhabitants of which prospered and
multiplied under her rule. Similarly, the Normans in England and

1 See chapters xv. and xvi.

282 EPIDEMIC AND ENDEMIC DISEASE

the English in Wales merely administered the conquered territory.
England and Russia govern empires vaster than the Roman,
and, so far from making any conscious effort to root out
the subject races, endeavour to render them peaceful and
prosperous.

470. But if history teaches anything with plainness, it is the
lesson that conquest, to be permanent, must be accompanied by
the extermination of the natives ; otherwise, in the fullness of
time, the conquered expel or absorb the conquerors. The Greeks
and Romans were expelled from their acquisitions. The Normans
were absorbed. The Moors have left scarcely a trace in Spain.
The Irish continually threaten the expulsion of the English, to
whom the Welsh are united on equal terms. In parts of South
America pure Spaniards have nearly disappeared. It is folly to
suppose the European possessions in Asia and tropical Africa
have any element of permanency. The local endemic diseases
fight for the natives, who yearly grow more numerous, intelligent,
and insistent in their demands for self-government. Presently the
Europeans, like the Romans, will be expelled. South Africa is
not effectually defended by diseases strange to Europeans ; but
they have imported none which the natives are unable to resist.
Therefore at the Cape and in the north of the Continent,
Europeans are threatened with absorption ; or if, as is very
unlikely, the two races remain for ever distinct, with subjuga-
tion. History affords no example of a race maintaining perpetual
supremacy over a more numerous subject people.

471. But in the Western Hemisphere conquest has usually
been followed by extermination. Disease has wrought more
widely and not less fatally than the sword. The races of nearly
half the world are becoming extinct, and are being replaced by
races from the other half, and in this great cataclysm our own
people has played a predominant part. The Spaniards and the
Portuguese, powerful maritime nations in the fifteenth and six-
teenth centuries, had the first start in the race and chose the
seemingly richer tropics. But, checked by malaria, European
emigration soon dwindled. Possibly there are now fewer individuals
of pure European descent in tropical America than there were
three hundred years ago. But the Britons, who colonized North
America and at a later date Australasia, multiplied enormously,
and the stream of new colonists, so far from dwindling, ultimately
gathered volume, till now by far the larger part of our race resides
abroad. Owing solely to the vast void created by disease, a people

MICROBES AS EMPIRE BUILDERS 283

who, four centuries ago, numbered no more than the present inhabi-
tants of Greater London, has increased nearly fifty-fold. The
greatest world-force to-day, it seems certain to maintain its
position, for the sword as a means of founding permanent empires
went out of date with the coming of civilization, and the regions
that disease can lay waste are all occupied, not by mere conquerors,
but by colonists rooted in the soil and resistant to every disease
that is likely to afflict them. No other race in the world has such
room for growth and expansion as the Anglo-Saxon.

CHAPTER XV
ALCOHOL

The essential constituents of alcoholic beverages — The reasons why men
drink — The types of men that drink for thirst, taste, and the cerebral effects —
The question as to whether alcohol is beneficial or harmless — The mental effects
produced by alcohol — Normally no man drinks except for the pleasure that
drinking affords — Inheritance and acquirement in relation to alcohol — The hypo-
thesis that men drink in proportion as they do, or do not, exercise self-control —
The causes that determine the extent of indulgence — The inheritance of sus-
ceptibility to the charm of alcohol — Individuals differ as regards susceptibility —
Selection in relation to alcohol.

W1

472. "^"^ 7"E see, then, that disease is the only factor, at any
rate the only clearly recognized factor, of selective
elimination sufficiently stringent amongst civilized
men to be a cause of progressive evolution. The racial changes
resulting from it have rendered many peoples of the Old World so
resistant to the endemic diseases of their own countries that they
are now able to dwell in large and settled communities and so
achieve civilization. On the other hand, civilization, with its dense
populations and constant intercourse with distant peoples, has
conveyed to and rendered prevalent in every country the diseases
to which the environment is suitable. The races to which civiliza-
tion with its endemic diseases came so slowly that the birth-rate
tended to exceed the death-rate, are adapting themselves to the
new conditions. The rest have become extinct or are drifting
towards extinction.

473. But parasitic micro-organisms are not the only causes of
selective disease amongst civilized men. Certain narcotics, of
which the principal are alcohol and opium, are causes of disease,
disablement, and death, as stringently selective and as widespread
as any parasitic species. Unfortunately, we now enter a region
of discussion which has ever been a playground of passion and
prejudice, born, on the one hand, of self-interest, and, on the other}
of a fanaticism as unreasoning as any that has been displayed in
religious controversy. Here the disputants have belonged mainly
to classes peculiarly unfitted for the calm discussion of what are

ALCOHOLIC BEVERAGES 285

really abstruse problems in heredity and psychology. No state-
ment has been too obviously absurd for acceptance or too obviously
true for rejection by the one side or the other. Nevertheless, in
dealing with alcohol we possess one great advantage : most people
are able to appeal not only to the observations of others, but to
their own sensations. If the reader has anything like an average
knowledge of life, he will possess ample materials drawn from his
personal experience on which to found a judgment. In science
independent thought, founded if possible on first-hand knowledge,
is not only a right but a duty. Applying the broad principles of
heredity already laid down, I shall set forth conclusions which
conflict with popular beliefs, but which, I think, the reader will find
not altogether unreasonable.

474. The essential constituents of every alcoholic beverage in
common use are alcohol, certain flavouring agents, and water.
These three constituents attract three separate classes of drinkers ;
or, at any rate, they supply separate and unlike motives for drink-
ing, one or other of which predominates in every drinker. Water
is an essential part of our bodies. When the quantity within us
becomes deficient, we crave to renew it, and this instinctive crav-
ing we term thirst. Many men drink alcohol only when they are
thirsty. The thing primarily desired by them is water. Alcohol
is added, as lime-juice might be, merely as a flavouring agent, as
something which renders the necessary draught of water more pleas-
ing. Drinkers of this sort usually prefer the lighter beverages,
such as beer and wines, which contain a considerable proportion of
water. Other men drink alcohol mainly to gratify the sense of
taste — to produce pleasant sensations by stimulating certain nerve-
endings in the mouth. The average connoisseur is a typical
example. He drinks for precisely the same reason as a child
consumes sweets, and he always chooses the beverages most
palatable to him. The third class of drinkers comprises people
who desire to experience the various sensations which result from
alcohol circulating in the blood and acting directly on the central
nervous system, the brain — sensations of well-being, of exhilaration,
of confidence, of general happiness, of comfort, of cheerfulness, of
restfulness, of somnolence, and so forth, which in different drinkers
mark different stages of intoxication. A drinker of this sort,
especially if his desires are very strong and he is unable to procure
anything more palatable, may drink thirst-creating and nauseous
compounds such as methylated spirits.

475. Of course the three primary constituents of alcoholic

286 ALCOHOL

beverages, the three sets of sensations to which they give rise, may
all attract a given drinker at one and the same time ; or a man
may drink at first to satisfy his thirst or his palate, and later for
the sake of the feelings which accompany intoxication ; or in the
beginning of his career as a drinker he may be influenced mainly
by one or other of the former motives, but later in life mainly by
the last. Nevertheless, the fact remains that the three main con-
stituents are distinct, the desires they gratify are utterly distinct,
and that, while some drinkers are influenced solely by one of these
desires, all drinkers are influenced at any given moment more by
one of them than by the others. The heated cyclist or cricketer,
who gulps a quart of light beer and is satisfied, evidently seeks
sensations which are not the same as those desired by the con-
noisseur toying with his choice wine, smelling, sipping, rolling it in
his mouth so as to get all the enjoyment possible from its taste
and aroma ; nor the same as those sought by the man who desires
a 'stimulant' or 'night-cap/ or who with deeper longing craves
intoxication, and drinks perhaps with a shudder some strong and
it may be distasteful spirit which increases his thirst.

476. Thirst and taste are not, by themselves, causes of excessive
indulgence. Both are satisfied by a very moderate degree of
indulgence ; and the experienced drinker, who knows what sensa-
tions to expect from various amounts of the beverage he is imbibing,
soon learns the quantity which will afford him the greatest gratifica-
tion. Both thirst and taste are incentives to instinctive actions.
The former impels to the drinking of dilute beverages, and ceases as
soon as sufficient water is imbibed ; while the palate is cloyed by
a few glasses even of the choicest wine, just as it would be by the
best of sweets. Excessive drinkers are drawn solely from the class
that seeks the sensations produced by alcohol when acting directly
on the brain. Of course, however, not every drinker who belongs
to this latter class takes alcohol in excess. Many, if not most, in
England at least, take no more than they would if impelled by
thirst or taste.

477. It is a moot point whether alcohol in small quantities —
the quantities that are drunk by the ' moderate ' people we meet in
society, who are able to go about the occupations of life apparently
unaffected mentally — is injurious. Many people, including a
minority of medical men, declare that the smallest amounts
are harmful, and support their contention by an appeal to the
statistics of insurance companies, some of which place in different
classes total abstainers and moderate drinkers, and report that the

ALCOHOL AND DISEASE 287

former live, on the average, distinctly the longer. But all inebriates
are not paragons of candour. None who seek to insure their lives
will admit that they are other than moderate. Were they so
honest as to admit excessive drinking they would not court
inevitable rejection by presenting themselves for medical examina-
tion.1 There can be no doubt that many people who have insured
as moderate drinkers really indulge to excess. Probably most
medical examiners have experienced the humiliation of having
recommended to insurance companies individuals who declared they
were temperate and showed no signs that they were otherwise, but
who were subsequently discovered to be much the reverse. If we
accept the dictum that the smallest quantity of alcohol is injurious,
we must believe, contrary to the evidence of our senses, that whole
nations like the Italians suffer chronic ill-health. Some men are
much more resistant to alcohol, physically and mentally, than others.
I have known many excessive drinkers who- have survived till old
age. Others perish early in life. Doubtless the truth is that,
while large quantities of alcohol are injurious to all men, they
are less injurious to some men than to others ; and that, while
small quantities, such as are drunk by Italian peasants, are in-
jurious to some men, they are little, if at all, injurious to most men.

478. Probably no substance that is eaten or drunk produces
quite the same sensations in every one. One man prefers beef,
another mutton, a third pork ; one prefers apples, another oranges ;
one tea, another coffee ; one delights in tobacco, another derives no
pleasure from it. If their sensations were exactly alike, their
preferences would be the same. Identical quantities of alcohol
make some men cheerful, others maudlin, others morose, others
amiable, yet others pugnacious; some are stimulated to greater
activity, others are lulled to sleep. However, it is evident that
whatever his sensations, the habitual and excessive drinker finds
them pleasant, or he would not, in spite of heavy penalties, seek to
renew them periodically.

479. In one particular all excessive drinkers agree : they pay
for the pleasant sensations experienced when alcohol is circulating
in the blood by feelings, following its elimination from the body,
which are the reverse of pleasant — sensations of abnormal thirst,
headache, nausea, nervousness, wakefulness, irritability, terror,

1 One Canadian company which does business in this country demands from
its ' proposers ' a declaration of the number of times they have been drunk
during the past five years, and the date of the last occasion. If nothing else is
elicited, at least a maximum of lying is.

288 ALCOHOL

delirium, and the like, which indicate temporary or permanent
impairment of health. In some cases, especially with habitual
drinkers, these disagreeable sensations are temporarily alleviated
by further indulgence in alcohol, the drinker taking " a hair of
the dog that bit him." Doubtless the fact that drinking often
affords temporary relief from the after effects of previous indulgence
conduces to continued indulgence. Some writers seem to hold
a belief that it is the sole cause of all excessive drinking, at any
rate of all excessive drinking that is of importance. Obviously,
however, they are mistaken. A week's incarceration in prison, which
may remove every unpleasant sensation, will seldom cure a
habitual drinker. Sailors, who start on a long voyage in miserable
case but return perfectly cured, are as prone as any class to deep
indulgence. Years ago I lived in New Zealand with bushmen and
" gum diggers." Alcohol was not obtainable in the neighbourhood.
Some of my companions, men in splendid health and vigour,
dreamed, as of heavenly delights, of the week or fortnight of
furious drinking in which they were wont to dissipate the earnings
of months. Clearly, then, the craving for drink is not always due
to a longing to counteract the ill-effects of previous indulgence, but
to a recollection of its delights. The relief which continued
drinking affords is a contributory cause, but never, of course, the
primary cause.1

480. The craving for alcohol is a resultant of two factors. The
first is an inborn (nutritional) capacity to enjoy or develop a power
of enjoying the sensations that alcohol awakens. The second is a
recollection of the sensations aroused by previous acts of drinking.
No one could possibly crave for indulgence in alcohol unless he
were so constituted as to enjoy the effect — any more than he could
crave for a draught of sea-water. On the other hand, no one is born
with a knowledge of the sensations aroused by drinking, therefore
none can crave for them without a recollection of previous experi-
ence. It is true that a man who has heard of the delights of
drinking may desire alcohol in the sense that a boy desires tobacco,
or an Englishman some tropical fruit ; but this desire is quite
distinct from that which besets the experienced toper. Both these
desires, again, are distinct in type from hunger, or thirst, or the

1 This discussion, with much else in the present chapter, may appear childish
to the reader — an attempt to prove the obvious. But it must be borne in mind
that we are now dealing with a subject about which an incredible amount of
nonsense has been written and accepted. It is necessary, therefore, to demon-
strate even the very obvious.

SUSCEPTIBILITY TO ALCOHOL 289

sexual craving. The latter are instincts, ' inborn ' characters, which
develop inevitably as the body develops, and which, though they
may be awakened to activity by fitting stimulus (the presence of
food, water, or a particular mate), are not then created by it in the
sense meant. In other words, they are not, like the drinker's longing
or the boy's desire for tobacco, necessarily dependent on memory.

481. Mental differences in relation to other narcotics are just as
marked as in relation to alcohol. For example, some natives of
China are satisfied with a very moderate indulgence in opium ; in
others the craving is so strong that, in effect, they commit suicide
to gratify it. The insensibility which follows the inhalation of
chloroform is a form of intoxication. Most people who have
experienced it only once or twice describe the sensations of ' going
off' and 'coming to' as horrible. But often pleasure attends
wider experience. Some people find pleasure even from the
beginning. Once a woman, who was inhaling the drug for the
first time, said to me, " You are sending me into heaven." I knew
a doctor's servant who was in the habit of stealing her master's
chloroform and rendering herself deeply insensible.

482. The individuals of every species vary from one another in
every particular. Probably there is not on earth an individual
who is exactly like another in any character. We have seen that
men manifestly vary in the sensations aroused in them by alcohol
—in the amount of pleasure which drinking confers, and conse-
quently in the degree in which they are tempted to repeat the
remembered experience. Some men who have taken alcohol all
their lives experience, apparently, not much more pleasure from
the act than they derive from the eating of an apple. Their
temptation to deep indulgence is of the slightest. From first to
last they are attracted more by thirst or taste than by the cerebral
effects. But beyond question the longing awakened in other men
is very intense. A woman inebriate, in desperate straits for drink,
once procured alcohol by a trick — the amputation of her own hand.
Pathological specimens in hospital museums, gruesome prepara-
tions of cancers, diseased intestines, and the like, have been spoilt
because people who had access to them drained the methylated
spirits in which they were preserved.

483. Until very recently the vitally important fact that the
degrees in which men are tempted by alcohol differ greatly was
hardly recognized.1 Even now very many well-meaning people,

1 As far as I am aware it was not recognized before 1896, when I published
The Present Evolution oj Man.

19

290 ALCOHOL

who think it is in conflict with their schemes of temperance reform,
endeavour to push it as much as possible into the background.
At any rate it was and is quite ignored in all discussions on intem-
perance. Men are supposed to be temperate or the reverse solely in
proportion as they exercise, or do not exercise self-control ; or,
what is very much the same thing, in proportion as they have or
have not been well trained.1 But since there are men who, very
plainly, are intensely tempted by alcohol, this hypothesis carries
the corollary that all men who drink at all crave furiously for the
sensations awakened by deep indulgence, and differ among them-
selves only because some of them exercise strenuous restraint.
But let the reader turn to the best of all guides for him, his own
experience of life. He is sure to have known many inebriates,
men whose desires for alcohol were as those of a shipwrecked
sailor for water. Some of them he has seen to struggle desperately
if unavailingly against an overwhelming desire. As much as any
man they seek to exercise self-restraint. Next let him examine

1 " It is often alleged, it is still more often assumed that the difference between
the sober man and the drunkard is that the one possesses and the other lacks
sufficient self-control to enable him to overcome his urgent and masterful desire
for drink. The repetition from mouth to mouth, and from book to book, of this
obviously false doctrine is one of the most striking instances of the ovine imitative-
ness of the human intellect, and of the ingrained habit of yielding unquestioning
assent to authority. There are countless millions of sober men and women in
the world, all of whom are ready to utter the parrot cry that they are sober
because of their superior self-control, because they have the strength to resist
temptation ; and this they say in perfect good faith, when, if they would only
think for one moment and interrogate their own consciousness in their own
experience, they could not fail to know/with irresistible conviction, that in fact they
are not tempted to drink at all. Drink has no temptation for them. It offers
them no allurement. It yields them no delight. It satisfies no craving. The
taste of it finds them as indifferent as it leaves them. They are drink-proof, not
because of any superior virtue, not because of any superiority of self-control,
but because drink holds out to them no temptation And, not being tempted,
they do not fall. They are no more meritorious for not getting drunk than a cat
is meritorious for not wetting its feet, or a child is meritorious for not falling
to the ground. Many such persons could not get drunk if they tried. The
sensations produced by the ingestion of alcohol are to them so unpleasant that
they are compelled to leave off long before they have taken enough to make them
drunk. If, then, the difference between the drunkard and the sober person is not
a difference in self-control, what is it ? ... The facts are that, on the one hand,
when alcohol is applied in solution in the blood to the brain tissue of one person,
there arises in that person pleasurable feeling. When applied in solution in the
blood to the brain tissue of another person, there occurs in that person no such
pleasurable feeling. The feeling is neutral, or is unpleasurable, or is displeasur-
able." (Mercier, The Presidential Address on the Physical Basis of Mind, delivered
at the sixty-seventh annual meeting of the Medico-Psychological Association,
July 23rd and 24th, 1908.)

THE TEMPERAMENT OF THE DRUNKARD 291

his own emotions. Is he so miserable as to be afflicted by this
intense and tormenting desire ? Is he saved from that which will
wreck home and happiness and life only by an effort as tremendous
as and more sustained than that which keeps the sailorjfrom draining
his last drops of water ? Or is it a fact that his desires for deep
indulgence are very faint — as faint as the everyday desire of a
landsman for water, so faint or non-existent that he is hardly, if
at all, conscious of them ? What of the people he knows best, his
own relatives and intimate friends? Are the majority of them
deeply tempted ? Has he any valid reason for supposing that the
lady whom he meets at dinner, and who sips her glass of wine in
such seeming contentment, is earnestly desirous of draining the
decanter ? It is sufficient merely to ask the question to demon-
strate its absurdity.

484. For the sake of comparison, it may be worth] while to
describe my own feelings at the present moment If a glass of
beer were before me, I should feel no inclination for it, though I
am capable of enjoying beer when thirsty. If a glass of some
sweet wine were here, I should enjoy perhaps half a glass, just as I
should enjoy a morsel of chocolate. When I was younger and my
delight in sweets greater, I should have liked more. A glass of
whisky would awaken only repulsion. When sleepless or tired or
when with friends I have often found it pleasant. I find, however,
that even a small amount affects me disagreeably some hours later,
and therefore as a rule I take none. I am not conscious at any
time of having exercised any self-control worth mentioning. I
dare say many people will doubt the truth of this introspection
— especially abstainers who have had no experience, and people
to whom even a glass of methylated spirits is a temptation.
But I think a great many others will find a parallel in their own
experience.

485. Plainly, then, as in the case of tobacco, a lifelong experi-
ence of alcohol endows some men with only weak and easily
satisfied desires, whereas a much shorter experience awakens in
others a keen longing which is satisfied with nothing short of deep
indulgence, or is resisted only at the cost of acute suffering.
Plainly again, not only does alcohol awaken deeper desires in some
men than in others, but it awakens them more quickly. Self-
control, therefore, though a factor of great importance, is not the
only or even the main factor in the causation of sobriety. It is
argued sometimes that men are temperate or the reverse because
those of the former class have, from the beginning and always,

292 ALCOHOL

exercised self-restraint, and so have never acquired through ex-
perience the desires which increased indulgence creates in the latter.
But we all know men and women whose whole lives are abandoned
to an unrestrained search for pleasure, and who are nevertheless
temperate in their drinking. Is it believable that these people con-
stantly resist urgent temptation which they continually feed with
inadequate indulgence? Abstainers form a class by themselves.
They are not exposed in the same way to temptation. But pro-
bably the reader is a moderate drinker. Let him inquire of his
own sensations.

486. Just as a limited experience enables the smoker to
ascertain the amount of tobacco and the periods and methods ot
indulgence which are most agreeable to one of his type, so a
certain experience endows the drinker with a similar knowledge.
As we see, some men, influenced mainly by thirst or taste, are
satisfied with a glass at meals. Others are satisfied with nothing
short of complete insensibility. Some, desiring only the drowsiness
which alcohol creates in them, take a " night-cap " ; others must be
sipping the whole day. In the latter case the drinker may not,
and usually does not become intoxicated in the ordinary accept-
ance of the word ; but a mental condition which borders on
intoxication is so pleasant to him that he seeks to maintain it
constantly during his waking hours, and in this way may imbibe a
quantity of alcohol which may exceed the average amount taken
by one who drinks when opportunity offers to the point of coma.

487. We must, however, always bear in mind that the drinking
habits of men are not solely determined by the pleasure conferred
by alcohol. Many men are unable to afford or are otherwise pre-
vented from obtaining as much as they desire. Some are so
trained that they regard all drinking with moral abhorrence, and
from birth to death never indulge in it. Others, seeing the misery
of their loved ones, or having the fear of physical, material, or
social ruin in sight, become abstainers later in life. All normally
constituted men are greatly influenced by fashion, that is, by the
tone of the society in which they live. It is probable that our
great-grandfathers encouraged one another to drink more, on the
average, than they really craved. It is certain that under the
present fashion many men voluntarily drink less than they would
enjoy. But when all this is granted, it still remains true that a

given experience of drink awakens stronger desires in some men
than in others, that under any given conditions men on the average
drink in proportion to their desires, that the men most tempted

VARIETIES OF DRUNKARDS 293

most often fall, and that the excessive drinker, whether actual
inebriate or continuous soaker, is invariably one to whom deep
indulgence is a strong temptation ; whereas the moderate drinker
is almost as invariably one who is so constituted that his tempta-
tion is much weaker. All deep drinkers suffer from the immediate or
remote effects of poisoning, and know well to what their sufferings
are due. It is almost inconceivable that any man would incur the
inevitable penalties were he not greatly tempted. We never hear
of men deliberately making themselves poor, contemptible, miser-
able, and ill with something, for example sea-water, which has no
intoxicating effect. On the other hand, a moderate drinker who
has had an average experience of alcohol and has in him the
makings of a drunkard, is not common. The human will is
seldom strong enough to resist the steady pull of vehement
temptation when the latter is constantly fed by partial indulgence.

488. Some drinkers, it is true, are so constituted that alcohol
affords them pleasure mainly as a relief from unhappiness. They
are one variety, but on the whole a somewhat rare variety of
excessive drinker. If the reader will again consult his own
experience of life, I think he will find that nearly all the inebriates
with whom he is well acquainted, slipped, after a longer or shorter
experience, according to the ease with which strong desires were
awakened in them, into bad habits under quite ordinary conditions
of life. Again, bad companionship is said to lead to intemperance,
and doubtless it often does. But usually the zest for such society
owes its origin to alcohol, which can furnish it only to those who
are susceptible to its charm. " Birds of a feather flock together."
A man who craves for drink would hardly choose the society of
abstainers or moderate men. The kind of pleasures that appeal to
a more or less inebriated man are not those which appeal to
respectable women, clergymen, scientific men, or athletes, as
such.

489. Now, since susceptibility to the charm of alcohol is an
' innate ' character which develops with the growth of the in-
dividual under stimulus of nutrition, it tends as such to be
1 inherited,' in the same sense as, for example, the shape of his
head. In this connection it matters not whether the individual
does or does not drink. Awake or dormant, his susceptibility is
still present. On that account drunkenness tends to run in families.
The child is " by nature " similar to the parent, and under similar
conditions tends to acquire the same trait. Often, however, it
happens that a sober or a drunken parent is succeeded by a child

294 ALCOHOL

who is the reverse. The child has two parents, and may inherit
mainly or exclusively from the one or the other. Or the conditions
of life under which parent and child develop may be different.
Thus a man, impressed by the u awful example " of his father, may
become an abstainer. But his son, falling amongst evil companions,
and seeing at first more of the delights than the woes of drinking,
may exhibit the character of the grandparent. The facts remain,
however, that, though many people who are very susceptible to the
charm of alcohol do not fall victims to it, yet, whether it be in-
dulged or not, the susceptibility exists, is greater in some people
than in others, tends to be inherited in its various degrees, and
people on the average tend to fall victims to it in proportion
to its strength in them. The clearest proof that degrees ot
susceptibility to the charm of alcohol tend to be reproduced by
offspring is found when we examine races. In the midst of
abundance of alcohol, generations of Spaniards or Italians lead
temperate lives. Under similar conditions Englishmen are more
drunken, Russians yet more drunken, while Red Indians furiously
drink themselves to death. Races are merely aggregates of more
or less nearly related individuals. Therefore, as in the case of
disease, the individuals of each race must tend to transmit their
degrees of susceptibility to offspring and descendants.

490. There can be no doubt, then, that some people are so
constituted as to be more tempted by drink than others, that they
tend to transmit this characteristic to offspring, and that, though a
proportion of those who have it are, in England at least, abstainers, or
in far rarer cases moderate drinkers, yet all really excessive drinkers
are drawn from their ranks. Again, there can be no doubt that
excessive drinking is injurious, and that a great number of people,
all of a particular type, indulge in it. The question arises, then,
whether it is so injurious and to so large a number of people, as
to act, like a microbic disease, as a stringent agent of selection.
In that case it must so shorten or in other ways so influence the
lives of a certain type of people, that the total number of offspring
and descendants they contribute to the race is much less than
would have otherwise been reared. According to the Registrar-
General, 221 1 people died of alcoholism in 1905, the rate per
million of the population being only 65. In the same year the
deaths from tuberculosis were 55,759, the rate per million being
1632. Judged, then, by the returns, excessive drinking is by no
means a stringent agent of elimination. The number of deaths
recorded must bear a very small proportion to the total number of

THE ELIMINATION BY ALCOHOL 295

excessive drinkers. Must we conclude, then, that alcoholism only
very rarely destroys its victims ?

491. The statistics of the Registrar - General are compiled
almost exclusively from medical certificates of death. When I
turn over the counterfoils of my old books of death certificates, I
find, here and there but very seldom, the word ' alcoholism.' The
term implies that the person whose end is recorded drank himself
quickly, violently, and relentlessly to death. He or she died,
not from the remote effects of alcohol, but from poison actually
circulating in the blood at the time of death, or during the few days
or weeks preceding. De mortuis nil nisi bonum ; but I could not
truthfully enter anything else. Sometimes such a one, after a more
or less prolonged career of drink and poverty, owed his actual
decease to a windfall of money. More common is ' cirrhosis of the
liver,' an expression which is usually, but, as Dr H. B. Donkin has
shown, not always a synonym for chronic or soaker's alcoholism.
The Registrar-General's returns indicate that 4008 persons died of
this complaint in 1905, a number which works out at a rate of
117 per million living. This number, even when added to that
due to acute alcoholism, is too small to indicate stringent selection.

492. But, looking through my counterfoils, I see recorded the
names of many people some of whom as I knew, and more of whom
as I suspected, had been injured by excessive drinking before they
died of accident or contracted phthisis, pneumonia, bronchitis,
apoplexy, or the more gradual forms of paralysis, erysipelas,
syphilis, kidney, heart, or arterial disease, or this or that other
complaint which was the immediate cause of death. The circum-
stances surrounding their ends make me very sure that in a large
proportion of cases they would not have contracted the fatal
disease, or would have recovered from it had they not previously
weakened their powers of resistance by intemperance. Some years
ago " The Harveian Society of London instituted an investigation
and found that in London, of 10,000 persons dying over twenty-
four years of age, the result was as follows : —

A. Deaths in nowise due to alcohol 8598

B. Deaths accelerated or partly caused by its abuse . 1005

C. Deaths wholly due to it 397

. . . These 1402 deaths constituted almost exactly 14 per cent,
of the total deaths. If this proportion still continues . . . the
total deaths in the United Kingdom for 1889, altogether or partly
caused by alcohol were 94,416, of which 26,736 would be directly
due to alcohol and 67,680 accelerated or partly caused by it.

296 ALCOHOL

... In that inquiry,1 conducted over totally different grounds,
the deaths of intemperate males of over twenty-five were 30 per
cent, of the whole, while 25 per cent, were careless drinkers, some-
times taking excess. This being the proportion among adult
males, we find no difficulty in believing that about one death in
seven is partly or wholly caused by alcohol, omitting for the
moment those caused indirectly." 2

493. Very possibly the above estimate exaggerates the mortality
due to alcohol, but that it is very considerable is shown by the
statistics of insurance companies. Thus the United Kingdom
Temperance and General Provident Institution, the policy-holders
of which are separated as sheep from goats into abstainers and
non-abstainers, found the mortality amongst the former 71.49 per
cent, of the total expected, whereas amongst the latter it was
96.66 per cent. In the Sceptre Life Office the percentage was
56.86 and 77.61. On the average the members of the Friendly
Society of Rechabites, who are abstainers, live longer and have less
sickness than Oddfellows and Foresters. The mortality amongst
grocers has increased appreciably since they were permitted to sell
wine and spirits. English and Russian soldiers, who consume
considerable quantities of alcohol, perish more readily of wounds
than Afridis and Turks, who consume little or none. Heavy
drinkers tend to fall into poverty, the slums of our cities being
full of them. Their children, who, if they survive, tend to inherit
their characteristics, perish in greater numbers than the offspring
of more temperate people. Women drinkers are often immoral
and sterile.

494. Evidently the elimination due to excessive drinking is
much greater than that indicated by the returns of the Registrar-
General, so much greater that there is every probability that
alcohol is an agent of stringent selection. We are able to test
this conclusion ; but, first, it is necessary to note that stringency
of alcoholic selection varies with time and place. It is greatest
when and where drink is most abundant and accessible, and the
prevailing social tone most favourable to its consumption. Thus
alcohol is more accessible to Italians than to Englishmen and a
fortiori to Red Indians ; to coal-porters more than to coal-miners.

The social tones prevailing during the Victorian era and the
Commonwealth were less favourable to its consumption than those
which prevailed during the period of the Georges and of the Restora-

1 Collective Investigation Committee of the British Medical Association.
* Alcohol and Public Health, by J. J. Ridge, M.D. London : H. K. Lewis.

THE EVOLUTION AGAINST ALCOHOL 297

tion. It is less favourable amongst clergymen than amongst
publicans. All this is very obvious and need not have been
mentioned were it not that a confused notion seems prevalent
amongst writers on the subject that selection is not selection if it
varies in intensity. Selection is selection, no matter what its
intensity. It may not be stringent enough to cause progression,
but selection it is nevertheless. Again, it must be noted that the
stringency of selection is not to be estimated by the magnitude of
the mortality due to the selecting agent, but by the greater or lesser
completeness with which it weeds out the unfit When the unfit
are very numerous, a large mortality may indicate a lesser degree
of stringency than a lower mortality when the unfit are less
numerous. For example, in Italy, where people are ' naturally '
disinclined to excessive indulgence, and where alcohol is very
abundant and accessible, the deaths of quite a few excessive
drinkers may indicate a greater stringency of selection than the
elimination of a much larger number in England.

495. The people that alcohol eliminates are those who are so con-
stituted mentally that they are tempted to take it in excess. There-
fore " the tendency of evolution is to produce a race . . . capable
of sitting down in the presence of floods of alcoholic liquor . . .
without the desire to get drunk." l Is there any evidence of such
an evolution ? If the reader will call to mind all the races of the
world of which he has a knowledge, he will find, as in the case of
a prevalent and lethal disease, that every race is resistant (i.e. tem-
perate) in the presence of alcohol in proportion to the length and
severity of its past experience of the poison. There is no exception
to this rule. Moreover, whenever we possess a sufficiently detailed
and prolonged history of a race ivhich is now temperate, we find that
it was anciently drunken. To this rule also there is no exception.
Of course, however, when we seek to compare the past with the
present of a race, we must not commit the absurdity of compar-
ing one year or decade with the next preceding or succeeding.
Man is a slow-breeding animal in whose race germinal changes
occur only very slowly, and the extent of his drinking is influenced,
not only by the depth of his desire, but by many other considera-
tions, such as the accessibility of alcohol and the tone of the society
in which he is reared. Therefore we must compare past eras or
centuries with much later times.

1 Sk E. Ray Lankester, Fortnightly Review, Sept. 1896, p. 413.

CHAPTER XVI
THE EVOLUTION AGAINST NARCOTICS

Alcohol in ancient and modern times — Among the lake-dwellers — In Egypt
— In Greece — In Italy — Among Jews — In West Africa — In Great Britain —
In Germany — In China — In the Western Hemisphere — Opium — The poisonous
effects of narcotics — The origin of the susceptibility to the charm of narcotics —
Objections to the theory of narcotic evolution — Education — Strength of beverages
— Civilization — The memory of past racial disaster — Convivial and industrial
drinking — The alleged effect of alcohol on the germ-plasm.

s

496. £^| TRONG solutions of alcohol are products of the know-
ledge and skill which civilization brings. The lowest
savages, for example the Tierra del Fuegians and
Australians, are unacquainted with means of manufacturing in-
toxicating liquor. Settled tribes almost always possess intoxi-
cants in some form, alcoholic or other ; but, unless they are well
advanced in civilization, the beverages they manufacture are weak
and far from abundant. Thus it is recorded that the natives of
Guiana were obliged to drink their cassava intoxicant (which,
however, was not alcohol) for three days before a state of drunken-
ness satisfactory to them was achieved. Moreover, especially in
cold and temperate climates, the alcohol made by savages is
usually derived from the fermentation of articles of food — milk,
honey, corn, and the like — which are rarely abundant with them.
Owing, then, to the insufficiency of the supply, due partly to
difficulties of manufacture and partly to lack of materials, excessive
drinking amongst most savages is comparatively rare and spas-
modic. Consequently the elimination of the unfit is far from
stringent. But, as in the case of such a disease as tuberculosis,
with growing civilization comes an increasing and more regular
exposure to the evil — in other words an increasing and more
effective stringency of selection. It follows that a race that has
evolved its own civilization or very slowly absorbed that of
another, tends to become resistant to alcohol and survive, whereas
a race which is suddenly introduced to civilization with its strong
solutions of alcohol, tends to drink to extinction.

497. Probably in all the world alcohol has been most abundant

ANCIENT INTEMPERANCE 299

and uninterruptedly accessible in the vine-producing countries of
the South of Europe and the forest region of West Africa. There
is evidence that it was manufactured from wild fruits such as the
raspberry and mulberry by the lake-dwellers of Switzerland and
the South of France during the Stone Age. We do not know when
the vine was first cultivated for alcohol, but the fact that at the
dawn of myth and fable grape-wine was in use all round the
Mediterranean, argues an immense antiquity. Probably palm-wine
has been used in West Africa and elsewhere for almost as long.
Both the vine and the palm enable men to manufacture abundance
of alcohol without trenching on their food-supplies. Just as we
are able to gather little from history about the endemic diseases
of antiquity, so we are able to learn little about its endemic
drunkenness. Usually the earliest references relate to the in-
toxication of some prominent person on some memorable occasion,
and then the reference is made, not because the person was
intoxicated, but because the occasion was memorable. Thus Noah
is represented as drunk when Ham discovered his nakedness, as
was Lot when he became the ancestor of the Moabites and the
children of Ammon. So also the suitors of Penelope were
inflamed with wine when Ulysses slew them, and we are told that
Alexander died of a surfeit of drink. Clearer evidence is to be
gleaned from laws and injunctions against excessive drinking,
such as are common in the Old Testament,1 and of which many
1 For example, " Who hath woe ? Who hath sorrow ? Who hath contentions ?
Who hath babblings ? Who hath wounds without cause ? Who hath redness of
eyes ? They that tarry long at the wine. They that go to seek mixed wine.
Look not upon the cup when it is red, when it giveth colour to the cup, when it
moveth itself aright. At last, it biteth like a serpent, it stingeth like an adder "
(Prov. xxiii. 29-32). " Woe unto him that giveth his neighbour drink, that
puttest the bottle to him, and makest him drunken also." " Blessed art thou,
O land, when thy king is the son of nobles, and thy princes eat in due season, for
strength, and not for drunkenness " (Eccles. x. 17). " Woe unto them that rise up
early in the morning that they may follow strong drink, that continue until night
till wine inflame them " (Isa. v. 1 1). " Woe to the crown of pride to the drunkards
of Ephraim ... that are overcome with wine " (Isa. xxviii. i). " But they also
have error through wine, and through strong drink are out of the way ; the priest
and the prophet have erred through strong drink, and they are swallowed up of
wine, and they are out of the way through strong drink : they err in vain, they
stumble in judgment. For all tables are full of vomit and filthiness, so that there
is no place clean " (Isa. xxviii. 7-8). Jews have still a feast, that of Purim, when
intemperance is not only permissible to them, but is absolutely encouraged-
Modern Jews show no disposition to avail themselves of the permission ; but
anciently it was different. " We need only mention the Purim, or deliverance
of the Jews from the rage of Hainan, which, until the reign of Theodosius, was
celebrated with insolent triumph and riotous intemperance " (Gibbon, The Decline
and Fall of the Roman Empire, vol. ii. p. 85, ed. Grant Richards, 1903).

300 THE EVOLUTION AGAINST NARCOTICS

are addressed to races which are now so temperate as not to need
exhortation. The oldest known Egyptian papyrus, which comes
to us from an antiquity of 7000 years, contains such an injunction,
which is repeated in many later writings. " The moralists reprove
these excesses, and cannot find words strong enough to express
the danger of them. Wine first loosens the tongue, even wresting
from him dangerous words, and afterwards it prostrates him, so
that he is no longer capable of defending his own interests. Do
not, therefore, forget thyself in the breweries ; be afraid that words
may come back to thee that thou hast uttered, without knowing
that thou hast spoken. When at last thou fallest, thy limbs failing
thee, no one will help thee, thy boon companions will leave thee,
saying, * Beware of him, he is a drunkard.' Then when thou art
wanted for business thou art found prone on the earth like a little
child." 1 " Young men especially should avoid this shameful vice,
for beer destroys their souls. He that abandons himself to drink
is like an oar broken from its fastening, which no longer obeys on
either side ; he is like a chapel without its god, like a house with-
out bread, in which the wall is wavering and the beam shaking.
The people he meets in the street turn away from him, for he
throws mud and hoots after them till the police interfere and carry
him away to regain his senses in prison." 2

498. The fact that the Spartans made drunken their helots that
they might serve as " awful examples " to the aristocratic youth
is clear evidence of the danger and probably the prevalence of
drunkenness amongst the latter. Lycurgus amputated the legs of
drunkards and destroyed the vines. Solon condemned an Archon
to death for being drunk. The Senate of Areopagus punished
men for too prolonged drinking. Pittacus of Mytelene inflicted
double punishments for offences committed in drink. It is
related that thirty-six competitors perished in one of Alexander's
drinking matches. The festivals in honour of Dionysus " became
more and more dissolute both in Greece and Rome until they
degenerated into saturnalia of the most disgraceful character." 3
Drunkenness is a constant theme of Homer and Aristophanes.

499. Apparently alcohol was not abundant in Italy when
Rome was founded, for " Numa, the successor of Romulus . . .
directed, from the great scarcity of wine that prevailed, that no
man should besprinkle the funeral pile with it, and when the

1 The Maxims ofAni, XVIII. Dynasty, about 1530-1330 B.C.

2 Maspero. Life in Ancient Egypt , translated by A. Morton, p. 31.

3 Samuelson, History of Drink, pp. 75-9.

ITALIANS AND JEWS 301

sacrifices to the gods were permitted in wine, it was declared, with
a view to encourage the plantation of vineyards, that all wine so
offered should be the produce of such vine plants as had been cut
and pruned." 1 The elder Pliny, Petronius, and other historians of
later Roman times, mention great excesses. The sobriety of the
modern inhabitants of the vine countries, including Jews, who until
lately dwelt mainly in the warmer parts of Europe, is well known.
For example, until lately, the Italian peasants drank at their
taverns, for a very trifling sum, by the hour, not by the quantity.
A publican who adopted such a custom among Englishmen would
be ruined, amongst Red Indians he would be murdered. An
English physician resident in Italy writes —

500. " I have met time after time Italians who confess without
shame that they have never drunk anything but wine ; they are
never drunken. Drunkenness upon Italian wine I have seen, but
only amongst my fellow-countrymen and women. Among my
servants I find that water as a drink is considered bad for the
stomach, and is feared just as water in a bath is feared, as a peril
and a danger. . . . On inquiry from old residents in the country I
learn that, however abundant the vintage, the contadini preserve
always their temperate habits, drinking their fill, but never becom-
ing drunken. Drunkenness in the British sense is so very rare as
to be a matter of great interest and discussion when it occurs ; . . .
even thirty years ago, when the export trade was practically nil,
and there was a great excess of production over consumption, there
was no drunkenness. In those days, I am told, wine was given to
horses, and whole barrels would be poured out in the road to make
way for the new vintage, when the price was only a few coppers
per flask ; ... it is given to infants, children drink it regularly, and
babies are bathed in it, but drunkenness in the English sense does
not exist."2

501. The sobriety of modern Jews has been the subject of
numerous homilies. In London, for example, a drunken Jew — or
Italian organ-grinder — is practically unknown. Hebrew sobriety
is often attributed by the members of that community to "the
fact, recognized by many non-Jews, that the absence of drunken-
ness amongst Jews is, in the main, due to their training, from their
earliest childhood, in the principles of their religion, which, amongst
other things, inculcates temperance and moderation in all things."
The Jews have the reputation of being as much addicted to

1Morewood, History of Inebriating Liquors, p. n.

* Dr H. Laing-Gordon, British Journal of Inebriety, Jan. 1904.

302 THE EVOLUTION AGAINST NARCOTICS

pleasure as other races, and Jewish abstainers are almost as rare
as Jewish drunkards. If, then, Jews are temperate only through
self-restraint, they must all be under the influence of that dire
craving which the toper feels, but must very bravely resist it. I do
not know if it is possible for anyone to believe this. Moreover,
the claim of superior moral training carries a corollary. The
Hebrew moral code inculcates a good deal besides sobriety — the
Ten Commandments, for example. It will hardly be maintained
that Jews are as conspicuously superior to the English, for instance
in morals in general, as they are in sobriety. If, then, Jews are so
teachable and so well taught as to be sober mainly through
religious training, must we conclude that their religious training is,
speaking comparatively, conspicuously lax and faulty with regard
to morals in general? This inference flows logically from the
Jewish claim, but no Jew will care to press it. Notwithstanding
the fulminations in the Old Testament, some Jews maintain that
their race has always been temperate. But, whether we trace
their descent from Noah or the savages of the Stone Age, we arrive
at an ancestry actually or potentially drunken. What caused the
change of type ? The only real alternative to miracle is Natural
Selection.

502. Palm wine is cheap and plentiful in West Africa, but it is
customary at missionary meetings to represent the natives as
debauched by the European liquor traffic. However, evidence
to the contrary is not lacking. " My business is to state facts,
not to reconcile those facts with the representations or fancies
of any other person. . . . The phrases that ' liquor is a great
scourge to the natives of this country,' that it 'commits great
ravages ' and ' possesses extraordinary power over the people,' are
not true. . . . The last phrase is certainly applicable to Great
Britain, but not to West Africa, . . . The whole subject of the
attitude of philanthropists towards liquor in this country is of
intense interest to the philosopher. . . . Therefore understand that
in my humble opinion the future of the people of this country is
not in any danger from liquor. One would like to be able to say as
much for Great Britain, and of her nearest neighbour, to which
nations, in the natural and logical course of circumstances, temper-
ance advocates should be sent from this country." 1

1 " Extract from a speech on the Liquor Question delivered by Sir W.
MacGregor, K.C.M.G., in Legislative Council, on the i6th Oct. 1901, and re-
published for general information."— Southern Nigeria Government Gazette, Sept.
9th, 1908, p. 1285.

THE SOBRIETY OF WEST AFRICANS 303

503. " The Honourable Mr Sapara Williams : ' I rise to support
the remarks which have been made by His Excellency the
Governor relative to the extracts which he has read from the
speech delivered by Bishop Tugwell before the Native Races and
the Liquor Traffic Committee, and published in the Diocesan
Magazine of the Western Equatorial Africa for July 1908. I have
read the speech as published, and standing here as an Unofficial
Member of Council, I am bound to say that it is the duty of
this Board to take special notice of the same and to denounce the
utterances therein contained. Every one knows that I am an
abstainer and one who is entirely opposed to the evils of intemper-
ance ; but that fact does not impose on me the obligation to
shut my eyes to facts in order to endorse these false statements of
the Bishop.' " *

504. " I do not say that every missionary who makes untrue
statements on this subject is an original liar ; he is usually only
following his leaders and repeating their observations without
going into the evidence around him. ... I have no hesitation in
saying that in the whole of West Africa, in one week, there is not one
quarter the amount of drunkenness you can see any Saturday in a
couple of hours in the Vauxhall Road, and you will not find in a
whole year's investigation on the Coast one-seventh part of the
evil, degradation, and premature decay you can see any afternoon
you choose to take a walk in the more densely populated parts of
our own towns." 2

505. " One of my native colleagues also gave a temperance
address. I shall not soon forget the earnestness with which he
exhorted his hearers to fight the gigantic demon strong drink.
{ For,' said he, * unless we put forth our best efforts in this direction,
there is a danger of becoming as drunken as the people of England.'
This was a rather startling way of putting the case, but it was
decidedly refreshing, as I remember there were so many in England
who appear to be under the impression that whole territories are
being depopulated by the importation of spirits. The statement
expressed by my colleague was forceful, but I unhesitatingly
endorse it. ... A friend of mine, a most ardent temperance
reformer, was appointed District Commissioner of Cape Coast a
few months prior to my first residence. At the end of his first
term of service he took the opportunity to write to a temperance
paper in this country to say that the friends of temperance would

1Op. cit., p. 1283.

* Miss Kingsley, Travels in West Africa, pp. 492-5

304 THE EVOLUTION AGAINST NARCOTICS

be glad to know that the ravages of the drink traffic were not so
serious at the Gold Coast as was generally supposed. Out of the
hundreds of cases tried at his court during the twelve months, not
one was traceable to the abuse of strong drink." 1

506. " But what are the facts of the case ? The author has for
many years been favourably situated for ascertaining the condition
of affairs in Africa. He has conversed with men of culture who
have resided for many years on the coast at various places of trade,
and the consensus of opinion as well as the facts that have been
narrated to him point to a widely different conclusion. The
exportation of strong drink from England to the West Coast of
Africa is enormous. It chiefly consists in rum ; and by far the
larger portion of this is forwarded into the interior, and is drunk
out of sight amongst the savage tribes who are rarely visited by
Europeans."2

507. The ancient Germans were exceedingly intemperate.
According to Tacitus, " intemperance proves as effectual in subduing
them as the force of arms." " They gloried in passing whole days
and nights at the table ; and the blood of friends and relations
stained their numerous and drunken assemblies. . . . Strong beer,
a liquor extracted with very little art from wheat or barley, and
corrupted (as it is strongly expressed by Tacitus) into a certain
semblance of wine, was sufficient for the gross purposes of German
debauchery. But those who had tasted the rich wines of Italy,
and afterwards of Gaul, sighed for that more delicious species of
intoxication. They attempted, not, however (as has since been
executed with so much success), to naturalize, the vine on the banks
of the Rhine and Danube ; . . . The intemperate thirst of strong
liquors often urged the barbarians to invade the provinces on which
art or nature had bestowed those much envied presents. The
Tuscan who betrayed his country to the Celtic nations attracted
them into Italy by the prospect of the rich fruits and delicious wines,
the productions of a happier climate. And in the same manner the
German auxiliaries, invited into France during the civil wars of
the sixteenth century, were allured by the promise of plenteous
quarters in the provinces of Champange and Burgundy. Drunken-
ness, the most illiberal but not the most dangerous of our vices, was
sometimes capable, in a less civilized state of mankind, of occasion-
ing a battle, a war, or a revolution." 3

1 Rev. Dennis Kemp, Nine Years at the Gold Coast.

2 Samuelson, History of Drink, p. 9.

3 Gibbon, Decline and Fall of the Roman Empire, vol. i. pp. 255-6.

GERMANS, BRITISH, AND CHINESE 305

508. "After the establishment of Christianity the monks, who
needed wine for sacramental purposes, introduced the cultivation
of the grape to Gaul and Germany." l Drunkenness increased
enormously, both amongst men and women.2 German intemper-
ance became " a byword amongst the nations, as the edict of Karl
IV. declared."3 The papal official at the court of Frederic III.
wrote to his master, " Nilhic est aliud vivere quern bibere," 4 " Living
here is nought but drinking." So plentiful was the wine that a
contemporary rhyme declares —

"In fifteen hundred and thirty-nine
The casks were valued at more than the wine."

People of all classes drank the whole day long like modern
soakers. " Amongst the vices," said a preacher in Germany in the
ninth century, " feasting and drunkenness especially reign, since not
only the rude and vulgar people, but the nobles and powerful of
the land are given up to them. Both sexes and all ages have made
intemperance into a custom . . . and so greatly has the plague
spread, that it has infected some of our own order in the priest-
hood, so that not only do they not correct the drunkards, but
become drunkards themselves." 5 Charlemagne and his successors
vainly attempted, by means of numerous edicts and laws, to control
the prevailing intemperance. At the present day modern Germans
and Frenchmen of the vine regions are as temperate as modern
Greeks, Italians, and Portuguese.

509. Great Britain has always been intemperate, and has sought
as long, as often, and as vainly as Germany to cure the evil by
laws. Though the vine was never cultivated to any considerable
extent, yet alcohol gradually became cheaper and more accessible
as the wealth and civilization of the country advanced. British
intemperance reached its culmination, therefore, at a later period
than that of Germany. However, since the eighteenth century,
when men got " drunk for a penny and dead drunk for two
pence," and had clean straw in which to sleep away the effects for
nothing, it has steadily diminished. At the present day, though
not so temperate on the average as the inhabitants of the vine
countries, most Englishmen are sober, notwithstanding the fact
that they are not abstainers.

510. At the present time the Chinese are very temperate in the
use of alcohol. The teachings of Confucius and his disciple

1 Samuelson, History of Drink, p. 104. 2 Op. cit., p. 109.

3 Op. cit., p. 112. 4 Op. cit., p. 112. 5 Op. cit., p. 114.

20

306 THE EVOLUTION AGAINST NARCOTICS

Mencius contain so little about alcohol that it is probable that
there was little excessive drinking, even in fifth century B.C.
" Whilst the princes and people are warned against voluptuousness
and extravagance, we seldom find drunkenness referred to as a
dangerous and prevalent vice." 1 But in the " Announcement about
Drunkenness," an imperial edict believed to have been promulgated
about 1116 B.C., it is stated that "our people have been greatly
disorganized and lost their virtue, which can be traced to their
indulgence in spirits." " Yea, the ruin of states great and small " is
invariably traced to the same cause, the use of spirits.2 Prince
Fung, to whom the Announcement is addressed, says, " The people
of Yin had followed the example of the sovereign, and the vice of
drunkenness with its attendant immoralities extensively character-
ized the highest and lowest classes of society. . . . The disastrous
consequences of drunkenness are strikingly set forth ; he is called
to roll back the flood of its desolation from his officers and people."3

511. The furious drinking of those savages, and those only,
who have had little or no racial experience of alcohol, Red
Indians, Esquimaux, Tierra del Fuegians, Australasians, and
others, is too well known to need description. They tend to drink
themselves to death at a single bout.4 Often, as in the case of the
ancient Germans, their intoxication is accompanied by homicidal
mania, a cerebral effect that tends to procure the speedy elimi-
nation of the drinker, and in its extreme forms is rarely found
amongst peoples that have long used alcohol.

512. The facts concerning opium are very similar. It has been
used in India for hundreds of years. So rarely do the natives of
that country take it in excess that none of the scientific witnesses
who appeared before the late Royal Commission on Opium had
ever seen an instance. It was introduced into China about two
centuries ago with disastrous consequences, but already many
Chinese take it in moderation. In Burma, Polynesia, and Australia,
where it was introduced within the memory of living man, the
aborigines take it in such excess and perish of it in such numbers
that their white rulers are obliged to forbid its use to them, while
permitting it to natives of India, Chinese, and other aliens — just as
in Australasia and Canada they are obliged to forbid the use of
alcohol to the aborigines, while permitting it to the whites.

513. Narcotics, like most diseases, have two sets of poisonous

1 Samuelson, History of Drink, p. 19.

2 Op. cit,, p. 20. 3 Op. cit., p. 20.

4 See Alison's History of Europe, vol. i. p. 21, seventh edition.

SECRETIONS AND EXCRETIONS 307

effects, the immediate and the remote. The former are those
which are experienced at the time of indulgence or within a short
period after, and are due mainly to the direct action of the drug
on the nervous system. Probably the earliest effect is always a
greater or lesser degree of paralysis, which besets at first certain
'inhibitory centres' of the brain, and, therefore, may present in
the beginning an appearance of stimulation. Thus, after a small
dose of alcohol the heart tends to beat faster, owing to paralysis
of the centres which inhibit and control its movements, and there
may also be mental changes involving some loss of self-control.
A deeper degree of paralysis, involving other nervous centres,
constitutes obvious intoxication. This initial paralysis, with its
associated pleasurable sensations, is exchanged, some hours later,
when the poison is eliminated from the body, for the well-known
after-effects — the temporary illness which follows a bout of
excessive indulgence. The remote effects are mainly gradual
degenerative changes in many tissues, including the brain. As a
rule they do not occur until after chronic excessive indulgence
of some months, or, more commonly, years. In England few
deaths occur from the immediately poisonous effects of alcohol,
but amongst Red Indians and others, whose tendency to very
deep indulgence is greater, they are more common.

514. Alcohol is an excretion, a waste-product of the yeast
fungus, comparable as such to the urine or carbonic acid excreted
by man. Opium and nicotine, on the other hand, are real toxins
elaborated by the poppy and tobacco plants. They serve, like all
other vegetable poisons and like the toxins of microbic diseases, as
a means of defence against enemies. We have seen that an acquired
immunity to a disease is a capacity, developed under the stimulus
of use, to tolerate a toxin which was previously more poisonous.
We have seen, also, that many individuals of human races that
have had no previous experience of measles and other acute lethal
diseases, are able to acquire immunity against them, though indi-
viduals of races that have had long experience are able to acquire
it more easily. It follows that, in addition to having evolved special
powers of acquiring immunity against particular diseases, man has
evolved a general power of becoming able to tolerate toxins, which
again is a part of the general power of making use-acquirements.
Doubtless, it is on this account that experience makes the indi-
vidual so tolerant of opium and tobacco that he is able to consume,
without immediate poisoning, immensely increased doses.

515. But no amount of experience enables a man to increase

308 THE EVOLUTION AGAINST NARCOTICS

his power of resisting tuberculosis nor greatly increases his power
of tolerating alcohol. That is, he cannot acquire immunity to
the former nor learn to take, without intoxication, doses of the
latter, a waste product (the chemical composition of which is
much less complex than that of the toxins)1 a hundred- or a
thousand-fold larger than those which were immediately poisonous
to him at the beginning of his experience. Therefore, in the case
of acute diseases and opium and nicotine, man has a means of
protection which is absent in the case of alcohol and chronic
complaints such as tuberculosis. Consequently a race that is for
the first time introduced to an acute disease or to nicotine or
opium does not start " from the scratch." It is advantageously
situated. It has undergone a previous evolution which, by
enabling it to acquire immunity, places it in a position of
advantage. In the case of tuberculosis and alcohol it has to
undergo an evolution which, in each instance, must be begun
almost at the beginning. Under severe modern conditions, the
races of the New World are able to survive acute diseases and
undergo evolution, but tuberculosis exterminates them. There-
fore, evolution against tuberculosis is much the more difficult and
tedious. Similarly, evolution against alcohol appears to be more
difficult than that against opium. An evolution of a few hun-
dreds of years has rendered the natives of India 'immune' to
opium, but an experience of thousands of years has rendered the
British only in a measure immune to alcohol in the sense that
Italians are immune to it.

516. Tobacco may be compared to chicken-pox. Nearly all
sufferers quickly and easily acquire immunity against this disease,
and all tobacco-smokers are moderate in the sense that they do
not desire to reproduce the immediately poisonous effects which
they felt as beginners. So few people perish from the one or the
other that no evolution results. Therefore races that have long been
afflicted by chicken-pox suffer as severely as races that are newly
exposed to it, while races that have long used tobacco indulge in
it as deeply as those who have had no previous experience.

517. Opium may be compared to malaria. Malaria lies mid-
way between tuberculosis and chicken-pox. It is more acute than

1 The power of acquiring a toleration does not, however, depend entirely on
the chemical complexity of the toxin. Thus, while it is said to be possible to
increase the toleration for arsenic, an absolutely simple substance, no appreciable
increase of toleration follows the use of many vegetable toxins, for example
digitalis and strychnine. See § 413.

THE MEANING OF "IMMUNITY" 309

the former and more chronic than the latter. But since native
West Africans suffer more from it as children than as adults, and
since adult negro immigrants from non-malarious countries suffer
more at first than the native adults and more than they themselves
do later, it is evident that individuals of a race that has long been
exposed to it are capable of acquiring a considerable degree of
immunity. Apparently, average Englishmen gain no such increase
of resisting power.1 Nevertheless, judging from the direction taken
by the evolution, it is probable that members even of a race that
has had no previous experience have some power of acquiring
resisting power — a power which, though it does not afford much
protection to a majority of individuals, yet has selection value.
Similarly, opium lies midway between alcohol and tobacco. The
individuals of all races are capable of increasing their power of
resisting opium ; that is they are able to acquire the power of
taking greatly increased doses without immediate poisoning,
without intoxication. But individuals of races that have long
experienced it tend to take it in less excess, tend more to be
satisfied with non-intoxicating doses than races to which the
drug is new. Experience of opium, therefore, tends to place a
race in the same position of advantage that it occupies from the
first with respect to tobacco.

518. It should be noted that the term ' immunity/ when applied
to microbic diseases and to narcotics, has not identical meanings.
Immunity to disease implies a physical power of resisting infection.
Immunity to a narcotic is a mental phenomenon implying such an
insusceptibility to its charm that the individual is not tempted to
excessive indulgence. Nevertheless, the analogy between diseases
and narcotics is very close.

519. We see, then, that alcohol and opium act as agents of
selection in the same way precisely as lethal and prevalent diseases.
They eliminate particular types of individuals. Individuals differ
in their susceptibility. The more susceptible are eliminated and
as a consequence the race undergoes protective evolution. When
thinking of narcotics, the reader must bear in mind evolution in
general. All progressive evolution depends on selection, all
stringent selective elimination results in evolution. When the
whole of the facts are taken into account it is not believable that
alcohol and opium, which are so enormously destructive of life
and so plainly selective, can be an exception to the rule. It has
been objected that, since alcohol awakens unlike sensations in

1 See § 393.

3io THE EVOLUTION AGAINST NARCOTICS

different men, thereby causing them to drink for diverse reasons,
it does not eliminate a particular type. The objection is merely
verbal. Whatever the shades of difference, all men drink because
the act awakens pleasurable sensations — because it gives actual
pleasure or because it soothes discomfort or suffering. The type
which survives is one in which acute pleasure is not awakened nor
suffering soothed by deep indulgence. It would be as reasonable
to argue that carnivora are not causes of evolution in antelopes
because some of the latter are eliminated on account of dull hear-
ing, others for defective sight, others for insufficient speed, and so
forth. Nor, as we have seen, is the argument valid that selection
is not selection because it varies in intensity with time and place,
and is never absolutely thorough. Some people ask how the
susceptibility to the charm of narcotics can have arisen in the
human race, and appear to think that they have indicated a valid
objection. Probably it is a by-product correlated to mental evolu-
tion in general — a by-product which was harmless while mind was
evolving, and only became injurious when men discovered that
certain vegetable poisons were capable of producing delightful
sensations. But the question as to how it arose is one thing. The
question as to whether it, being existent, is a cause of selective
elimination is quite another thing. It certainly exists.

520. The theory that alcohol and opium, like lethal and pre-
valent diseases, are causes of protective evolution, is so opposed to
popular notions that it is apt to be received with initial incredulity.
I can only beg the reader to test the chain of fact and reasoning
link by link. I believe that he will conclude ultimately that, if
evolution has occurred in any instance, then it has occurred in this
instance also. Is it undeniable that men differ in the sensations
awakened in them by alcohol (and opium) ; that some are so consti-
tuted that after a given experience they are much more tempted
to excessive indulgence than others, for the reason that their
sensations are more pleasurable ; that, as a general rule, men yield
to temptation in proportion as they are strongly tempted ; that the
average moderate drinker shows no indication that he is strongly
tempted to deep indulgence ; that the average excessive drinker
shows every indication that he is so tempted, for otherwise no one
would do actions so painful and ruinous, both in the immediate and
remote future,; that he tends to transmit his degree of suscepti-
bility to descendants; that drink tends to shorten the lives of
excessive drinkers and otherwise lower the number of their possible
descendants ; that the amount of this elimination is large ; that

RACIAL DIFFERENCES 31 1

therefore alcohol is an agent of stringent selection ; that every race
on earth that has had little or no experience of alcohol tends to be
excessively intemperate when afforded the opportunity ; that
therefore this excessive susceptibility is the primitive condition of
humanity ; that every race that has had previous experience is tem-
perate in the presence of abundant supplies of alcohol in proportion
to the length and severity of its experience ; that therefore there is
no escape from the conclusion that such races have undergone
protective evolution ? The subject requires careful and unprejudiced
thought. Hitherto men have been content to accept without
question the simple belief that men are sober or intemperate in
proportion as they do or do not exercise self-control — a belief
which involves the corollary that, since drunkards are vehemently
tempted, therefore all moderate men are as much tempted but oppose
even more vehement resistance. The reader should test this hypo-
thesis by examining his own psychology and that of his intimates.
521. Formerly it was universally believed that certain races
(e.g. Italian and Spanish) were 'naturally' more temperate than
others (e.g. English and Red Indian). But since the theory of
alcoholic evolution was formulated, the surprising discovery has
been made that the races hitherto supposed to be the most
temperate are really the most drunken of all. Thus it is stated
that the per capita consumption in the South of Europe is greater
than in the North, and much greater than among Red Indians or
Australian blacks, and the ' obvious ' inference is drawn that South
Europeans are much the most intemperate of all. According to
this theory, if a party of one hundred men consumed two bottles
of spirits, each man taking his share, while one member of a party
of similar strength drank a whole bottle by himself, there would be
twice as much intemperance in the former party as in the latter.
In the South of Europe practically every man, woman, and child
takes alcohol ; but excessive drinkers are rare. In the North
multitudes of men, more women, and nearly all children take
no alcohol at all ; multitudes take it in moderation ; but a con-
siderable minority are excessive drinkers. The Western aborigines
are rarely able to procure alcohol ; but, when they have the
opportunity, they all of them almost invariably take it in excess.

522. Racial differences with respect to alcohol are admitted
by most people, but are attributed to all sorts of causes other than
evolution. Climate : Since South Europeans are sober, a warm
temperate climate has been thought to be conducive to moderation.
But only those races inhabiting warm temperate climates which

312 THE EVOLUTION AGAINST NARCOTICS

have undergone prolonged alcoholic selection are moderate. All
the rest, for example Andamanese, Red Indians, Polynesians, and
Australasians, are very drunken. Jews and South Europeans are
temperate in all the climates to which they migrate. West Africans
are temperate in the torrid zone.

523. Education, and general mental training. What is there in
the education of Jews and South Europeans that should render
them more capable of exercising self-control than North Europeans?
The upper classes in England and elsewhere amongst civilized
races are supposed to be better trained mentally than the lower.
Certainly they have more information derived from reading and
are also less inclined to excess. But the upper classes of the
present day are in general derived from those of former times, and
therefore are precisely the classes which have had the greatest
command of alcohol, and have been most weeded out by it
Recruits from lower to higher classes are almost always tem-
perate people ; contrariwise intemperance has lowered many
families from a higher to a lower stratum. There has been,
in this particular instance, a process of Social as well as Natural
Selection. It must be remembered that though education may
create a moral abhorrence, it cannot alter sensations — neither
those created by alcohol, nor tobacco, nor salt, nor sugar, nor
anything else. The sensations created by excessive indulgence in
a majority of people in the upper classes are apparently different
from those experienced by many in the lower, in that, on the
average, they are so much less pleasurable that they awaken desires
which are very much less keen. Poverty and its accompaniments,
hardship, want, overcrowding, dirt, insanitation, and lack of in-
tellectual pleasures are supposed to conduce to the intemperance
of our poorer classes. Doubtless they do, but to a very limited
extent. Under similar or worse conditions, for instance in the
East End of London, Jews and Italians are extremely temperate.
In their own countries the lower classes of South Europeans are
as temperate as the upper.1 The fact that South Europeans (e.g.
Italians and Spaniards) living in cities or engaged in manufactories,
tend to be more intemperate than their rural compatriots, has been
supposed to demonstrate the influence of the environment (i.e.
mental training) as against that of heredity. But the influence of
the environment has been denied by no one. It is maintained

:: It is interesting to note that while the intemperance of the English lower
classes is often attributed to their poverty, the comparative sobriety of the poorer
Chinese has been assigned to the same cause (see History of Drink, p. 32).

ALLEGED CAUSES OF INTEMPERANCE 313

merely that the degree to which any individual indulges depends
on the interaction of two factors, one of which (susceptibility)
is innate, and the other of which is environmental. Proof that the
environment is influential is not proof that innate'susceptibility has
no influence.1 It is known that when men are gathered together in
large numbers in cities or manufactories they tend, owing to the
relative lack of restraint, to be more intemperate in every way than
when living in the country. The question, therefore, is not whether
the individuals of the same race are more intemperate in one
environment than in another, but whether, when individuals or
races are placed under conditions that are practically identical,
the one individual or race tends to be more intemperate than the
other. Compare, for example, Italian peasants with English
peasants, and Italian ice-vendors and organ-grinders in London
with English street musicians and costers.

524. Strength of beverages. Races are supposed to be drunken
or temperate according to the strength of the beverages they
consume. No doubt a man who desires to get drunk will, as a rule,
if he have the opportunity, choose a strong solution of alcohol,
whereas one who is prompted mainly by thirst or taste will select
a more dilute and palatable drink. But it is quite as possible to
get drunk on a weak as a strong solution, and it is done very often.
More Englishmen are intemperate on beer than on spirits, and
on the average their alcohol is twice or thrice as dilute as the
wine of South Europeans.2 Those savages who are able to manu-
facture only very dilute solutions — or, indeed, no alcohol at all —
are the most drunken people on earth when opportunity offers.

525. Civilization is supposed to conduce to moderation. This is
certainly true, but not for the reason implied. North Europeans
are more civilized than South Europeans and West African savages,
but more drunken. Civilization has always implied abundance of
alcohol. Therefore all races capable of living under civilized condi-
tions have undergone alcoholic evolution. The incapacity of Red
Indians to resist alcohol is as much a bar to their survival under
modern conditions as their inability to withstand tuberculosis.

526. The memory of past disasters. Races, like the Italians,
which have suffered much — two or three thousands of years ago —
are supposed to bear in mind so keen a recollection of their
miseries that they are now temperate in consequence. Whereas
races like the English who have suffered less — but who are now

1 See § 693.

8 See The British Medical Journal, I5th Dec. 1900, p. 1733.

3H THE EVOLUTION AGAINST NARCOTICS

suffering, and for two or three thousands of years have been
suffering, are supposed to be proportionately less aware of the
dreadful results of intemperance, and on that account to be more
drunken. The existence of a temperance propaganda and of
prohibitory laws amongst North Europeans and their colonists,
and the absence of them amongst South Europeans, is a fit com-
mentary on this shocking nonsense.

527. Convivial and industrial drinking are terms which have
been applied to indulgence occurring during leisure and work time
respectively. Other things equal, men drink, smoke, play cricket,
or indulge themselves in any other way in proportion to their
desires. One of the " other things " is opportunity for indulgence,
which varies with time, place, and occupation. Thus I have two
occupations, medicine and authorship. I smoke a great deal when
I am writing, but not at all when I am attending to sick people.
So also a judge or preacher smokes less during the performance of
his duties than the average gardener. A coal-miner is forbidden
under the severest penalties to smoke or drink during his working
hours. He is even searched before descending into the pit. A
coal-porter on the other hand, is restrained from immoderate
indulgence in alcohol only by expense and the fear of the police.
It does not require a very high degree of intelligence to conclude
that, other things equal (e.g. a desire for alcohol), the average
porter will consume more during his working hours than the
average judge or miner. Again, some occupations demand delicate
manipulative skill, others nothing more than violent muscular
effort. The imbibition of a quantity of alcohol which interferes
little, if at all, with the latter, spells inefficiency in the case of the
former. For example, a watchmaker or engraver will become
incapable on smaller quantities of alcohol than a dock-labourer or
market-porter. As a consequence, others things equal, skilled
workers tend — if only by the dropping out of the incapables — to
be more temperate than rough labourers.

528. In two kinds of occupation, then, is excessive drinking
during working hours comparatively rare — those in which drink
is more or less inaccessible to the workman, and those in which
it quickly renders him inefficient. Speaking practically, all
* industrial ' drinkers are * convivial ' drinkers also. So that in
effect the former imbibe all day long, whereas the pure convivial
drinker, who is also a worker, imbibes only in the evening. Doubt-
less it often happens that the man who has been half drunk
previously becomes wholly drunk when his work is finished and he

A NEW INTERPRETATION 315

is comparatively free from restraint. Consequently, as might be
expected, industrial soakers consume more, and therefore suffer
more, than merely convivial drinkers. In point of fact, occupations
in which industrial drinking is easily possible show higher
proportions of illness and death from excessive indulgence than
occupations in which it is difficult or impossible.

529. In every occupation, even the coarsest, excessive drink-
ing, owing to the expense and loss of efficiency, is a bar, and is
universally known to be a bar, to success. If, then, a man, in spite
of pains and penalties — loss of health and efficiency, liability to
dismissal from employment, and the like — drinks to excess during
his working hours, it is reasonable to conclude that he is greatly
tempted by alcohol. Indeed, we may fairly conclude that on the
average such a one is more susceptible to its charm, more tempted
by it, than his fellow who abstains from prudential motives and
drinks only in the evenings when he is at leisure. That, at any
rate, I think, is the conclusion which ninety-nine people of normal
intelligence out of a hundred would reach. But a belief that men
drink alcohol for enjoyment and that individuals vary in the
degree and kind of enjoyment conferred by it leads inevitably to
a theory of alcoholic selection, a conclusion greatly disliked by many
people, especially temperance enthusiasts. Recently, therefore, a
new interpretation of the facts has been formulated,1 a considera-
tion of which will at any rate serve to demonstrate the dreadful
kind of thinking which finds favour with many earnest reformers.
We are told, in effect, that it is absurd to suppose that men differ
in the degree in which they are tempted by alcohol.

530. " It has led some less responsible students of the question
to assume that the view conveniently expressed in the formula,
that inebriety is a symptom of disease offers a complete and valid
explanation of all the facts of alcoholism. Thus it has been
asserted that intemperance is always a manifestation of a definite
brain condition which creates a specific craving for alcohol. And
some enthusiasts have even gone further, and, assimilating this
hypothetical drink-crave to a peculiarity of anatomical structure,
have regarded the potentiality of being a drunkard as a simple
inborn trait, which, we are gravely assured, being clearly unfavour-
able to its possessor, must secure his early elimination in the
struggle for existence, and so lead through natural selection to the
evolution of a race immune from drink !

1 See, for example, Alcoholism, by W. C. Sullivan, M.D. London: James
Nisbet & Co.

316 THE EVOLUTION AGAINST NARCOTICS

531. "Extravagances of this sort, apart from such direct
error as they may engender, are likely to have a mischievous
influence, in that they divert attention from the real biological
aspects of the question, and make an unnatural divorce between
the organic and social causes of alcoholism, which, as we have
already pointed out, can only be understood in their mutual
relations.

532. "For the proper apprehension of the question we must,
therefore, at the outset get rid of this figment of an inebriate
diathesis and replace it by the rational view, that the explanation
of inebriety is to be sought, not in any specific tendencies of an
abnormal brain, but in the reaction of the normal organism to
the ordinary physiological effects of alcohol." 1

533. Now very obviously the foregoing passage contains
numerous very grave, if unconscious, misrepresentations of the facts
and reasoning which led to the belief that there is such a thing
as selection by alcohol and that it has resulted in protective
evolution. Doubtless the alcoholic diathesis, the susceptibility,
has often been regarded as a symptom of a diseased mind.
Indeed, in England chronic drunkenness is in many cases
associated with mental defect,2 possibly because feeble-minded
persons have small powers of restraint.3 But no reasonably
well-informed student of heredity has ever held, as is implied in
the passage, that mental defect is a normal accompaniment of
the alcoholic diathesis. Were the latter a symptom of a diseased
mind we should have to consider all primitive humanity and half
the races now inhabiting the world, including the whole of the
aborigines of the Western Hemisphere, as mentally diseased.
Every one knows men and women of great intellectual power who
drink to excess, and it is not believable that North Europeans
are on the average more defective mentally than South Europeans.
Doubtless, the diathesis, through the indulgence it tends to
provoke, is a frequent antecedent of disease, but by itself it is no
more a disease than temerity is a wound.

534. Again, no students of heredity and evolution, not even
"less responsible students," have assimilated this hypothetical
drink-crave to a peculiarity of anatomical structure, unless by
that is meant the belief, common to all psychologists, that
mental facts are correlated to cerebral facts. If the " potentiality

*0p.cit.,pp. 58-9-

2 See Branthwaite, British Journal of Inebriety, Jan. 1908.

8 See § 699.

INDUSTRIAL DRINKING 317

of the drunkard " is not in the last analysis " a simple inborn
trait," then, in the name of clear thinking, what is it ? Even
if we suppose it to be an acquirement, we must in the last analysis,
as in the case of other acquirements, postulate an inborn foundation
for it. Whether the inborn foundation is simple or compound is
irrelevant. The word ' simple ' has not to my knowledge been used
by any adherent of the theory. Possibly we are all potential
drunkards in the sense that, under very exceptional circumstances,
we are all capable of acquiring a liking for intoxication ; but it
is beyond doubt that some of us are so constituted that we become
drunkards more readily than others. This liability to acquire
a liking for intoxication is the diathesis, the inborn trait, the
susceptibility. If the writer from whom we quote means to imply
nothing more than that the diathesis is not the only factor in the
causation of inebriety, then his language implies also that some
one has stated that it is. But, in point of fact, no one has been
so excessively foolish. The influence of education, fashion, self-
restraint, accessibility of alcohol, and the like have all been fully
admitted. For example, it has been admitted that abstainers,
who will not drink, and Fuegians who cannot procure drink, may
have the diathesis strongly developed and yet not be drunken.
It has been held only that the craving for drink is the resul-
tant not of one factor, but of two, inborn susceptibility and
previous experience, and that the greater the susceptibility the
more easily does the experience awaken the craving. Yet again,
no one has so much as hinted that alcoholic evolution would
lead to a race ' immune to drink ' in the sense implied. Evolution
is never perfect. It has been maintained merely that evolution
tends so to decrease the susceptibility of a race exposed to
selection that it becomes increasingly temperate, even in the
presence of increasing supplies of alcohol.

535. During the Middle Ages the belief was prevalent that
alcohol — presumably in moderation — was beneficial to health
and strength. Rightly or wrongly — wrongly, I think, except in
certain cases of depressed health — this belief has survived to the
present day, particularly amongst medical men and nursing
mothers. I suppose, however, that no human being who has
an average experience of life, and is not a real lunatic, believes
that alcohol taken in excess is beneficial. By excess I mean here
an amount which obviously impairs health and efficiency. Certainly
no sane excessive drinker, however ignorant, no man who has
experienced the resulting temporary paralysis, indigestion, loss of

3i8 THE EVOLUTION AGAINST NARCOTICS

appetite, headache, thirst, 'hot coppers,' nervousness, delirium
tremens, and the rest, is under any such delusion.

536. It is true, of course, that, if a soaker of the lower classes
be questioned, he may lie, and, like sots of a higher social standing,
may excuse himself by declaring that he takes alcohol for his
health's sake, or his work's sake, or his stomach's sake ; but the
last to believe him will be his own mates, who perceive in
him the consequences of heavy drinking. To ascertain his real
sentiments it is only necessary to ask his opinion of some other
soaker — of one who drinks to the same excess as himself. Indeed,
when sick, sorry, and repentant, he will admit his fault, and swear
an amendment, which, as a rule, temptation subsequently annuls.
He knows, of course, that " a hair of the dog that bit him " will
temporarily mitigate the unpleasant feelings aroused by previous
drinking ; but he knows also that the only permanent cure for
his miseries is abstinence or moderation. In many cases, lack of
money will afford experience of the advantages of sobriety.
That his virtuous assumption of drinking for his work's sake is
a pure fiction is proved by the fact that, when he has lost his job
and is idle, he drinks, if he can, as much as or more than ever.
Moreover, for thousands of years laws against excessive drinking
have been common, and denunciation of it an everyday affair.
Almost every pulpit, schoolroom, and reputable newspaper conducts
a campaign against it. The temperance question is, and has long
been a burning one with the public. Our workmen have a collo-
quialism, " drinking himself to death," which is commonly applied
to chronic soakers. Slums, workhouses, prisons, and asylums are
full of the victims of alcoholism. Whenever possible, employers
insist on sobriety. In every workshop and factory the men who
abstain, at any rate during working-hours, are known to achieve
better results and greater prosperity than their fuddled comrades.

537. In spite of all this — by way of proving that there is no
such thing as alcoholic selection — we are now assured that the
British workman who imbibes to excess, drinks, not because he
enjoys drinking, but merely as an aid to labour. "This is the
fundamental factor." 1 It is supposed that he is poisoned day by
day and ultimately perishes, not because he is tempted by pleasure,
but on the altar of duty; whence it follows, that the people
eliminated by alcohol are not those who are especially tempted by
it. The fact that every race is temperate precisely in proportion
to the length and severity of its past experience of drink is quietly

1 Alcoholism, by W. C. Sullivan, M.D., pp. 115 ; see also pp. 61, 114, 116.

INDUSTRIAL DRINKING 319

ignored. It is admitted that the " worker who does his labour with
the help of alcohol is sure to have recourse to the drug for his
ideals of pleasure," l and that " exceptions to this rule are rare." 2
In other words, while it is admitted that after five or six o'clock
the worker drinks for the sake of enjoyment, it is assumed that
before that time he drinks from altruistic motives. With the
setting of the sun his sensations are supposed to undergo a
radical change. We are told, therefore, that, to wean workmen from
excessive drinking, nothing more is necessary than to convince
them that the habit is injurious to health and work. Thereupon
industrial drinking, the only harmful form of indulgence, will cease.3
538. The unconscious humour of this surprising hypothesis is

1 Op. cit., p. 62. 2 Op. cit., p. 87.

3 The hypothesis under discussion is interesting as a type of, and is really not
much more absurd than a great deal that has been written on the problem of,
alcoholism since the theory of alcoholic evolution was formulated. For example,
if we seek to demonstrate the existence of alcoholic selection and its corollary
evolution, plenty of people will at once inform an astonished public that universal
intoxication is advocated as a cure for national drunkenness. If we protest that
we advocate no such thing and that we would object to it as strongly as to
universal disease, the reply is that it follows logically from our opinions. It is
quite useless to indicate to intelligences of this order that their logical conclusions
are not necessarily ours, especially when we have strongly and categorically
repudiated them ; that unpleasant truths are not the less true for being unpleasant,
and that the only rational way of refuting opinions they dislike is not to make
mis-statements but to break the actual chain of alleged facts and the inferences
drawn from them. It may be thought that I am unfair in saying that the drunken
British workman is described as sacrificing himself on the altar of duty. But
clearly, if drinking makes a man feel better, if it creates in him a " sense of well-
being," if his dislike of labour is lessened thereby, he is susceptible to its charm.
The hypothesis that men who vary in all known characters do not vary in this one
particular of receiving pleasure from alcoholic indulgence is too grotesque for
serious discussion. It has been trumped up by people unfamiliar with the facts
of biology to meet the exigencies of the moment. Therefore, if it be said that
men drink because of the sense of well-being which the act creates in them, then,
since it is admitted that alcohol is a considerable cause of ill-health, incapacity,
and death, that poison must tend to eliminate especially people who are most
susceptible to its charm. It follows that the hypothesis under discussion, which
is supposed by its supporters to controvert the theory of alcoholic selection, can
do so only when it premises that men at work drink alcohol, not because they
like it, not because it creates a sense of well-being, but from some other cause.
The cause alleged is a superstition, said to be derived from the Middle Ages and
still prevalent amongst workmen, that an amount of drinking, which anyone not
a lunatic would know to be injurious, is an aid to labour. Apart from its amazing
inferences, the volume from which I have quoted is an excellent work. It is
well and clearly written, contains a mass of useful statistics, and proves — if proof
be needed — quite conclusively that, other things equal, men drink most when
their opportunities are greatest, and that the man who drinks to excess all day
long suffers, as a rule, more than the man who drinks only in the evening.

320 THE EVOLUTION AGAINST NARCOTICS

greatly enhanced when we read the facts and inferences on which
it is founded. " The petition of the Middlesex magistrates, for
example, in support of the Gin Act of 1736 especially singles out
journeymen and apprentices as the classes particularly addicted to
this sort of excess " l (i.e. industrial drinking). Surely it is suffi-
ciently clear that the action of the magistrates indicated a know-
ledge that excessive drinking in work time is injurious, and that the
drinking of the journeymen and apprentices was excessive. The
notion that industrial drinking is a comparatively modern in-
stitution is absolutely erroneous. In many parts of Europe, for
thousands of years, water has only exceptionally been used as a
beverage. Even as regards our own country, it may be laid down
as a general rule that, before the introduction of tea and coffee,
men, whenever able, used alcohol at all times of the day, both when
working and playing. Beer and cider were common industrial
drinks with our ancestors, especially with agricultural labourers, who
were the great majority of the nation, and to whom it was customary
to make a regular allowance. The condition of affairs now pre-
valent in Russia, as depicted in the following extract, formerly
obtained in England.

539. "Feodor asked me if I would like to go to the haymaking
next day. . . . ' Is Feodor at home?' I asked. Then a man
appeared from a neighbouring cottage and said, ' Feodor is in the
inn — drunk.' * Is he going to the haymaking ? ' I asked. ' Of
course he is going.' ' Is he very drunk ? ' I asked. ' No, not very ;
I will tell him you are here.' Then a third person appeared, a
young peasant in his Sunday clothes, and asked where I was
going. I said I was going to make hay. ' Do you know how to ? '
he asked. I said I didn't. * I see,' he said, ' you are just going to
amuse yourself. I advise you not to go. They will be drunk, and
there might be unpleasantness.' . . . Then the haymaking began.
The first step that was taken was for vodka bottles to be produced,
and for every one to drink vodka out of a cup. Then was a great
deal of shouting and an immense amount of abuse. ' It doesn't
mean anything,' said Feodor. ' We curse each other and make it
up afterwards.' Then they drew lots for the particular strip they
should mow; each man carried his scythe high on his shoulder.
(' Don't come too near,' said Feodor ; ' when the men have taken
drink they are careless with the scythes.') " 2

540. The following are descriptions of devoted workmen who

*Qp.cit.,p. ii.

* Maurice Baring, A Year in Russia, pp. 291-3. London : Methuen & Co., 1907.

INDUSTRIAL DRINKING 321

are supposed to believe that really tremendous drinking bene-
ficially affects their working powers : " We may take as a type for
our description the originally healthy workman who is engaged in
a trade that encourages, or at least allows, the habit of regular
drinking throughout the working day, and who probably goes in
also for an occasional convivial bout at the week-end or on special
festivals. After a period, longer or shorter according to the
intensity of his excesses, such a drinker will begin to show signs
of more or less persistent disorder, usually in the digestive and
nervous functions; he will be aware of a diminished and more
capricious appetite ; he will suffer from pain and oppression
referred to the region of the heart ; he will often have nausea or
vomiting on awaking in the morning ; his sleep will be disturbed
by disagreeable dreams, by attacks of muscular cramp, by electric
starts in the limbs ; more or less tremor in the hands and feet,
and in the tongue and muscles of the face, will be evident early in
the day.

541. "As the intoxication continues, and by its own effects
supplies the motive for increasing excess, all these symptoms
become aggravated ; the morning sickness is regular, and is often
accompanied by the vomiting of blood ; the tremor is constant ;
nightmares and insomnia divide the hours of rest, and foreshadow
characters which will appear later in the full development of
delirium tremens."1

542. " As can readily be imagined from the amount of the
docker's average wages, the non-alcoholic part of his dietary is apt,
under any circumstances, to be deficient, and the money which he
spends on liquor leads necessarily to a further lowering of his
ordinary food allowance. Not only does his dinner money very
frequently go on beer before the meal time arrives, but even when
he brings his dinner with him from home he will often sell it for
a few pints to some more temperate comrade. This condition of
under- feeding contributes, of course, to the more rapid development
of the lesions of chronic alcoholism ; and it is usual for industrial
drinkers at this work to suffer from gastric catarrh and severe
nervous disorders before they reach the age of forty." 2

543. " The industrial drinking habits which we have described
in the ordinary docker class reach a further degree of development
in some special varieties of waterside labour. We may take as an
instance the Thames Street fruit porters. Amongst these porters
the method of work and payment is this : The overseer takes on a

1 Op. tit., pp. 49-50. * Op. tit., p. 8 1.

21

322 THE EVOLUTION AGAINST NARCOTICS

limited number of men, each man paying a nominal deposit for his
knot ; the porter then starts work, receiving at the warehouse door
for each box he takes in a brass ticket marked with the amount of
his fee, id., 2d. or 3d., according to the size of the box. These
tickets he can get changed for money later in the day by the clerk,
or he can bring them at any time to a public-house which enjoys
the special privilege of cashing them, the porter taking a certain pro-
portion of their value in drink. The second alternative is, of course,
nearly always adopted, and, as a consequence, a large number of these
men do their work almost exclusively on beer. As soon as its effect
is sufficiently visible to suggest risk of accident, the man has to give
up his knot for the day, and is replaced by a fresh hand. These
conditions produce the maximum development of industrial
alcoholism." 1

544. The belief that parental drinking commonly tends to alter
the germ-plasm, and so results in filial degeneration, was universal
until recently, and is still very prevalent amongst medical men.
As in the case of diseases it is founded mainly on * common sense,'
and on statistics which indicate that the progenitors of physical
and mental ' degenerates ' have often been intemperate. Every
reason which is valid against microbic disease as a cause of
degeneracy is valid against alcohol. It is not to be denied, of
course, that parental drinking may sometimes (when the germ-
plasm has varied unfavourably in such a way that it has lost its power
of resistance) be a cause of filial degeneracy, but in view of the
fact that races which are now temperate are not degenerate, but
were originally drunken, it is impossible that it can be a common
cause. It must be remembered that in the case of many races
alcohol like malaria affects practically every individual. We have
all known people, derived from drunken stocks, who were physically
and mentally fit and capable — that is, people whose germ-plasm
was resistant to the direct action of alcohol. It follows that, even
if alcohol does tend commonly to alter the germ-plasm, especially
on its first introduction to a race, the constant elimination of
susceptible strains and survival of resistant types would infallibly
tend to establish a high degree of insusceptibility.

545. To sum up — the questions the reader must decide when
studying alcoholism from the point of view of heredity and evolu-
tion are'(i) What, fundamentally, are the motives which induce
men to become intemperate ? Do they drink to excess because
they enjoy the sensations thus awakened, or from some other motive,

1 op. tit., pp. 83-4.

THE CHIEF PROBLEMS OF HEREDITY 323

such as a sense of duty ? (2) Do men differ in their ' by nature '
susceptibility to the charm of alcohol ? (3) Is alcohol a lethal agent ;
and, if so, is it selective ? (4) Bearing in mind the universal truth
that races are temperate when exposed to alcohol in proportion to
their past experience of it, but show no other change that can be
traced to it, is alcohol a cause of protective evolution or of degenera-
tion? The very obvious truths that men of the same race drink,
as a general rule, more when their opportunities for drinking are
greater, and that the amounts they drink depend to some extent
ou their previous moral training, are not in dispute.

546. Two problems of heredity are of outstanding importance.
The first is the problem of the causation of variations. The second
is the problem of the proportion which the ' innate ' characters of
any species bears to its ' acquirements.' In the section of this
work just concluded we have considered, by the light of the evidence
furnished by microbic diseases and narcotics, the problem of the
causation of variations, and have concluded that, when we take all
the evidence into account, it is inconceivable that the great mass
of variations can be other than spontaneous. In the next section
we shall consider the second problem. For this the study of mind
affords peculiar facilities.

CHAPTER XVII
IDEALISM AND COMMON SENSE1

Mental adaptation — Objections to the hypothesis that minds are products
of evolution — Memory — Sense-impressions — What a sheet of paper means —
We are directly aware of nothing but a stream of feelings — The mental differences
between the higher and the lower animals — How we construct external objects —
The differences between feelings ordinarily recognized as such, and those which
are thought of as properties of external objects — Idealism and common sense —
Coherent thought and common sense — Except at rare intervals all men think in
terms of common sense — There are no thorough-going idealists — The two views
are quite incompatible — Invariable succession and necessary succession.

T

$47. f | ^HE bodies of the higher animals are compounded of
' characters/ which, in turn, are compounded of
smaller characters. With the possible exception of
a few traits (by-products of evolution) correlated to more useful
traits, the larger and older characters — hands, limbs, hair, nails,
and the like — are almost all adaptations ; or, if vestigial remains,
have been adaptations. The smaller and newer characters, the

1 Many of the words used in the following discussion (chapters xvii., xviii.
and xix.) have gathered special meanings during the course of controversy.
By matter I mean something which is not mind, but which exists external to mind,
and has properties that excite sensations in it, and is thus mediately known to it.
By feeling I mean not merely sensation, but any state of consciousness. By
mind I mean the stream of feelings. By idealism I mean the philosophy which
supposes that " the sensations, which, in common parlance, we are said to receive
from objects, are not only all we can possibly know of the objects, but are all that
we have any ground for believing to exist," and which declares " we have no
evidence of anything which, not being itself a sensation, is a substratum or
hidden cause of sensations," and that " such a substratum is a purely mental
creation to which we have no reason to think that there is any corresponding
reality exterior to our minds " (J. S. Mill, Examination of Sir William Hamilton's
Philosophy, 3rd ed.). By common sense I mean merely the notion, held con-
sciously or unconsciously by every one during ordinary thought, that our minds
tell us of a universe of real or material things external to the minds. I do not use
the word as implying immediate or intuitive cognition of real things. I have
thought the discussion necessary, partly because I wish, as far as possible, to
establish the nature of the relation between mind and body, and partty (since it is
sometimes said that science explains nothing, and that there is no such thing as
necessary truth) because I wish to define what appears to me to be the scope of
science, and the significance of certain terms that I use, such as cause, invariable
succession, necessary succession, necessary truth, explain, and understand.
324

MENTAL ADAPTATION 325

variations, are not necessarily adaptations, but they are the
materials out of which nature manufactures adaptations. The
constant occurrence of them is an adaptation. Similarly, the
minds of animals are compounded of characters — sense-impres-
sions, emotions, memory, and the like. Doubtless, individuals and
races differ, on the average, as much in mind as in body ; yet, here
again, the older and the more important, the specific or varietal
characters, the ' faculties,' are all or almost all adaptations. We
can think of no animal that affords evidence of possessing mind,
but we find that it is as certainly adapted mentally as physically
to its environment. For example, human sense-impressions,
emotions, instincts, and memory all fulfil this function. Therefore,
when studying mind as when studying body, we must ever keep
this great truth of adaptation before us. The facts are such, that
if our hypotheses, our interpretations of the facts, do not accord
with it, they are certainly erroneous.1

548. We saw that, when the whole of the facts are taken into
account, only two hypotheses of the causation of physical adaptation
are conceivable, or at any rate have been conceived, with any
degree of clearness — miracle, and natural selection. This is not less
true of mind. We are bound in science not to appeal to the
supernatural till it has been demonstrated that natural explana-
tions are inadmissible. Nevertheless, some writers, even amongst
those who believe that the human body has evolved under the
action of Natural Selection, have been inclined to attribute to
mind a supernatural origin. On the one hand, they have insisted
that mind is so unique that it can have been evolved out of nothing
else in nature ; on the other, they have asked how it is possible
that such human ' faculties ' as the mathematical, the musical, and
the devotional, which, seemingly, have never contributed to the
preservation of life, can have been brought into being by the
action of Natural Selection. Mind is certainly unique ; neverthe-
less, as we shall see, this difficulty is not absolutely insurmount-
able. At any rate, it is not a unique difficulty. It is not a greater
difficulty than many others which science first ignores and then
proceeds as if they had been surmounted, leaving the consideration
of them to metaphysics, which seeks to be more thorough.2 The
study of memory, intellectually the most important of all the
faculties, has been constantly neglected, and we shall find that
the evolution of this one character, easily explainable by the
theory of Natural Selection, furnishes the key to all such appa-

1 See §§ 616 and 648. 2 See § 590.

326 IDEALISM AND COMMON SENSE

rently unsolvable riddles as that of the existence of the devotional
and mathematical faculties.

549. The moment we begin to discuss mind in any but a very
superficial way, we encounter the problem of the connexion be-
tween mind and body. Unless I start by dealing with this problem,
and making quite clear my own beliefs and the reasons why I
hold them, some of my readers will presently raise hands of horror,
and declare that I am not scientific, but metaphysical. Probably
some of them will do so in any case. For my own part, I propose,
in this and the two succeeding chapters, to be much horrified at
the metaphysical attitudes of other people. In the end I think
I shall be in a position to insist that, if I am metaphysical,
I am so only to an extent that every one must be metaphysical.

550. I am writing on a sheet of paper. For the moment I am
thinking of it, in the ( common-sense ' way usual with me and other
people, as a real substantial thing, of the existence of which I am
aware through my senses. My sight and touch tell me that it is
oblong, thin, and smooth. My sight tells me that it is white, and
marked in parallel blue lines. Sight, touch, and hearing assure
me that it is crisp. Smell informs me that it has a faint, pleasant
odour. Taste would inform me that it has a flavour which is not
pleasant. Muscular sense declares that it has weight. Thus, in
ordinary colloquialism, the sheet has ' caused ' certain sensations
in me, by means of which I perceive it, by means of which I gain
a perception of it. Memory supplements this information ; I link
up the sensations I have just received with other information which
I received in the past, and with thoughts concerning it. I recognize
this thing which now lies before me as what I have been accustomed
to term a sheet of paper. That is, I form a conception of it as a
sheet of paper.

551. But to go deeper, what is the real meaning of the statement
that my senses and thoughts have given me information ? Obvi-
ously I can be aware of nothing, including my own body and even
my mind, except through sensations, recollections, and thoughts,
through my feelings. They are the only conceivable means of
communication between the universe and that inner essential me
which I am accustomed to regard as possessor of mind and body,
and the observer of my universe.1 Now, still using the language

1 This is not to say that there is any such inner essential " I." There may be.
I do not know. I am conscious only of a changing stream of feelings amongst
which are feelings by means of which I contemplate (recollect or foreshadow)
other feelings which are past or which may arise. I say only that in my everyday
thinking I am accustomed, more or less unconsciously, to postulate this being.

MENTAL SYMBOLISM 327

of common sense, of everyday life, consider the sense of sight.
We are told that I see the paper because light, which is some sort
of vibration in the ether that surrounds us, passes from a luminous
object (e.g. the sun) to the paper, where some of it is absorbed, and
whence the remainder is reflected to the retina of my eye, where
it sets up chemical changes. These chemical changes set up other
chemical or molecular changes in my optic nerve. These, yet
again, set up other similar changes in my brain. Thereupon
there dawns within that dark box, my skull, a feeling which I
call a sight of the paper. In an analogous way my other
senses convey their items of information. Now, plainly, feeling,
which has neither extension, nor colour, nor weight, nor any
other of the properties which I am accustomed to ascribe to
material things, cannot in the remotest degree resemble the
chemical changes in my brain, optic nerve, or retina, or the
vibrations of the ether that lies between the retina and the paper.
Nor can it, an immaterial thing, resemble the material thing, the
paper. It can, at best, be only a sign and a symbol to me of the
real thing, the paper.

552. I find that some of my feelings are so unlike that I can
institute no comparison between them. Thus the ' crisp ' sensation
of touch which I get when I indent the paper is quite unlike the crisp
look of it, or the crisp crackle I hear. I use the same word in each
instance, but the several sensations it describes are not at all
similar. I may say, indeed, that all these sensations are faint or
vivid, but then I indicate no essential likeness except the degree
in which they impress me. If feelings may be incomparable, how
much more incomparable must be feelings and material things?
Besides, how can light, undulations in the ether, passing between
the sheet of paper and my eye, convey anything at all like a real
sheet to my retina ? How can the series of changes in my
optic nerve convey anything of the sort to the brain ? How
can the series of changes in the latter create or accompany a
feeling which is remotely like the paper ?

553. I write the word 'paper/ and it stands to me for a sign
and a symbol of the sound, the spoken word * paper/ which it is
incomparably unlike. Similarly, the spoken word is only a symbol
of the seen, felt, heard, tasted, smelt, or weighed thing, ' paper.'
So also, in a sense even more thorough, my several feelings of paper
are only signs and symbols of the * real ' thing, which, as I suppose,
awakens them. That real thing is altogether outside the circle of
my consciousness, within which are nothing but feelings. By no

328 IDEALISM AND COMMON SENSE

manner of means can I gather anything more than a symbolic
knowledge of it.

554. Indeed, to go yet deeper, it is a question whether I can
gather even a symbolic knowledge. I have surmised that my
feelings have been awakened by a real object, but it is impossible
to test that hypothesis. The symbolism of my dreams, if symbolism
it be, is, I am accustomed to believe, very misleading. How can I
know whether the symbolism of my waking hours is of a more
truthful kind ? My waking feelings seem to link together better
than my dream feelings, but the fact that they link better together
does not prove that they are symbols of anything. At any rate
this is certain, that what I term the ' properties ' of the material
object, extension, weight, colour, and the like, are really feelings
in me. Strip the material object of these properties, of these my
private feelings, and what remains of it ? The remainder, if
remainder there be, the ' matter in itself,' the noumenon^ is quite
inconceivable. For me it has no thinkable existence. I close my
eyes, and have a recollection of .the sheet. That recollection is
not more a mental and less a material thing than the perception
I had when my eyes were open.

555. It is evident that the only existence of which we are really
aware is a stream of feelings. That stream of feelings is the whole
of consciousness. For us the universe is a universe of appearances,
of phenomena, which we construct out of our own feelings. Time
and space are only modes of thought, the former being concerned
mainly with appearances that occur in succession, the latter with
appearances which co-exist. We speak of mind and matter, but
from first to last we know of nothing but mind. We are conscious
of nothing else. Matter is a metaphysical abstraction, an unknown
and unknowable something which has been surmised by common
sense, but only surmised, to be in some way the cause of phenomena.
But our minds are so constructed that we are impelled to attribute
material existence to many appearances. Thus this sheet of paper
appears to me a thoroughly material object. If I tear, or burn,
or crumple it, I seem to be wrecking a material thing with material
hands. It is only when I pursue a very unusual line of thought that
I am able to realize that I am dealing throughout with groups of feel-
ings which experience tells me tend to follow one another in certain
sequences. The sight of the paper, the intention to tear it, the
sight, and sound, and tactile sensations of tearing, and the feeling
of an intention accomplished are all equally mental phenomena.

556. We shall see later that it is probable that animals low in

THE CIRCLE OF CONSCIOUSNESS 329

the scale of life, for example most insects, intuitively regard the
objects revealed to them by their senses as real existences. On
the other hand, it is likely that the human mind begins as a chaos
of feelings, some of which, by a process of gradual and unconscious
inference, are ultimately referred to external bodies as properties
or qualities of them. In other words, the insect has an intuitive
belief in the existence of the universe which his mind constructs,
while the human being slowly builds up a similar belief.1 The
latter then divides his feelings into classes, one of which is regarded
as a collection of mental happenings, and the other as a collection
of external objects. Thus the pain caused by a cut from a knife
is regarded as a feeling, whereas the colour, extension and weight
'of the knife' are supposed to be properties of a material object.
Ultimately the human being finds it extremely difficult to think and
speak of his ' physical ' universe as other than a collection of external
objects. Both thought and language become moulded on that belief.
Thus I, while insisting that material objects are unknown to us, have
just used words which imply an unquestioning faith that insects,
human beings, and knives are realities external to me. I have also
used the words ' we ' and * us,' and have written this book on the as-
sumption that other people will read. But other people, other minds,
are just as much unknown to me, just as much outside the circle of my
consciousness as sheets of paper. Indeed, other minds are, if any-
thing, more outside the circle of my consciousness than material
bodies ; for I can only arrive at the notion of these other minds by
observing that bodies move in such a way (talk, gesticulate, etc.)
that they seem to be, like my own body, under mental control.

557. And now I wish to fix the reader's attention on a matter
which is of very great importance, but which is never accorded due
weight. He must bear with me if I use such words as * reader,'
c nurse,' ' wall,' and the like, and so constantly express myself in
common-sense terms. Language affords no other way of indicat-
ing my meaning. If I had always been an idealist, if from the
beginning I had ever regarded my feelings merely as feelings, if I had
never draped them about supposed external objects as properties of the
latter, if 1 had never put a materialist construction on them, I should
now be living in a chaos of unmeaning feelings. We do not know
to what extent a newly born infant has an intuitive belief in an

1 Of course, I do not mean that the human infant at first regards all his feelings
merely as feelings and afterwards changes his opinion. Like the insect he does
not think about it. I mean merely that he learns to do that which the insect does
intuitively.

330 IDEALISM AND COMMON SENSE

external world, but there are good reasons for believing that his
intuitions cover but a very small portion, if any portion, of his total
mental field. He is emphatically a creature who learns. When I was
born, a flood of new, and strange, and doubtless incomprehensible
feelings beat upon me. Probably, for example, the walls of my room
were not conceived, as they were later when my education was well
advanced, as material things having extension and other properties ;
they were only patches of light and shade, and were not even thought
of as such. The nurse consisted only in similar patches. Her
movements resulted in changing patches which were not dis-
tinguished from the changes caused by the purposeless movements
of my own eyes. Probably the sounds she made as well as the
feelings that came from my skin and other organs were not
differentiated, were not understood, in any way.

558. But gradually my wonderful faculty of memory did its
work. By means of it I stored impressions in my mind, and learned
with ever-increasing power to link them together.1 And this link-
ing was performed, not merely by recording likenesses and
differences, coexistences and sequences, but also by processes of
inference which were none the less real because at first rudimentary,
and of only gradual growth in scope and accuracy. In this way
groups of feelings gained coherence, and linked themselves to other
groups. Thus, at length, I gathered the notion that certain
patches of light and shade proceeded from a permanent material
wall were properties of the wall. Thereupon all the feelings
successively excited by the wall began to fall into their places, like
pieces in a well-designed mosaic. Though the patches changed
when my position was changed, or when there was more or less
light, or when the direction of the light was changed, or when the
nurse moved about, yet I began to connect all such changes not
with changes in the wall, but with changes in my position, and so
forth. Another vast group of feelings linked themselves together
in the notion of a material nurse, and cohered notwithstanding even
greater changes in her. An even vaster group were gathered in
the notion of a body, consisting of head, trunk, and limbs, which
I came to regard as peculiarly mine, which was I, and from which
I derived some feelings (e.g. ' physical ' pain and pleasure) that were
unlike those excited by all other bodies.

559. Here then is the point I wish to emphasize — the truth that
/ have been able to classify by feelings, and become a rational
being) only because from early infancy I have referred them to

1 See § 666.

THE CONSTRUCTION OF THE UNIVERSE 331

external objects. In other words unless groups of my feelings had
draped themselves about a supposed material wall, and others about
a supposed material nurse, and so on, they would not have cohered at
all. It was the hypothesis, which gradually and inevitably, owing
to the constitution of my mind, I formed of the existence of external
objects that gave them meaning and order, and, therefore, coherence.
Otherwise my memory could no more have held them together
than it now can the shifting colours of a kaleidoscope. Though
all the evidence indicates that our memories are particularly re-
tentive when we are young,1 yet I can remember nothing of what
happened to me during early infancy. It is hard to explain this
fact except by the hypothesis that my world was then for me a
very complex kind of kaleidoscope that furnished not only
sensations of sight, but multitudes of other sensations as well, which,
because they were then incoherent, could not be remembered. It is,
therefore, the coherence of my sensations about supposed external
objects that has rescued me from chaos.

560. To illustrate by an example how my * material ' world was
created : a little while ago I linked together a group of entirely
dissimilar feelings (visual, tactile, etc.), by conceiving them as
properties of a sheet Bof paper. This group I then linked with
other groups, other sheets of paper, the recollection of which had
dwelt more or less vaguely in memory, and by thinking about
which I had reached the general conception of a sheet of paper as
distinguished from perceptions and recollection of particular sheets
of paper. The economy of thought achieved by means of such
general conceptions is very great; thus I do not now need to
remember thousands of individual sheets of paper, but only a con-
ceptual one which is my notion of that kind of object. Now, again,
as I sit thinking, I link up the group of feelings which represents
to me the sheet of paper with another group which represents the
table on which it is lying. The compound group thus constituted,
forms part of a more highly compounded group which represents
the room in which I am. That, yet again, is linked with memories
of the room, with memories of the house and its inmates, the street,
the town, the surrounding country, the whole of my world. So
the universe as conceived by me was constructed. Very early a
division was made between feelings which were recognized as feel-
ings (e.g. emotions and recollections) and groups of feelings which
were supposed to be material objects in the external world. Only
long after manhood was reached did I begin to suspect that I

1 See § 652.

332 IDEALISM AND COMMON SENSE

have never been really aware of anything but my private
feelings.

561. Between the feelings which I ordinarily recognize as mere
feelings (recollections, imaginings, and the like), and those which
I refer to external objects as properties of them or as caused
directly by them (i.e. my sense-impressions), there exists a vast
difference. Thus, what I suppose to be the sight of a dog, or the
pain caused by his bite, is immensely more vivid than my thoughts
about such an event Moreover, sense-impressions follow one
another in an infinitely more coherent and orderly way than do
thoughts. Indeed, so orderly is the procession of the former that
we feel intense surprise when the usual order is apparently broken,
and we immediately cast about to restore it, or, in other words, to
discover a cause for the break, which we firmly believe to be only
apparent. Thus, if I had the feeling of a dog biting me when no
dog was in sight, I should feel unbounded astonishment, and should
immediately form all sorts of hypotheses to account for the event.

562. Doubtless, it is this peculiar vividness, and above all
coherence of sense-impressions, the way they link themselves in
related groups, which cannot be altered at will but may be verified
by repeated observation even after a length of time, that has given
rise to my notion of external objects (included amongst which
is my own body) ; whereas the lack of a similar coherence and
vividness amongst other feelings (e.g. thoughts) has led to the
unhesitating recognition of them as mere mental phenomena.
Thus, all the impressions which I gather from the objects in this
room cohere together so strongly that as they are collectively
to-day, so, very nearly, they were yesterday, and will be to-morrow.
They are invariably so similar, so closely repeated in the same
groups, that they have driven me to think they represent the same
external objects — the same table, the same chair, the same walls,
and roof and floor. If I wish to see again what once I saw on the
way from New Zealand I can do so; for, if the journey be
repeated, a long train of similar sense-impressions will follow one
another in similar array. Forgotten scenes, appealing to awakened
memory, will insist as strongly as anything I can still recall on a
reality independent of my mind. Even when I read a description
in a book, I am able to verify it by examining the place or object
described. But in my thoughts I can pass, and habitually do pass,
in a moment from the room to India or Honolulu, or Mars, and
in two consecutive instants can be concerned in a dog-fight round
the corner, or a Saxon coronation. It is no wonder, then, that I

MENTAL COHERENCE 333

have been led to refer thoughts to a mental world, and sense-impres-
sions to external objects as properties of them, or as caused directly
by them. Indeed the coherence and vividness of my sense-impres-
sions is my only ground for inferring the existence of a reality
which is beyond them, and which, as I suppose, they symbolize —
for I do not think they can do more — to my mind. So coherent
and capable of being tested in diverse ways is the story told by
sense-impressions, that nothing is more certainly true than the ex-
istence of the reality they insist on — except that which is very much
more certain, the existence of the sense-impressions that tell the story.

563. Evidently, as I say, my feelings have gained coherence
and meaning, and I have achieved such knowledge and skill in
thinking as I possess only because I have thought in the common-
sense way to which I have been driven, as it seems, by the very
constitution of my mind. Without that previous common-sense
thinking, my thoughts would now be infinitely more chaotic than
any that occur in my dreams. For, at least, in my dreams my
feelings do not constitute a meaningless procession. All of them are
grouped or linked together by being thought of as properties of, or as
caused directly or indirectly by, external objects. Even now, when
for an hour or more I have forced myself to think in idealist terms,
and have decided that I know nothing of what lies beyond my
feelings, yet, so strong is my tendency to think in a common-sense
way, that my wife and child have only to come into the room, and
the whole philosophic tangle is instantly dissipated. I return
forthwith to common sense. They become warm, living material
realities. Realities, too, become the room and all within it, the
house, the street, the whole universe.

564. Now, if my feelings have gained coherence only because I
have draped groups of them about external objects, which I do not
know to be other than illusions, of what value is the coherence?
If the objects are illusions, the coherence is delusive. How am I
to know that my thinking is in any way better than the imaginings
of a madman (phenomenal to me), who, like me, depends on his
feelings, and is unlike me only in that he perceives some groups or
links together some groups differently? It would be absurd to
argue that my mind is normal and his abnormal. For the
thoroughgoing idealist there are no such things as mental nor-
mality and abnormality. He knows no more of other minds than
of material bodies. Indeed, the assumption that there are other
minds, normal or abnormal, is tantamount to a complete
abandonment of the whole idealist position. For if there are

334 IDEALISM AND COMMON SENSE

other minds that have perceptions similar to those which occur in
my mind, there is no reason to doubt that there are bodies, that
there is a something, a reality, external to those minds, which
causes the similarity of feeling. That something is what common
sense, which postulates other minds, designates as " matter." It
follows, that, though the coherence which common sense has
bestowed on my feelings is (regarded as nothing more than
coherence) very real, and though it lingers when I think as an
idealist, yet, beyond the satisfaction it affords me, it has no value
to me (as an idealist) ; for, as far as I know, it is founded on
illusion. Idealism, then, leads to a cul-de-sac^ from which there is
no escape ; and the thoroughgoing and consistent idealist has no
right to proceed beyond a wondering and bewildered contemplation
of his own feelings.

565. But there are no thorough-going and consistent idealists.
There never have been any. All idealists have thought more or
less coherently, and have failed to note that, if common sense is
based on illusion, coherent thinking is based on it also. Very
certainly, notwithstanding ardent effort, / am no consistent idealist.
I find that I constantly act under an intense common-sense
conviction that I am a material item in a material world, which
contains many similar items. As it is with me, so I suppose it is
with these other items, these other men. Now and then, though
seldom, a rare individual may think for a little space in futile
idealistic terms — terms which, as we see, have become possible to
him only because common sense has previously trained his thinking
powers. But ever his mind tends to swing back to the common
sense that has become engrained in his nature. Therefore he
makes provision for his family, and performs other altruistic
actions, engages in politics, distinguishes between immaterial
minds and material brains, is pleased or vexed with his friends,
speaks to other people, and writes books for them to read — even, it
may be, books which demonstrate more or less logically and con-
clusively that neither they nor the books have any known existence.
As Clifford, who declared, " I do believe that you are conscious in
the same way as I am ; and once that is conceded, the whole
idealist theory falls to pieces," x but who, nevertheless, wrote and
lectured at great length as an idealist, said very properly, " A true
idealism does not want to be stated, and conversely, an idealism
that requires to be stated must have something wrong about it." 2

1 Lectures and Essays, Letter to Sir F. Pollock, p. 33.

2 Lectures and Essays, Philosophy of the Pure Sciences, p. 209.

OTHER MINDS 335

Formerly, these inconsistent idealists, while tacitly admitting the
existence of other people, denied that of matter, for which
" Berkeley placed God ; Kant and after him Schopenhauer placed
Will\ and Clifford placed Mind-Stuff"'*- Now, to crown all, Pro-
fessor Karl Pearson, pinning his faith to Hume, and declaring that
he knows nothing beyond the veil of his sense-impressions, is
highly contemptuous of the opinions of these metaphysicians —
and so joins their company. Even Hume wrote for other minds.2

1 Pearson, Grammar of Science, ed. 1900, p. 68, footnote.

2 In this question of other minds lies the crux of the whole problem. When
I declare that the only existence known to me is the stream of feelings which
constitutes my own mind, and that this stream, especially when I divest it of the
coherence conferred by common sense, does not furnish evidence of the existence
of anything outside of it, I am on safe ground. But when I suppose that there
are other minds, I make a guess which I cannot test, and which is therefore of the
same nature as that made by the materialist. Attempts have been made by
idealists, who deny or doubt the existence of material objects, to demonstrate
the existence of the other minds to which they appeal. For example, J. S.
Mill (Examination of Sir William Hamilton's Philosophy, 3rd ed.), declares, " I do
not believe that the real externality to us of anything, except other minds, is
capable of proof " (p. 239). He distinguishes between actual sensations and
Permanent Possibilities of Sensations. The latter are those groups of sensations
which we drape, or under fitting conditions might drape, about supposed external
objects ; and which, so grouped, may recur again and again. Calcutta is such a
Permanent Possibility. " I do believe," says Mill, " that Calcutta exists, though
I do not perceive it, and that it would still exist if every percipient inhabitant
were suddenly to leave the place, or be struck dead. But when I analyse the
belief, all I find in it is, that were these events to take place, the Permanent Possi-
bility of Sensation which I call Calcutta would still remain ; that if I were suddenly
transported to the banks of the Hoogly, I should still have the sensations, which,
if now present, would lead me to affirm that Calcutta exists here and now. We
may infer, therefore, that both philosophers and the world at large, when they
think of matter, conceive it really as a Permanent Possibility of Sensation. But
the majority of philosophers fancy that it is something more ; and the world at
large, though they have really, as I conceive, nothing in their minds but a Per-
manent Possibility of Sensation, would, if asked the question, undoubtedly agree
with the philosophers " (p. 235). In spite, then, of the circumstance that these
Permanent Possibilities may exist before the percipient mind, and survive after it,
Mill rejects, as unprovable, the notion that they are caused by matter — by that
which is not part of the mind, but external to it, and which possesses properties
that excite in the mind sensations which symbolize those properties., Neverthe-
less, because a certain Permanent Possibility (the recurring group of sensations
which he calls his body) is constantly associated with his mind, he endows this part
of his mind with all his mind ; at any rate, because other of his Permanent Possi-
bilities (which he calls the bodies of other people) resemble his body, he supposes
that these Possibilities have minds of their own. In other words, he supposes
that Possibilities which are not external to his mind have themselves minds which
are external to it. From groups of his sensations he thinks he can legitimately
infer the existence of other minds ; but, though he believes that other minds can
have identical sensations only when placed under identical conditions (e.g. at
Calcutta), he thinks he is not in a position to infer the existence of an external

336 IDEALISM AND COMMON SENSE

566. These two views, entirely incompatible but often inter-
mixed, the idealist and the common sense, carry with them
consequences that are immensely important to the thinker. Since
the idealist supposes that he is aware of nothing but the phenomena
happening in his own mind, he is unable to account for their
appearances, their coexistences, and their sequences.1 Even after
being trained by common sense to think coherently, he can do no
more than observe and record them. Thus he observes that in the
compound phenomenon ' dog' there tends to coexist the subsidiary
phenomena canine trunk, head, limbs, and tail ; and that, when the
phenomenon dog has the appearance of biting the phenomenon
idealist, there tends to succeed the phenomenon pain in the
phenomenon leg. But he has not the remotest idea why certain
phenomena tend to coexist with the phenomenon canine body,
nor why the appearance of biting should be followed by the
feeling of pain. He is, or should be, bound by the terms of his
philosophy not to pass outside the circle of his own feelings, and
therefore cannot, or at any rate should not, explain the dog and
the feeling of pain by the theory of evolution through Natural
Selection. For, of course, the notion of Natural Selection (which
is supposed to have occupied millions of years) occurring amidst
the phenomena, the mere phenomena, of his mind is exquisitely
absurd. It is true that most modern idealists, like most cultured
people whose culture is not entirely in the air, are adherents of the
theory of Natural Selection ; but when they are so they are
thinking in common-sense terms, and an absurdity is none the less
because an inconsistency is added. It follows that all notions
of causation, in the meaning the word ordinarily bears in the
language, are as inconceivable to the consistent idealist as are
material bodies. For him the word implies nothing more than
mere invariable succession — not a succession which is invariable
because it results from the unvarying action on each other of material
bodies which have unvarying properties. Accordingly he declares,
now with some approach to consistency, that the mission of science
something which causes the common sensations. To me, on the other hand, it
seems that we have no title to believe in other minds unless we first believe in
real bodies external to our own minds. That, moreover, appears to be the order
in which the human mind acquires these beliefs. To this day, as when giving
chloroform, I draw my inferences about other minds by the behaviour of what
I conceive to be the material bodies associated with them.

1 " Another inference, apparently more paradoxical still, needs to be made,
though, as far as I am aware, Dr Hodgson is the only writer who has explicitly
drawn it. That inference is that feelings, not causing nerve-actions, cannot even
cause each other " (James, Principles of Psychology, vol. i. p. 133).

NECESSARY SUCCESSION 337

is merely to describe phenomena and record their coexistences
and sequences.

567. On the other hand, to the common-sense thinker, who
supposes that both minds and material bodies exist and that the
former can be aware of the latter, causation implies more than
mere invariable succession. It implies necessary succession.1
For, believing that material bodies have properties or qualities
which bring them into certain relations with one another, he
believes also that, given these properties and relations, certain
consequences must follow. Thus, though he perceives that day
and night invariably succeed one another, yet he repudiates the
idea that they alternately cause each other. He knows of no
property in the one which can cause the other. On the contrary,
he supposes that day and night succeed because the round,
opaque, material earth rotates and so presents successive
parts of itself to a luminous body the sun. Given these
conditions, the non-occurrence of day and night would be in-
conceivable to him. Given the absence of the opacity of the
earth, or of its rotation, or of the luminosity of the sun, and he
would be forced to believe that day or night would be eternal,
though he has no experience of such a condition. A single
chemical experiment will convince him that a certain substance
exists because two or more elements have united ; but no amount
of experience will convince him that fine weather is the cause of
the rain that succeeds it. In other words, there is for him a
distinction between post hoc and propter hoc.

1 See § 578.

22

CHAPTER XVIII
NECESSARY TRUTH

Idealism and experience — Common-sense and experience — Kinds of pro-
perties— The limits within which we can know and think — Truths reached through
simple enumerations — Necessary truths — Mathematical axioms — Cause and effect
— Causation is a common-sense notion — Science is common sense — Thorough-
going idealism is unassailable, but leads to a cul-de-sac.

A

568. ^ LL knowledge, all thinking is founded ultimately on
experience that has been stored by the memory.
Experience begins with sense-impressions. The
one thing that no one can doubt is the existence of his own
feelings. There lies before me what common-sense regards as a
sheet of paper. I may, after much thought, have doubts about
the existence of that sheet, but I can have none about the existence
of the sensations that seem to reveal it to me nor of my thoughts
about them. If I think as a thorough-going idealist, I can note
these feelings ; if I go so far as to use the coherence of thought
that common sense has established, I can also observe and re-
member their co-existences and sequences. But there the matter
ends. The origin of them and of their co-existences and sequences
remains an unfathomable mystery. On the other hand, if I make
the assumption which common sense makes, if I suppose that the
sheet has a real existence external to me and that my feelings
are aroused by the properties or qualities of it, then the matter
does not end there. A limitless field of thought opens up. If this
object has a real existence and certain properties, then innumerable
other objects have real existences and properties which are not
merely my feelings but the exciting cause of them. Above all,
just as the properties of the sheet of paper and those of my mind
bring the two things into relation, so are all other things brought
into relation by means of their properties. In this way the
universe is linked together and becomes a unity.

569. If, then, the assumption that there is a universe external
to my mind, and that it is revealed to me by my feelings, be given,
it follows that, though knowledge begins with sense-impressions,

THE PROPERTIES OF MATERIAL OBJECTS 339

which reveal the qualities of things, it does not end with them.
They constitute but a minor part of it. The main portion of it
is reached through the discovery of relations, a process which
involves, not merely perception, but thought. Thus, through
thought we link together dissimilar impressions (tactile, visual,
etc.) in groups by recognizing their relations to one another, and
so, by referring our impressions to the qualities of external objects,
construct our notions of the latter. For example, we construct
the notion of a sheet of paper by thinking that it has certain
properties. Facility in linking together impressions (i.e. skill in
thinking, skill in perceiving relations) is laboriously acquired
during infancy ; but later, when the facility has become so great
that we accomplish the task without effort, we forget the initial
difficulty and are apt to suppose, with the old school-men, that the
thinking is performed through intuition. In this way, also, we
learn the relations between the various objects thus constructed —
for example between the ink, the pen, the paper, the table, the
room, the house, the street, and so on. Here again the relations
are not all perceived at a glance, but are thought out by a
process that becomes more and more complicated, but more facile,
as experience multiplies, knowledge increases, and skill grows.

570. I notice that, though the number of objects in nature
appears to me to be limitless, the number of the different kinds
of properties they possess is much smaller. Objects have pro-
perties in common, for which reason we are able to classify them.
I observe that some properties, for instance extension in space
and persistence in time, are possessed by all real things within my
experience. Indeed I cannot conceive a real thing that does not
possess them. Others, for instance definite and persistent shape,
colour, and weight that I can feel, are very common. Others,
such as certain colours, are rare. Yet others, such as a particular
shape or place (e.g. the precise shape and place in the universe of
my face at this moment), are possessed by one object only.
Though the number of the different kinds of properties which I
can perceive are limited, yet they are so numerous and may be
possessed by objects in such varying degrees and combinations
that an infinite variety of objects is thereby rendered possible.
Thus a beetle has some properties (e.g. extension and weight) that
are possessed by a house ; but, because some of his properties (e.g.
vitality) differ from those of the house in kind while others differ
in degree, the two objects are very different and therefore dis-
tinguishable.

340 NECESSARY TRUTH

571. The coherent thinking of common sense is founded on
these likenesses and differences between the properties of things
and on the fact that the properties of all things are conditioned by
the properties of other preceding or co-existing things. Thus,
owing to some of its properties, a certain object is classified by the
postman as a letter, and, owing to others is distinguished from all
similar objects as one belonging to a certain person in a certain
country, town, street, and house. The postman, the letter, and
the person to whom it is addressed, have relations to one another
which are conditioned by their respective properties. Now when
we speak of cause and effect, what we always mean is that the
properties of a thing, or set of things, are, or have been, conditioned
(altered or preserved) by the properties of another thing or set of
things. Thus, some of the properties of the letter (e.g. its situa-
tion) are altered by the postman because he has certain properties
(e.g. a desire to perform his duty), and because the person to whom
it is addressed has certain properties (e.g. a certain name and
situation). The words in the letter are preserved because the
paper on which they are inscribed has the property of prolonged
persistence.

572. If we follow any line of thought sufficiently far we are
sure in the end to reach limits which mark, apparently, the
beginnings of the unknowable and the unthinkable (e.g. the
nature of things in themselves, and the terminations, if any, of
space and time). Nature is parsimonious and adapts our minds,
like our bodies, to practical uses. But within those limits ex-
perience stores our memories with data which enable us to reason.
All, or nearly all, our reasoning consists in a tracing of cause and
effect — in a tracing of how the objects we think about are, or have
been, or will be, conditioned by their respective properties. At first,
especially during infancy, we trace the more obvious relations.
But we build continually on the data thus gathered till our reason-
ing, tracing effects from many combined causes or from causes that
are far remote, grows increasingly complex and subtle.

573. The limits within which we can think seem to be fixed
more by our perceptive than by our thinking powers. We can
think only of things that have properties of the same kinds (ex-
tension, persistence, colour, etc.) that we have already perceived.
Thus, though I can think of a dragon or a demon unlike anything
that ever was on land or sea, yet I find I can confer on it only
those kinds of properties, however strangely combined and
exaggerated, that are already known to me. I am as little capable

THE LIMITATIONS OF THE SENSES 341

of conceiving new kinds of properties as a congenitally deaf man is
of imagining sound or a congenitally blind man colour — which a
blind man once imagined to be like the sound of a trumpet. Men
are sometimes paralysed as regards sensation and movement, that
is, they lose in some parts of their bodies the tactile and muscular
senses. Conceivably they might be born and might exist entirely
without them. Judging from the analogy of congenitally blind
and deaf men, if I had never possessed any senses but those of
smell, taste and hearing, I could have no idea of extension. So
slowly did I develop mentally after birth that apparently I grad-
ually built up my idea of it. It was, therefore, not an intuition,
an instinctive bit of knowledge, but an acquirement, an induction
from experience. And, if my notion of space was not an intui-
tion, it is hard to believe, so inconceivable does existence which is
not spatial now seem to me, that I have any other intuitive ideas.
Moreover, as we shall see later, all ideas are founded on memory,
and, therefore, cannot be intuitive or instinctive. An instinct is a
mere impulse to action.1

574. On the other hand, I have no doubt that, if I could see the
colours that lie beyond the red and violet ends of the spectrum, I
could think in terms of them. Probably, therefore, if a new power
of perception, analogous to sight or hearing for instance, were
suddenly conferred on me, my intellectual powers would suffice to
enable me to use the materials provided by it for purposes of
thought.

575. It is certain that our senses, even when at their best, are
not sufficient to enable us to perceive completely all the properties
of objects ; thus we can see only within a certain range of the
spectrum and smell odours and taste flavours of a certain intensity.
It is practically certain that we cannot perceive at all some of the
properties of objects ; thus, apparently, a bat has some sense lack-
ing to us which enables it to perceive some property unknown to
us, for it is said to be able to avoid obstacles when flying in what
appears to us absolute darkness. Again, we are unable to perceive
that property in material bodies which acts across apparently empty
space, and the effects of which we term gravitation. We are able
to perceive only how it affects the relations of material bodies to
one another. It is possible that all the properties of some real
things are altogether outside the range of our perceptions, and, there-
fore, that some real things exist of whose existence we cannot be
aware (at least directly) — whose properties are inconceivable to us,

1 See §§,618 etseq.

342 NECESSARY TRUTH

576. Our perceptive powers are mainly ' innate,' that is, the
infant is born with senses that do not greatly develop afterwards
under the stimulus of use. Since, then, these powers are ' inherited/
we can perceive only within that very limited range within which
our ancestors perceived. But our thinking powers are mainly
' acquirements ' ; they develop under the stimulus of use (under
increase of knowledge and practice in using it) to meet all sorts of
contingencies ; and, therefore, by perceiving different objects (not
different kinds of properties) and by combining the materials
supplied by our perceptions differently (by perceiving or imagining
different relations) we can think not only in a different, but often in
a more far-reaching way than our ancestors. Our sciences have
grown in this way. It is not his senses, his perceptive powers,
but his powers, dependent on memory, of growing mentally under the
stimulus of use, that confers on man his intellectual pre-eminence
over brutes. But of this more anon.1

577. I do not know how it happens that real objects have
(for instance) extension in space and persistence in time. My
senses supply no data, and, therefore, in this case also, I seem to
have reached the limits of the thinkable. Here I cannot trace
cause and effect; I can only note that all things known to me have
these properties. But the fact that all the real objects I have met
are possessed, in some degree, of extension and persistence, has
given me the notion that they are present in all real things.
That notion, however, may not be correct, for real objects lacking
them may exist and I may be unaware of them because my senses
are incapable of being influenced by their kinds of qualities. It is
true that we can use a form of words and declare that a point is
that which has no magnitude — no extension ; but such a point, a
thing without qualities that we can perceive, cannot really be thought
of.2 We do not conceive a new thing when we use that form of
words ; we merely try to strip a thing we know of the qualities by
which we know it. I seem, then, to have reached the notion that
all real bodies have extension and persistence by an induction
from a ' simple enumeration ' ; that is, I have concluded that what
has always held good within my experience always would hold
good were my experience universal. In the same way I have
reached the notion that all bodies in nature are susceptible of
movement (of having their spatial relations to one another altered),
and the notion that matter is impenetrable (that no two bodies in
nature can occupy the same part of space at the same instant of

* See § 624, et seq. 8 See J. S. Mill, Logic, Bk. II. chap, v., § i.

KNOWLEDGE BY CAUSES 343

time). Thus also I have reached other general notions. It seems
then that I have gathered many notions of what seem to me uni-
formities in nature (Maws' of nature) by this process of simple
enumeration. Such a process is a form of reasoning, but it is the
most rudimentary form. " This is the kind of induction which is
natural to the mind when unaccustomed to scientific efforts " l
" True knowledge is knowledge by causes. For that knowledge
that proceeds by simple enumeration is a puerile thing, and con-
cludes uncertainly, and is exposed to danger from any con-
tradictory instance, and for the most part pronounces from fewer
instances than it ought, and of these only from such as are at
hand." 2 " Popular notions are usually founded on induction by
simple enumeration ; in science it carries us but a little way, we
are forced to begin with it ; we must often rely on it provisionally
in the absence of means of more searching investigation. But for
the accurate study of nature we require a surer and more potent
instrument." 3 It is a remarkable fact, however, that in much recent
work (e.g. in the statistical work of idealist thinkers) it is maintained,
or at least implied, that the method of simple enumeration is the
only means by which correct (and, therefore, scientific) results can
be ensured.

578. But, after I have learned by such enumeration that real
things have properties that vary in kind and degree and that
certain uniformities exist in nature, I have data that enable me to
think in a new way. I can now say to myself, " If it is true that
real bodies exist and have properties which bring them into rela-
tion with one another in definite ways, and z/it is true that certain
uniformities run through nature, then given certain conditions,
even combinations of conditions of which I have no previous
experience, certain results must follow, and can be thought of by
me even when I have had, and can have had no previous experience
of them. When I think thus, I think in terms of cause and effect ',
and have passed from the notion of invariable to that of necessary
succession. The latter is not identical with the former ; it is a
superstructure reared on it.

579. Thus, after I have acquired through experience definite
ideas of plane surfaces and of lines which are straight, perpen-
dicular, and parallel, I am able to pass the bounds of direct
experience and declare that straight lines, on the same plane
surface and perpendicular to another straight line, will never meet,

1 Op. cit., Bk. III., chap, iii., § 2. 2 Ba.con*Novum Organon, i. 105.

3 J. S. Mill, Logic, Bk. III., chap, iii., § 2.

344 NECESSARY TRUTH

no matter how far they be produced. Given these real things
(surfaces and lines), those qualities (plane and straight) and that
relation (perpendicular), then, that other relation (parallelism)
necessarily follows and from that also the necessary truth that
parallel straight lines will never meet — for the notion of straight-
ness, combined with that of parallelism, implies that lines having
that quality and that relation will always preserve the same distance,
and, therefore, will never approach, and, therefore, never meet.1 It
matters not that I have never seen surfaces that are absolutely
plane nor lines that are quite straight, perpendicular and parellel,
but only surfaces and lines that nearly approach perfection in
these particulars.2 ' Absolutely ' and ' nearly ' are relative terms
indicating, not different kinds of qualities, but only different
degrees in qualities. Therefore, when I have experience of things
that are nearly straight, perpendicular and parallel, I can think
in terms of things that are absolutely so.

580. Again, I can through direct experience, through actual
measurement, reach the notion that the three angles of a certain
triangle, which is bounded by straight lines on a plane surface, are
equal to two right angles. Moreover, by repeating these observa-
tions on other triangles I can, through simple enumeration, reach
the notion that what is true of one such triangle is probably true
of all similar triangles. But a notion so reached will appear to me
merely an expectation, not a necessary truth. It will only seem to be
the latter, if I deduce it, as Euclid does, from the previously known
and admitted properties and relations of lines, angles and triangles.

581. In mathematics we are able to discover many necessary
truths, for here the conditions are, speaking comparatively, so little
complicated that we are able to perceive and conceive things and

•their properties and relations with greater completeness and
certitude than elsewhere, and, therefore, can think more exactly
and confidently. Nevertheless, in everyday life we are continually
endeavouring to deduce such truths. That is, we are continually
endeavouring to deduce from the previously known and admitted
properties and relations of things, effects that, given those pro-

1 I am informed by Professor H. H. Turner that much or all of this is con-
troverted by the " New Euclidians." But the example even if faulty will serve to
illustrate my meaning. It may be noted also that in mathematics we do not
. deal with sequences of events. We suppose, however, that, given certain facts,
certain other facts must necessarily be true also, and we proceed to discover the
latter. The thinking, therefore, is of the same nature as when we deal with
sequences of events — with cause and effect.
8 See Mill, Logic, II. v. 147,

DEDUCTIVE TESTING 345

perties and relations, must follow. Thus, given that my cook has
certain properties (e.g. the will and the ability), given the existence
of food in the house, given a multitude of other things, it follows
necessarily that my housemaid will presently summon me to
breakfast. Here, I do not know all the conditions as perfectly as
in geometry, but, if I did and could think as adequately about a
matter so complicated, I could be just as sure in the one case as
in the other. The important point is that in this case also I have
reached the expectation that I shall be summoned to breakfast
otherwise than by an induction from a simple enumeration of
instances of former like events. I could have ignored the qualities
of the cook and the other things concerned and reached the
expectation by remembering that I have been so summoned for a
long series of mornings. But, as a fact, I did not do so. It is
when we think in terms of cause and effect that the need for test-
ing our thinking by making a deductive appeal to reality arises.
Such a testing is necessary even in the mathematics in which the
conditions are relatively simple and clearly defined, and the
chances of error are correspondingly slight. Thus, when we
multiply one number by another (e.g. 123 by 345), we are able to
make sure that the product, the conclusion to which we have led
by our reasoning, is correct only by some such test as is furnished
by dividing it by one of the factors and then ascertaining whether
the quotient agrees with the other factor. The more difficult the
problem, the more complex the conditions or the more prolonged
the chain of reasoning, the more necessary it is to apply tests ; —
as in biology, where the conditions are often exceedingly complex
and so obscure that it is often difficult to separate essentials
from non-essentials, real causes and effects from accidental
accompaniments.

582. In science, as in everyday life, we endeavour to deduce
effects from causes, or causes from effects, and so link up our
knowledge in uniformities, which, though based ultimately on
results obtained by simple enumeration, are other, and additional,
and as superior to them as a temple to its foundations. All the
sciences in which we have succeeded best in this endeavour are the
most ' scientific/ the most deductive, the most completely knit into
compacted wholes.1 Mathematics and physics are examples.
Zoology and botany formerly rested on a simple enumeration of
likenesses, differences, co-existences, and sequences. Doubt-
less they had practical uses and satisfied scientific workers of that
1 See J. S. Mill, Logical!, iv. 4.

346 NECESSARY TRUTH

class which is content with such a catalogue as a grocer makes of
his stock. But consider the improvement effected by Darwin,
when, deducing necessary truths from given data, he linked
together plants and animals by chains of causation. Knowledge
was then supplemented by understanding. Something more than
a mere memory of perceptions came into play. That something
was Reason.

583. What, then, do we mean by the expression 'necessary
truth ' ? How is it to be distinguished from * invariable ' occur-
rence? A necessary truth is not one reached by intuition.
Apparently no such truths are known to us. Nor is it one reached
by induction from simple enumeration ; for that merely endows us
with a sense of probability, of expectancy. It is always one which
we have reached through what seems to us valid reasoning from an
apparently complete consideration of all the relevant properties and
relations of real things. It is not, of course, more certainly true
than the existence of those real things and of their properties and
relations ; but, given those existences, those properties, and those
relations, it is certainly true provided we have reasoned correctly
and taken all that is essential into consideration. It is an effect
that we have inferred from its cause, or a cause that we have in-
ferred from its effect. It is a conclusion drawn from premises
antecedently formulated or implied, and true z/ the premises are true.

584. If the reader will try to think of any notion the truth of
which appears necessary to him, he will always find that it bears
this character of an inference from premises which have previously
been granted. For example, though we are told that every axiom
of geometry is a ' self-evident ' and ' fundamental ' truth ; " that is,
its truth should not be deducible from any other truth more simple
than itself " ; yet, as a fact, we do, in every instance, derive
geometrical axioms from truths which we regard as more funda-
mental, simple, and self-evident than themselves — from the
qualities and relations of the things we are considering. Some reason-
ing is always done before we admit the truth of an axiom. Thus the
axiom that " Things which are equal to the same thing are equal
to one another," is but another way of saying that "If things are
equal to the same thing they are equal to one another, for the
reason that they will then have identical properties and relations."
The reasoning may be so swift and easy that only more think-
ing reveals its existence, so swift and easy that an attempted
exposition of it appears like stating the same thing in another and
a more involved way ; the inference may be so obvious that only

THE NATURE OF NECESSARY TRUTH 347

careful consideration reveals that it is an inference ; but the given
premises, the reasoning, and the inference are always there. An
axiom may seem self-evident to us who have unconsciously drawn
the inference a thousand times a day for years ; but it is not self-
evident to an infant who must not only acquire a knowledge of
the data on which it is founded, but also skill in thinking sufficient
to enable it to perceive their relations and how they affect one
another.1

585. To take other examples ; we do not regard a line as
necessarily straight unless we have reasons for doing so, unless we
draw an inference, unless we think it traverses the shortest distance
between two points and apprehend what that means. Uncon-
sciously we reason out that a line that does not traverse the
shortest distance cannot be straight. A straight line is not
necessarily perpendicular to another unless it makes equal angles
with it. Straight lines are not necessarily parallel unless they make
equal angles with a third straight line on the same plane. Straight
lines on the same plane will necessarily meet if produced far
enough unless they are parallel. Evolution through Natural
Selection may be true ; but it is not necessarily true unless off-
spring resemble their parents on the whole but differ from them
in details, unless they outnumber them, unless only the fittest
survive on the average, unless the fittest belong to types, and so
on. In brief, for us a necessary truth is always an effect or cause
which we have been able to trace so perfectly to its cause or
effect that no doubt of the nature and reality of the connexion
remains in our mind. It is a truth which we think we not only

1 Dr Whewell and others have held that "it is not experience which proves
the axiom ; but that its truth is perceived a priori by the constitution of the
mind itself, from the first moment when the meaning of the proposition is
apprehended, and without any necessity of verifying it by repeated trials, as is
requisite in the case of truths really ascertained by observation " (Mill, Logic, v. 4).
This view is opposed by Mill who thinks that we learn the truth of axioms wholly
through experience. The two opinions do not appear to be absolutely contra-
dictory. Whewell admits that we must have experience — that the meaning of
propositions and all that that implies in the way of experience, must be appre-
hended. Mill admits as necessary truths those " necessarily following from
hypothesis." I think I learned originally through experience that two halves
make a whole ; but now that I have learned " the meaning of the proposition "
I hold that belief on other grounds as a necessary truth. In this way, at first
mere experience led me to believe in the mathematical axioms and most of the
other necessary truths that I now hold as such ; but they did not become necessary
truths to me till I had reached them in another way. The view I suggest differs
from those of Whewell and Mill in that axioms, as such, seem to me products of
reasoning, not of intuition or of mere repeated experience.

348 NECESSARY TRUTH

know, but which we think we can account for in terms of other
admitted truth. Moreover, it is always a truth which has been
or which can be reached otherwise than by simple enumeration
and which, therefore, can be tested in one or more ways, for
example by simple enumeration. Thus, after declaring that,
given certain conditions (e.g. universal gravitation, the rotating
earth, and the moon), a certain result must follow (e.g. the tides),
we can test our supposed necessary truth by appealing to instances
which occur in reality. Therein it differs from a truth which as
yet has been and can be founded only on simple enumeration (e.g.
the statement that all real bodies have extension) ; for such a truth,
which has not been deduced from any other, can be tested, if that
deserves to be called testing, only by continuing the enumeration.
586. We see then that a necessary truth is one which we have
reached by tracing the relation of cause and effect. We observe
that certain bodies in nature have certain properties or qualities,
for example extension and gravity, by means of which they are
brought into relation with one another and so affect one another.
A law of nature is a uniformity that we have observed in nature.
Usually we mean by the term a uniformity of sequence ; that is, a
uniformity in the way in which bodies affect one another. Uni-
formities of sequences imply uniformities of qualities and relations,
and, therefore, of consequences. Doubtless, it is this notion of
necessary consequences that has given rise to the term ' law.' l
Thus, if it be true that material bodies attract one another, it must
be true also that they tend to approach one another. A necessary
truth is merely a particular instance of a general uniformity, or
else it is a consequence correctly deduced from such a uniformity.
When we formulate such a truth, we declare, in effect, "If the
general law is true, then, since the bodies we are considering have
qualities and relations that bring them within the range of that
law, this particular instance or consequence of it must be true also."
In practice the term necessary truth is used, as a rule, in cases in
which the inference is not very obvious — in cases in which conse-
quences rather than instances are dealt with, in which more than
one quality and relation and therefore more than one uniformity is
concerned, and in which, therefore, the conclusion is reached by

1 " A law, then, in the strict scientific sense is a fully established statement
of universal and necessary connexion . . . more loosely, the term is frequently
used to denote mere empirical generalizations. . . . These, however, express no
necessity and, consequently, are not laws in the strict sense . . . ' empirical law '
is, correctly speaking, almost a contradiction in terms." (Wei ton, Manual of
Logic, vol. ii. p. 200.)

INTERPRETATION 349

reasoning that is more or less complex or prolonged. The declara-
tion that a conclusion is a necessary truth amounts to a claim that
we have reasoned correctly from premises (law or laws) that are
admittedly true. No matter how simple or complex the case,
when we declare that we have ' explained ' or ' understood ' an
occurrence, we mean merely that we have interpreted it in terms of
one or more uniformities of which we are aware. Moreover, this
tracing of instances and consequences to general uniformities, and
therefore to the qualities and relations of objects, is all that we
mean by 'tracing a chain of causation.' Thus, knowing the
common uses of pokers and that iron can be raised to a high
temperature by fire, we explain the hotness of a poker, we describe
the cause of the hotness, by saying that the poker has been in the
fire. On the other hand, knowing the qualities of ice, we should,
if we found a hot piece of it, be at a loss for an explanation.
Knowing that intact brains are essential to the existence of human
beings, we suppose we have the explanation of the death of a man
when we discover a bullet imbedded in his brain. We explain the
rise of the tide and the fall of a stone by the same law. We ex-
plain the rise and fall of water in a harbour by the tides of the
ocean, the tides by the influence of the moon, the influence
of the moon by the law of gravitation. We cannot as yet
explain the law of gravitation by reference to a wider
uniformity ; it is for us an ultimate law ; but between it and the
rise and fall of water in a harbour lies a chain of explanation, of
causation, and of necessary truth. When Huxley declared that,
" Fact I know : and law I know : but what is this Necessity, save
an empty shadow of my own mind's throwing ? " x he referred
to these ultimate uniformities which as yet we cannot explain,
and which perhaps we shall never be able to explain by reference
to more general laws. He referred to necessary truth when he
said " even thoughtful men usually receive with surprise the
suggestion, that the form of the crest of every wave that breaks,
wind-driven, on the sea-shore, and the direction of every particle of
foam that flies before the gale, are the exact effects of definite
causes; and, as such, must be capable of being determined,
deductively, from the laws of motion and the properties of air and
water." 2 " The very postulate of knowledge compels us to think
every variation and every detail, even the smallest, as so deter-
mined by conditions that, under the circumstances, it could not
possibly be other than it is. When the conditions of every detail
1 Essays, vol. i. p. 161. * Hume, p. 122.

350 NECESSARY TRUTH

of a phenomenon are so fully and exactly known that not only
a phenomenon of this general character, but just this very
phenomenon, with exactly these details, and each in exactly this
amount, must follow from those conditions, and from those only,
then that phenomenon is fully explained." 1 But when we think
of necessary truth, we must do so in terms of that reality to which
our minds seem to testify. If we question the reality, we can
declare, " Fact I doubt : and law I doubt : and, therefore, necessity
I doubt." But, given the fact and law, then necessity is beyond
all doubt.

587. When tracing cause and effect, we do not refer explicitly
to all the qualities of the objects we are considering. Every object
has many qualities. Thus iron has persistence in time, extension
in space, weight, colour, frangibility, ductility, hardness, and a
multitude of others. It could not become hot, it could not even be
an object for us, unless it had at least many of them, for example,
persistence and extension, yet we do not think or say that the
poker becomes hot because it has persistence and extension.
Many pokers are not hot ; even ice which cannot become hot has
persistence and extension. We refer especially to the quality in
iron, its temperature, which is changed by the fire, and the quality in
the fire which is concerned in the change. The last is termed the
cause, the change in the first is termed the effect.

588. More than one quality may be concerned in a cause ; thus
both the momentum and the hardness of a bullet are concerned in
the effect produced when it strikes another body. More than one
quality may be concerned in an effect ; thus the position, shape,
and temperature of a piece of iron may be changed when it is
struck. Nevertheless, no matter how many of the qualities of an
object are concerned when it acts on or is acted on by another object,
in practice we think only of those which are especially concerned :
or indeed, only of those of with which we are especially concerned.
Of course, no cause or effect stands isolated in the external world ;
we merely isolate it in thought. In reality it is connected not with
a chain, but with a circle of cause and effect. Thus a bullet, on
which certain properties were conferred during manufacture, flies
because it is impelled by the explosion of powder, ignited by a
spark in a gun, which was fired because a man, who was present
through a concatenation of circumstances that reaches back
through eternity, pulled a trigger because he was made angry by
certain events, and so on. Yet we say only that the one man was

1 Welton, Manual of Logic, vol. ii. p. 188.

THE NOTION OF CAUSATION 351

shot because he angered the other man. A knowledge of the
whole circle of causation would imply perfected science, a thorough
knowledge and understanding of the whole universe during all past
time. In a sense, at any instant, we can point to the termination
of effect, for at any instant the effect has not proceeded beyond
that instant; but the circle of causation had its beginnings only in
the beginnings, if any, of time and space. But this totality, both
when we consider the qualities of objects, and the circle of
causation, is utterly unwieldy. Therefore, as in practice we select
for purposes of thought certain qualities of objects, so also when
tracing causation we select certain parts of the circle. We
suppose a chain, and, even then, think only of those links that
appear to serve our purpose best.

589. In this way, by supposing that objects have reality out-
side our minds, and by supposing that they have qualities by
means of which they act and react on one another in a uniform
way, we gather the notion of a universe which, so far from being
chaotic, is orderly to its minutest details ; and in reference to
which, as far as we are able to perceive the order and trace cause
and effect, we are able to use such words as^ ' understand,' ' explain,'
' why,' ' reason,' and the like with intelligible meanings. If we
did not, and more especially if we had not, supposed a material
universe, our thoughts, as we have seen, would be without
coherence. Or rather, we would have no thoughts, but only
feelings. Very emphatically, then, the entire notion of causation
belongs wholly to common sense. It has, or should have, no place
in idealist thinking.

590. All science, like all ordinary thinking, is founded on
common sense. " Every science assumes certain data uncritically,
and declines to challenge the elements between which its own
* laws ' obtain and from which its deductions are carried on. . . .
Of course these data are themselves discussable, but the discussion
of them (as of other elements) is called metaphysics." 1 That is,
every science thinks in terms of what are supposed to be real
existences and omits to discuss the question whether they are, or
are not, real. " All physical science starts from certain postulates.
One of them is the objective existence of a real world." 2 It is true
that we are told that " a scientific law is related to the perceptions
and conceptions formed by the perceptive and reasoning faculties in
man ; it is meaningless except in association with these ; it is the

1 James, Principles of Psychology, Preface, v-vi.

2 Huxley, Essays, vol. iv., p. 60.

352 NECESSARY TRUTH

rhume or brief expressien of the relations and sequences of certain
of these perceptions and conceptions, and exists only when
formulated by man.1 . . . The law of gravitation is not so much
the discovery by Newton of a rule guiding the motion of the
planets as his invention of a method of briefly describing the
sequences of sense-impressions, which we term planetary motion. . . .
We are thus to understand by a * law of nature/ a resumes mental
shorthand, which replaces for us a lengthy description of the
sequences among our sense impressions." 2 According to the law
of gravitation, all bodies in nature attract each other proportion-
ately as their masses and, inversely as the squares of their distances.
Now in what intelligible sense can the sense-impression, the earth,
be said to attract the sense-impression, the sun ? What are their
masses, and what the squares of their distances ? To all appear-
ances the planets, the sun, and the other stars are of no great
magnitudes, at no great distances, and float lighter than feathers
through the air. Even if they be conceived as nothing more than
sense-impressions between which, after a previous training by
common sense, Newton was able to discover relations which are
quite unlike their apparent relations, how do we know that Newton
existed as a thinking entity? As a fact, the law of gravitation
has been accepted by astronomers and physicists as describing a
relationship between material bodies external to the human mind
— bodies and a relationship between them which the human mind is
thought to be aware of at present, but which existed long before
the evolution of any such mind. Obviously also, since the word
' attraction ' is used, the relationship indicated, as in the case of
many other laws that have been formulated, is one of causation.
It is not a mere invariable succession such as that of night and
day, the notion of which is reached, not through a consideration
of the qualities of the related objects, but through simple enumera-
tion. I say 'formulated,' for the laws that are reached through
simple enumeration (e.g. the law that all material bodies have
extension), are, as a rule, discovered by every one and therefore
are not worth formulating by anyone.

591. " In the scientific sense, a law is a statement of a necessary
connexion ; it is not something imposed upon reality from without,
but is the outcome of the nature of reality itself. The perception
of natural laws is due, no doubt, to the synthetic activity of mind,
but it is possible only because the connexion actually exists in
reality. It is because the world is a systematic unity that we are
1 Pearson, Grammar of Science, ed. 1900, p. 82. * Op. ctt., p. 86-7.

SCIENTIFIC MATERIALISM 353

compelled to think it as such. A law, then, in the strict scientific
sense, is a fully established statement of universal and necessary
connexion."1 As a simple matter of fact, no chemist, astronomer,
zoologist, botanist, or medical man, for example, ever does, under
his ordinary conditions of thought, conceive elements, worlds,
animals, plants, or human beings, as groups of his private feelings.
They are to him concrete realities existing external to himself,
and a principal part of his labours is to gather information from
and impart it to other concrete people. It is just this fact that
science, in more senses than one, is " organized common sense "
that imparts to it its intellectual richness and splendour, that
rescues it from the intellectual leanness, meanness and barrenness
of the grocer's catalogue.

592. Nevertheless, though idealism is possible only to the man
who has learned to think in terms of common sense, though it is
utterly unable to advance beyond the fact that his feelings exist,
though the idealist philosopher can do nothing but wonder im-
potently, its position seems quite unassailable. That is, the
position of through-going idealism seems quite unassailable. That
kind of idealism which uses the whole paraphernalia of common
sense, which appeals to the phenomena that common sense has
compounded and so rendered coherent and to other minds, which
is idealist only during occasional asides when it proclaims itself
idealist, that kind is assailable at every joint. It is only a tour de
force by people who in their appeals to other people assume the
very thing they profess to deny. To sum up : my own attitude —
I must be egotistical when I speak in terms of idealism — is this ;
I admit I cannot pass beyond the circle of my feelings, which may
lie to me, or which, if they tell the truth, can tell it only in a
symbolic way. I do not positively know that there is a universe
external to my consciousness in which exist material objects and
minds like my own, which know or can know the things that I
know. But, having made that admission, I return wholly, or
almost wholly, to common sense, which has rescued, and still
rescues, me from mental impotence. I assume that the universe
exists as a reality, and that my feelings, and those of other people,
symbolize it much as written words symbolize spoken words.
I suppose that the real things of which the universe is constituted
have properties which bring them into relation with one another,
and that thence arise relations of cause and effect, and ultimately
my notions of necessary truth. I can test the evidence furnished

1 Wei ton, Manual of Logic, vol. ii. p. 200.
23

354 NECESSARY TRUTH

by common sense in so many ways, and if the tests are conducted
with sufficient care, I so invariably find the evidence consistent
with itself, that it seems to me highly probable that my assump-
tions are correct. As to the actual nature of the reality which I
think my mind symbolizes, I make no guess. I use the word
* matter,' but only as a convenient name for a something of which
I have no immediate knowledge. Since I suppose that my mind
symbolizes reality, I suppose also that the uniformities which I
detect in nature are due to a uniformity of causation which
depends on the qualities and relations of material objects, not on
a mere invariable and utterly unaccountable succession of mental
happenings, which is all that the idealist has a right to postulate.
Therefore, though I do not know the whole circle of causation,
but only a little part of it, yet, within the narrow limits of
my knowledge, the universe appears to be comprehensible, and
I am able to say that I understand and can explain. I am,
then, in one respect, an idealist, and in another a materialist.
I am an idealist in that I know I know my feelings, but
nothing else. I am a materialist in that I believe my feelings
symbolize reality. My attitude differs from the common sense of
everyday life and of science (which accepts appearances for what
they seem to be) in this matter of symbolism. I suppose I am
like a man who is deaf, and knows that he is deaf, but who can
read. I am not like a deaf man, who, being able to read, supposes
that he can hear, or, at the other, the idealist, extreme, like one
who, being able to read, supposes he can neither hear nor read.

593. Granting the existence of material objects, then evidently
there are two distinct ways in which we may classify facts,
and so create science. On the one hand, we may arrange our
data accordingly as the objects we have under consideration
have, or have not, properties, or, as they are termed in biology,
4 characters,' in common. Thus, since a man possesses certain
characters in common with other living beings, we classify him
as an animal, a vertebrate, a mammal, and so on. In this way
systematic zoology, botany, and anatomy have been developed.
Here the mental faculties we employ are principally observation,
recollection, comparison, and the like. On the other hand, we
may arrange our facts in chains of causation. This is the
method adopted in mathematics, physics, to a great extent in
astronomy, and in biology when we discuss problems of heredity
and evolution. Here, regarding the properties of objects as causes
or effects, we proceed principally by formulating hypotheses, which

KINDS OF THINKING 355

we test and establish (or disprove) by making a deductive appeal
to reality. In other words we reason. The kind of thinking-
employed in the one case differs sharply from that employed in
the other. For example, if a systematic botanist wishes to
demonstrate the truth of a disputed statement, his main task, as
a rule, is to prove the correctness of the data from which he
starts his thinking. In other words, he has to demonstrate that
he has observed, recollected, and compared correctly ; for, while
his facts are often multitudinous and complex, the thinking
founded on them is usually relatively simple, and therefore
unlikely to be wrong if the facts are correct. The mathematician,
on the contrary, usually founds thinking that is relatively diffi-
cult on facts that are comparatively simple. His main task is to
prove the correctness of his reasoning. We shall see later that
skill in thinking, whether of the kind employed by the systematist
or that which is used by the mathematician, is an ' acquirement.'
It develops under the stimulus of use. Moreover, skill in the one
kind of thinking does not necessarily imply skill in the other kind.
No one disputes that we have created true science when we have
arranged our facts ' systematically.' Nor has any one ventured to
deny that mathematics and physics, in which causal relations are
traced, are products of real scientific thought. Occasionally,
however, a biologist, while neither denying the facts nor contro-
verting the thinking founded on them, denounces ' speculation '
and ' theorizing.' 1 It is unscientific, of course, to found speculations
on imaginary facts or formulate guesses which are incapable of
proof or disproof; and, certainly, hypotheses of this kind are not
uncommon in biology. But, judging from the language sometimes
used, it is not merely the faulty use of a right method of work
that is condemned, but the method itself. Manifestly, however, if
it be possible to link facts in chains of causation, it is proper to do
so. Knowledge is then supplemented by more knowledge, and by
understanding besides, and the structure of science is all the more
complete because we have added the woof to the warp of it.
Since verified facts are abundant in biology, and since as living
beings we are familiar with the conditions of life, it should not be
beyond the powers of the human intellect, which has discovered
the calculus and the law of gravitation, to indicate in general
terms the uniformities of sequence under which the structures of
plants and animals have arisen. At any rate the attempt to do so
is not unscientific.2

1 See § 826. 2 See §§ 828, et seq.

CHAPTER XIX
THE RELATION OF MIND TO BODY

Huxley and Clifford — Their inconsistencies — Mind and body are causally
related — Professor William James — Theories of the relation of Mind to Body —
Probably mind is the work done by the brain — The bodies of human progenitors
and descendants are more closely alike than their minds.

R

594. ""f"^ ETURNING now altogether to the thinking of every-
day life and of science, common sense tells us
that we have minds and bodies, and that these
two sharply distinct things influence one another — have causal
relations with one another. This causal relation has been denied,
however, and sometimes on very high authority.

"The consciousness of brutes would appear to be related to
the mechanism of their body simply as a collateral product of its
working, and to be as completely without any power of modifying
that working as the steam-whistle that accompanies the work of a
locomotive engine is without influence on its machinery. Their
volition, if they have any, is an emotion indicative of physical
changes, not a cause of such changes. . . . Much ingenious argu-
ment has at various times been bestowed on the question. How
is it possible to imagine that volition, which is a state of conscious-
ness, and, as such, has not the slightest community of nature with
matter in motion, can act upon the moving matter of which the
body is composed, as it is assumed to do in voluntary acts ? But
if, as is here suggested, the voluntary acts of brutes — or, in other
words, the acts which they desire to perform — are as mechanical
as the rest of their actions, and are simply accompanied by the
state of consciousness called volition, the inquiry, so far as they
are concerned, becomes superfluous. Their volitions do not enter
into the chain of causation of their actions at all. . . . The soul
stands related to the body as the bell of a clock to the works,
and consciousness answers to the sound the bell gives out when
it is struck. . . . Thus far I have strictly confined myself to the
automatism of brutes. ... It is quite true that, to the best of my
judgment, the argumentation which applies to brutes holds equally

356

THE AUTOMATON HYPOTHESIS 357

good for man ; and, therefore, that all states of consciousness in
us, as in them, are immediately caused by molecular changes of
the brain-substance. It seems to me that in men, as in brutes,
there is no proof that any state of consciousness is the cause of
change in the motion of the matter of the organism.

" If these positions are well based, it follows that our mental
conditions are simply the symbols in consciousness of the changes
which take place automatically in the organism ; and that, to
take an extreme illustration, the feeling we call volition is not
the cause of a voluntary act, but a symbol of that state of the
brain which is the immediate cause of the act. We are conscious
automata." l

595. "All the evidence that we have goes to show that the
physical world gets along entirely by itself, according to practi-
cally universal rules. . . . The train of physical facts between
the stimulus sent to the eye, or to any one of our senses, and the
exertion which follows it, and the train of physical facts which
goes on in the brain, even when there is no stimulus and no exer-
tion— these are perfectly physical trains, and every step is fully
accounted for by mechanical conditions. . . . The two things are
on utterly different platforms — the physical facts go along by
themselves, and the mental facts go along by themselves. There
is a parallelism between them, but no interference of one with the
other. Again, if anybody says that the will influences matter,
the statement is not untrue, but it is nonsense. Such an assertion
belongs to the crude materialism of the savage. The only thing
which influences matter is the position of surrounding matter, or
the motion of surrounding matter. . . . The assertion that another
man's volition, a feeling in his consciousness which I cannot
perceive, is part of the train of physical facts which I can perceive
— this is neither true nor untrue, but nonsense ; it is a combination
of words whose corresponding ideas will not go together.2 . . .
Sometimes one series is known better, and sometimes another ; so
that in telling a story we speak sometimes of mental and some-
times of material facts. A feeling of chill made a man run ;
strictly speaking, the nervous disturbance which coexisted with
that feeling of chill made him run, if we want to talk about
material facts ; or the feeling of chill produced the form of sub-

1 Huxley, Animal Automatism, quoted in part by James, The Principles of
Psychology, vol. i. p. 131.

2 W. K. Clifford, Lectures and Essays, Body and Mind, pp. 262-3, quoted by
James.

358 THE RELATION OF MIND TO BODY

consciousness which coexists with the motion of the legs, if we
want to talk about mental facts. . . . When, therefore, we ask,
'What is the physical link between the ingoing message from
chilled skin and the outgoing message which moves the leg ? ' and
the answer is ' A man's will,' we have as much right to be amused
as if we had asked our friend with the picture what pigment he had
used in painting the cannon in the foreground, and received the
answer, ' wrought iron.' It will be found excellent practice in the
mental operations required by this doctrine to imagine a train, the
fore part of which is an engine and three carriages linked with
iron couplings, and the hind part three other carriages linked with
iron couplings ; the bond between the two parts being made up
out of the sentiments of amity subsisting between the stoker and
the guard." l

596. In the passages quoted both authors, professed idealists
however, draw a common-sense distinction between brain and mind
on the ground that the former is a material object, whereas the
latter is not. Huxley thinks it impossible that mind can affect
matter; but, regarding mind as a 'product' of the working of the
brain, believes that matter can affect mind. It is hard, however, to
conceive how one thing can directly affect another without being
affected back again. If light reaches an object, it is reflected or
absorbed ; if the sun attracts the earth, the earth attracts the sun ;
if I touch a stone, the stone touches me; if my arm makes a
movement, the arm suffers change. All relations are mutual. If
it be true that brain can affect mind, then, judging by all analogy,
it should be true also that mind can affect brain.

597. Clifford is even less consistent. He supposes that mind
and matter do not affect one another ; but his mind was evidently
aware of, was affected by, guards, stokers, engines, carriages, and
pictures, which he describes as material existences. He derides
the 'crude materialism of the savage,' but the materialism of
common sense, which he here adopts, is every whit as crude.
He declares that "all the evidence that we have goes to show
that . . . the physical facts go along by themselves, and the
mental facts go along by themselves. There is a parallelism
between them, but there is no interference of one with the other."
But to imagine this unrelated but exactly coincident working is
to imagine the greatest of miracles. Moreover, the hypothesis
involves the corollary that mind is useless, and that the unfeeling,
unthinking brain is by itself responsible for all the more wonderful

1 Op. cit., Right and Wrong, pp. 328-9, quoted by James.

THE AUTOMATON HYPOTHESIS 359

activities of the higher animals, including man. To the student
of evolution, who realizes the extreme parsimony of nature, and the
universality of adaptation, such a notion, Huxley notwithstanding,
should be unbelievable.1

598. Common sense tells me that there is at this moment a cup
of coffee on my table, which I see and smell, because I have material
eyes and a material nose, but which I would neither see nor smell if
I had lost the eyes and nose. I become conscious of a desire to drink,
and, apparently because of that desire, my hand, a thing as material
as my brain, goes out and seizes the cup. I drink with a material
body, and feel a satisfaction which is mental. My entire life is
filled with such convincing experiences, and so, as far as I am able
to judge, is the life of every one else. At any rate, the evidence is
such that every human being over the age of a few weeks, and I
think every conscious animal that can think at all, is convinced, in
effect, that mind and body influence one another — that, for example,
he can move his body at will, and that when his body is injured he
suffers pain as a consequence. The whole of our private and public
conduct, the entire structure of the family and of society, is founded
on this belief that mental and bodily actions are not links in separate
chains of events, but links in the same chain. Thus we bestow
material gifts, seek to please those we love, and imprison and even
hang men who have consciously broken the law — whose minds, as
we suppose, have influenced their bodies. But we do not punish or
even blame a man when he unconsciously develops a cancer which
offends sight and smell, or an infectious disease which starts a
destructive epidemic. Continually, therefore, we blame the mind
for the doings of the body, and punish the body for the doings of
the mind.

599. In fact, given the existence of the body, then, as far as the
evidence goes, there is nothing in the whole range of experience so
certain apparently as that mind and body affect one another. It
is not the lack of evidence that is the obstacle to belief, but the
difficulty of conceiving \\.QVJ a material thing can affect an immaterial
thing, and vice versa. But matter itself is inconceivable. Having
swallowed the camel, we have no right to put on an air of
delicate discrimination and strain at the gnat. When evidence is
massive and apparently conclusive — as it is in this case, if any-
where— the probabilities are that the apparent inconceivability of
a thing is due, not to its non-existence, but to our mental limita-
tions— to our ignorance, lack of the right perceptive powers, and

1 See James, Principles of Psychology, vol. i. pp. 138-144.

360 THE RELATION OF MIND TO BODY

the like. We have no senses by which we can perceive minds ;
therefore we are unable to conceive how they affect or are affected
by brains ; but that does not confer on us the right to declare
dogmatically that there is no relation save a parallelism. Other
existences, though equally inconceivable, are readily believed in
by all of us, including Huxley and Clifford, merely because suffi-
cient evidence demonstrates their existence. Thus both authors
accepted the theory of gravitation as a true statement of fact ;
that is, they supposed that the earth attracts bodies to its surface
by means of an immaterial something, which, acting across millions
of miles of space, affects even the sun and the stars. " One cannot
thus blow hot and cold. One must be impartially naif or impartially
critical." 1

600. For the idealist, material bodies (e.g. brains) do not exist.
His insurmountable difficulty is to account for the coexistences and
sequences of phenomena.2 It is, for example, no easier for him to
imagine that iron (a mere appearance) can couple railway carriages
(also mere appearances) than to imagine that feelings of amity can
perform the task. To adult people, thinking in common-sense
terms, the idea that immaterial minds can influence material brains
seems, on the face of it, very absurd — as absurd as that sentiments
of amity can couple railway carriages. On the other hand, the
notion that the chains of physical and mental facts are distinct and
separate seems reasonable — as reasonable as that feelings cannot
connect railway carriages. But why does the one seem absurd and
the other reasonable ? Only, I think, because experience has im-
pressed on us, till we accept its teaching as a natural law, that,
while sentiments do not directly influence such things as railway
carriages, physical things do. An infant would feel no sense of
absurdity in the one case or of reasonableness in the other ; nor
should we had our experience been different. We consider things
reasonable or absurd accordingly as they do, or do not accord with
previous experience. Our experience is that sentiments do not
influence such things as railway carriages, with which they have no
direct connexion. Therefore, though the evidence that brains and
sentiments are directly connected, and that they influence one
another is immensely massive, we, or at least some of us, reasoning
from analogy, tend to suppose that neither connexion nor influence
exist. It would be quite as reasonable to suppose that there is no
such thing as gravitation or magnetism.

1 James, Principles of Psychology, vol. i. p. 137.

2 See § 566 (footnote 2).

THE AUTOMATON HYPOTHESIS 361

601. Like Huxley and Clifford, many modern writers insist on
" these two notions, of the absolute separateness of mind and matter,
and of the invariable concomitance of a mental change with a
bodily change." l " But this ' concomitance ' in the midst of * absolute
separateness ' is an utterly irrational idea. It is, to my mind, quite
inconceivable that consciousness should have nothing to do with a
business that it so faithfully attends."2 ... "To comprehend
completely the consequences of the dogma so confidently enunciated,
one should unflinchingly apply it to the most complicated
examples. The movements of our tongues and pens, the flashings
of our eyes in conversation, are of course events of a material order,
and as such their antecedents must be exclusively material. If we
knew thoroughly the nervous system of Shakespeare, and as
thoroughly all his environing conditions, we should be able to show
why at a certain period of his life his hand came to trace on certain
sheets of paper those crabbed little black marks which we for short-
ness' sake call the manuscript of Hamlet. We should understand
the rationale of every erasure and alteration therein, and we should
understand all this without in the slightest degree acknowledging
the existence of the thoughts in Shakespeare's mind. The words
and sentences would be taken, not as signs of anything beyond
themselves, but as little outward facts, pure and simple. In like
manner we might exhaustively write the biography of those two
hundred pounds, more or less, of warmish albuminoid matter called
Martin Luther, without ever implying that it felt.

" But, on the other hand, nothing in all this could prevent us
from giving an equally complete account of either Luther's or
Shakespeare's spiritual history, an account in which every gleam
of thought and emotion should find its place. The mind-history
would run along the side of the body-history of each man, and
each point in the one would correspond to, but not react upon, a
point in the other. So the melody floats from the harp-string, but
neither checks nor quickens its vibrations ; so the shadow runs
alongside the pedestrian, but in no way influences his steps." 3

" My conclusion is that to urge the automaton theory upon us,
as it is now urged, on purely a priori and ^oft-metaphysical
grounds, is an unwarrantable impertinence in the present state of
psychology'' 4

1 Chas. Mercier, The Nervous System and the Mind, p. 1 1 .

2 James, Principles of Psychology, vol. i. p. 136.

3 James, Principles of Psychology, vol. i. pp. 132-3.

4 Op. cit., vol. i. p. 138.

362 THE RELATION OF MIND TO BODY

602. Assuming, then, that brain and mind influence one another,
what is the connexion between the two ? It has been said very
crudely, but I think with some element of truth, that the brain
secretes thought as the liver secretes bile. It has been said equally
crudely that the mind, like heat and electricity, is a form of motion.
It has been said that mind and body are different aspects of the
same thing, a statement which is merely verbal in the sense that it
conveys no intelligible idea. It has been said that mind and body
are distinct but temporarily related things, and that mind bears the
same relation to body as the musician to his instrument ; in which
case the actions of the body are comparable to the music. It has
been thought that mind is the music that proceeds from the
instrument, the body, and that the environment is the musician,
the thing that stimulates the body, the brain, to produce the music.
This is the common-sense, and, I think, the correct, notion. But
it is a notion which is capable of expansion.

603. To me, bearing in mind the theory of evolution, it seems
probable that thinking and feeling are forms of doing, and that the
brain is the doer; or, in other words, that mind is one of the
products of brain activity, one of the functions of the brain, one
of the things that it does. I say one of the things, for not only
does the brain, as I suppose, think and feel, but it receives and
despatches stimuli. I do not know how brain produces mind any
more than I know how one material body attracts another across
space. But, as far as I am able to judge, the evidence indicates
that mind arises only when there is an expenditure of energy in
the brain ; — when there is no brain there is, apparently, no mind ;
when a portion of the brain is destroyed or injured, and ceases to
function, or functions imperfectly, a corresponding portion of the
mind is eliminated or is imperfect ; accordingly as the brains of the
higher animals are complex and ample so are their minds ; mental
exhaustion bears a relation to physical (brain) exhaustion ; and so
on. I assume, therefore, as the most probable conjecture, that
mind is somehow a consequence of the work of the brain. When
energy is expended in the muscles of the arm, molecular movements
occur, from which finally result the muscular contractions, by means
of which the arm is moved and the hand does its varied work. So,
apparently, when energy is expended under conditions which
exist in certain forms of nervous tissue (e.g. brains), mind results,
and the brain does its varied work. But when I think of the
chain of events that end in the movements of the hand, I think
from first to last of nothing but matter in motion. If I had a

MIND AND ENERGY 363

sufficiently powerful microscope, I should be able to perceive the
whole chain, and, within narrow limits, to think of it in terms of
causation. Even now my perceptive powers are such that they
supply me with materials which enable me to imagine it. But no
microscope, however powerful, could enable me to perceive how
the molecular movements in the brain result in mind. Even if I
could see the movements of the molecules of another man's brain,
even if I learned that certain movements in certain regions of his
brain always coincided with certain of his feelings and thoughts, I
should yet be unable to perceive the link between the two trains
of happenings, the mental and the physical. And, since my
perceptual powers, however aided, are such that I could not
perceive the link, therefore I cannot think in terms of it.1 Never-
theless, this is not the main difficulty. It is merely part of the
larger difficulty raised by the idealist — the difficulty of conceiving
how, even if material bodies exist, our minds, which are so
profoundly different from material objects, which do not occupy
space, and have none of the properties by means of which material
objects act and react on one another, can be affected by such
objects, can become aware of them. But, if we accept the common-
sense view, and suppose that material bodies both exist and affect
our minds, then, though we cannot conceive how the minds are
thus affected, it seems to me that we have no alternative but to
suppose that our minds are produced by our brains. As far as we
know, our minds are nothing other than streams of feelings, states
of consciousness. Ex hypothesi, some of these feelings symbolize
material objects. When we become aware of an object, that
object causes — in the full sense of the word causes — that feeling to
arise. But its action on the mind is not direct. It first produces
a change in a sense-organ. This change produces in turn a change
in a nerve, and that again a change in the brain. Thereupon we
become aware of the object. It follows, that if material objects
exist, and if our minds are aware of them, then our brains produce —
in the full meaning of the word produce— the feelings that symbolize
them. And, if it be admitted that they produce these items in the
stream of feelings, we have no grounds for denying that they pro-
duce any of the items, even the highest flights of thought.

604. When we know the conditions exactly, we are able to
measure work in terms of the energy expended ; for example, we
are able to say that under certain conditions a certain expenditure
of energy will raise a certain mass a certain distance. We are

1 See § 573.

364 THE RELATION OF MIND TO BODY

unable to measure feeling in this way — to say that a certain
feeling arises in relation to a certain part of the brain when there
is a certain expenditure of energy in the latter. Consequently —
merely because we cannot measure feeling in this way — it has
been argued, in effect, that there is no connexion between the
two. A vast amount of nonsense has been written on this basis.
For example, we are told that the thoughts of a Shakespeare and
those of an imbecile bear no relation to the amount of energy
respectively expended by them. Here the excellence of the
thinking, as excellence is estimated by us, is taken as a criterion,
and it is assumed that the greater the excellence the greater
should be the expenditure of energy. The assumption is obviously
absurd — as absurd as if it were argued that, because good and bad
railway engines give different results, therefore the expenditure of
coal has nothing to do with their movements. Moreover, this
hypothesis, that sensation and thought and the concurrent
expenditure of energy, bear no proportion to one another, is
contrary to the universally accepted belief that every mental
change, every feeling, is correlated with a brain change; for it is
not denied by any one that cerebral changes, like other physical
events, result from, and are proportionate to, the expenditure. It
is certain that feeling is unknown to us except in connexion with
the work of nervous tissue. But, since the conditions under which
the expenditure occurs are but little known, we cannot estimate
the amount of it in terms of feeling ; and, apparently, because our
perceptive powers are limited^ we are unable to conceive how the
working of the brain gives origin to mind.

605. Of course, as just indicated, mind may be considered as
comparable, not to the music that proceeds from the instrument,
but to the player who plays on it. But this hypothesis of an
independent agent seems, at least, unnecessary. We shall see
immediately that there is convincing evidence that mind is a
product of evolution. As a function of nervous tissue, we can
conceive of it as coming gradually into being under the influence
of natural selection. Or rather, we can conceive the brain as
evolving and becoming capable of doing more and more varied work,
just as we can conceive the hand as so evolving. But, if we think
of mind as an independent player who operates on the brain, and
so directs the activities of the body of which the brain is a part,
how shall we account for the existence of this player ? Is there a
definite amount of mind in the universe as there is of substance
and energy, and is he somehow evolved out of this fund ? Is a

THE EVOLUTION OF MIND 365

certain amount of mind somehow captured and attached to each
brain, human and brute? Or is he and others of his kind miracu-
lously created out of nothing-, when brains, including those of lower
animals, come into being and begin to function ? In any case the
player, if he exists, lies, if anything, even farther outside the range
of observation than even ' matter in itself.' We have no means of
knowing anything about him. All we know quite certainly is that
there is mind, and the mind tells us that it is associated with a
brain, and with expenditure of energy. To us mind is a function
of the brain.

606. The physical characters of animals develop in response to
stimuli, in directions and within limits that have been closely fixed
by evolution. On that account the body of every normal man is
very like the body of every other normal individual of the same
variety. Thus the lungs and brain of one person are very like the
lungs and brain of any other. We attribute these likenesses to the
fact of a common descent. But, in spite of this common descent,
the mind of every man so develops as to be immensely different
from the mind of every other man, pastor present. For example,
while my father acquired a knowledge of military science, my mind
has grown in such a way that I know — more or less imperfectly —
the art of medicine. My neighbour, the sailor, likes and dislikes
one lot of people ; I quite another lot. He is familiar with one set
of scenes ; I with quite other scenes. If we suddenly exchanged
bodies we should scarcely be conscious of the change till the mirror
or the behaviour of other people revealed it ; if we exchanged
minds we should be as lunatics in one another's environments. Had
I been captured as an infant by savages, and reared by them, I
should now resemble my educators mentally much more nearly
than my progenitors. For example, I should know only the
things that they know — the scenes, the people, the aspirations.
Obviously then intellectual characters cannot have been evolved
in the same sense as physical characters. Thus, a knowledge of
medicine can never have been evolved in my case in the same
sense that brains have been evolved. How then does it happen
that I possess a knowledge of medicine? It seems to me, as the
only probable explanation, that mind is not a thing distinct from
the brain, but only the work of the brain — just as manipulation is
the work of the hand. Nature has not directly evolved immaterial
minds any more than she has evolved manipulations. She has
merely evolved brains and hands capable of doing work useful to
the individual. The kind of brain she has evolved in the human

366 THE RELATION OF MIND TO BODY

species is particularly capable, within limits that vary with indi-
viduals, of learning to do infinitely varied and complex work, with
a constantly increasing degree of facility and skill. For that reason
my brain has done, not what the brains of my predecessors could
not do, but what they did not do (e.g. the work which results in
the knowledge of medicine). I believe, then, if we consider these
two facts together, the facts that human brains are much alike, but
human minds very different ; and if, moreover, we think in terms
of common sense and accept the theory of evolution, then we are
forced to conclude as the only course open to us, that mind is the
work, or rather part of the work, of the brain.

CHAPTER XX
REFLEX ACTION, INSTINCT, AND REASON

Mind is associated with nervous tissue — It is adaptive — It is related to move-
ment— The evolution of mind — Reflex and voluntary actions — Intelligence and
reason — Memory — Traditional knowledge — The mental characteristics of ants —
The instincts of man — Sucking — Crying — Weariness — Hunger — Thirst — Imita-
tiveness — Sexual and parental love — The mutation theory — The importance of
mental acquirements.

A1

607. ^ MASS of evidence indicates that mind is especially
associated with nervous tissue. In fact, there is no
clear evidence that consciousness, even in the form
of the most rudimentary feeling, is anywhere present except in
conjunction with those masses of nerve cells which are termed
ganglia, the largest of which is the brain. Mind appears to be
rudimentary, or even non-existent in animals in which ganglia
are relatively little developed or absent. It is found in greater
amplitude in the higher animals in which the ganglia are better
developed. In the highest animals it appears associated exclusively
with the brain. Moreover, mind seems invariably associated, not
only with ganglia, but also with sense organs — eyes, ears, tactile,
and taste organs, and the like — which are mostly situated at, or
near, the surface of the body, and which receive from the external
world and transmit to the ganglia messages (stimuli) derived from
light, sound, contact, and the like — messages which in some way
awaken an activity which is correlated to consciousness.

608. Mind is useful to the animal that possesses it only in so
far as it controls his actions by initiating, guiding, or inhibiting
them. If the animal is of a relatively simple type, living in a com-
paratively simple environment, his equipment of nervous tissue
and mind is correspondingly simple. If, on the other hand, he
is fitted for more complex surroundings, and if, therefore, his
activities must be adapted to meet a number of more or less
remote contingencies, to achieve more or less far off aims, his brain
and mind display a corresponding complexity. Compare, for
example, a sea-anemone, whose consciously directed movements,

367

368 REFLEX ACTION, INSTINCT, AND REASON

if any such occur in him, are adapted only to meet the needs of
the moment, with a man, who, in early youth, may form a plan
(e.g. the achievement of wealth), and pursue it undeviatingly in
ways remote from the end during all the varied scenes of a long
life.

609. Since mind is clearly adaptive, and since it increases in
amplitude and complexity from the lower to the higher animals,
it is apparently as much a product of evolution as the function of
any physical organ, for example the hand. Certainly, we have
as much reason to suppose it is such a product — to suppose that the
functions of the brain have undergone evolution in the same sense, in
the same way, and by the same means as the functions of the hand.
It is, in fact, a 'character' (a reaction to stimulus) of the indivi-
dual, which, as far as we are able to surmise, was, like other useful
characters, absent in remote ancestors, had its origin in variations,
and, passing through simple to more complex types, underwent
evolution (as a function) by the action of Natural Selection.
There is evidence that we are able by careful selection to increase
or decrease in any desired direction the intelligence of our
domesticated animals. In parasites and other animals which have
forsaken an active existence, mind appears to have undergone
retrogression through cessation of selection. Again, some animals,
which lead an active existence early in the individual life, but
which lapse into an inactive adult stage, seem to lose their minds
just as they lose their larval organs. In brief, mind owes its
existence to its utility.

610. Various authors have supposed that, " the beginnings of
mental life date back from the beginnings of physical life. The
question of the origin of mental development thus resolves itself
into the question of the origin of life." 1 If they are right we are

1 Wundt, Principles of Physiological Psychology, Eng. Trans., vol. i. p. 31.
Here Wundt is very unconvincing. We are told that " the beginnings of a
differentiation of mental function can, however, be found even in the protozoa.
. . . The only sense that is plainly functioning is the sense of touch . . . the
cilia with which these infusorians^'are furnished . . . are . . . organs of motion.
They function as organs of touch, and sometimes appear sensitive to light as
well " (pp. 33-4). But reaction to stimulus does not necessarily imply sensation.
The environment of infusorians is so simple, their reactions to it so few, that
sensation superimposed on the reactions made by them would appear to be a
useless epi-phenomenon. No sensations, as far as we are aware, accompany
much more complex reactions in our own bodies, for example the normal move-
ments of our intestines. " In the compound organisms we observe a more
radical differentiation of mental function and its bodily substrate. The cell-
mass of the yolk, originally homogeneous, divides first of all into a peripheral and
a central layer of different structural character, while the cleavage cavity gradually

THE ALLEGED UNIVERSALITY OF MIND 369

guilty of great cruelty when we boil our vegetables alive. Other
writers, influenced by the uniqueness of mind, attribute some sort
of mentality even to lifeless objects. Judged, however, from the
standpoint of evolution, there does not appear to be any warrant
for these fanciful speculations. As we shall see, the function of
mind is adaptation. It is difficult to believe that a thing so
clearly useful, so evidently bearing the marks of evolution, can
have existed prior to its usefulness. If there was any unique

widens out to form the future body cavity. At this stage sensation and move-
ment appear to reside exclusively in the outer cell-layer, the ectoderm, while
the nutritive functions are discharged by the inner layer or entoderm." Here,
then, according to Wundt is a phenomenon hitherto non-existent in nature —
i.e., living cells devoid of sensation which nevertheless perform perfectly well
their complex function of elaborating nutriment for themselves and other cells.
Loss of sensation is attributed to evolution. " At a higher level of evolution a
third layer of cells, the mesoderm, forms between the two. This discrimination
of organs is accompanied by differentiation of the elementary constituents of the
tissues. When the separation of ectoderm and entoderm is first accomplished
the cells of the former discharge the combined functions of sensation and move-
ment. The initial step towards the separation of these two cardinal functions is
apparently taken in the hydridae and medusas, where the ectoderm cells send out
contractile processes into the interior of the body. The sensory and motor
functions are still united in a single cell, but are distributed over different portions
of it. In the next stage the properties of sensation and contractibility pass to
special and spatially separated cells " (p. 36). At this stage, then, the stage
reached by the higher animals, Wundt supposes that sensation has departed from
the contractile cells. Nevertheless they contract on receipt of stimulus precisely
as they did before its departure. But the only evidence of sensation they ever
afforded was contraction. That evidence still remains and is as inconclusive in
the one instance as in the other. If contact alone caused an infusorian to
contract efficiently, the sense of touch would be as useless to it as to a muscle
cell. Before we attribute sensation to such low animals we should at least feel
sure that this wonderful product of evolution is so useful to them as to be an
important factor in securing survival ; that is we should feel sure that touch alone
without the sense of touch is not sufficient for their needs. The functions of life,
concentrated in a single cell in the case of the unicellular organism, are distributed
amongst skin, nerve, muscle, and other cells of higher types. But this separation
of function does not involve the corollary that no new functions (e.g. sensation)
have been evolved. Touch is a discriminating agency ; but discrimination does
not necessarily imply a mental element. Thus, apparently unaided by sensation,
gland cells discriminate between the substances conveyed to them by the blood.
It follows that an infusorian may well display tactual discrimination and yet
feel no sensation. Besides infusorians, many cells have cilia. In multicellular
organisms " all the cilia of adjoining cells do not move at once, but in regular
succession, the movement travelling from one cell to the other, but how this co-
ordination is brought about we do not know. At least, it is independent of the
nervous system, as ciliary movement goes on in isolated cells (i.e. cells that have
been scraped away) and in men it has been observed two days after death."
(Landois and Stirling's Physiology, vol. ii., p. 613). Here the cell, which is
admittedly devoid of sensation and is cut off from nerve stimuli, behaves exactly
like an infusorian which has been stimulated by touch.
24

370 REFLEX ACTION, INSTINCT, AND REASON

thing in nature out of which it was evolved, a thing outside the
range of our perceptive powers, then that thing was not mind in
any real sense any more than nitrogen and other chemical
elements are muscle.

6 1 1. Granting that mind is a product of evolution, that it
originated in connection with movement, and that it occurs only
in connection with nervous tissue, to me it seems probable that
the order of evolution was as follows. First, through Natural
Selection, cells, the function of which was contraction and without
which movement would have been impossible, appeared in multi-
cellular organisms. Many unicellular organisms are contractile,
and some have contractile flagella. Doubtless the contractility
of the cells of the higher types was derived from [them. Next,
as animals became larger and more complex, as other cells under-
went differentiation, as the masses of the cells which were
contractile increased in size, number, and complexity, a nervous
system was evolved, which consisted of lines of communication
(nerve fibrils) and one or more central ganglia. The ganglia
received stimuli through the ' afferent ' fibrils from the surface,
and translated them into other stimuli which passed outwards
through the ' efferent ' fibrils and awakened the activities of various
other cells, especially the contractile cells. The function, therefore,
of nervous cells was to co-ordinate the reactions of the organism
and so adapt it to the environment. Next there were evolved on
the surface, at the ends of the nerve fibrils, organs which delicately
discriminated between different classes of stimuli — light, heat,
contact with foreign bodies, and the like. Nerve currents, passing
from these surface organs, were transmuted in the ganglia into
appropriate stimuli for the several masses of contractile and other
cells. As yet there was no consciousness.

612. Next, the surface organs which received stimuli from the
environment evolved into sense organs, where originated nerve
currents that gave origin in the ganglia to sensations — delicately
discriminating stimuli which indirectly (through the efferent nerve
currents to which they gave rise) exploded the right stores of
energy latent in this or that mass of contractile cells. Throughout
the process was one of increasing adaptation to the environment.
Thus mind dawned. It will be noted that here I attempt nothing
more than a description of the conditions under which, as I
suppose, mind appeared. I indicate when, not how, it appeared.
I do not know how nervous tissue does this work. I only suppose
that it was rendered possible to nervous tissue through the selection

REFLEX ACTIONS 371

of favourable variations. Lastly, through the continued action of
Natural Selection, sensations took on those peculiar tones which
we designate as pleasure and pain. Thereupon desire and will
came into being. The animal was now no longer an automaton
in the ordinary sense of the word. It felt, and in a real sense
desired ; and some of its activities were under the control of its
desires, or rather of the will which the desires awakened. The
whole process, I suppose, involved a very gradual co-ordinated
change in which other cells besides nerve cells participated.
There was no mutation, no sudden appearance of nervous tissue
or of mind ; for such a sudden development could have been useful
only if it had involved simultaneous changes in several classes
of cells — changes so numerous, complex, and adaptive, that their
simultaneous occurrence would have been altogether miraculous.

613. All the movements of living beings, which result from
their vital activities but are not under nervous control, may be
termed ' protoplasmic.' The movements of plants and unicellular
animals and ciliary movements are examples. Movements made
under nervous control are either reflex or voluntary. All move-
ments under nervous control, but with which no feeling is
associated, are reflex. There are many such in our bodies, for
example the normal movements of our heart and intestines. But
some movements, which are rightly termed reflex, have a great
deal of feeling associated with them. Sneezing and the con-
vulsions resulting from tickling are examples. Here, not only does
feeling accompany the action, but it initiates it. Neither sneezing
nor the convulsions of tickling occur in the absence of feeling ; for
example, in people under the influence of chloroform. If I cough
because I choose, the action is voluntary ; if I cough because I
must — because an irritation in the larynx compels me to cough —
the action is involuntary. But often I can control the reflex, and
delay, and in some cases even prevent it. A reflex action, there-
fore, is not necessarily one which is not associated with sensation, nor
one which is not initiated by sensation, nor one which is not
controllable by the will. It is one which is under nervous control
but which is not directly INITIATED by the will. This definition
is unlike those commonly accepted, but I think it can be justified.

614. The same action may be voluntary at one time and reflex
at another. If the reader will think of all the reflexes he can call
to mind, he will find that their distinguishing peculiarity is that
they cannot be set agoing by the direct impulse of the will. Thus
no matter how strong his willing he cannot really sneeze when he

372 REFLEX ACTION, INSTINCT, AND REASON

wishes. It is true he may set himself sneezing by voluntarily intro-
ducing an irritant into his nose ; but the irritant, not the will, is
the direct cause of the act. So also he is able to make himself
sick by tickling the back of his throat, but he cannot vomit by a
pure act of will. Swallowing is another example, and a very good
one. The act of swallowing seems at first strictly voluntary.
Really it is purely reflex. We are able to swallow only when
we have something to swallow ; that is, only when the mechanical
stimulus which starts the reflex is present at the back of the throat.
The reader can easily test this by swallowing his saliva and then
trying to repeat the act. He will succeed only after he has
collected more saliva — supplied more mechanical stimulus.

615. The reflexes are all * inborn and transmissible,5 that is
they all develop in the individual under the stimulus of nutriment,
and reappear in all normal offspring. With rare exceptions, they
are extremely useful to him, indeed essential to his survival. For
example, no child lives who does not inherit the cardiac and
intestinal reflexes which were possessed by his ancestors. The
exceptions are one or two reflexes which seem to be mere by-
products of evolution — traits correlated to more useful traits. The
convulsions of tickling are examples. When feeling is associated
with the adaptive reflexes it always contributes to their usefulness.
In some cases (e.g. the feeling caused by food in the larynx, which
in turn causes swallowing) feeling is the discriminating spark which
awakens the reflex. In other cases, by promise of pleasure or
relief from pain, it awakens desire, which, as in the case of hunger,
awakens the will to perform those voluntary actions which
necessarily precede and supply the stimulus for the reflex act. In
some instances, as in the case of the reflexes of the bladder and
lower bowel, the will acts usefully, not because, as in the case of
swallowing, it initiates the performance of voluntary actions which
in turn supply stimuli for reflexes, but because for a longer or
shorter time it controls or inhibits the reflexes — because it is able
to delay their performance till a more convenient time. Such
reflexes are always initiated by a feeling which tends to awaken,
not only the reflex, but also the will that inhibits it. The duration
and amount of the control which the will is capable of exercising
is always proportionate to its usefulness. Thus it is short and
slight in the case of sneezing — as a rule no longer than gives time
to swallow food already in the mouth. It is a little longer in the
case of breathing. In the case of coughing it is short in proportion
to the severity of the irritation. On the other hand the control is

VOLUNTARY ACTIONS 373

more persistent and more perfect in the case of bladder and bowel.
But always the reflex impulse tends to grow stronger, till at last
it overpowers the will. No adaptive reflex which is not associated
with feeling (usually pleasure or pain) is under the control of the
will. Thus we cannot voluntarily control the beatings of our
hearts nor the movements of the middle portions of our alimentary
canals. All adaptive reflexes which are normally associated with
feeling are directly or indirectly under the control of will. Thus,
as we see, the bladder reflex which promises relief from pain is
directly controlled by the will, whereas the swallowing reflex
which promises pleasure is indirectly controlled by it, for the will
provides those voluntary actions, the provision of food, the chew-
ing and removing of it to the pharynx, which in turn awaken the
reflex impulse to swallow.

6 1 6. We see then how clearly the reflexes are adaptive, how
plainly they bear the marks of .evolution. On the other hand, we
see how complex they are both physically and mentally ; and yet
how perfectly they link up with the rest of the physical and mental
activities of the individual. Every complex animal has these
wonderful reflexes. Except through actual miracle such manifold
co-ordinated activities could not have arisen by mutation. Unless,
therefore, we attribute them directly to a supernatural origin, we
must assume that they arose gradually by the continual selection
of fluctuating variations — by a process which gradually and con-
currently altered the whole organism. Here also we have an
example, emphasised as we shall see by the whole study of mind,
of facts which are familiar to everyone, which nevertheless since
their relations are complex and difficult to trace, cannot be
classified except after careful thought. ' Obvious inferences/ such
as are all that are needed in anatomy and that kind of botany and
zoology which takes no account of the sequences of events in the
evolution of the race, here lead, and have repeatedly led, only to
confusion and error.

617. Voluntary acts are either instinctive or (in the lack of a
better term) rational. As far as I am aware, no one but myself
regards instinctive actions as voluntary. Usually they are classed
as a kind of reflex. However, I feel confident I am right. A
voluntary act is one which is prompted by the will. If we think
carefully we find that the will, in turn, is always prompted by
desire; and that desire again is always prompted by present or
prospective pleasure or pain. The desire may be so faint that we
can hardly detect it ; but unless it is present we do not, we cannot,

374 REFLEX ACTION, INSTINCT, AND REASON

act voluntarily. It may be so strong as to be irresistible, in which
case it enlists a corresponding strength of will. Desire cannot be

awakened except by present or prospective pleasure or pain

not necessarily ' physical ' pleasure or pain, but pleasure or pain of
some sort — for example a whimsical pleasure in demonstrating
that we are able to disregard ' physical ' pain, in which case the
desire to achieve the pleasure transcends the desire to avoid the
pain.

6 1 8. An instinct may be defined as an ' innate and inherited ' mental
impulse or inclination to do a certain definite act, the instinctive act,
on receipt of a certain definite stimulus. Therefore it is a mental
character which is developed in the individual under the stimulus
of nutriment, but which is awakened to activity by experience (the
appropriate stimulus). For example, the sexual instinct is an
' innate ' character that is aroused by the presence of an individual
of the opposite sex. I think psychologists believe instinctive
actions to be types of reflex action only because, when studying
the question, they have limited their attention mainly to the
instincts of the lower animals. We have then, very often, no
means of knowing whether any given action is, or is not, prompted
by desire and directed by the will. But when we consider our
own instincts we are on safer ground. Our knowledge is not
then derived by inference from the actions of another animal, but
from actual experience of the mental phenomena. We know
our own instincts therefore with an intimacy with which we
cannot know those of the lower animals, amongst which all our
own instincts have their counterparts. Consequently it is safer to
reason from our instincts to those of lower animals than to
adopt the reverse process. Since we are derived from lower types,
presumably, our instincts are of the same nature. They may
differ in degree, they can hardly differ in kind.

619. Consider, then, our own instincts, for example the instinct
to sleep periodically, to rest when tired, to sport when rested, to
eat and drink when hungry and thirsty, the instincts of imitative-
ness and curiosity, and the deferred instincts of sexual and
parental love. In the case of each we feel strongly, if sometimes
vaguely, the prompting desire to seek pleasure or to avoid pain
which is the actual and direct stimulus of the will to do, which, in
turn initiates the instinctive act, and which therefore sharply
differentiates it from the reflexes which are never directly prompted
by the desire to do an action. Thus, sleepiness prompts us,
strongly inclines us, voluntarily to assume attitudes of repose, as

VOLUNTARY ACTIONS 375

also does weariness. Clearly it is the presence of the desire that
renders the act voluntary. Every instinctive impulse is nothing
other than a desire, even when the object of desire is not easily re-
cognised. Were the desire not present we should not act. Hunger
inclines us to procure and chew our food ; both actions are dis-
tinctly voluntary. Imitativeness, curiosity, sexual, and parental
love, also prompt us to acts which are entirely voluntary. It is
true that sometimes, when the prompting desire is very strong, we
are colloquially said to act ' against our wills.' As a fact, however,
except in the case of the reflexes, we never do act against them,
though we often act against our judgments. Wise and good
actions are certainly all voluntary ; but, equally certainly, not all
voluntary actions are either wise or good. When the starving
sailor kills and eats his comrade he may abhor and struggle against
his desire. Nevertheless from the act of killing to the act of
chewing his [actions are voluntary. He performs them simply
because his desire, his will to eat, is stronger than his will to
abstain.

620. It must be borne in mind that, especially in the case of
beings like men whose desires are complex, two or more impulses
inciting to different actions may be in operation at the same time.
When one is distinctly stronger than the other, we yield to it at
once ; when they are equally balanced, we have a feeling of irre-
solution. Suppose a man falls in love with his friend's wife, the
feeling would be an instinct, and would impel to instinctive acts.
Opposed to it might be a desire to do right. He will certainly
yield to the stronger desire, and, in each case, his action will be
voluntary. It is very probable that before taking one course or
the other he will seek to reinforce his desire to do right by
picturing all the consequences of doing wrong. But if he acts
wrongly he will not be acting against all his desires, but only
against one of them \ not against his whole will, but only against
the weaker incitement of it. No one is held blameworthy for his
reflex actions. It is felt that he does not initiate them by his will,
and that even when he is able to some extent voluntarily to
control them, he must sooner or later yield. But for every
kind of instinctive act he may be held blameworthy. Therefore
it is recognised that they are initiated by his will. On that
account they involve questions of right and wrong, meriting praise
or blame.

621. Apart from his reflexes, what man ever acted except
under the influence of desire? The anchorite abstains from

376 REFLEX ACTION, INSTINCT, AND REASON

pleasure only because he desires and anticipates greater pleasure
in heaven. The patriot dies because his desire for his country's
good overmasters his desire for life. The tigress that has captured
prey goes hungry because her instinctive desire for food is
opposed by a yet stronger desire to feed her cubs. If I
deliberately burn myself, it is only because my desire to do so
is stronger than my desire to avoid pain. In every case the
action, whether instinctive or 'rational/ is prompted by desire,
and, if prompted by desire (which awakens the will) is plainly
voluntary, plainly different from those distinctly non-voluntary
actions which we term reflex. Compare, for example, the actions
to which hunger prompts with the peristaltic action of the stomach
when hunger is satisfied. The former are instinctive, the latter are
reflex. Wherein lies the distinction ? Clearly in the circumstance
that the instinctive actions are prompted by desire and initiated
by the will, whereas the reflex actions are neither prompted by
the one nor initiated by the other.

622. The term voluntary is sometimes limited to deliberate acts.
Thus, if I avoid a danger by taking thought, I am quite rightly
thought to act voluntarily. But, if I impulsively start away
from it, my action is held by psychologists to be involuntary or
even ' reflex.' But we shall see later that speed and absence of
deliberation imply, not necessarily lack of will, but only a quick
and smooth working of it, one principal condition of which is
absence of opposing desires. When we are hungry and have only
one dish, we set to work without hesitation. If half-a-dozen
dishes are placed before us, we may deliberate before setting to.
But our action in the one case is just as voluntary as in the
other. Will is one thing, deliberation is quite another thing. All
deliberate actions are certainly voluntary ; but, quite certainly, not
all voluntary actions are deliberate. When we are beset by two
or more nearly evenly balanced desires, we hesitate, reflect,
deliberate. But these mental processes are quite distinct from
will. They may incline the scale in one direction or the other
and so end the paralysis of will which results from balanced
desires. But obviously they are no part of the will, nor even a
necessary accompaniment of it.

623. Voluntary action then may be defined as action which
is prompted by desire. An instinct, we see, is an 'innate' and
' inherited ' inclination, an impulse, to act in a certain way under
certain conditions. At a fixed stage in his development the
caterpillar builds himself a cocoon. His dwelling is a wonderful

INTELLIGENT ACTIONS 377

structure, but from our human point of view, the most wonderful
thing is that he does not learn to build it. He may never have
seen a cocoon before, and he constructs only one in his life. Yet
his work is perfect, or at least excellent, and it is as good at
its beginnings as at its endings. Evidently he owes nothing to
experience beyond the stimulus to act, but is impelled and guided
throughout by that ' innate and inherited ' faculty which we term
instinct. Since his cocoon-building instinct does not appear at
the beginning of conscious life, it is termed a deferred instinct.
He has many such, for instance the instincts of flight and mating,
which do not appear until after he has undergone his meta-
morphosis into a butterfly.

624. On the other hand, man, unlike the caterpillar, cannot
build his house unless he first learns to build it. He depends, not
on instinct, but on stored experience. The faculty by which
experience is stored in the mind is termed memory. The faculty
by which we use stored experience is termed intelligence. When
the contents of memory are very vast, and the processes of thought
by which they are utilised comparatively difficult and complex,
intelligence is termed reason. INTELLIGENCE and REASON depend,
therefore, on MEMORY, on ability to learn, on capacity to profit by
stored experience. Memory is not the whole of intelligence, but
it is the basis of it. Without memory, there could be sensation
and emotion, but no thought-, for the materials for thought would
be lacking. Thinking depends on such processes as association,
comparison, discrimination, inferring, and the like, which in turn
depend on memory.

625. In a sense, the caterpillar has discrimination; thus, he
can distinguish his food or his mate from other objects ; but he
has not the kind of discrimination which is so much used by man.
His discrimination does not depend on a comparison of present
things with things formerly known or imagined, but merely on
differences of feeling awakened by different objects. He does
that which he feels is pleasant, not that which he has learnt is
pleasant. If a man had no memory he could compare no two
objects or ideas. He could have no ideas. He could perceive
men and women who might awaken emotions and impulses in
him, but he would not know them for men and women, nor as
big or small, dark or fair, near or far, nor would he know the ends
of the actions to which he was impelled. Such thoughts, de-
pending as they do on association and comparison, could not
arise in his mind, which, at the end of a long life, since he had

378 REFLEX ACTION, INSTINCT, AND REASON

learned nothing, would still be as blank as that of a newly born
infant.

626. We always measure the intelligence of an animal by its
power of profiting by experience. Thus, a cat is more intelligent
than a rabbit, because it can learn more ; a dog, for the same
reason, is still more intelligent. An animal with a purely instinc-
tive mind, with * innate and inherited ' impulses to act in this or
that way but no memory, can have no conception of its past, and
therefore no idea of its future. It lives wholly in the immediate
present, feeling but not thinking. It acts entirely on simple
inclination, not on reflection. Like the caterpillar building his
cocoon, it makes provision for the future, not with any idea of
providing, but simply because stimulus from the environment
causes it to react in a certain way, gives it an impulse to a certain
course of action the performance of which bestows pleasure of the
kind that a child derives from playing or eating, and with the
ultimate result of which it is no more consciously concerned than
a playing child. If a caterpillar sheltered in a hole with the idea,
founded on experience, of avoiding danger, his action would be
intelligent. If, appealing to a memory, in which a great number
of complex experiences were stored, he took thought and designed
himself a shelter in which provision was made for all sorts of re-
membered or imagined dangers, his action would be rational. But
if, making no appeal to the past nor taking any thought for the future,
he builds only because impelled by an ' innate ' inclination, then, no
matter how elaborate the edifice he rears, his action is instinctive.

627. In proportion as animals are low in the scale of life, they
appear incapable of learning. Thus, memory seems rudimentary
or absent in most insects. But often they are wonderfully equipped
by instinct. To take, again, the example of the caterpillar: on
emerging from the egg, driven by an innate inclination which is
the instinct, the animal moves from place to place. It co-ordinates
its muscles without practice perfectly at the first attempt. In
other words, its movements are instinctive in a double sense ; they
are prompted by instinct and they are co-ordinated instinctively.
The animal does not learn to do them. In the human being, on
the other hand, even when the prompting is instinctive, the power
of co-ordinating the movements for the performance of the
instinctive act is for the most part slowly and laboriously acquired
through experience. For example, maternal love is an instinct ;
but facility in all the movements to which the instinct prompts the
mother is ' acquired.'

INSTINCT 379

628. Prompted by another ' inherited ' ' inborn ' impulse, the
caterpillar seeks its proper food. Yet another instinct prompts it
to inhabit such situations as afford concealment from its enemies.
Next, at a certain stage of its growth, an instinct prompts it to
provide shelter for its helpless pupal stage by spinning a cocoon
or by some other device which has been followed invariably by its
ancestors. As a butterfly, it is under the influence of an entirely
different set of instincts. Inhabiting an altogether different en-
vironment, it moves instinctively by means of other organs, adopts
new devices to escape its enemies, seeks and feeds in a different
way on different food, pursues the female and mates with her.
She, impelled by an instinct unfelt by the male, deposits her eggs
in one of the few spots in the vast and complex world in which
she moves in which her offspring will have a chance of surviving.

629. The caterpillar has sense organs and a nervous system;
we have every reason to believe that it feels. But there is little or
no evidence that it remembers or thinks. Memory would be little
use to it ; therefore parsimonious nature bestows little or none.
Cast adrift in a hostile world, it must come into existence ready
armed for the battle of life. The necessity of following, by its
own unaided efforts, the right line of action is as pressing at the
beginning of life as subsequently. It has no time to learn, and
during the rapid and strange changes in its career little oppor-
tunity of acquiring knowledge which would beneficially affect its
future. Many of its most important actions, such as cocoon
building and mating, are done only once. Since memory and its
corollaries, comparison, discrimination, idealism, imagination, re-
flection, intelligence, reason, and all that they imply are most
developed in the higher animals and are imperceptible lower in
the scale, since they gradually increase in number, range, and
utility, they are clearly later and higher products of evolution than
instinct. Memory, itself, the faculty by means of which we learn,
arises under the stimulus of nutriment. Therefore it is ' inborn.'
But all that is stored in the memory, all the mental growth which
arises through its use and the use of its contents is 'acquired.'
Therefore intelligence and reason are 'acquirements.' A man
who has no memory, whose mind is blank of all that memory
supplies, and who, consequently, cannot compare, discriminate, or
perform any of the operations which the possession of a stored
memory would enable him to accomplish, is not intelligent.1 The
only mental operations possible to him are sensations and instinc-

1 See § 762.

380 REFLEX ACTION, INSTINCT, AND REASON

tive emotions. But, though intelligence is altogether an acquire-
ment, I think no one will deny that we speak correctly when we say
that it has undergone evolution in the higher animals. Like many
instincts and physical characters, it arises late in the development
of the individual (for it arose late in the evolution of the species),
but it is none the less as essential a part of his mental growth as
any trait which arises under the stimulus of nutriment. In fact,
though students of the subject have never realised that intelligence
is an acquirement, yet it has been universally recognised that the
mental evolution of the higher animals has consisted mainly in
the evolution of intelligence and reason — that is, as we see when
we think closely, of the evolution of memory and of the mental
growth which the possession of memory renders possible.

630. Family life, which is practised by all the higher animals, is
not only a product of memory but is also that which has rendered
possible the evolution of a voluminous memory. The offspring are
^-cognized by the mother, and in the case of some animals by
the father who then recognises his mate also. This recognition
implies some degree of memory and consequently intelligence.
The young, instead of being cast adrift at birth to fend for them-
selves, are watched and protected, and, by the highest animals,
taught. Time and opportunity are thus afforded for learning about
the world, and, more particularly, of acquiring the traditions, the
stored experiences of the race. Animals which have no family
life, for example most fish, amphibians (e.g. frogs), and reptiles,
may possess a memory, but it is always very rudimentary. They
may learn a little from experience, but only a very little; their
intelligence is very low, their thoughts must be few and simple.
The recognition of offspring by parents is usually, but erroneously
assumed to be instinctive. It is certainly acquired through experi-
ence after the birth. But once the child is known, the more
intelligent the animal the more perfect is the subsequent recogni-
tion. The hen will adopt strange eggs and chickens, and even
ducklings and pea chicks. The ewe, the cow, and the human
mother may have strange offspring foisted on them immediately
after parturition, but they are not easily deluded after they have
performed the first offices of tenderness.

631. With the opportunity which parental protection affords to
the young to profit by experience comes the ability to profit by it,
and with the latter a proportionate retrogression of now useless
instincts. Intelligence is substituted for unthinking impulse. All
the instincts are not lost, but in the higher animals we find no such

HUMAN MENTAL DEVELOPMENT 381

elaborate impulses as in the lower. Such a being as the caterpillar
is able to fend for itself from the first, but just in proportion as
animals are intelligent they are helpless at the beginnings of
consciousness, and correspondingly capable later. A young pig
can run as soon as it is born, but the acquirements of the * learned '
pig are small compared to those of a dog which is more helpless
at birth but so teachable, so capable of learning, that it becomes
the companion of man. All our domesticated animals, except such
small and harmless types as silk- worms, are teachable, and for that
reason we are able to tame them. A tiger or a leopard cannot easily
be domesticated because instinct forms too large and memory too
small a proportion of its total mentality. Domestication, in the
sense meant, implies intelligence, and therefore memory.

632. Of living beings man is by far the most helpless at birth.
He cannot even seek the breast. In him instinct is at its minimum
and memory at its maximum. For him, more than for any other
animal, is prolonged and elaborate tuition necessary. But, so vast
is his memory and so great his power of utilising experience
stored in it, of growing mentally under the stimulus of use,
that in later life he is beyond comparison the most capable of
the inhabitants of the earth. Compare what even a dull man
knows, including the words of a language with their inflections
and articulations, with what is acquired by the cleverest dog or
monkey and the immensity of the difference is at once apparent.
We may take a frog and rear him solitary from the egg in an
aquarium. If, when he is adult, we remove him to a pond, he will
take his place with his fellows at once. He has little if anything
to learn. Instinctively he ' knows ' his food and how to seek it,
his enemies and how to avoid them, his mate and how to deal with
her. But how forlorn and helpless would be a man reared from
infancy out of sight and sound of his kind and then turned into a
world where his experienced fellows struggled for existence.

633. Traditional knowledge — that is knowledge imparted by
one generation to the next — is common enough amongst the
higher animals and forms no inconsiderable part of their mental
equipment. Thus we may see the hen, impelled by an instinct,
teaching her chickens, as she herself was taught, to seek food, and
the cat teaching her kittens how to ambush mice. The young
animals, on the other hand, discover an instinctive interest and
pleasure in copying their elders. While insects and others of the
lower type learn nothing from the presence of man, birds and
mammals learn much. When inhabiting desert islands they have

382 REFLEX ACTION, INSTINCT, AND REASON

none of that fear of him which in our country they learn from dire
experience. We have a saying, " as wild as a hawk " ; but Darwin
relates how he almost pushed a hawk from its perch with the
muzzle of his gun in the Galapagos islands. Sea-birds round our
coasts, where they are molested, are exceedingly shy ; at London
Bridge they feed from the hand. Formerly Arctic seals, impelled
by fear of polar bears, inhabited the outer margin of the ice floes ;
now they have retreated from the more dangerous neighbourhood
of man to the landward edge. Antarctic seals, harried by the
great carnivora of the ocean, are watchful in the water ; on land
or the surface of the ice, where, till lately, they met no danger, they
may be slaughtered like sheep in the shambles. They are capable
of profiting by experience, but they are slow to learn, and can
acquire but little. Judged by our human standard they are very
stupid. The means of escape adopted by Arctic seals compared
with the means of capturing them, the ships, guns, and the rest,
afford a measure of the intellectual difference.

634. When animals are social and so have the opportunity of
learning, not only from their parents but also from other members of
the species, the power of making mental acquirements and conse-
quently of handing on the traditions of the race is often correspond-
ingly great. It reaches a remarkable degree of development even
amongst insects, some species of which live in great communities.
Young ants are carefully tended and are said to receive instruction
from their elders. A capacity to profit by experience implies, of
course, memory. There is, however, more decisive evidence.
Some species of ants have the habit of capturing the pupae of other
species and of so training the young individuals that develop from
them that they peform duties which were quite unknown to their
ancestors. Therefore it is clear that the slaves profit by experience.
Consequently their actions are intelligent not instinctive.

635. So important are the duties of the slaves, so much do they
learn, so long has the habit of slave-making been followed by their
masters, that in some species the latter have evolved into mere
fighting machines, incapable even of feeding themselves. Many
important physical and mental characters have undergone
retrogression in them — not through lack of use, for doubtless the
animals used while they possessed them, nor even through
lack of utility, for powers of self-feeding must have always been
useful, but solely through lack of sufficient survival value. That is
to say, the parts, however much used and useful, underwent
retrogression because the acquirements of the slaves supplied a

THE INSTINCTS OF MAN 383

substitute so efficient that individuals (or rather the communities)
that possessed them in higher degrees did not survive in greater
numbers than those that possessed them in lower degrees. Since
ants possess such high powers of making mental acquirements, it
is only reasonable to suppose that their instincts, like those of man
and like many of the mental and physical parts of the slave-holders,
have undergone retrogression. Whence it follows that many of
their so-called instincts — for example the habit of warring in dis-
ciplined hosts, of keeping pets, of preserving aphides for the sake
of their sweet secretions, of clearing areas of ground, growing food
plants on them, and storing the seed, of nipping the rootlets of
seed to prevent germination, and so forth — are quite possibly, not
instincts but items of traditional knowledge and habits entirely
comparable to that traditional knowledge, to those traditional
mental attitudes, those ways of thinking and acting, which play so
large a part in human lives.

636. The instincts of man, though comparatively few and
simple and though overshadowed by the enormous mass of his
acquired mental characters, by his intelligence, are yet essential to
his existence. Some of his actions are wholly instinctive, for not
only are the inclinations to perform them innate, but also the ability
to do so. The act of sucking in a young infant is an example.
This action is often termed a reflex. But it is entirely voluntary
in the adult. No man ever sucks unless he chooses to suck. If,
then, it is reflex in the infant, it must altogether change its char-
acter later which no other reflex is known to do. Thus, though
we may learn to breathe and cough, yet we continue to do both
because we must. Sucking, on the other hand, is always voluntary
in the sense that it is invariably prompted by an emotion, a
desire, and that it is initiated by the will. Doubtless the new
born infant does not consciously desire milk (of which [it has no
previous experience) when it sucks, any more than a child desires
bodily development when it plays. But when the emotion is
awakened by the mother's nipple the act itself is delightful and is
instinctively performed as long as the delight continues — that is
while the milk flows and the hunger is unsatisfied. Were there no
prompting emotion, no delight, the act would not be performed.
Crying, an act prompted by discomfort or pain, is also entirely
instinctive at first. The function of the cry is an appeal for aid ;
but here again the infant has no notion of its real meaning. It
cries only because it is impelled by a certain emotion, the instinct,
to a certain act, the instinctive act. Yet again when tired or

384 REFLEX ACTION, INSTINCT, AND REASON

sleepy, we instinctively, without learning, place ourselves in an
attitude of rest. Doubtless we learn in time what attitudes are
most comfortable, but no learning is needed to secure cessation
of movement and relaxation of all our voluntary muscles and the
consequent assumption of a restful position.

637. Hunger and thirst are terms which are applied both to the
instinctive desires to take food and water and to the antecedent
sensations which awaken them. Thus, when we say we are
hungry we may mean either the feeling of discomfort in the region
of the stomach, or the wish for food, or both. The recognition of
food as such by the sense of taste is also instinctive. Normally
we eat and drink only nutritive substances, those which contain
food or water, with pleasure. Probably, however, this instinct is
more perfect in the lower animals than in man in whom it seems
to have undergone some retrogression. The infant, protected as
it is by its mother's intelligent care, tends to swallow any small
object that comes to hand ; the caterpillar and the puppy, which
is aided by its sense of smell, are rarely in fault. In all animals
the amount of food desired is limited by the needs of the individual,
though even in this case the instinct appears more perfect in the
lower animals than in man. Instinctive also are those voluntary
movements of tongue and jaws which occur when food or water
is placed in the mouth. Unlike the caterpillar, however, man
must learn all those actions by means of which he procures
food.

638. The impulse to play is an instinct, but it prompts to no
action for which our muscles are instinctively co-ordinated. Its
sole function is to impel us to make physical and mental acquire-
ments. Under its influence we use our bodies and minds which
develop in response to the stimulus thus supplied till we are fitted
to the ancestral environment We have already dealt at length
with physical use-acquirements.1 The mental acquirements
resulting from play are strictly homologous and not less important.
They enable us to co-ordinate our muscles for purposeful action
and so perform our voluntary actions as swiftly and surely as
reflexes. The vague movements of the infant become purposeful
if awkward ; his awkward movements become easy and sure ; and
these easy movements at length become ' automatic.' Only those
animals sport which make physical and mental acquirements, and
they sport only when play is useful, and in a way that is
useful. The caterpillar does not sport ; he has no physical and

1 See chapter i.

PLAY, IMITATIVENESS, AND CURIOSITY 385

mental * acquirements ' to make ; his actions are all entirely
business-like. It is true that gnats and other insects indulge at
certain seasons in dances which appear to us sportive ; but there
is every reason to believe that they are impelled, not by the
playing, but by the sexual instinct. On the other hand, young
ants are said to be sportive. The young of the higher animals
are playful in proportion to the extent to which their bodies and
minds are capable of development under the stimulus of use. In
each instance the sport is exactly adapted to fit the individual for
the future business of life. The little girl ' naturally ' turns to her
doll, which she nurses as she will her baby. The play of the boy
as naturally involves contests which foreshadow the grimmer
struggles of adult life. As he grows older the character of his
sport changes. More and more it becomes an affair of wit and
dexterity, an appeal to wider experience, and a means of adding to
it. When the girl's play with her doll and the sports of the little
boy have served their purpose and ceased to be useful, they cease
also to excite interest. Compare the ambush and pounce of the
kitten, the ardent chase and overthrowing of the puppy, and the
climbing proclivities of the monkey and the kid. When full
physical and mental development is attained, the desire for sport
wanes. It lingers longest in the most intelligent animals, those
whose memories are the most capacious, who are most capable of
profiting from experience. Little remains of the instinct in the
adult cat or horse ; the dog retains it longer ; while man, who is
capable of learning even in old age, retains it in some measure to
the end. Hence, for example, his pleasure in billiards and cards.

639. Imitativeness and curiosity are instincts which impel the
young individual to store his mind with useful traits. Like
sportiveness, they are developed in every species in proportion to
the power of making mental acquirements, and they persist in the
individual only as long as they are useful. Imitativeness impels
him to copy his progenitors, and so make for himself those
acquirements which enabled them to exist and rear offspring in
their world. The kitten, the puppy, and the monkey may be
seen observing with interest and subsequently imitating their
elders. The most imitative of all living beings is a child, who
from the time he copies his elders in walking, speaking, and
manipulative dexterity, to the time when he acquires his ultimate
political and religious notions, is constantly under the influence of
this instinct. A large part of a little child's sport consists in pre-
tending to be such and such a person, or to do such and such a
25

386 REFLEX ACTION, INSTINCT, AND REASON

thing. All acting is imitating, and much of a child's play is
acting. Fashion is nothing other than a manifestation of imitative-
ness ; the infectious fury of mobs, and the steadfast purpose of
men in armies, is little more. Human society, which could not
exist unless the units composing it were much alike, is founded on
it. It is the principal means by which the traditions of the race
are transmitted to remote generations.

640. The function of curiosity is obvious. Like imitativeness,
it impels to the acquirement of useful mental characters. Almost
as strong in the adult as in the child, it persists in men throughout
life. It is alike conspicuous in the aged gossip and in the man of
science.

641. Sexual love is an instinct which prompts to actions which,
like swimming, are instinctive in the lower animals, but which man
acquires the ability to perform. At any rate, the ability to perform
all the actions which lead up to the sexual act are acquired by him.
The instinct is better developed, as a rule, in men, who play an
active part, than in women, who play a passive part. No man could
have offspring unless he had the instinct ; but women, who in past
times have often been the helpless slaves of their masters, may
have offspring in the absence of sexual inclination.

642. Parental love is an instinct which impels to the care ot
offspring ; but none of the actions prompted by it are instinctively
performed by human beings. The lower animals are innately
capable of tending their young ; but the human mother must not
only learn during her own infancy to co-ordinate her muscles
for the tending of a child, but she must learn from other mothers
how to do it. However, some innate maternal impulses, which
prompt to actions that need no special learning, survive. Thus
almost every human mother delights in teaching her child to walk
and speak, characters which are essential to its well-being.1 Very
beautiful and illuminating is the pleasurable participation of even
dull and care-worn women in the play of their babies and very
young children. Parental love is more highly developed in women
than in men. In " the state of nature " in which the race evolved,

1 Apart from the parental instinct, the pleasure we feel in imparting information
seems as instinctive as the pleasure felt in receiving it. Every normally con-
stituted individual delights to awaken interest in this way. To-day, for example,
we bought my little boy, for use in school, a pair of drawing compasses, a pro-
tractor, and a set square. It is many years since I handled these instruments,
but I remembered some of their uses, and I am sure the child was not more eager
and pleased in learning than I was in teaching. The utility of both the imparting
and the receiving instincts are very obvious.

MENTAL TRAITS OF CATERPILLAR AND MAN 387

a child might survive its father's, but not its mother's neglect. The
mother who lacked parental instinct left few offspring behind her.
Complementary to the mother's instinct to tend her offspring is the
latter's delight in and acceptance of her care. For example, the
cat's instinct to carry her kitten in a particular way (by the skin of
the neck) is associated with the passive attitude of the kitten — in
all except the tail, which is tucked out of harm's way — when it is
so carried.

643. To sum up, the caterpillar, and all animals at a similar
stage of evolution, are mentally a mere bundle of sensations and
instincts. The latter, which lie latent till they are awakened in
due season by the former, develop under the influence of nutriment,
and are nothing other than emotions or desires which impel to
the performance of certain definite actions, the instinctive actions,
the capacity to perform which is also innate. On the other hand,
man has, not only sensations and instincts, but a memory. He
develops mentally, not only under the stimulus of nutriment, but
also under that of experience (use). His power of feeling sensa-
tions and instinctive impulses is innate. His memory, his power
of making mental acquirements under the stimulus of experience,
is also innate. But all that is stored in his memory, all that comes
to it through the sensations and emotions he feels and the
conscious and unconscious inferences he draws from them is
acquired. Mentally, therefore, he is a bundle of (i) sensations ; (2)
instincts, which in him are, in most cases, merely incitements to
make acquirements ; (3) capacities for making acquirements (i.e.
memory) ; and (4) actual acquirements. Since the caterpillar
feels, he has a mind. Man not only feels, but thinks. He has not
only sensations and instincts, but, in addition, an intellect. The
evolution of mind is beautifully recapitulated by the stages of
the mother's care for her offspring. Up to the time of birth, the
care is entirely reflex. After birth, it is instinctive in the higher
animals. In still higher animals, intelligence steps in, and both
aids, and to some extent replaces, instinct. Thus it is intelligence,
not instinct, that impels us to send our children to school.

644. It is not possible, of course, to indicate precisely the stage
of evolution (i.e. the kind of animal) in which sensations first
appeared as sparks to explode reflex action, and in which, there-
fore, mind dawned. Nor is it possible to indicate when sensations
first took on tones of pleasure and pain, when desire and will awoke,
and instinct and voluntary action appeared. Nor again can we
indicate when memory began, and brought in its train as it evolved

388 REFLEX ACTION, INSTINCT, AND REASON

thought and intellect, intelligence and reason. But the fact
remains that all these faculties are products of evolution, means by
which individuals and races are adapted to their environments.
They all arose from small beginnings, and increased gradually with
the needs of the species as its relations with the environment
grew more and more complex. Sensation followed reflex
action, instinct followed sensation, memory followed instinct, and
intelligence memory.

645. The mental traits — sensations, desires, instincts, memory,
intelligence — fit in exquisitely with the physical traits — skin, bone,
blood-vessel, nerves, reflexes, and all the rest. In mind and body
the living animal is an immensely complex and wonderfully
adjusted machine — a machine vastly more complex and perfectly
adjusted than anything that has ever been invented by man as the
work of his hands and brain. A single important adaptive change
in this machine cannot occur separately. It must involve a
thousand or ten thousand readjustments, a thousand correspond-
ingly important changes in mind and body. Thinking of all this,
we realize the full force of the statement that the organism is a
bundle of adaptations and co-adaptions. We realize also the full
force of the main objection to the mutation theory. It is possible
to accept that theory if we think only of such things as the colours
and shapes of leaves, or other changes which do not necessarily
ruin co-adaptation. But when we take the whole of the facts
into consideration, when we think of the complex way in which
the mental and physical adjustments of the higher animals inter-
lock and how fine the adjustment is, we are driven to the conclusion
that evolution can have been founded only on the continual
selection and blending of multitudes of small variations, by means
of which all co-adapted parts underwent change together, and the
organism was moulded as a whole. In other words, we are forced
to believe that nature selected for survival, not individuals who
varied widely from the rest of the species in this or that particular,
but individuals who varied comparatively little as regards the
size of their variations, but much as regards the number of their
variations, and who, therefore, were better adapted on the whole
to the gradually changing environment than their fellows that
perished ; and who blended their variationSj so that it was not so
much the successful appeal of the individual that counted in the
racial struggle for persistence, but the experience of the entire
species or variety. Indeed, notwithstanding the wealth of material
furnished by fluctuations, so vast is the complexity of the higher

THE ACQUIREMENTS OF THE NORMAL MAN 389

organisms, and so delicate the adjustment of their parts and
faculties, that many thinkers have been driven, in spite of the fact that
there is apparently no alternative, to doubt whether Natural Selec-
tion is adequate for the task. Our faith is restored only when
we contemplate the special and beautiful devices which Natural
Selection has evolved to help its work of adaptation and co-
adaptation — on the one hand, bi-parental reproduction and the
tendency of retrogressive variations to preponderate over pro
gressive variations, both of which automatically plane away all
redundancies ; and, on the other, the power of developing under the
stimulus of use which brings about co-adaptation in the characters
of the individual through the influence which related parts and
faculties exercise over one another's growth.

646. Again we have seen how much neglected has been the
study of ' acquirements ' ; it has even been supposed that evolution
is founded entirely on ' inborn' traits. But consider what man
would be without his mental acquirements. The congenital idiot
and the normal man start life equal, except in one particular. The
idiot has little or no memory, no power of learning, no power of
growing mentally under the stimulus of experience, whereas the
normal man has that power. This, at birth, is the sole difference
between the two.1 But an empty memory, a mere possibility of
learning, is nothing. If the normal man had not filled his memory,
he also would be an idiot. Now is, or is not, the intelligence of
the normal man, which has arisen only because he, personally, has
made acquirements, a product of evolution ? Is not this mental
growth, which consists entirely in acquirements, and which
separates him mentally from such animals as the idiot and the
caterpillar, as much a part of his normal growth as his head or
his instincts ? If it is, then surely, the study of acquirements,
including the entire field of the intellect^ is at least as well worth the
attention of the student of nature as the study of any other class
of character.

647. It. may be argued that 'the task of the biologist is
complete when he has traced the growth of memory, which is all
that is inborn, and, therefore, all that has undergone evolution.'
But to this there are two sufficient answers. First, no serious
attempt has ever been made to trace the evolution of memory.
Though it is the foundation of all intelligence, it has, of all mental
characters, been the most neglected by biologists in general and
psychologists in particular. Indeed to this day there are some

1 See §§ 762, et seq.

390 REFLEX ACTION, INSTINCT, AND REASON

who suppose that memory (like extension in space) is a property
of all living protoplasm, and who attribute it, therefore, even to
the protozoa and to plants. Others, declaring that without memory
there can be no feeling, place the beginnings of the faculty at the
beginnings of conscious life. Second, if we regard the power of
growing mentally under the stimulus of experience as the essential
thing, and the intelligence and reason which result from the exercise
of this power as accidents, even then, if we are consistent, we
must regard all the characters of living beings, including memory,
as accidents ; for, in exactly the same sense, all ' inborn ' characters
arise merely because there has been evolved a power of developing
under stimulus — in this case that of nutriment. Here, then, is
the point on which I wish to fix the reader's attention. As he
peruses the remaining chapters of this book, he must constantly
bear in mind, not only that he is studying * acquirements? but that
acquirements are products of evolution, parts of normal growth,
characters without which the individual, who belongs to a species
which has evolved the power of making them, cannot achieve complete
maturity. If we study mind from this point of view, we shall not
only observe it in a light that is new, but also in one which will,
I think, enable us to penetrate more deeply into its mysteries
than has been possible hitherto.

648. The reader perceives that I am what is termed an
' extreme ' Darwinian or Selectionist. Indeed I am a very extreme
Darwinian. For me the great outstanding truth concerning living
beings is the wonderful closeness with which, notwithstanding the
vast multitude and diversity of species and characters, they
are all adjusted by all their structures, faculties, and chemical
reactions (for the individual is a complex chemical factory) to their
environments — an adjustment which includes an equally close
adjustment of their parts and faculties to one another, as well
as such fundamental characteristics as the degree of variability
of each character, and the normal limitation of variability to a
portion of the germ-tract. Experience tells me that just in
proportion as I increase my knowledge of any species, I am forced
to believe that parsimonious nature has bestowed on it little or
nothing but adaptations. Of necessity I know my own species
best ; and I, a medical man, can think of hardly a human structure
or faculty to which I am unable to assign a useful function. I
know, and as a human being can know, comparatively little about
species that are far remote from my own, such as beetles, butter-
flies and plants ; and of the uses of their structures and faculties

ADAPTATION 391

I am correspondingly ignorant. But, when I see in such a species
a structure, the function, the utility, of which I am too ignorant
to perceive, I do not leap to the conclusion that it has no function,
or no useful function. I remember my own species, and, bearing in
mind that all species apparently fit their environments as well as
my own, I seek, if possible, to learn the function and usefulness
of the structure. Even when I fail, which is very often, I yet
remain convinced that almost certainly both the function and the
usefulness exist.

649. From the time that Darwin taught that plants and
animals had undergone evolution for their own benefit, not for
that of men, this opinion has been, until very recently, the accepted
scientific view. But now a new school of thought, or if not of
thought at least of opinion, has arisen, which (as may be judged
from the following passages, examples of many that might be
quoted) tells us that more correct and less dogmatic is the opinion
that, in many instances at least, the structures of remote species
have not been evolved because of their usefulness, but, on the
contrary, have come into being and have persisted in spite of a
complete uselessness. " The claim of the opponents of the theory
that Darwinism has become a dogma contains more truth than
the nominal followers of this school find pleasant to hear ; but let
us not, therefore, too hastily conclude that Darwin's theory is
without value in relation to one side of the problem of adaptation ;
for, while we can profitably reject, as I believe, much of the theory
of natural selection, and more especially the idea that adaptations
have arisen because of their usefulness, yet the fact that living
things must be adapted more or less well to their environments in
order to remain in existence may, after all, account for the wide-
spread occurrence of adaptation in animals and plants."1 "To
imagine that a particular organ is useful to its possessor, and to
account for its origin because of the imagined benefit conferred,
is the general procedure of the followers of this school." 2 The
writer is mistaken. The 'claim' that evolution is other than
adaptation appears, not so much unpalatable as absurd to the
followers of Darwin ; the reasoning by which it is supported
excites, not chagrin, but amazement. The following is a case
in point. " As an example of a change in the organism that is
of no use to it may be cited the case of the turning white of the
hair in old age in man and in several other mammals. The
absorption of bone at the angle of the chin in man is another

1 T. H. Morgan, Evolution and Adaptation, p. ix. * Op. cit., p. 453.

392 REFLEX ACTION, INSTINCT, AND REASON

case of a change of no immediate use to the individual. We also
find in many other changes that accompany old age, processes
going on that are of no use to the organism, and which may, in
the end, be the cause of its death. Such changes, for instance,
as the loss of the vigour of the muscles, and of the nervous system,
the weakening of the heart, and partial failure of many of the
organs to carry out their functions."1

650. "Though there is no question of absolute perfection in
nature, it appears that, under given conditions, adaptation is and
was sufficiently perfect to make it very difficult to put one's finger
on any defect. When we think we can do so, it generally turns
out that the defect is in the mind of the critic rather than in the
organism criticized." 2 Occasionally we are told that the palaeonto-
logical evidence lends support to the mutation theory in that an
examination of the records stored in the strata of the earth
indicates, as a rule, not gradual changes of type, but sudden
changes. The nature of this evidence may be judged by any
one who makes a careful examination of the cut surfaces of
ditches and canals. If by means of such an examination he is
able to achieve a knowledge of the fauna and flora now inhabiting
our planet sufficiently minute and detailed to enable him to
indicate the mode of origin of our new varieties, then, allowing
for the destructive effects of immensely longer time, he will have
some title to declare that strata deposited in past ages furnish
evidence of value concerning not only changes of type, but of the
mode of change. In that case, however, since the changes found
in geological strata are very vast, and since the connecting links,
if any, are absent, he must decide in favour, not of the hypothesis
that animals and plants have arisen by mutation, but in favour of
the hypothesis that they have arisen by special creation ; for not
even the most ardent mutationist will maintain, for example, that
marsupials suddenly gave origin to placental mammals.

1 Op. cit.t p. 25 ;fsee also § 359 of the present work.

* Dr D. H. Scott, Presidential Address, Linnean Society, May 24th, 1909.
Nature, July 22nd, 1909, p. 115 ; see also § 86.

CHAPTER XXI
THE EVOLUTION OF MEMORY

The evolution of mind — Definition of memory — Distinction between memory
and its contents — Memory stores most actively in the young — Memory does not
grow with use — A vast memory is the distinguishing peculiarity of the human
being — The mental distinctions between ancient and modern, savage and civilized
men — Distinction between man and the lower animals — Conscious and uncon-
scious memory — Distinction between reflex and automatic action — The stereo-
typing of mental acquirements — As we sport with our bodies, so we sport with
our thoughts — There is no impassable mental gulf between man and the lower
animals — The neglect of memory by writers on evolution — Darwin — Spencer —
Romanes — Lloyd Morgan — Baldwin — The Mendelians — The Biometricians.

651. A CCORDING to the theory of mental evolution formu-
Z-^ lated in the preceding chapter, mind is not derived
from the non-mental. Just as life was quite a new
thing in the world when it first appeared, just as nervous tissue
however gradual its evolution was new, just as manipulation was
new, so was that particular function of nervous tissue which we term
mind. No doubt living cells and the chemical elements of which
they are compounded preceded nervous tissue, but that particular
combination of a certain class of living cells and fibrils to which
we apply the term had no previous existence. So also its function
— one of its functions — mind had no previous existence, nor even
an antecedent which remotely resembled it. If this hypothesis be
correct, mind in its earliest beginnings was associated with a series
of variations of nervous tissue which proved favourable. It
appeared at first in the form of rudimentary sensations which
served as sparks to explode reflex actions — dim and faint percep-
tions of light, heat, sound, touch, and the like, which were more
delicate and discriminating than the stimuli that had hitherto
awakened action. The individual now received stimuli from a wider
and more complex environment ; and his actions, which became
correspondingly more numerous and varied, were adapted to
meet more and more distant contingencies, and achieve ends more
and more remote. Later to mere sensations were gradually added
tones of pleasure and pain, with which came desire and its corollary
the will, and with all a further increase of complexity of action and

393

394 THE EVOLUTION OF MEMORY

remoteness of aim. Compare, for example, the simplicity of the
internal sensationless reflexes of a butterfly, and the immediate
ends to which they are directed, with the complexity and remote-
ness of aim of the actions to which he is aroused by feelings of
hunger or sexual desire, or by the sight of danger. Lastly when,
owing to the evolution of many reflexes and instincts, the nervous
system had grown highly complex, memory arose, though not of
course as a necessary consequence of the complexity. This also
was new and unlike anything that had formerly existed in nature.
Memory, the name we apply to the power of making mental
acquirements, of growing mentally in response to the stimulus of
experience, is strictly the counterpart, the homologue, of the power
of growing physically in response to the stimulus of use. Indeed
the physical power may be termed the physical memory, while the
additions made to our bodies through it are the homologues of
the mental growth, the stored experience, which results from the
exercise of the mental power. In both cases, as we have seen,
the powers are ' innate ' or nutritional characters found only in the
higher animals, and in their greatest developments only in the
highest. Probably they originated about the same time, and
perhaps in the same type of living beings.

652. Memory is the power of making mental acquirements.
Though we speak of our recollections of past events as memories,
yet, strictly speaking, these acquirements are only the contents of
memory. The memory itself is purely innate, and is not increased
by experience, though the volume of its contents is so increased.
In other words, the power of learning does not increase from birth
forwards. On the contrary, it diminishes. A young infant, for
example, is more capable of learning than an older person. At
birth, the mind of a child, except for sensations and a few instincts,
is blank. Sights and sounds and other feelings convey no mean-
ings to it. But soon, so great is its power of learning, the messages
sent by the organs of sense are understood. In a few weeks it
evolves order out of chaos, and comprehends to a wonderful degree
the world around it. It learns to co-ordinate its muscles, and in a
year or two is able to walk and speak a language, and do a vast
deal besides. In these early years, the years of man's greatest
mental activity, he makes his most valuable and fundamentally
indispensable physical and mental acquirements. But, as he
becomes more and more completely equipped for the battle of life,
his powers of adding to the store slowly decline. In adult life the
gains tend to be balanced by the losses. In old age the mental,

THE CHILD'S POWER OF LEARNING 395

like the physical losses, exceed the gains. Compare the perfection
with which the young are able to acquire the manners of a society,
and every accent, inflection, and intonation of one or more
languages, with the imperfections displayed when the task is under-
taken later, and the superiority of the youthful powers of learning
at once becomes manifest. There are many things which we are
better able to acquire later in life than during infancy; for example,
mathematical knowledge; not, however, because our powers of
learning are greater, but only because we are able to build on
acquirements previously made. Similarly, while a child, whose
power of growing physically is so great, cannot in a few weeks or
months acquire the muscles of an athlete, a man, whose develop-
ment is sufficiently advanced, but who is less capable of growth,
may do so. It is sometimes said that an infant cannot make the
physical and mental acquirements which are possible to a child,
nor a child those which are possible to an adult, merely because the
anatomical developments of brain and body are not yet sufficiently
advanced. This statement is true, of course. But the hypothesis
it is meant to support — that the developments which render
possible various actions arise independently of, not in consequence
of, previous use — is not true. The question is easily tested.
Would a child who had not previously learned to walk or do
simple arithmetical problems, develop body and mind sufficiently
to enable it to play cricket and learn the calculus ?

653. As we add to our mental stores our minds grow, but not
our memories, not our powers of learning. So, also, as we add to
our store of physical acquirements our bodies grow, but not our
power of growing physically. Systems for improving the memory,
of which many have been invented, do not improve it in the least.
They merely direct the attention more strongly to facts which
are considered worthy of remembrance, and, by making them form
mental associations with familiar objects or common happenings,
seek to secure their recall to mind.1

654. Our minds are as busy storing experiences when we are
merely ' passing the time ' as when we consciously endeavour to
memorize ; but in the former case there is so much that is almost
identical with other experiences that it cannot be recalled in detail.
On that account we can recall but few of the common, the unremark-

1 See James, Principles of Psychology, vol. i. pp. 659, et seq. " No amount
of culture would seem capable of modifying a man's general retentiveness . . .
all improvement of memory consists, then, in the improvement of one's habitual
methods of recalling facts."

396 THE EVOLUTION OF MEMORY

able happenings of our daily lives. So, also, if we saw a thousand
sheep jump in succession over a gate, we could recall, not the
action of every sheep, but in the main only a general notion.
The ultimate result is, that our minds are not burdened with a
mass of unnecessary details, but store only what is likely to be
useful. Our general impressions are concentrated, condensed
recollections. Concentrated memories also, as we shall see
presently, are all our acquired dexterities in thinking and acting.
Moreover, apart from the concentration which occurs in the
formation of general impressions, much that is seemingly lost and
forgotten is none the less stored, and waits ready to be dragged
into the conscious mind by some associated fact or idea. Thus
when walking down the street we may see a face which is recorded
but not recalled unless a second meeting awakens the memory.

655. Every animal species is fitted by its structures and their
associated faculties to its particular place in nature. In some
cases it holds its own largely through the great evolution of some
one structure or group of structures in co-adaptation with which
the whole mind and body is modified. Thus the bat is especially
distinguished by the great development of its fingers and of the
web between them, and the elephant by its trunk. The principal
distinguishing physical peculiarity of man is the enormous relative
size of that upper part of the vertebrate brain which is termed the
cerebrum, and which we have every reason to believe constitutes
his organ of memory and thought, and of all the mental processes
and physical co-ordinations that depend on them. The cerebrum,
especially the human cerebrum, is one of those organs which, after
birth, develop under the influence of use, its growth being cor-
related to the growth of the mind under the stimulus of experience.
In evidence of this is the fact, that if one hemisphere of the
cerebrum be injured, as by disease, the other tends to hypertrophy
under the stimulus of increased use.

656. Associated in a special way with man's great brain are
his organs of speech and manipulation. These three structures,
the brain, the vocal apparatus, and the hand, undoubtedly
underwent concurrent evolution by the constant survival, during
what must have been a period of intense competition, of those
individuals who were 'naturally' (i.e. innately) the best capable
of receiving and storing experience, of using it for the intelligent
manipulation of objects, and of communicating it to their fellows
and descendants through the medium of speech. Even the
highest of the lower animals are able to learn from one another

TRADITIONAL KNOWLEDGE 397

only by example, or through such very elementary verbal signs
as calls, growls, or cries of alarm, which express no more than
simple emotions. Therefore their traditional knowledge is as
nothing compared to that of man, who, by means of articulated
speech, indicates not only sense-impressions and emotions, but
also complex items of knowledge and processes of thought which
have been garnered, elaborated, and systematized during tens of
thousands of years by millions of predecessors. Without speech
or some such method of communicating abstruse information, his
great brain and its special functions would be useless. Knowledge
and powers of thought are of no avail, unless they can be trans-
lated into action, and for this the hands are necessary. To set
free the forelimbs, which had hitherto been organs of locomotion,
for their new function of manipulation, man gradually became a
biped, and assumed the erect attitude — not, of course, by any
conscious effort, but by the constant survival of the fittest, those
best structurally adapted to walk erect.

657. Savage man differs from lower animals mainly in that
he has, relatively to his size, a larger brain, a more capacious
memory, and greater powers of using its contents and communi-
cating them to others of his species. Modern man differs from
ancient man because he is heir to a greater accumulation of
traditionally transmitted experience. Civilized man differs from
the savage chiefly in that he has invented and more or less
perfected certain artificial aids to memory, thought, and speech

written symbols by means of which he is able to store in

an available form information immensely more abstruse and
voluminous than would otherwise be possible. His books are
artificial memories and vehicles of communication of unlimited
capacity and unerring accuracy. Moreover, by means of these
symbols he is able, as in the mathematics, to perform feats of
thinking quite beyond the powers of . his unaided mind, just
as by means of mechanical contrivances, he is able to perform
physical feats beyond the unaided powers of his body. Obviously,
the mental change which occurred when savage races achieved
civilization did not necessarily imply germinal alteration. But,
because each generation communicated its growing traditions to
the next, it so exactly mimicked evolution that innumerable
writers have been deceived. The belief is almost universal that
the savage differs innately in mind from the civilized man.1 He

1 Dr Alfred Russel Wallace is a rare exception. See his very interesting
article on Evolution and Character in the Fortnightly Review, Jan. 1908.

398 THE EVOLUTION OF MEMORY

may differ, and very possibly does differ, to some extent, but the
evidence on which an opinion may be founded is lacking.

658. To memory, then, is due the advance of the savage beyond
the lower animal ; to tradition, the child of memory, the advance
of modern man beyond ancient man ; to facts and thoughts stored
in books the advance of civilized man beyond the savage. To
written symbols also are due his vast potentialities for future
advance. In the past of the earth the brute, the mammoth, the
bear, the tiger, the horse, the ox, and the sheep, became ever
more and more helpless in the presence of a knowledge and an
ingenuity, the outcome of organized knowledge, which gathered
direfully with the rolling years, and which, though accumulating
for ages, were yet comparatively new things in this enormously
old world.

659. The lower animals in proportion as they lack memory —
in proportion as they are incapable of profiting from experience,
but develop more or less exclusively under the stimulus of
nutrition — move in a narrow, instinctive groove. Their mental
traits are 'innate and inherited,' and, therefore, every individual
follows nearly exactly in the footsteps of its predecessors. Since
they cannot learn they cannot adapt themselves to circumstances.
Removed from the ancestral environment, they perish. Cast in a
rigid inexpansive mould, they resemble one another of the same
species as much mentally as physically. It is different with man.
He is pre-eminently the educable, the reflective, the adaptable
animal — the animal who develops mentally under the stimulus of
use. Since men can learn, and since the experiences of no two
men are quite similar, they differ in knowledge, ideas, aspirations,
modes of thought, and motives for action. Therefore none are
very closely alike mentally. The child does not follow exactly in
the footsteps of his parent. So great is human educability (i.e.
adaptability) that though the mind of the savage differs immensely
in all except instincts and powers of learning from that of the
civilized man, yet if the child of the latter were trained from birth
by the former he could not be other than a savage. Indeed the

" offspring of civilized parents captured by savages (e.g. American
Indians) have actually developed into utter savages. On the
other hand, some savages, for example the Maoris of New Zealand,
have passed in a single generation from barbarism to civilization.
The Maoris, as I judge from personal experience, are not innately
inferior mentally to Europeans. They are unable to compete with
the intrusive whites only because they are more susceptible to

CONSCIOUS AND UNCONSCIOUS MEMORY 399

imported diseases. The average individual amongst us, and
doubtless amongst the Maoris, may be trained to fill the role of a
beggar or a king, a scientist or a monk, a thief or legislator. He
is so intelligent, so adaptable that he is able to dwell in the tropics
or in the Arctic, in the city or the wild, on land or on sea. Memory,
knowledge, intelligence, reason, adaptability, are all links in a
single chain of efficiency.

660. Memory is of two sorts, conscious and unconscious. The
conscious memory contains experiences which can be ^-collected,
such as scenes we have beheld, or the words of a language. The
unconscious memory contains impressions which cannot be recalled
to mind, but which are none the less important. Indeed, many of
its contents were never present in consciousness in the sense that
a sight, an emotion, or an idea is present. Thus we learn to use
our legs in walking, a process that involves a precise but unconscious
adjustment of the actions of numerous muscles, the very existences
of which are unknown except to the anatomist. In a sense, therefore,
we know as little about walking as any insect. All our acquired
dexterities, both in thinking and acting, belong to this category.
They are mental acquirements stored by the unconscious memory.
Thus we learn to reason ; but, though we recall some of the times
and lessons by which we learned to think well, and though results
may make us conscious of a growing facility in reasoning, yet the
facility itself, like dexterity in walking, is a thing that is outside
our consciousness. So also, to some extent at least and especially
in youth, we unconsciously imitate our fellows, adopting in great
measure their mental tones and attitudes without knowing how or
when we were influenced. Many experiences, too, once capable of
being distinctly recalled, are added to that hidden store, and,
though apparently lost, remain potent for good or evil. Our minds
are like floating icebergs, of which the visible part is but a fraction
of the whole, and which are moved by deep currents in a seemingly
unaccountable way.1

1 I speak of the ' unconscious memory.' The expression is in common use, and
is convenient. But, properly speaking, memory is the faculty for storing and
recalling to consciousness feelings that have been there before. An unconscious
memory, therefore, is a contradiction in terms. Probably what we call uncon-
scious memory is nothing other than a growth in efficiency, or in size, or in com-
plexity, or in all three, of brain ; a growth which enables that organ to perform
work which till then it was incapable of performing, or which it was incapable of
performing as easily or as well. In physiological and psychological writings this
cerebral change is usually spoken of as an " opening up of paths " in the brain.
If by that is meant a building-up in the brain analogous to that building which
occurs when an addition is made to our means of telephonic communication, the

400 THE EVOLUTION OF MEMORY

66 1. We learn to do new things, acquire new knowledge, and
think new thoughts with toil. But practice confers facility. In
the end we know or perform with ease that which was acquired
with difficulty. We cannot unlearn, however, as we have learned
by an act of will. The facility (the brain change) lingers, and, as
a consequence, since we tend to lose our powers of making new
acquirements, our action and thoughts, our mental tones and
attitudes, our whole outlook on life, becomes more or less
* automatic ' or stereotyped.1 In other words, our acquirements
come at last to resemble reflexes and instincts. Not only do
they take the place of those reflexes and instincts which retro-
gressed when memory was evolved, but they are infinitely more
numerous. So like are they to reflexes and instincts that they are
often so misnamed. Thus psychologists usually place automatic
actions in the reflex category. As a fact, reflexes and automatic
actions are as poles apart ; but of this more presently.2

662. Again we often apply the term ' instinctive ' to emotions
and 'physical' dexterities which have been acquired. For
example, deceived by the quickness and readiness of the act, we
speak of such actions as that of a boy when he dodges a blow as
instinctive. But the boy has learned to dodge, and would learn to
dodge still better and quicker if he went into training for the prize
ring. When untaught by experience, he can no more dodge a blow
than he can solve a problem in quadratics. His action is intrinsi-
cally different from that of a house-fly, which learns nothing from
experience, and dodges as well at the first attempt as at the last.
It is the mode of origin, not the quickness, readiness, or facility in
performance which constitutes the difference between reflex and

expression may pass, though it is apt to mislead. But, if by it be meant that
' channels ' are somehow made in the brain analogous to those which water wears
on or under the ground, the expression is, probably, not only misleading, but
wrong in every sense. There is nothing to justify it except an impossible analogy.
It is admitted that mental happenings are correlated to cerebral happenings. If
mental growth occurs, for example increased thinking capacity, we have every
reason to believe that this growth is correlated with actual cerebral growth
analogous to muscular growth — though possibly this growth may often imply
little or no increase in the size of the brain, but only an adjustment which
increases its working power.

1 It would be well for the avoidance of subsequent confusion if the reader
carefully noted the meaning here given to the word ' automatic.' An automatic
action is one which we have learned to perform, but which, through practice, has
become so easy of performance that, like a reflex action, it is done, apparently,
without mental effort. It is sharply distinguished from a reflex action in that it
is a product of individual experience.

8 See §§ 676 et seq.

IMITATION REFLEXES AND INSTINCTS 401

instinctive actions on the one hand, and, on the other, actions which
are often termed automatic, or intelligent, or rational, but which as
a class are best distinguished as actions the performance of which
depends on stored experience, on memory. So alike are our
acquired emotions and dexterities to their ' innate ' counterparts
that a being from another planet, who for the first time saw a man
walking, cycling, or reading, could not distinguish the nature of
these acquirements from such instinctive actions as the running,
flying, or building, of an insect. The patriotic emotion of a
Spartan or a Japanese differs from that of a bee or an ant merely
in its mode of origin. Were the religious fervour of a Salva-
tionist or a dervish, or the hatred of religion which characterises
the atheist, innate, it would be an instinct. But these emotions,
like many of our ' physical ' dexterities, are obvious acquirements.
This, then, is the main distinction between man and the low
animal ; — the emotions and (apart from the reflexes) the dexterities
of the man are mainly HABITUAL or 'acquired ;' those of the low
animal are wholly or almost wholly instinctive or ' inborn' The
former develop under the stimulus of use ; the latter under that
of nutriment.

663. A principal function of our faculty of making mental
acquirements, of our conscious and unconscious memories, is to
supply us with those automatic and stereotyped ways of thinking
and acting which are our substitutes for numerous reflexes and
instincts. Our conscious memories supply us in part with our
stereotyped mental attitudes — desires, beliefs, aspirations, habitual
ways of thinking, and so forth. Our unconscious memories, not
only aid in building up our mental attitudes, but give us our stereo-
typed ways of acting — those automatic ways of acting (e.g. walking,
reading, cycling, etc.), we have just considered. At the same time
our physical ' memories ' (our powers of making physical acquire-
ments) enable us to develop, in perfect co-adaptation with our
mental acquirements, our bodily parts, our brains, limbs, lungs,
heart, and the like. As we grow older our imitation reflexes and
instincts increase in number and importance ; they form a larger
and larger portion of our total reaction to the environment. They
equip us for the battle of life with a thousand faculties for acting
readily^ quickly, and easily. In the aggregate they are immensely
superior to real instincts and reflexes for they render the individual
adaptable ; they enable him to grow into fitness to the particular
environment in which he is reared ; and, even if he changes it, to
grow to fit the new one. Whether he be artist or sailor, beggar
26

402 THE EVOLUTION OF MEMORY

or king, he develops just such dexterities in thought and action as
are necessary to him, but is burdened with no more. Our human
memory ) our power of growing mentally in response to the stimulus
of use and experience is a device by means of which nature has
surmounted the difficulty of evolving an untold number of reflexes
and instincts. Each real reflex and instinct demands for its
evolution and maintenance a separate process of selection. For
example, the reflexes of the heart and the bowels, and the instincts
of hunger and sexual love are entirely separate things not evolved
by the same process of selection and not equally well developed
in every individual. If the individual is defective in any important
reflex or instinct, he leaves no offspring. Therefore nature must
maintain all. When they are very numerous, individuals defective
in one or another are so many that the death-rate tends to exceed
the birth-rate. Therefore there is a limit to their number. In
other words there is a limit to the complexity of the individual in
innate characters, and therefore a limit to the number of innate
reactions he is able to make to the environment. On the other
hand in memory nature evolves and maintains only one thing.
But that one thing, as I say, is capable of supplying any number
of emotions and automatic reactions which answer precisely the
same purpose as innate reactions.

664. It is a principal business of our lives to acquire these
dexterities in performance (e.g. walking), these imitation reflexes
(e.g. quick withdrawal from a cause of pain) and these imitation
instincts (e.g. patriotism). But, though a great advantage is gained
when the acquirements are made, one almost as great is lost. We
then think and act more quickly in familiar situations. When the
adult stage is reached we are by virtue of them as fit or more fit
than an insect to face the battle of life. But each important ac-
quirement is written, as it were, in indelible ink on the sheet of the
mind. This matters comparatively little in the case of those
automatic actions which take the place of reflexes. They are
almost always useful, as for example, the automatic co-ordinations
of our muscles by means of which we walk, speak, cycle, swim, knit,
or dodge blows. But our bad as well as our good acquirements
are imitation instincts. Once acquired, they tend perpetually to
pull us down. Moreover, as we grow older, we tend to lose our
splendid human capacity for learning. Old habits, good or bad,
persist ; new habits cannot easily be acquired.

665. In addition to the acquired dexterities and mental
attitudes which depend on records unconsciously retained, our

SKILL IN THINKING 403

memories supply us with a vast fund of facts, ideas, emotions, and
the like, which may be more or less vividly recalled to mind and
which, therefore, afford the materials for such mental processes as
association, comparison, and discrimination — in brief with the
materials of allthatis comprised under the term thought. By appeal-
ing to our conscious memories we are able to note sequences of
events in the past and deduce necessary truths and so to fore-
see to a very useful extent the sequences of events in the future,
and in this way make provision for coming events and dangers. By
virtue of the intellectual powers thus conferred we are rational
beings in the strict sense of the word. Unlike the purely instinctive
animal which is impelled merely by emotion, we guide our more
complex and less habitual actions by thought, by intelligence and
reason. But though the whole domain of the intellect pertains to
the conscious memory, yet we are able to labour usefully in it only
by virtue of powers conferred by the unconscious recorder of our
experiences. We learn to think, to reason just as certainly as we
learn * physical dexterities,' but, as in the case of the latter, the
springs of our ' mental ' dexterities cannot be recalled to mind in
the sense that an event or a fact may be recalled. That is, though
we may remember that we are skilful in thinking, and though we
may call to mind the ways in which we acquired the skill and the
results we obtain by the exercise of it, yet the skill itself depends
on concentrated experiences which cannot be recalled to mind any
more than those on which skill in walking depends. The skill is
useful, but the power of picturing it in mind would be of no
practical utility ; and therefore nature does not bestow it.

666. An instinct impels us to sport with our limbs and so
supply them with the stimulus necessary for growth and our minds
with the practice which confers dexterity in using the limbs. This
growth of ' physical ' dexterity is, as we see, really a mental growth.
So also, an even more imperious instinct impels us to sport with our
thoughts. From birth forwards we think perpetually and cannot
help doing so. Fresh experiences recall antecedent experi-
ences with which they are compared, and, these again call up
yet other experiences. In our idlest moments we are busy
thinking. In this way we learn dexterity in thinking, and this
acquired dexterity is an essential part of intelligence and reason.
Obviously, therefore, reason is not, as all psychologists imply, an
' innate ' character like memory. It is learned just as surely as
reading and walking are learned. No child is born capable
of reasoning, and much of our school-room education is a

404 THE EVOLUTION OF MEMORY

formal endeavour to develop the faculty by means of special
exercises.

667. The range of thought possessed by any species is always
proportionate to the greatness of the conscious memory, which
records not only items presented by the senses, but also those
acquired through the imagination and intelligence. On this
account the dog has a greater range than the cat, and man than
the dog. Man's unique intellectual powers depend wholly on his
vast and capacious memory by means of which he acquires both
the materials (facts and ideas) and the methods (association, dis-
crimination, and the like) of thought — materials and methods
which render him intelligent, rational, 'self-conscious/ capable
of 'conceptual thought' and of 'apprehending universals,' and
abstract ideas such as those of right and wrong, and of performing
feats of thinking as in mathematics, philosophy, and science, or of
imagination as in music, poetry, and fiction, or of ingenuity as in
engineering and warfare, or of becoming devout or patriotic, and
so forth. The fact that he alone, of all animals, is capable of these
mental operations has caused many writers to declare that an
impassable gulf separates him from the rest of living nature. But
plainly there is no impassable gulf. None of the traits mentioned
are 'inborn' or special products of evolution or creation. The
infant possesses none and can possess none until his memory is
stored with the materials of thought and he has learned through
imitation and practice fit methods of thinking. He differs from
lower animals only in that his memory is so large that it alone is
capable of being stored with these traits amongst many others.
That which has been created by evolution is his huge cerebrum,
the organ of memory, the thing which does the work which is
memory, reason, and all the rest which results from acquirement.
Both cerebrum and memory are found in lower animals, and there
is no greater difficulty in conceiving man's mental evolution
through the continued selection of mentally superior individuals
(that is, of individuals who are mentally superior because they have
a superior quality of brain) than of conceiving the evolution of the
elephant's trunk, the bat's wing, or any other structure that
especially distinguishes this or that animal.

668. Not only may memory vary as a whole, but it may vary
in particular directions in different individuals. Thus, while one
man may possess exceptional powers of acquiring the facts and
methods of mathematics and of learning to use his knowledge for
purposes of fresh discovery, another man may be similarly dis-

MENTAL EVOLUTION 405

tinguished with respect to music, literature, engineering, or warfare.
But there is nothing more wonderful in this than in the fact that
some part of a structure (e.g. a nose) may be relatively more
developed in one man than in another. Men often differ very
greatly in mental capacity, in innate power of making this or that
acquirement, and doubtless these mental differences are associated
with innate cerebral peculiarities, and tend, therefore, to be trans-
mitted to offspring ; but it must be borne in mind that mental
differences need not imply correspondingly great cerebral
differences. When we attempt to estimate the latter by means of
the former, we examine them, as it were, through a magnifying
glass. The amount of nervous tissue in the brains of ants is very
small and the differences apparently are not very great, yet the
species differ vastly in their mental characters. Small cerebral
variations, therefore, may imply great psychological differences.

669. None of the objections by which it was sought to contro-
vert the doctrine of man's mental evolution from lowerjtypes could
have been maintained had the faculties (mathematical, devotional,
musical, and the like) concerning which controversy raged been
traced to their true source, memory. The evolution of memory
can be traced with the same degree of certainty as that of brain or
any other physical structure ; but I think I am right in saying
that hitherto no one has attempted to trace it. Its importance
has not been realised ; and only very scanty space is devoted to
it in standard works on evolution. The root of the mischief has
lain in the initial failure to note the real nature of the difference
between ' inborn ' and ' acquired ' characters, and to compare the
parts they have played in evolution and development. Acquire-
ments, as I say, have been regarded as transient unimportant
traits, mere accidents, appearing in one generation and disappear-
ing in the next. Some attention, indeed, has been given to the
faculty of growth under the stimulus of injury (regeneration), but
wonderfully little has been attracted by the more important faculty
of growth under the stimulus of use and experience.1

670. The older students of psychological evolution supposed
that memory was an invariable accompaniment of consciousness
and therefore had no notion that it was a late and high product
of evolution. Darwin, as far as I have been able to ascertain,
devotes only one short paragraph to it, in which he merely relates
three incidents which tend to show that memory is present in
baboons, dogs and cats.2 He discusses, however, at greater length,

1 See §§ 20, et seq. z Descent of Man, p. 112.

406 THE EVOLUTION OF MEMORY

imagination, imitativeness, and reason, all of which depend on
memory but which he treats as independent faculties. Spencer
regarded instinct as compound reflex action and the precursor of
intelligence, which he thought resulted from still further compound-
ing. On the other hand, Lewes, thinking, like Spencer, in terms of
the Lamarckian doctrine but arriving at an opposite conclusion,
believed that the intelligence of ancestors becomes the instincts of
descendants. That is, he believed that mental characters which
developed in the ancestors under the stimulus of experience were
1 inherited ' by descendants — i.e. were transmuted into characters
that developed under the stimulus of nutriment. He failed to
note the fact, fatal to his hypothesis, that the human being, the
latest product of evolution, is of all animals the most equipped
by acquirements and the least by instinct. Richet insisted that
"without memory no conscious sensation, without memory no
consciousness." Romanes declared : " The most fundamental
principle of mental operation is that of memory, for this is the
conditio sine qua non of all mental life." l " The power of learning
by individual experience is therefore the criterion of mind." He
adds, however, " But it is not an absolute or infallible criterion
... it serves to fix the upper limit of non-mental action more
precisely than it does the lower limit of mental; for it is probable
that the power of feeling is prior to that of consciously learning." 2
671. When a particle of food goes the wrong way I cough.
That particular reflex is quickly abolished by chloroform or even
a local anaesthetic. Therefore it is initiated by sensation, by mind.
But a newly born infant coughs just as well as a man. Here it
has nothing to learn. The act is quite involuntary and has no
connection with memory. But it is highly useful. Therefore

1 Mental Evolution in Animals, p. 35, Romanes proceeds : " But memory
on its obverse side, or the side of physiology, can only mean that a nervous
discharge, having once taken place along a certain route, leaves behind it a
molecular change, more or less permanent, such that when another discharge
afterwards proceeds along the same route, it finds, as it were, the footprints of
its predecessor. And this, as we have seen, is no more than we find to be the case
with ganglionic action in general." This notion of nervous discharges making
paths which render more easy the passage of subsequent similar discharges is
found in almost all psychological works, and furnishes an easy but as we have
already noted a fundamentally deceptive illustration. In low animals, in which
only reflexes and instincts occur, nothing is added to the mental and nervous
equipment by experience. In higher animals, in which memory is present,
the stimulus of experience, so far from opening a path, adds a growth.
Hence the increase in volume and complexity both of the child's mind and of
his brain.

* Mental Evolution in Animals, p. 60.

ROMANES ON MEMORY 407

mind without memory is useful. Romanes himself, by means of a
somewhat cruel experiment, afforded clear evidence of the lack of
memory in low animals and the usefulness of sensation in its
absence. " I am more surprised with my failure in this respect
with the higher Crustacea ; for although I have tried similar
experiments with them I have never been able to teach them the
simplest things. Thus, for instance, I have taken a hermit crab
and put it into a tank filled with water, and when he had pro-
truded his head from the shell of the whelk in which he was
residing, I gently moved towards him a pair of open scissors, and
gave him plenty of time to see the glistening object. Then,
slowly including the tip of one of his tentacles between the open
blades, I suddenly cut off the tip. Of course the animal immedi-
ately drew back into the shell, and remained there for a consider-
able time. When he again came out I repeated the operation as
before, and so on for a great number of times, till all the tentacles
had been progressively cut away little by little. Yet the animal
never learnt to associate the appearance of the scissors with the
effect which always followed it, and so never drew in till the snip
had been given. Nevertheless, that memory does occur among
the higher Crustacea is proved by an observation quoted in
Animal Intelligence (p. 233), concerning a lobster mounting guard
upon a heap of shingle beneath which it had previously had hidden
some food." 1

672. That memory is absent or very rudimentary in hermit
crabs is proved by the experiment. That the action of the lobster
indicates memory is not so certain.2 Though named in the margin,
memory had no place in Romanes' famous diagram which precedes
his works on Mental Evolution and which was "intended to represent
in one view the whole course of mental evolution," 3 and concerning
which he wrote, " I feel confident that the general structure of our
knowledge concerning the evolution of mind is now sufficiently
coherent to render it highly improbable that this diagrammatic
representation of it will, in the future, be altered in any of its main
features by any advances that science may be destined to make." 4
In his list of the products of intellectual development memory is
placed before the primary (i.e. the earliest) instincts.5

673. Recent writers make also as little mention of memory as
a factor in mental evolution as Darwin. The mental 'plasticity'

1 Op. cit., pp. 122-3. z See § 689.

3 Mental Evolution in Animals, p. 63. 4 Op. cit., pp. 63-4.

6 See Romanes' diagram.

408 THE EVOLUTION OF MEMORY

of Baldwin, Osborn, and Lloyd Morgan l is of course memory, but
the fact is nowhere recognized. Nor, indeed, is the importance of
the so-called plasticity appreciated. " Professor Morgan here
develops (Chap. XIV., Habit and Instinct) a suggestion which has
been put forth by Professor H. F. Osborn, and independently
reached by the present writer, as Morgan points out, namely, that
by learning intelligently and imitatively to do the things which
are essential, certain animals are screened from the operation of
Natural Selection, and so hand on their capacities to future
generations, while the race accumulates further congenital varia-
tions in the same directions (what Morgan calls ' Coincident
variations '). Thus evolution takes the direction marked out in
the first instance by the individual's learning."2 In other words,
it is supposed by Baldwin, Morgan, and Osborn that useful
acquirements may enable a race or a line of individuals to survive
until the descendants have varied in such a way that the useful
traits appear in them, not under the stimulus of experience, but
under that of nutriment.3 In this way, as according to Lewes'
theory though not as he supposed by the transmission of acquire-
ments, that which was intelligent in ancestors becomes instinctive
in descendants. For example, if learning to swim or to speak a
language enabled ancestors to survive, it is supposed the descendants
may vary so as to swim or speak instinctively. That is, unthinking
impulse is supposed to be substituted in descendants for learning,
thought, intelligence, and reason in ancestors. This theory, of
course, affords an instance of the prevalent biological obsession
that nutritional characters are more important, more innate, more
a possession of the species than characters which develop under
the stimulus of use and experience — the latter being regarded as
mere accidents limited to the individual and not like nutritional
characters, part of the heritage of the race. The whole course of
the evolution of the higher animals demonstrates the erroneousness
of this opinion. So far from the ' innate ' replacing the ' acquired,'
the contrary is the invariable rule. For example, in man the
highest and the latest product of evolution, that which is ' inborn '
is at its minimum, while that which is * acquired ' is at its maximum.
It is not realized by the writers mentioned that to the animals that
have the power of making acquirements, these characters are

1 See, for example, Development and Evolution, by James Mark Baldwin (The
Macmillan Company), and Animal Behaviour, byC. Lloyd Morgan, p. 172 (Arnold).
Neither of these authors mention memory. At any rate I can find no mention,
and the word does not occur in their indices.

8 Development and Evolution, pp. 390-1. 3 See § 114.

MENDELIANS AND BIOMETRICIANS 409

infinitely more useful than similar ( innate ' characters could pos-
sibly be. They render the individual adaptable. I do not think
I overstate the case when I insist that, until this truth be grasped,
all biological speculation concerning the evolution of the higher
animals must be, in great measure, futile.

674. Very recent biological work has been mainly Mendelian
or biometric. Memory has been discussed by neither the one
school nor the other. Mendelian experiments could, at most, tell
us nothing more than whether the reproduction of memory is or
is not alternative, and it would not be easy to devise experiments
which would elucidate even that much. They would not indicate
the nature of memory. The problem is one for the thinker, not
the experimental observer. Biometricians, as we shall see, have
worked on the assumption that various characters which seem
clearly part of the contents of memory are ' innate ' or instinctive.
Indeed, it is probable that, more than any other section of biologists,
they have failed to realize the importance of the acquired factor in
the human mind.1

675. Speaking generally, very recent writers who deal with
mental evolution suppose that first reflex action, then instinct, and
lastly intelligence and reason were evolved ; other faculties such as
imagination, discrimination, and the power of drawing inferences,
being variously placed in the general scale. There seems good
reason to believe, however, that the true order of the evolution was
first reflex action, next instinct, and lastly memory. Imagination,
intelligence, reason, and the rest are merely operations which
animals perform because their memories have undergone sufficient
evolution. Without memory there could be no such faculties ; for
they are concerned solely with the contents of memory, associating,
comparing, discriminating, adding to them. In a real sense they
are themselves part of the contents of memory ; for infants learn
to think just as truly as they learn to walk or learn the facts about
which they think. The range and quality of the thinking are
entirely conditioned, on the one hand, by knowledge, and, on the
other, by the power of learning to think ; that is, from first to last
by memory.

1 See §§ 706 et seq.

CHAPTER XXII
NATURE AND NURTURE

Acquired emotional impulses are copies of instincts, and automatic actions of
reflexes — Distinction between reflexes and automatic actions — The way in which
our dexterities arise — The fovea centralis of attention and will — Automatic
actions differ from reflex actions in that they are controlled by the attention and
the will — Dreams — The distinction between recollection and bearing in mind —
The difference between physical and mental acquirements — Nature and nurture —
Capacity and mental acquirements — Ability and efficiency — The factors of
efficiency — Instincts and acquirements — Imbeciles — Racial mental characteristics
— The influence of religion — Opinions founded on biometry.

SPEAKING generally, the impulses to action (emotions)
which we gradually acquire and store in our memories,
for example, patriotism and religious enthusiasm, are
all close copies of instincts. They resemble instincts in all
except their mode of origins. Like them they prompt, with
various degrees of urgency, to voluntary actions. The resemblance
is made all the closer by the fact that, just as a great deal of our
acquired physical growth is a prolongation, a mere continuation, of
growth that was previously made under the stimulus of nutriment,
so some of our acquired impulses to action (e.g. love for some one
woman, a curiosity concerning some particular science), are pro-
longations or reinforcements of instincts. In other words, many
of our permanent impulses to action are partly instinctive and
partly acquired ; and the acquired part of the emotion so closely
resembles the inborn portion that we cannot distinguish where the
one begins and the other ends. The resemblance is made yet
closer by the fact that the performance of only a few of the actions
to which human instincts (e.g. the sexual and the parental) prompt
are instinctive in the sense that they can be performed without
previous learning. Thus the human mother not only acquires the
special learning which enables her to tend her child, but during
her own infancy acquired the necessary power of co-ordinating the
muscles of her limbs. The question, then, arises whether imitation
reflexes (automatic actions) are as close copies of real reflexes as
acquired emotions are of instincts, We learn to do habitual

410

AUTOMATIC ACTIONS 411

actions, for example, walking, speaking, writing, reading, sewing}
cycling, swimming, and the like, with toil and difficulty. At first
the performance is awkward, and the action on which we are
engaged requires our ' undivided ' attention. Gradually, however,
performance grows more facile till at length we are able during it
to do some other less habitual action at the same time. The
latter, then, in turn requires our * concentrated ' attention, until,
perhaps, it also becomes habitual. When an action has become
so easy of performance, so habitual, that we are able to do it
* unconsciously,' it is said to be automatic. It is then so close a
copy of reflex action that psychologists usually include it in that
category.

677. A true reflex, as we have seen, is not initiated by the will*
and is, besides, an action which the individual is born with the
power of performing. Therefore, it resembles an instinctive action
in that the power of perfoming it is innate, but differs from the
latter in that it is involuntary ; whereas it differs from an auto-
matic action in that the power of performing it is innate, not
acquired. The problem before us is whether automatic actions
resemble true reflexes in being quite involuntary. The question is
important, for, as I say, psychologists usually include automatic
actions amongst the reflexes, just as they often include acquired
emotions amongst the instincts ; with the result that the full im-
portance of the distinction between the inborn and the acquired,
and, therefore, the part played by acquirement (i.e. the contents of
the memory) in the building up of the normal human mind is lost
to sight. We have here no mere question of nomenclature, nor
even merely a problem of pure science. Immense practical issues
hang on the conclusions we reach. For example, if we were able
to attain a thorough knowledge and agreement as to how the
human mind developed — what it is possible and what impossible
to create or eliminate by means of careful mental training — we
should also, in all probability, be in equal agreement as to the best
methods of educating our children. Even if a thorough knowledge
and agreement be unattainable by us, we shall, nevertheless, be
nearer both if we found our conclusions on careful investigation,
instead of careless assumption.

678. A few facts may be first noted, (i) Every automatic
action (e.g. knitting, cycling) was clearly voluntary when first we
began to learn it. (2) As a rule, any action which has become
automatic is still clearly voluntary when we begin to perform it ;
thus, we usually begin to walk through an impulse which is plainly

412 NATURE AND NURTURE

due to an exercise of will, though afterwards, when we are thinking
of other things, the performance becomes automatic. (3) Every
clearly voluntary action is now in part automatic, for we have
learned a general automatic power of co-ordinating our muscles
for every kind of action. (4) Every automatic action becomes
voluntary directly our attention is concentrated on it; thus, the
automatic action of a woman who, when she is knitting, thinks of
other things, becomes clearly voluntary when she concentrates her
attention on her work.

679. At the back of the eye is a small spot, the fovea centralis^
which is the region of the most acute vision. When we wish to
see an object distinctly, we turn our eyes so that the retinal image
of it falls on the fovea centralis. That constitutes the action of
fixing our eyes on the object. The images of the other objects
within the area of sight are cast on the peripheral regions of the
retina surrounding the fovea> and are seen much less vividly —
those nearest the fovea being most, and those farthest least dis-
tinctly seen. Normally, when we are attending to the things we
see, the major part of our attention is concentrated on the object
on which the sight is fixed. But we are not entirely oblivious of
its setting, for any unexpected occurrence within the area of sight
immediately attracts our concentrated sight and attention, which
could not happen were we quite unconscious of it. This diffusion of
some of our sight and attention while most of them are concentrated
on particular objects is extremely useful ; for thereby the concen-
trated faculties are continually guided to fresh objects of interest
or importance. Thus, having sufficiently admired one flower on a
bush, our sight and attention does not wander vaguely round in
search of other objects of admiration, but swiftly passes to flowers
which previously were marked on the peripheral portion of the
retina. The recollection of the first flower is then stored in the
memory, and to it, as our concentrated sight and attention wander
about, we are able to add memories of other flowers. Con-
sequently, we do not live solely in the immediate present. We
are able to compare the various flowers on the bush with one
another and with flowers seen perhaps long ago. Thus our minds
are built up.

680. It seems, then, as regards the objects of sight, we are able
to attend to more than one thing at a time. At any moment, our
attention is more or less concentrated on one thing, but some of it is
diffused, with varying but much lesser degrees of concentration, on
Other things. The object on which our sight is for the time being

THE ATTENTION 413

fixed is, as a rule, of all the objects within sight, the most interesting
to us during that time. For that reason we ' look at ' it. For that
reason it ' claims our attention.' Sometimes, indeed, but then only
by a conscious effort, we do not concentrate our attention on the
object of sight on which our eyes are fixed, but on some other
object in the peripheral area of vision. Thus, in a drawing room,
though we may be gazing full at the face of a friend, we may
really be watching through the ' corner of our eye ' the pretty girl
beside us, who is talking to some one else. More commonly,
however, when, as is often the case, we are ' not attending ' to the
object that falls on the fovea centralis of the retina, our attention
is concentrated, not on any object of sight, but on something else.
Thus, while we are almost entirely oblivious of our friend or the
pretty girl, we may be concentrating our attention on some
interesting gossip that is being whispered behind us. Our con-
centrated attention, the fovea centralis of our attention, wanders,
like the fovea centralis of the eye, from one sensation (auditory,
tactile, etc.) to another ; or it may ignore sensations altogether,
and, as when we are in a brown study, be concerned only with our
thoughts. Our concentrated attention is what is colloquially termed
' active,' while the diffused attention is termed * mechanical.' Thus,
when we are thinking of the pretty girl or the gossip, we are
actively attending to one or the other and mechanically to our
friend. But the latter attention, however mechanical, however
diffused, is still attention. We are not quite oblivious of the
friend. We still converse mechanically.

68 1. The degree of concentration of attention varies greatly.
It may be so concentrated that we are almost unconscious of the
rest of our surroundings. It may be so diffused that it is hard to
say which object is claiming the most of our attention. But there
always is some concentration and some diffusion. Now, we
invariably remember best those things on which we have concen-
trated our attention most. Thus, as a rule, we can recall only the
seen things on which we have fixed our sight, and even then only
when we have paid attention to them at the time. All the rest
we have seen, or otherwise felt, is vague in recollection, if it be
recollected at all, in proportion to the degree of the diffusion of
the attention. Thus, I have been invited to see an interesting
town, by a friend who was even more interesting, and have walked
miles with him, and have come away with hardly a recollection of
the place, but full of vivid remembrances of what my friend said.
If he had been less interesting I should have remembered more of

4H NATURE AND NURTURE

the town. Doubtless, in that case, my concentrated attention
would have fluctuated back and forth from him to it. Since,
however, only my diffused attention was given to the town, I
remember little of it. Only enough attention was given to enable
me to walk about and avoid obstacles.

682. The will is associated with the attention. We never will
to do anything unless our attention is attracted to it We are able to
do several actions at once. Thus a few minutes ago I was standing,
smoking, pouring water into a cup, stirring its contents, and trying
to think of a good example of several actions done simultaneously.
My attention was concentrated on the last-mentioned act, the
others being more or less automatic. Were they, or were they
not under the constant control of my will ? Suddenly it occurred
to me that my action at the time afforded the example I required.
Thereupon, as I noticed immediately, I ceased to smoke, to incline
the kettle, and to stir the cup. I do not know how it is possible
to explain these cessations, except by supposing that the new
thought occupied so much of my attention, and therefore of my
will, that the latter ceased to direct the smoking, inclining, and
stirring, though the still more automatic actions of standing and
holding the kettle continued. Had my attention been very strongly
concentrated it is possible that even they might have ceased. I
remember, as a student in Edinburgh, watching with mischievous
expectation a party of tourists in whose near neighbourhood a
signal cannon, unsuspected by them, was about to be discharged.
At the sound of the explosion almost all action ceased for an
instant in the crowd. It stood as if paralysed. Many of its
members let fall sticks and parasols, and many seemed c ready to
drop ' — to cease the automatic action of standing. Similarly, any-
thing that interests us very greatly tends to cause cessation of
automatic action unless some of our attention is directed to it by
conscious effort. On the other hand, during ordinary preoccupa-
tion, we are able to hold within the peripheral parts of our atten-
tion things we desire to bear in mind. This happens even during
sleep, for often we are able to wake, if we desire it, at an earlier
hour than usual. It seems, then, that even the most automatic of
our actions is maintained only because some part of our attention is
directed to it, and some part of our will engaged in its performance.

683. I think, therefore, there can be no doubt that automatic
actions differ from reflexes, not only in that the ability to perform
them is acquired, but also because they are always initiated,
controlled, and guided throughout by the will. Therefore they

FAMILIAR AND SURPRISING THINGS 415

are not such close copies of reflex actions as certain other actions
are of instinctive doings. While we are learning to perform them
they engage our attention and will strongly. But as they become
habitual and are performed with increasing ease, we are able to
distract more and more of the attention and the will to less
habitual actions; but never the whole attention and will. The
will does not fall into abeyance as we become dexterous, it merely
works very smoothly and easily so that little mental effort is
required. As already noted, it is one of the main businesses of our
lives to acquire the power of performing frequently recurring
actions automatically, and so set free the concentrated part of the
attention and the will — the fovea centralis of our attention and
will — for other objects.

684. It is said sometimes that lower animals differ so much
from us in brain and mind that we can form no conception of their
mental states. Doubtless this is true in a great measure. The
senses and, therefore, the outlook on the world as well as the
instincts of many animals differ greatly from ours. Moreover, no
other animal possesses such an enormous memory as man ; none,
therefore, learns so much about the world or is so preoccupied
with the past and the future. On the other hand, since most of
our instincts and those of lower animals are derived from progeni-
tors that were common ancestors, our innate emotional impulses
cannot be very different ; and, though our powers of thought are
transcendently great, yet all that is conferred by our unconscious
memories, our ' physical ' dexterities and mental attitudes, includ-
ing many of our prepossessions and prejudices, tend to become
close copies of instincts and instinctive activities. It is possible to
imagine a state of mind in which experiences are not recognised as
old acquaintances — a state of mind in which nothing appears
familiar or unfamiliar ; in which everything is taken as a matter
of course and nothing causes surprise ; in which there is no idea
of the past or of the future but only a consciousness of the
immediate present ; in which, while most sights, sounds, tastes,
tactile sensations, and the like leave us unmoved, some of these con-
centrate our attention and will and incite more or less vehemently to
definite actions the aims and ends of which are unthought of. Such
a state of mind should be very like that of purely instinctive
animals. Things are familiar or unfamiliar only because memory
differentiates between the two, and surprising things are surprising
only because they run counter to our previous experiences.1

1 See § 561.

416 NATURE AND NURTURE

Doubtless, an African elephant or a dragon from the pit would
excite no greater interest or surprise than a rabbit in a new born
baby or in a beetle of any age.

685. Probably our dream world resembles in great measure the
real world of a purely instinctive animal. In proportion to the
depth of our slumber, our memory, or some part of it, seems in
abeyance. We may " know sleeping thoughts at the moment they
arise, and not retain them the next moment." l As a medical man
I am frequently rung up at night, and, having formed the habit of
taking note, I observe that, invariably, I awaken out of a dream,
which I remember if I mentally record it without delay, but which
otherwise I forget almost immediately, especially if I am roused
out of very deep slumber. In lighter slumber, when I hover on
the borders of waking, memory also is more awake. It is then I
have my ' vivid ' dreams, those I remember best. I think, there-
fore, that my mind as a whole never sleeps. In deepest sleep I
dream and weave the sensations that come to me from my body
into the fabric of my dreams. Of all my mind my memory alone
rests, more or less profoundly, when I sleep ; and, when I awake, it
is my memory that awakes.

686. The main differences between our sleeping and waking
mental experiences arise from the fact that we are unable to store,
to profit from, the former. They are not retained in the memory
to anything like the same extent as the latter. Moreover, when
dreaming we refer to experiences recognized as past much less
than when awake. We live mainly in the immediate present,
accepting experiences, as they arise, without to any extent
consciously associating them with what has gone before. It is
thirty years since I studied for the Royal Engineers and more
than twenty since I sought to become a medical student. Never-
theless, occasionally I am still rendered miserable when asleep by
the thought that I may be * ploughed ' in Latin. All that has
happened between youth and middle age is quite forgotten. It is
true that the objects we see in our dreams have usually been stored
in our memories whence they are evoked ; but they do not come
to us surrounded, as it were, by a halo of recollections. They are
not usually greeted as remembered things. We feel that they are
good or bad, delightful or horrifying, just because they seem by
nature to be so, not because of the recollections with which they
are invested — as if the physical characters in the brain with which
they are correlated had developed through the stimulus of

3 Isaac Walton.

THE DREAMING STATE 417

nutrition, not through that of use and experience — as if they had
developed as Adam's navel is said by the theologians to have
developed. Just so might an insect see his hitherto unimagined
mate or enemy with delight or fear.

687. I dreamed lately that I sat in a railway carriage suffering
from headache, which a commercial traveller who was next to me
tried to cure. I felt extremely grateful. At the same time, as quite
an independent person who knew nevertheless he was the same
person as the sufferer, I sat opposite, and marked the proceedings
of the traveller with some professional contempt and disapproval.
The personalities of sufferer and observer alternated rapidly, but I
accepted without question the fact that I was both. Because in
my waking hours I appeal to past experience and therefore am
able to reason from it, I know now that the situation was an
impossible one ; but I did not appeal to it then. In another
dream I looked at the top of my own head as I lay asleep and
noted with regret but no surprise that I was extremely bald. In
my dreams I have flirted with Queen Elizabeth and in the same
night have been in heaven and hell and have not been astonished
that the one bestowed no more delights than the other. Dreams,
being thoughts, are as * swift as thought ' : between two intervals
of waking — five minutes by the clock — I have dreamed volumes.
Yet of all the immense mass of our dream experiences how little
we remember ! Though, as I say, I appear always to dream when
asleep I recollect nothing that occurs during deep sleep unless I
am suddenly awakened and at once make the record. Even of
the visions of light sleep I commonly remember little. It is
significant, that though recollection slumbers, yet all the instinc-
tive emotions may be felt during sleep. On all counts, therefore,
it seems evident that the faculty that slumbers more or less deeply
during sleep is memory, and more especially the part of memory
which is concerned in recording (not recalling) experiences. In
other words though we have plenty of experiences during sleep our
minds do not then grow under their stimuli. We become like
instinctive animals ; we neither record facts nor grow dexterous
in using them. Since reason deals with the contents of memory
and is itself one of the contents, reason also sleeps with a sound-
ness which is in proportion to the soundness with which the
memory slumbers.1

1 See Sir Arthur Mitchell's most interesting work Dreaming, Laughing, and
Blushing, pp. 5-9. It is sometimes said that intoxication is marked by a pro-
gressive loss of faculties beginning with the highest, the last evolved, and ending
27

4i 8 NATURE AND NURTURE

688. Do purely instinctive animals sleep ? If they do, what is
the faculty that slumbers ? When they rest, as a fly in darkness,
and hardly any stimulus awakens their senses, are they unconscious
in a truer sense than we are during sleep? Or do they also
see visions ? Our visions are supplied by a more or less paralysed
memory ; what supplies their visions, if they have any ? Most of
the experiences stored in our memories are acquired through the
sense of sight. Is the fact that all animals with well developed
memories close their eyes during sleep connected with the fact
that their memories need rest ? It is true that the eyes of such
animals are especially vulnerable, but that peculiarity may be the
effect not the cause of the fact that eyes are covered by eyelids.
Apparently the eyes of insects see well enough ; and yet they are
not protected.

689. Many insects, for example solitary wasps, are not pro-
tected during the beginnings of conscious life by their parents.
Therefore, of necessity, they are fully or almost fully equipped for
the battle of life by instinct. Nevertheless they are able to return
burdened with loads of food to the cells in which they have de-
posited their eggs. By what means do they find the road — by
instinct or memory? The word memory is used in two senses,
one of which implies recollection, and the other bearing in mind.
We recollect when we recall an experience which was formerly in
consciousness but has passed out of it ; we bear in mind when we
keep an experience in consciousness. Thus I recollect a blow if,
after the memory of it has passed out of consciousness, a sight of
my opponent recalls the experience. I bear in mind if I continue
to dwell on the experience after having been struck. Probably
the kind of memory which is absent in purely instinctive animals
is the power of storing experiences so that they may be recalled.
Therefore it is possible that the wasp may instinctively bear in
mind, during all the vicissitudes of her hunt for food, the situation
of her nest ; in which case, she is, like higher animals, able to
attend to more than one thing at a time. On the other hand, if
she recalls the situation of her nest, of which she was previously
unmindful, she possesses a true memory ; but in that case, since
she is very incapable of learning other things J she has a memory

with the lower, the more anciently evolved. The interpretation of this appears
to be that intoxication, like sleep, is a kind of paralysis by which the memory in
particular is affected. The highest faculties and the most skilful actions are those
which depend on the greatest amount of stored experience. The ' brute ' muscular
strength and the innate mental and nervous characters (instincts and reflexes)
are relatively little affected. l See Lubbock, Ants, Bees, and Wasps.

HUMAN MENTAL ACQUIREMENTS 419

which is capable of storing only a particular and a very limited
set of facts. The latter hypothesis seems, at least, improbable.

690. From birth to adult age our physical development is due
mainly to the stimulus of use. After the attainment of manhood
almost all growth which is not pathological or a mere storing of
spare nutriment as fat, is due to that cause. The growth thus made
during youth is enormous, but it occurs only on certain predestined
lines and within well-defined limits. By limiting the amount of use
to which this or that structure is put we may limit its growth ; by
putting the structure to a more than normal amount of use we
may increase its size somewhat beyond the ' normal.' But there
our power ends. The hand is put to a greater variety of uses than
any other organ in the body. Yet, even if we begin with the infant,
we can only make it large and coarse, or small and fine. It still
remains a hand which closely resembles in size and shape altogether
normal hands. It is very different in the case of mind. Consider
the millions of ' physical ' dexterities we are capable of learning.
These are all really mental. For example, our hands do this or
that thing dexterously because our minds have learned to direct
them readily and rightly. The ' normal ' dexterity of the penman
differs widely from that of the woodcutter, the sailor's from that of
the surgeon. Yet any of them may be acquired by the average
young individual. But physical dexterities are as nothing com-
pared to the rest of our mental acquirements ; they are as nothing
compared even to the mental acquirements that are most closely
related to them. Thus, the architect's manual skill with ruler and
pencil is but a small part of his total mental acquirements as
architect, and that again is but a small part of his total mental
equipment as a man of the world, his other physical dexterities, his
acquired mental attitudes, his knowledge of men and things. The
average man is capable of becoming an average architect; or,
instead, he may acquire skill in one or more of a thousand other
occupations.

691. Physically most of us could fill the places of most other
men ; that is our physical structures are capable of doing the
work that their physical structures do. Mentally not one of us
is capable of filling the place of any other. I, for example, though
as large and strong in body, could not mentally fill the place of a
workman with whom I am acquainted. I have not the same skill
and mental attitudes which have fitted him into a certain niche, the
same prejudices, the same ethics, the same knowledge of his world
based on past experience. My religious and political convictions

420 NATURE AND NURTURE

are different. I do not love the same old people, the same wife, the
same children, the same fireside, the same friends. Yet I might
well have fitted his niche had I been reared to it.

692. It is evident, therefore, that while human bodies can grow
in only one way, human minds may grow in any one of a thousand
ways. As already noted, if the child of refined and educated
English parents were reared from birth by African cannibals, then
in body, when grown, he would resemble his progenitors more
than his trainers. Does anyone believe that the same would be
true of his mind? All Anglo-Indians know the disastrous effects
of too much association with natives on the plastic minds of white
children. They become unfitted for the environment of the
average Englishman. Even when an adult young Englishman
migrates to the United States or the colonies and returns after
twenty years, we perceive marked mental differences between him
and his stay-at-home contemporaries. Indeed, he seems to us
to have become quite similar to the people with whom he has
dwelt, though, doubtless, Americans or colonists, whose observa-
tion is sharpened by familiarity can detect differences. The
English child we imagined as reared by African savages would
certainly display no hint of the language and general knowledge
of his parents, no tincture of their moral, social, religious, and
political ideals and aspirations. He would ruthlessly murder and
enjoyingly eat the stranger. He would harry the stranger's
property and annex the stranger's wives by the wool of their heads
whenever practical. He would treat his own wives as beasts of
burden, and perhaps thrash them as a matter of routine. His
aesthetic ideals would be satisfied by a little paint, some beads,
and plenty of grease ; his moral ideas by a homicidal devotion to
the tribal chief. His god would be the tribal fetish, to whom he
would offer human sacrifices. He would go naked and unashamed.
The common-sense of mankind has universally recognised this
radical difference between man's mind and body. We allow our
children to train their own bodies, being satisfied that they will
develop physically well enough under the influence of sufficient
food and the exercise to which the instinct of play impels them ;
but to the training of their minds we devote the most anxious
care. We mould them, and we know we mould them. No one
fears that his child will be made short or dark by association
with short or dark companions ; but everyone dreads that
his child may become silly or bad if his associates are silly or
bad. Clearly, then, the mind of the individual is 'shaped' by

CAPACITY AND ACQUIREMENT 421

his immediate surroundings in a much greater degree than his
body.

693. Sometimes it is asked if nature or nurture plays the more
important part in the mental development of the human being.
As a fact this question is nonsensical. It is as if we asked whether
the locomotive or the steam played the greater part in transporting
the train. The truth is that nature has rendered man trans-
cendently responsive to the nurture of use and experience. The
question should be "To what extent has nature rendered man
responsive to the stimulus of nutriment and to what extent to that
of use and experience?" Nature has rendered all living beings
equally responsive to nurture. The caterpillar is responsive to
the nurture of nutriment. Man differs from the caterpillar in that
nature has rendered him responsive in addition to the nurture of
use and experience. He differs from other animals in that he is
immensely the most responsive of all to this kind of nurture. It
is the one peculiarity which strongly differentiates him. Mental
experience is, after all, only a form of use. We use our minds
when we store experiences; or rather, if mind is a function of
brain, we use our brains. When, for example, we acquire a new
manual dexterity, our brains acquire a new function ; through use
they learn to do a new thing. Doubtless the acquirement is
accompanied by actual growth of brain, which however, especially
in adult life when gains are being balanced by losses, need not
imply an increase in bulk, but only a relative increase in certain
of the brain constituents such as nerve cells or connections
between nerve cells. In youth, when man is making the great
mass of his mental acquirements including the more important of
his * physical ' and mental dexterities (e.g. walking and reasoning),
there is rapid growth in the bulk of the brain, which is most rapid
just when the acquirements are being most rapidly made. In old
age, though the individual may still be making mental acquire-
ments, he is usually losing more than he acquires. Then, while
the total mass of his brain does not decrease, the nervous elements
tend to be replaced by fibrous tissue.

694. If we wish to avoid hopeless confusion it is necessary
to distinguish sharply between two entirely different things ;
between, on the one hand, capacity to make mental acquirements,
and, on the other, the mental acquirements themselves, between
the memory and the things that are stored in the memory. The
capacity is an * innate,' a nutritional character ; the acquirements
arise under the stimulus of experience. Thus a man may have

422 . NATURE AND NURTURE

exceptional mathematical ability by means of which he achieves
considerable mathematical learning if afforded the opportunity.
The ability is ' inborn ' and tends to be { inherited ' by offspring ;
the acquirements are not. That is, the child, if he lives and grows
at all, is sure to have food and therefore to develop, unless he has
varied, the parental capacity; but he is not sure to have the
parental training, the nurture of the same use. Therefore, even if
he 'inherits' the parental ability, the child of a great mathe-
matician may, or may not, achieve similar distinction. But such
a one is more likely than the child of an ignoramus, not only to
inherit ability, but to receive the right training. Without the
training the ability is naught; just as without coal the engine is
naught. Nutriment, therefore, bestows on the child the parental
aptitudes ; association with the parent tends to bestow the
parental acquirements. Consequently children tend to resemble
their parents for a double reason ; first, because they tend to have
much the same capacities, and second, because they make much
the same acquirements. We must bear in mind, however, that the
parent is not the only influence in the child's environment.
Therefore, not only may the child vary from the parent in capacity,
but also he may differ in acquirements.

695. Mathematical efficiency depends on mathematical acquire-
ments made by virtue of mathematical capacity and in response
to mathematical experience. The efficiency is impossible without
the acquirements, and the acquirements without both the capacity
and the experience. The same is true of all other intellectual char-
acters. But the part played in the creation of efficiency by
capacity on the one hand, and by experience on the other — by
nutriment on the one hand and use on the other — varies with
different characters and in different species. The caterpillar
apparently owes nothing to acquirement ; he has no substratum of
capacity wherewith to store experience and therefore cannot
utilize it. The acquirements of the cat, for example the increased
efficiency in hunting which practice bestows, are, as a rule, nothing
more than mere extensions of pre-existing instincts comparable to
those extensions of its physical structures which are bestowed by
use. Some of man's acquirements are also mere extensions of
instincts. Thus, both parental and sexual love tend, within limits,
to be increased by association with the objects of affection.
Speech is an extension of the infant's tendency to utter useful
but inarticulate cries. In this case, however, the extension is im-
measurably greater than the thing extended. But unlike extensions

INSTINCT AND ACQUIREMENT 423

of instinctive actions and unlike his physical acquirements, most
of man's intellectual characters cannot, except through very
strained interpretations, be regarded as extensions of previously
existing innate characters. Thus many of his manual dexterities,
his efficiency in reading, his devotion to a religion, or an ethical
code, resemble nothing instinctive in him. They are wholly
' acquirements.'

696. We must distinguish not less sharply between instinct
and acquirement, than between capacity and acquirement. A
glance at the literature of the subject demonstrates that numbers
of human characters are accepted as innate on inadequate evidence.
Modesty is supposed to be innate. But what kind of modesty ?
that of the Mohammedan women, or that of the nun, or that of
the savage ? Savage women have no modesty in the European
sense, but I have known mission natives exhibit an extraordinary,
and, as it seemed to me an Englishman, an absurd degree of
prudishness. In Tonga, for untold centuries, the natives went
about naked and unashamed, and, judged by English standards,
sexual intercourse amongst them was almost promiscuous. A few
years later mere flirtation was regarded as a horrible crime and
was legally punishable. It is impossible to doubt that English
women trained by savages would show no trace of the traditional
modesty of their race. Modesty is not an instinct, but an acquire-
ment dependent on memory. The only instinct with which it is
connected is that of imitation. Morality also is supposed to be an
instinct. But what kind of morality? Like modesty, morals
vary with time and place. Real instincts are universal in the
species, and in measurable time unchanging. We often read of
the special instincts of savages, for example their instinct for
tracking game. But no savage, having all the while no notion of
the aim or end of his actions, has an innate impulse to follow
certain marks on the ground till he catches a kangaroo or a deer.
Manifestly his so-called instincts are acquirements. He excels
the civilized man for the same reason that the native Frenchman
excels the foreign resident in the perfection of his French — because*
he has learned at the most receptive age.

697. Even characters which have a large instinctive element
are extended, modified or even in some cases in a sense suppressed
in the human being by acquirement. Appreciation of sexual
beauty is an instinct, but the kind of beauty admired depends
greatly on acquirement. As a rule we admire women who are
decorated in the latest fashion. At the present day we can

424 NATURE AND NURTURE

perceive no element of beauty in the chignon or crinoline of the,
as it seems to us, terribly inartistic Victorian era ; but our fathers
were ravished by the appearance of the women who wore them.
Various savages admire mutilations which are horrifying to us.
Indeed almost all races practise some form of mutilation and find
it beautiful ; thus we crop and shave the magnificent human
mane which, judging from its great evolution, must have been a
principal instrument of fascination amongst our remote ancestors.
I, personally, am nauseated by the sight of long hair on a male
human head. Doubtless sexual jealousy is in a measure in-
stinctive ; yet while the husband is jealous of the lover, the latter
is seldom jealous of the former ; were the emotion purely in-
stinctive they should be equally jealous. The jealousy of an
Australian black is as nothing compared to that of the Mohamme-
dan. Parental affection is an instinct, yet many people have
cheerfully practised infanticide ; and the average parents of various
races are good or bad according to the prevailing fashion.
Perhaps the most convincing evidence that parental actions are
mainly founded on acquirement is afforded by the fact that
civilized parents whenever possible tend to delegate them to the
hands of servants. The actions to which they are prompted by
purely instinctive impulses, for example thirst, hunger, weariness,
and sexual love are never delegated.

698. To sum up : the distinguishing peculiarity of the human
being as compared to other animals is that his characters arise
much less under the stimulus of nutriment and much more under
that of use. Most of his nutritional characters are mere foundations
on which * acquirements ' are reared. Biologists commonly suppose
that innate characters are much more important than acquirements.
But if, were it possible, we deprived an adult human being of his
acquirements nothing would be left but the likeness of a new born
infant which possessed the sexual instinct, and a few adult physical
traits such as hair, teeth, external ears, and organs of generation.
Manifestly the physical and mental maturity of the normal human
being depends mainly on acquirements, the making of which is
just as essential a part of adult development as the growth of heart
and limbs is of foetal development. This truth, though opposed to
scientific tradition and on that account rarely recognized, is really
a matter of common knowledge and is so plainly true that I think
it has only to be formally stated to be recognized as true. It
may be that there is more of what is innate and less of what is
acquired in this or that human character than I have been led to

THE MIND OF THE IDIOT 425

believe. But the fact that human acquirements, especially mental
acquirements, are of immensely greater magnitude and importance
than is commonly supposed cannot, I believe, be doubted.

699. A little thought renders it evident that the essential defect
of the feeble-minded person, the idiot, and the imbecile, is lack of
memory.1 He is unable to profit like the normal individual from
experience. This defect of memory may be, and usually is, general,
so that the individual is able to learn very little. Or the defect
may be limited to some particular ; for example the individual
may be unable to acquire the code of morals prevalent in the
community in which he exists — an acquirement which on the
average and in the long run would be of great advantage to him.
The truth that the higher intellectual faculties are less developed
in the feeble-minded than lower faculties is due entirely to the fact
that the former can be acquired only by people whose receptive
powers are considerable. In effect and in fact the feeble-minded
person is an instance of reversion to a pre-human mental state.
Judged by the human standard every dog and monkey is an
imbecile. But the reversion of the imbecile is not complete ; for,
while he has lost part of his power of profiting by experience, he has
regained no part of the lost power of being guided by instinct.
Therefore he is correspondingly helpless as compared to a lower
animal. On the other hand, the instincts (e.g. the sexual) which
normal human beings still possess often appear unduly prominent
in him ; but only because he cannot learn to control them.

700. But though human beings develop mainly under the
stimulus of use and experience, doubtless they differ * by nature '
amongst themselves just as much as animals that develop solely
under the stimulus of nutriment. In the last analysis all variations
are nothing other than variations in powers of responding to
stimuli — nutriment, use, and injury — and we have no reason to
suppose that variations in the capacities for responding to the
stimulus of use are smaller or fewer than variations in the capacity
for responding to the stimulus of nutriment or injury. Doubtless,
therefore, men vary not only in general mental capacity (i.e. power
of making mental acquirements) but also in particular departments
of capacity. At the one extreme is the absolute idiot who has no
power of storing and utilizing experiences, and, at the other, the
genius who has exceptionally great powers. It has been observed
that some imbeciles have considerable capacity in some particular
department. Thus, they may have great powers of remembering

1 See §§ 762 et seq.

426 NATURE AND NURTURE

this or that class of facts, but no power of learning to utilize them.
So also, while it is possible that some geniuses may be men
endowed with exceptional all-round capacity, they are usually
distinguished from the average type by exceptional capacity in
some particular department of mental activity. It is probable, for
example, that Shakespeare had more poetic capacity (i.e. power of
responding to poetic experiences, of recording and learning to
utilize such experiences) and less artistic capacity than Michael
Angelo, who presumably had less mathematical capacity
than Newton, who in turn had less military capacity than
Napoleon, who again was inferior in philosophic capacity to
Darwin.

701. But, admitting all this, it must still be borne in mind that
(i) the stimulus of nutriment is capable of developing the bodies
and minds of men in only one way ; that is, we cannot by changing
the kind of nutriment which the human being is capable of
assimilating, produce different kinds of bodies and minds ; under
all kinds of nutriment a man will still have much the same sort of
limbs, lungs, sensations, instincts, and memory ; (2) changes in the
kind of stimulus of use cannot produce very great changes in the
bodies of men ; as in the case of nutriment, they may develop
this or that organ more or less according to the amount of use
supplied, but that is all ; limbs and lungs and other structures will
still be of the same kind no matter what the stimulus ; (3) but
differences in the stimulus of experience supplied to the mind are
capable of causing tremendous differences in mental development.
For example, while the bodily parts of a yokel (e.g. his brain)
differ little in appearance from that of a cultured man, the mental
difference is obviously very great It follows, that in comparing men
or races we are on safer ground when we suppose that their bodily
differences are innate (i.e. germinal) than when we suppose that
their mental differences are innate. Doubtless, as I say, differences
in mental capacity are just as great as innate physical differences ;
but they are apt to be overshadowed and concealed by vaster
acquired differences.

702. Perhaps the most convincing evidence that human mental
and moral characters arise mainly under the stimulus of experi-
ence is afforded by the history of races and nationalities. Like
individuals, races differ in their mental characteristics. Thus the
English have one set of characteristics, (knowledge, ideals, and
so forth), the Japanese a second, the Russians a third, and West
Goast Africans a fourth. Most historians and men of science

RACIAL MENTAL CHANGES 427

adopt the easy view that the mass of these differences are innate
in the same sense that physical differences are innate.

703. Man is a very slow breeding animal. Innate changes of
importance cannot occur in his race at all swiftly — in the course of
a few centuries — except under excessively stringent selection ; and,
owing to the strong tendency to retrogression thereby created, such
changes can only be maintained afterwards by selection almost as
stringent and continued over a very long period. But, in the
absence of all recognisable selection, some races have changed
their mental characteristics with great rapidity. Thus the Greeks
and Romans, separating quickly from the surrounding barbarians,
displayed, for a few centuries, extraordinary intellectual qualities,
and then sank, quite as suddenly, into abysmal degradation. At
the Renaissance and the Reformation, after more than a thousand
years of stagnation, various European nations began to display
qualities comparable to those of the great Pagans. Their material
and intellectual progress has continued to the present day ; but
even now, when we are able to watch contemporaries, we are
unable to detect any form of stringent selection save that by
disease. The Japanese furnish a very striking modern instance.
Another similar instance is afforded by the fact that, in a single
generation, the ferocious cannibals of New Zealand have become
progressive and law-abiding. Nothing apparently prevents them
taking an equal place with the whites as citizens of a progressive
and civilised state except their physical inability to withstand
imported disease.

704. Every race that has changed its religion has immediately
undergone a great moral and intellectual change. The inhabitants
of Syria and North Africa are examples. At first they were
Pagans and shared to some extent the Greek and Roman character-
istics ; next they became typical Christians of the Dark Ages ;
lastly they became typical Mohammedans, — fierce, turbulent,
fanatical, stagnant. Races of diverse origin, which follow a given
religion, resemble one another more closely in mental characteristics
than sections of the same race which follow diverse religions.
Thus all Mohammedan nationalities have mental peculiarities
which separate them sharply from Christians on the one hand and
Pagans on the other. Mohammedan Greeks mentally resemble
their co-religionists more nearly than their compatriots. The
Teutonic Catholics of Ireland are quite indistinguishable from the
Celtic Catholics, but they differ sharply from Protestant Teutons.
Catholic negroes are typical Catholics of the more ignorant type ;

428 NATURE AND NURTURE

the negro Baptists and Methodists of the United States are in
many respects typical Baptists and Methodists resembling those
of Wales. Jews who abide by their religion retain their character-
istics ; those who abandon it merge indistinguishably into the
surrounding population. Indeed all the world over peoples of the
same colour are divided mentally much more sharply by religious
differences than by anything else.

705. To me it appears, if only we think carefully enough and
take all the facts into account, that it is impossible to come to
conclusions other than the foregoing. They amount to nothing
more than is implied in the statement that man is mentally an
extremely adaptable, malleable, educable, intelligent, and in-
tellectual animal ; and, therefore, that he is much more a creature
of habit than of instinct. Educability is nothing other than a
power of growing mentally under the stimulus of experience ;
intellectuality is nothing else than a having so grown.

706. Some authorities, however, founding themselves on
statistical inquiries, are of a contrary opinion. At least they claim
to have proved that man is less educable, less a creature of acquire-
ment, than I have supposed. Thus Professor Karl Pearson1
issued schedules to school-teachers and requested them to supply
information as precise as possible concerning certain mental and
physical characters of (i) pairs of brothers, (2) of sisters, and (3) of
brother and sister. Some of the physical characters were capable
of being measured. Others were estimated, as, of course, were all
mental characters. The physical characters included health,
athleticism, length, breadth, and height of head, colour, smooth-
ness, waviness, or curliness of hair, and colour of eyes ; the mental
characters included ability in various studies, noisiness or quiet-
ness, self-consciousness, self-assertion, shyness, conscientiousness,
popularity, and temper. Pearson chose children rather than adults
owing to the difficulty of obtaining correct information concerning
the latter. " In the first place it seemed to me absolutely impos-
sible to get a quantitative measure of the resemblances in moral
and mental characters between parent and offspring. You must
not compare the moral character of a child with those of its adult
parents. You can only estimate the resemblance between the
child and what its parents were as children. Here the grand-parent
is the only available source of information ; but not only does age

1 " On the Inheritance of the Mental and Moral characters in Many and its
Comparison with the Inheritance of the Physical characters." The Huxley Lecture
for 1903. The Anthropological Institute of Great Britain and Ireland.

BIOMETRY 429

affect the clearness of memory and judgment, the partiality of the
relative is a factor which can hardly be corrected and allowed
for." 1 He argued that resemblances between children of the same
family is as clear a proof of inheritance as resemblance between
parent and child — in which, doubtless, he is right.

707. It was found that, on the average, the children of the
same family resembled one another as closely mentally as physic-
ally. Pearson admits that certain physical characters such as size
of head and body are influenced by ' nurture, food, and exercise,'
but since brothers and sisters resemble one another in these traits
in the same degree as in such physical characters as the cephalic
index, and the colour of hair and eye, which are not affected by
' home influence,' he concludes that the environment is not a dis-
turbing factor when calculations are made respecting the degree of
resemblance due to inheritance. A similar line of reasoning is
applied to mental characters. In effect his conclusion amounts to
this — that if, as regards any set of characters, brothers and sisters
resemble one another on the average in the same degree, then all
the resemblances must be due to the same cause. For example, if
the resemblances are equal as regards geniality, probity, eye-colour,
hair-colour, and the cephalic index, then geniality and probity
must be inherited in the same sense as the physical characters
mentioned. " The sameness surely involves something additional.
// involves a like heritage from parents. The degree of resemblance
between children and parents for the physical characters in man
may be applied to the degree of resemblance between children
and parents for psychical characters. We inherit our parents'
tempers, our parents' conscientiousness, shyness and ability, even
as we inherit their stature, fore-arm and span." 2

708. But eye-colour cannot be influenced by environment,
whereas there is at least some reason to believe that geniality and
probity may be so influenced, and the environment of different
families differs greatly. Pearson meets this difficulty by the state-
ment that " We are too apt to overlook the possibility that the
home standard is itself a product of parental stock, and that the
relative gain from education depends to a surprising degree on the
raw material presented to the educator. We are agreed that good
homes and good schools are essential to national prosperity. But
does not the good home depend on the percentage of innately wise
parents, and the good school depend quite as much on the
children's capacity, as on its staff and equipment ? " 3 According

* P. 180. * Loc. cit., p. 204. 3 Loc. cit., pp. 179, 180.

430 NATURE AND NURTURE

to Pearson, then, there must be, on the average, a tremendous
germinal difference between Englishmen of the upper classes and
those of the lower, between Englishmen of the country and those
of the town, between Englishmen of to-day and those of a century
or two ago, between Englishmen and foreigners, between Greeks
and Romans of the period of national greatness and their immedi-
ate predecessors and successors, between Greek Mohammedans and
Greek Christians, and so forth ; and an English child reared by
African cannibals should develop the moral and intellectual as well
as the physical characteristics of his progenitors not of his educators.
709. Moreover, " If the conclusion we have reached to-night be
substantially a true one, and for my part I cannot for a moment
doubt that it is so, then what is its lesson for us as a community ?
Why simply that geniality and probity and ability may be fostered
indeed by home environment and by provision of good schools and
well equipped institutes for research, but that their origin like health
and muscle, is deeper down than these things. They are bred, not
created. That good stock breeds good stock is a common-place
of every farmer ; that the strong man and woman have healthy
children is widely recognized too. But we have left the moral and
intellectual faculties as qualities for which we can provide amply
by home environment and sound education." l . . . " Looking
round dispassionately from the calm atmosphere of anthropology,
I fear there really does exist a lack of leaders of the highest
intelligence, in science, in the arts, in trade, even in politics. I
do seem to see a want of intelligence in the British merchant, in
the British professional man and in the British workman. But I
do not think the remedy lies solely in adopting foreign methds of
instruction or in the spread of technical education. I believe we
have a paucity, just now, of the better intelligences to guide us
and of the moderate intelligences to be successfully guided. The
only account we can give of this on the basis of the results we have
reached to-night is that we are ceasing as a nation to breed
intelligence as we did fifty or a hundred years ago. The mentally
better stock in the nation is not reproducing itself at the same
rate as it did of old ; the less able, and the less energetic are
more fertile than the better stocks. No scheme of wider and
more thorough education will bring up in the scale of intelligence
hereditary weakness to the level of hereditary strength. The only
remedy, if one be possible at all, is to alter the relative fertility of
the good and bad stocks in the community. Let us have a census

1 Loe. «'<., p. 306.

BIOMETRY 431

of the effective size of families among the intellectual classes now
and a comparison with the effective size of families in the like
classes in the first half of the last century. You will, I feel certain,
find, as in the case of recent like censuses in America, that the
intellectual classes are now scarcely reproducing their own
numbers, and are very far from keeping pace with the total growth
of the nation. Compare in another such census the fertility of the
more intelligent working man with that of the uneducated hand
labourer. You will, I again feel certain, find that grave changes
have taken place in relative fertility during the last forty years.
We stand, I venture to think, at the commencement of an epoch
which will be marked by a great dearth of ability. If the views I
have put before you to-night be even approximately correct, the
remedy lies beyond the reach of revised educational systems ; we
have failed to realize that the psychical characters, which are, in
the modern struggle of nations, the backbone of state, are not
manufactured by home, school and college ; they are bred in the
bone; and for the last forty years the intellectual classes of
the nation, enervated by wealth or love of pleasure, or follow-
ing an erroneous standard of life, have ceased to give us in due
proportion the men we want to carry on the ever-growing work
of our empire, to battle in the fore-rank of the ever intensified
struggle of nations.

710. " Do not let me close with so gloomy a note. I do not
merely state our lack. I have striven by a study of the inheri-
tance of mental and moral characters in man to see how it arises,
and to know the real source of an evil is halfway to find a remedy.
That remedy lies first in getting the intellectual section of our
nation to realize that intelligence can be aided and can be trained,
but no training or education can create it. You must breed it,
that is the broad result for statecraft which flows from the equality
in inheritance of the psychical and physical characters in man." x

711. Pearson adopts the ordinary view that the body and
mind of the individual are compounded of ' innate ' and * acquired '
characters, that only the former tend to be ' inherited,' and, there-
fore, that evolution (or any sort of intrinsic racial change) depends
entirely on them, acquirements being mere somatic * modifications.'
On the other hand, the view upheld by me has been that no kinds
of characters are more innate or inheritable than any other kind,
that the terms ' innate ' and ' acquired ' are misnomers and the
causes of endless confusion, misunderstanding, and misinterpretation,

1 Loc. cit., pp. 206-7.

432 NATURE AND NURTURE

that the so-called innate characters are simply characters which
have developed under one kind of stimulus (that of nutriment)
whereas the so-called acquirements are equally important characters
which have developed under other kinds of stimuli (those of injury
and use), that all evolution (or any sort of intrinsic racial change)
consists in a germinal alteration which implies increased or
decreased capacity to develop in a definite way under the influence
of this or that stimulus. According to this view the superior
innateness and inheritability of nutritional characters are only in
seeming. They develop more certainly than acquirements merely
because the stimulus of nutriment is always present in every
individual who develops at all, whereas the stimulus under which
this or that acquirement arises may be absent. Moreover, I have
supposed, not only that the evolution of the higher animals has
consisted mainly in a continually increasing power of developing
under the stimulus of use, but also that it has consisted in a con-
currently decreasing power of developing under the stimulus of
nutriment — the former power possessing great advantages over,
and therefore displacing the latter.

712. Of all this evolution, which to me appears to be so mani-
fest, Pearson seems unaware. As results of our differing opinions,
the moral and intellectual characters are to Pearson instincts ;
whereas I cannot conceive how such characters can be instincts.
An instinct, as I understand it, is merely an emotional impulse, the
prompting of which the individual is sure to follow unless it is
opposed by other instincts or acquirements. It is utterly unintelli-
gent, utterly non-moral. It has nothing to do with thought except
as a subject of thought, or with a sense of right and wrong except
in so far as this sense approves or disapproves of its promptings.
Moral and intellectual characters, as proved by unlimited evidence
and from their very nature, are acquirements. Taking all the facts
into account, I cannot imagine a purely instinctive animal, a beetle
or a caterpillar, as moral or intellectual, or a human being as such
except by virtue of the characters supplied by his memory. In effect,
the moral and intellectual beings that Pearson imagines, since they
are not moral or intellectual through acquirement, are imbeciles.1

713. The differences between Pearson and me are so great
that it is useless to discuss details in this place. Directly or
indirectly I have already done so, supporting my own opinion in
almost every chapter of the present volume by a mass of evidence
which is enormous, and which, however new (or newly applied),

1 See § 699.

THE INHERITANCE OF MENTAL TRAITS 433

cannot, I think, be controverted.1 As far as I am able to judge, I
have drawn no illegitimate inferences. Pearson's reasoning, in the
very cases which he instances, appears to me demonstrably wrong.
His main inference is that, since offspring resemble one another in
the same degree in, for example, probity and eye-colour, therefore
these characters are both ' innate.' But, if his reasoning is valid
as regards the mental and physical characters named by him, it
should be valid also as regards other characters not named. Now
English school children resemble one another absolutely in that
they all possess heads, lungs, livers, and so forth. Here the degree of
resemblance is ' unity.' They reproduce these characters with much
greater certainty than eye and hair-colour and variations in fore-
arm and span. They also resemble one another absolutely in that,
when they have reached a certain age, they can all read, write, and
speak the English language, and in that they have English notions
of modesty with respect to clothes. Here, again, the degree of
resemblance is roughly ' unity.' At any rate they reproduce these
characters with much greater certainty than they do eye-colour and
the like. Moreover, in thecase of the boys, there is a mental tendency,
almost as universal as their sex, to wear trousers ; in the case of
the girls, to wear frocks. The children would be infinitely reluctant
to appear at school without these garments. Must we suppose,
then, that this sameness involves a like heritage, a similarity of the
germ-plasm, and that English children ' inherit ' these characters,
which are universally regarded as acquirements and would. probably
be admitted as such by Pearson, with a degree of certainty which
is almost as great as that with which they inherit heads, livers, and
sexual organs ? I do not mean in the least to be offensive in the
examples I have drawn. I have selected them merely in order to
indicate as strongly and vividly as possible the reasons that have
led me to think that Pearson's thinking, founded as it is solely on
biometric data, though much more massive and conclusive evidence
is available, and quite untested as it is by any appeal to reality, is
totally mistaken and illegitimate. Biometry is capable of demon-
strating the degrees in which given characters tend on the average to
be reproduced by offspring under given conditions. But, if we wish
to ascertain the category to which any of these characters belongs
— whether it is * inborn ' or ' acquired ' — we must draw an inference
which biometry, a mode of observing not of thinking, cannot help
us to draw ; and which, therefore, must be tested as carefully as
when our facts have been otherwise gathered.

1 See also chapter xxv.
28

434 NATURE AND NURTURE

714. When we compare one modern species with another, the
more intelligent type invariably has, proportionately to the size
of its body, a larger brain. Thus the dog has a larger brain than
a rabbit, and a man than a dog. Presumably, therefore, intelli-
gence and size of brain are correlated in some degree at least.
Doubtless the correlation is not absolute ; for brains vary in their
constituent elements, for instance, in the relative amounts of grey
and white matter. " The leading feature in the development and
separation of man from amongst other animals is undoubtedly the
relatively enormous size of the brain in man and the corresponding
increase in its activity and capacity. It is a very striking fact
that it was not in the ancestors of man alone that this increase in
the size of the brain took place at the same period, viz. the
Miocene. The great mammals, such as the titanotherium, which
represented the rhinoceros in early Tertiary times, had a brain
which was in proportion to the bulk of the body, not more than
one-eighth of the volume of the brain of the modern rhinoceros.
Other great mammals of the earlier Tertiary period were in the
same case ; and the ancestors of the horse, which are better known
than those of any other modern animal, certainly had much
smaller brains in proportion to the size of their bodies than has
their descendant."1

715. Biometricians, however, founding their opinions on
statistical data, have denied that the law that intelligence is
correlated to size of brain obtains in the case of human races and
individuals. According to them " there is no marked correlation
between skull capacity and intellectual power." What, however,
is the real meaning of their facts, for there can be little doubt that
the facts are correct? The mind manifestly grows under the
stimulus of experience. Mental facts are correlated to cerebral
facts. Therefore, we have every reason to believe that the brain
grows under the stimulus of use. We know, in fact, that if one
hemisphere of the brain atrophies from any cause, such as disease,
the opposite hemisphere tends to hypertrophy ; and we cannot
account for this increase except by supposing that it results from
increase of function. After birth, then5jthe growth of the mind and
brain is conditioned, on the one hand, by the inborn capacity to
grow under the stimuli of experience and use, and on the other, by
the amount of stimulus. Individuals may differ both with respect
to the capacity and the amount of stimulus their minds and brains
receive. It follows, within limits that vary with the individual,

1 The Kingdom of Man, by Sir Ray Lankester, p. 22.

BRAIN VOLUME AND MENTAL CAPACITY 435

that the growth of the brain after birth is in some degree
proportionate to the extent to which it is used. But the degree of
intelligence achieved does not depend solely on capacity and
amount of experience. It depends also on the kind of experience.
An individual may acquire a false and foolish conception of his
total environment with as much toil as a true and wise one.
Mediaeval monks had on the average larger brains than their con-
temporaries, and the Chinese as a race have larger brains than most
races, but it does not follow necessarily that they were, or are, more
intelligent. The real problem, therefore, is not whether there is a
correlation between skull capacity and intellectual power, but whether
the capacity to develop a large brain is correlated to a capacity to
become exceptionally intelligent in one or more directions.

716. The right conclusion to which the biometric facts, com-
bined with the rest that we know, lead us, appears to me, not that
the men who can develop large brains have on the average no
greater power of becoming intelligent than men who can only
develop small brains, but that the former may be worse trained
and therefore less intelligent. In other words, the biometrical
facts tend to demonstrate that right mental training is of as much
importance as capacity.

CHAPTER XXIII
PHYSICAL DETERIORATION AND MICROBIC DISEASE

Summary — The factors in development — Methods of improving development
— Human selective breeding — The effects of diet — Of exercise — Of mental training
— Physical deterioration — The opinions of biometricians — Of medical men— The
right method of improving the physique of urban populations — Microbic diseases —
External and internal sanitation — Contagious, water-borne, insect-borne, earth-
borne, and air-borne diseases.

o

717. /^^\UR study of heredity from the purely scientific stand-
point is ended. We have reached certain conclusions,
certain broad principles, ' laws,' or, ' brief, simple, and
comprehensive classification of facts,' from which necessary con-
sequences may be deduced.1 No characters are really hereditary;
or, if the term be admitted, all characters are equally hereditary.
Characters differ, not because some are inborn and inheritable while
others are acquired and not inheritable, but because they arise
under different classes of stimuli. Evolution is only another name
for adaptation, and in the last analysis all adaptation results from
the Natural Selection of favourable variations. A variation is due
to an alteration in the germ-plasm. Variations are either ' spon-
taneous' or due to the direct action of the environment on the
germ-plasm. The latter class of variations are relatively rare, and
can very seldom, if ever, be other than unfavourable. Therefore
Natural Selection builds solely, or almost solely, on spontaneous
variations, and a main part of its work is, on the one hand, to
provide for the occurrence of spontaneous variations and regulate
their magnitude, and, on the other, to render the germ-plasm in-
susceptible to the direct action of the environment. It follows
that the variability of species and characters is not a fixed quantity ;
on the contrary, each species and each of its characters tends to be
variable, on the average, in a degree best suited to secure adapta-
tion. In other words, the tendency to vary, displayed by all
living beings, is itself an adaptation which is subject to variations,
by means of which Natural Selection regulates the amount of
variability and provides for the occurrence of variations all round
1 See §§ 76 (footnote), 590, 819 et seq.

436

SUMMARY 437

the specific mean. It follows also that the germ-plasm of every
species is less susceptible to the direct action of influences to which
it has long been subjected than to influences of which it has had
little or no previous experience. All, or nearly all, the variations
which furnish material for Natural Selection are fluctuations ; that
is, they are small plus or minus variations of characters previously
existing, and, even so, not of the whole character but only of parts or
qualities of it. By their accumulation and blending during ages,
old characters are lost and new characters created ; or, more
commonly, old characters are so modified as to be in effect new
creations. All development is an abbreviated and inaccurate re-
capitulation of the life-history of the species. Retrogression plays
as important a part in evolution as progression. Variations are
either progressive or retrogressive. Natural Selection has so dealt
with species that retrogressive variations tend to predominate
somewhat over progressive variations because they tend to be more
numerous, or larger, or prepotent in the blend, or on all these
accounts. As a consequence all characters tend to retrogress on
cessation of selection. Species fit their environments so closely,
and their physical and mental parts and qualities interlock so
exquisitely, that in nature mutations can rarely be adaptive.
Owing to their size, and to the alternative mode in which muta-
tions tend to be reproduced, they have an appearance, but only an
appearance, of great stability. When reproduction is bi-parental
and the species is sexually dimorphic, all individuals have three
sets of characters, a non-sexual set of characters all of which are
patent, and two sets of sexual characters of which one set is patent
and the other latent. The function of sex is to blend characters,
and the ultimate effect of blending, combined with the prepotency
of retrogressive variations, is to cause the retrogression of useless
variations and characters and to make evolution depend, not on
the persistence of the variations of individuals, but on the per-
sistence of the blended variations of the race as a whole. All bi-
parental inheritance is blended, the apparent non-blending of the
sexual and Mendelian characters being due to the fact that the
patent set from the one parent blends with the latent set from
the other. Natural Selection differs from Artificial Selection
in that the former is founded mainly on fluctuations, whereas the
latter is founded mainly on mutations. Mendelian reproduction is
an anomaly of sexual reproduction whereby non-sexual characters
are reproduced and blended in the same mode as sexual characters,
one of each allelomorphic pair being patent and the other latent.

438 PHYSICAL DETERIORATION & MICROBIC DISEASE

The present progressive evolution of man, at any rate of
civilized man, is chiefly, if not exclusively, against disease which
is, apparently, the only selective agency acting on him sufficiently
stringent to do more than merely maintain characters previously
evolved. Human beings differ from lower animals mainly in that
they owe their development, especially their mental development,
to a much greater extent to the stimulus of use and experience.

718. The evidence on which these conclusions are based is very
massive and appears to me conclusive. But the reader is now in a
position to judge for himself. Some evidence remains for con-
sideration, but it can be dealt with conveniently as we apply our
'laws' to the practical problems of human life. The following
are the factors in all development: (i) capacity for growth in
directions more or less fixed in every species, but so differing with
different species that the latter differ in their characteristics ; (2)
stimulus which awakens the capacity ; and (3) nutriment which
supplies the material for all growth (as well as the stimulus for
much of it). Capacity for growing physically and mentally, for
responding in such and such a way, in such and such a degree, to
such and such a stimulus, depends on the antecedent evolution of
the race and the variations of the individual. A variation, indeed,
is nothing other than an alteration of capacity to grow, an altera-
tion which is founded on an alteration of the germ-plasm. Capacity
arises in the race through slow processes of selection ; and can be
altered in it only through selection or cessation of selection. It is
that with which every individual begins life, and is wholly an 'inborn '
or nutritional character which cannot be increased in the individual
by use though it may be diminished or lost in him through injury.1
It must be borne in mind, however, that the effect produced by
such alteration of stimulus is limited by the capacity of the indi-
vidual ; thus, no matter how a given man be fed or trained, he cannot
achieve more than a certain degree of height, strength, or capacity.

719. If, then, we desire to improve a human race, two ways of
attaining our aim are conceivable, (i) We may follow the plan
of Nature and of plant and animal breeders and alter by selection
the racial CAPACITY for growth in this or that direction ; or (2), by
altering the conditions under 'which the individuals of the race

1 If anything may be rightly described as innate it is capacity. In a sense all
capacities for growth lie latent in the fertilized ovum, and, with variations, are
passed on to the descendent germ-cells. Thus mathematical knowledge is a pure
' acquirement ' in every sense of the term ; but that which enables it to arise under
the stimulus of experience has its roots in the ovum.

SELECTION AND TRAINING 439

develop^ we may alter the kind and amount of STIMULUS they
receive. Thus, if we wish to increase the size and strength of
Englishmen, we must breed from individuals who grow big and
strong under present conditions, or we must try so to improve the
surroundings that, with the same average capacity for growth,
individuals will grow bigger and stronger than they do at present.

720. Human selective breeding presents obvious difficulties.
It is possible that in a future not very remote some control will be
exercised by law or an enlightened public opinion over the multi-
plication of particularly undesirable types, for example, imbeciles
and people very susceptible to tuberculosis or the charm of alcohol.
But selection with a view, not merely to prevent marked deteriora-
tion, but to raise the general standard of the race is at present an
impracticable dream. Moreover, even were such selection practical
it would have to be undertaken with the greatest caution. Mis-
taken notions as to what characters are desirable in human beings
might entail disastrous and not easily remedied consequences.
That mistakes in human breeding might easily be made is evident
from the fact that many races, including our own, practise mutila-
tions as a means of improving beauty, and that the majority of the
people of all races greatly admire and strive to perpetuate a very
real kind of stupidity.1 On the other hand, it is comparatively easy
both to alter the conditions under which development occurs, and,
even in the very next generation, to remedy altogether any
mistakes that might be made. Clearly, therefore, it is better to
exhaust the possibilities which may be achieved by such means as
improved food, housing, and physical and mental training, before
we attempt to tread the difficult and dangerous path of selective
breeding.

721. It is important, therefore, to ascertain as precisely as
possible what characters in human beings it is practicable to
improve by altering the environment, to what extent they may be
thus improved, and by what means the improvement may be
brought about. Only so shall we reach that bed-rock of fact and
clear understanding without which the discussion of such great
problems as physical and mental deterioration, alcoholism, public
health, social and moral reform, education, and the like, is vague
and unprofitable. I am not aware that any very thorough-going
endeavour to analyse the characters of living beings, especially
human beings — any endeavour to separate the ' inborn ' from the
' acquired ' — has been attempted hitherto. I say especially human

1 See §§ 805 et seq.

440 PHYSICAL DETERIORATION & MICROBIC DISEASE

beings because, owing to more intimate knowledge, we are better
able to analyse our own characters than those of other types. As
far as I am able to judge, the apparently fundamental divergencies
of opinion which separate various classes of scientific workers
(biometricians, Mendelians, and those who endeavour to take other
classes of facts into account), social reformers, educationalists,
and the like, are due mainly to this neglect. Every section
appears to the others to be building on a basis of unproved
assumption. A common platform is lacking. In attempting the
task of analysis it is only too probable that like most other pioneers
I shall often be in error. Nevertheless, however wrong I may be
in the conclusions I reach, yet at least the reader will be placed in
possession of a good deal of material evidence which he will be
able to link up with that already set forth in this volume, and apply
to the problem as to whether it is possible to obtain improvement
in this or that character (e.g. intelligence) by altering the conditions
under which individuals develop, or whether improvement is
possible only through selective breeding. It should be borne in
mind constantly that selection alters only capacity for develop-
ment, whereas improved surroundings alter only the stimuli which
awaken capacity. Apart from selection, then, improved human
development may be achieved by altering the supply of nutriment,
by removing causes of injury, and by altering the training which
the body and mind receive.

722. All human diets contain certain necessary constituents,
water, proteids, carbohydrates, various salts, and the like. Almost
all diets, whether vegetable, animal, or mixed, contain in excess
one or more of these constituents, and a deficiency of others. If in
any diet the quantity of a necessary constituent is deficient, the
instinct of the individual prompts him to eat till the deficiency is
supplied, the excess of the other constituents being wasted, or
within limits which vary with the individual, stored in the tissues.1
For this reason a mixed or varied diet is usually the most
economical, though the variations of the individual and the kind
of life he leads must be taken into account. We tend instinctively
to grow tired of a diet which contains this or that constituent in
excess, and to turn with avidity to one which has less of it, but
more of a constituent in which the first was deficient. Under
1 This power of storing excess of nutriment in the tissues, especially as fat
against a period of scarcity is, speaking relatively, of little use to the average
civilized man whose supply of food is regular and secure ; but it must have been
very useful to his remote ancestors, as it now is to many lower animals — for ex-
ample, bears during hybernation or insects when undergoing metamorphosis.

NUTRIMENT 441

special conditions, as when doing hard muscular work in cold
climates, we long for the particular constituents, for example, fat
and sugar, which are then especially needed. Excess of this or that
constituent may cause injury (e.g. gout) in susceptible individuals ;
individuals may vary unfavourably so as to desire excess ; and
often individuals develop abnormal and injurious tastes, as for
alcohol or opium. We shall consider these abnormal desires
separately ; but meanwhile it may be stated in general terms that
instinct impels the individual to consume about the right quantity
of nutriment, and to combine the right constituents in about the
right proportions.

723. Such nutriment as the normal individual receives, pene-
trates to all parts of his body and nourishes all his tissues. It
is possible to control the quantity taken and so produce the general
effects of extreme starvation, or over-feeding, or anything between ;
but beyond this, our power is very limited. For example, we
cannot by special forms of diet increase the size of the muscles
as compared to the glands, or suppress one mental trait (e.g. the
sporting instinct) while developing another (e.g. mathematical
talent).1 Apparently when nutriment is in excess no tissue uses
an excessive quantity of food, though some structures eliminate
the excess, and others store it for the future needs of the whole
body. When the supply is defective, some tissues suffer less than
others. Thus, inactive structures which need little nutriment, such
as bones, or very important structures (e.g. the heart), seem then
to develop better than more active or less vitally important parts
such as the voluntary muscles. Again, wholly ' inborn ' parts, those
for which nutriment supplies not only the material, but the
stimulus for growth, appear to suffer less than structures which
grow under the stimulus of use. Thus the hair, teeth, eyes,
external ears, instincts, memory, and the like, of a half-starved
child, seem to develop better than its limbs or its mental acquire-
ments, and the structures of a foetus, all or nearly all of which
are wholly ' inborn,' appear to have the advantage in their
competition for nutriment with the physical acquirements of an
ill-nourished mother.

724. Except in the case of certain unfortunate sections of the
community, the British are a well nourished race. Both the
quantity and the quality of their nutritive supply are sufficiently

1 Though this is true of human beings it is not true of all animals. Bees, for
example, develop into workers or queens accordingly as they are fed on one kind
of food or another.

442 PHYSICAL DETERIORATION & MICROBIC DISEASE

good, and where they are defective, the effects and the remedy
are obvious. It follows, since human diet, consisting as it does
of certain essential constituents, cannot be greatly varied, since
nutriment penetrates to all parts of the individual, since the supply
of nutriment is usually sufficient, and since instinct prompts to
the consumption of about the right kind and quantity of nutriment,
that we cannot hope to improve materially such a people as the
English by altering its nutritive supply. Especially we cannot
hope to improve its inborn traits — its capacities for development,
and those characters which arise under the stimulus of nutriment.
If, therefore, we wish to alter them, the only conceivable method
is selection. Probably, however, no one would wish to use a
method so difficult to manage rightly, so destructive of liberty,
so fraught with suffering to the innocent as selection, merely to
change the shapes and sizes of such physical structures as ears,
eyes, lungs, and the like, and no one who understands the functions
of the instincts would lightly wish to tamper with these exquisite
mental adaptations. It would be excellent, of course, if we
exalted the potential physical and mental powers of Englishmen
by increasing their innate capacity to develop under the stimulus
of use and experience ; but it is so much easier, so much more
within the range of practical politics, to alter stimuli by changing
the conditions of life than to alter capacities by selection that,
before attempting the latter, we should, as I have indicated in
general terms, be very sure that the conditions under which the
British dwell are such as ensure the utmost development and the
best kind of development possible. Only after we have ascer-
tained beyond reasonable doubt that nothing more is achievable
by altering the conditions can selection be desirable.

725. The different parts of the human body develop under the
stimulus of use on lines almost as rigidly fixed as those on which
they develop under the stimulus of nutriment. Indeed, the physical
growth made under the former stimulus is usually a mere exten-
sion of that made under the latter. For example, a human limb
develops after birth on lines very similar to those on which it
developed before. When the direction or character of the growth
is changed it is usually by injury, not by use. But while nutri-
ment penetrates to all parts of the body and is thus, except as to
the quantity consumed, largely beyond control, we are able to
regulate in great measure the extent to which the different parts
of our bodies are used. Thus we may lead a hard laborious life
as that of a navvy or hunter, or a sedentary one as that of a clerk

EXERCISE 443

or a tailor ; we may use our legs much or little as compared to
our arms ; during childhood we may have opportunities of indulg-
ing in many active games, or we may be cramped in a factory or
the slums of a great city. Though the diet of the navvy may be
less appetizing than that of wealthier people, yet it is usually
sufficient in all essentials to secure full physical development.
Not so the work of the clerk or the tailor. It follows, that when
individuals, especially individuals belonging to different sections
of the community, differ in those characters which develop under
the stimulus of use, the difference is less certainly founded on
germinal differences than when they differ in the characters which
arise under the stimulus of nutriment, for example, eye-colour.

726. Probably, on the average, some sections of the community,
for instance the men of the leisured classes who take plenty of
exercise, develop under the stimulus of use nearly as well as their
capacities permit. It is quite certain, I think, that other sections,
for example, clerks and slum-dwellers, would, under other condi-
tions, develop better than they actually do. In the case of 'use-
acquirements/ unlike ' inborn ' traits, it is evident, then, that there
is scope for considerable physical improvement in certain classes
without any resort to selection. But, here again, the means of
securing improvements are so obvious as to be non-controversial.
Therefore they need not be discussed at length. The debated
point is the extent to which slum-dwellers, for instance, owe their
physical inferiority, on the one hand, to the conditions under
which the individuals are reared, and, on the other, to germinal
peculiarities which, as is alleged, constitute them an instrinsically
degraded race. Speaking generally, biometricians assume that the
inferiority is germinal and, therefore, beyond cure except by selec-
tion. Medical men believe it is partly acquired, partly due to the
inheritance of parental acquirements, and partly a consequence of
the direct action of the environment on the germ-plasm of un-
fortunate or vicious parents. Believing that good surroundings
cause intrinsic racial improvement and bad conditions degenera-
tion, they suppose that only a prolonged revival of good conditions
will remove the degeneracy. To me it seems overwhelmingly
probable that slum-dwellers, factory hands, and the like, are
physically inferior, not because they are as a class incapable of
developing as well as the best sections of the community, but
mainly, if not solely, because their surroundings are such that they
have not had the chance of developing as well as they might. I
think we have only to improve their surroundings sufficiently and

444 PHYSICAL DETERIORATION & MICROBIC DISEASE

the deterioration will vanish in the very next generation. Judging,
however, by the evidence given before various Royal Commissions
by multitudes of medical men and others, I have been very much
alone in this opinion until recently. We shall deal more at length
with the question immediately.

727. If the physical use-acquirements are mere extensions of
growth made under the stimulus of nutriment, the same is more
rarely true of mental acquirements. Sensations, instincts, and
memory (all ' innate ' traits) differ sharply from the contents of the
memory (all ' acquired ' characters.) It is true that a few instinc-
tive emotional impulses (e.g. the parental) are extended by ac-
quirement. It is true also that we acquire through experience
emotional impulses to action and ' physical ' dexterities which are
close imitations of true instincts and instinctive movements. The
latter emotions and dexterities, however, are not usually extensions
of previously existing characters. For example, nothing like an
inborn love of a particular religion or of dexterity in handling a
billiard cue is inborn in the individual. These and their like are
entirely new creations due to experience and developed in the
individual in lieu of any one or more of a thousand alternative
emotions and dexterities equally possible of attainment.

728. It follows that, in the case of mind more than in the case
of the body, there is scope for improvement without resort to
selection. The human being is capable of developing mentally so
greatly, in so many directions, and under the influence of so many
varieties of experience, that probably no man, no matter how
careful his training, nor what ideals — moral, social, religious,
intellectual, practical, and so forth — his educators had in mind,
ever received a perfect mental up-bringing, ever developed mentally
in as perfect adaptation to his total environment as was possible to
him. In the absence of perfect knowledge and wisdom, the choice
of his guardians has always fallen short of perfection. A man can-
not be taught all knowledge, and many useful or admirable mental
habits and attitudes are incompatible with others. Nevertheless,
as fitting the individual for his environment, the mental training
of most men somewhat approaches the ideal. And this is more
especially the case in savage and therefore comparatively simple
states of society. Sport, imitativeness, curiosity, and the instinct
to play with the contents of the memory, lay the foundations, and
the child's educators, consciously and unconsciously, strive to repro-
duce in him the traits which enabled them to survive in the
common environment. Other traits, even if ideally desirable,

PHYSICAL AND MENTAL TRAITS 445

would not, speaking generally, be useful. Thus, under a dominant
church, clear, far-reaching, fearless love of truth conduced more
often to death by torture than to survival during the dark ages of
Europe. Even now they are apt to handicap the individual in
many walks of life ; though under our more complex and en-
lighted conditions a greater diversity of mental type is both possible
and beneficial to him.

729. From the point of view of the social reformer the impor-
tant fact is that man's intellectual powers, including his capacity to
learn even in old age and to communciate his acquired knowledge,
thoughts, and mental attitudes to his fellows, confer on him great
powers of altering the mental and material environment and of
adapting himself, and more especially the next generation, to the
alteration. Improved mental development may thus be made, if
not positively beneficial to the individual in his struggle for
existence, at least not positively injurious. For example, in the
course of one or more generations a savage environment may be
exchanged for one more civilized ; or an atmosphere of prejudice
and superstition may be made to yield to one relatively more
enlightened. Modern Japan, in which ideas are now openly
prevalent the expression of which only a few years ago would have
entailed death, is a case in point. Though the mind of this race
has altered in some very important particulars, though it has
some intellectual characters different from those which it lately
possessed, yet we have no reason to suspect any germinal altera-
tion such as would probably be indicated by a marked change in
physical growth.

730. To sum up : racial capacities for physical and mental
development cannot be altered except by selection, or lack of
selection, or in rarer instances (as in the case of European breeds
of dogs in India) through injury to the germ-plasm. Speaking
practically, physical and mental characters which develop under
the stimulus of nutriment cannot be improved in the mass of the
population except through selection. Physical characters which
develop under the stimulus of use may be considerably improved
without selection in many sections of the community ; but each
improvement, however beneficial, can consist only in mere
extensions of growth previously made under the stimulus of
nutriment. On the other hand, it is probable that the mental
characters which develop under the stimulus of experience may be
immensely improved in many directions in all sections of the
community by careful training and without resort to selection.

446 PHYSICAL DETERIORATION & MICROBIC DISEASE

In considering any practical problem, therefore, we must first of all
determine what we propose to improve — whether germinal potentiali-
ties, or characters which developed under the stimulus of nutrition, or
of use, or of injury — and then consider in what way they may best
be improved — whether by selection or by altering the stimulus, and
if the latter, how the stimulus may best be altered. These, then,
are the general considerations we must bear in mind.

731. Physical deterioration in slum-dwellers, factory hands, and
sedentary workers generally, may be due to one or more of several
conceivable causes. It may be ' innate ' or germinal, in which case
it must depend on antecedent selection, or on lack of it, or on
injury to the germ-plasm, such as is said to occur in European
dogs in India ; or it may be due, not to inferior capacities for
development, but merely to inferior growth resulting from lack of
sufficient food, or exercise, or from injury (e.g. by disease) to the
growing bodies, the soma, of the young. As already indicated,
speaking generally, biometricians and medical men believe that the
inferiority is, in great 'measure, innate. But they do not trace the
alleged ' degeneracy ' to the same source.

732. Biometricians suppose that in the past a process of social
sifting has separated the innately superior from the innately
inferior families of the population,1 the former rising to the
upper and middle classes, the latter becoming the dregs that settle
in the slums and other habitations of the wretched. But, if this be
true of the town, it should not be less true of the country. Pre-
sumably the sifting process has occurred everywhere, and in former
centuries as well as at the present time. Our towns and factories
have only during the last few generations absorbed a considerable
proportion of the population. If, then,;the biometric hypothesis be
correct, agricultural labourers should be almost as physically
inferior to members of the upper and middle classes as slum-
dwellers and factory hands. But, to say the least, of this there is
no evidence. Doubtless some of the inhabitants of the slums, as
of the country, are people who have sunk through the germinal
physical inferiority (i.e. incapacity to develop as well as their

1 May I remind the reader that the words ' innate ' and ' acquired ' may be
used in two senses, one of which is correct and the other incorrect. None of the
characters of the same individual are more innate or acquired than any other.
If any of his characters are innate, then all are innate. If any are acquired, then
all are acquired. But different individuals are innately alike if their germ-plasms
were alike ; they are innately different, if their germ-plasms were different.
They are alike, or unlike, by acquirement if stimuli from the environment have so
moulded them that they have grown alike, or unlike.

SLUM CONDITIONS 447

fellows under similar conditions of life) of themselves and their
progenitors. But selection is keenest where the struggle for life
and comfort is hardest — in the lowest stratum of society. Amongst
the very poor in cities, the offspring of the physically and mentally
weak are often of necessity more exposed to neglect and
disease than the children of their stronger fellows. Moreover they
suffer more from a lack of good and sufficient food. Consequently
in slums, far more than in the country, there is still a real, though
limited, elimination of the ' naturally ' weak in bone and muscle
such as occurs under savage conditions, an elimination which tends
to counterbalance any social sifting. The sifting, if real, is further
off-set by the fact that the town, offering better wages and superior
opportunities for enjoyment and openings for ambition, attracts the
best, the most robust and enterprising of the peasant stock. But
the main objection to the biometric hypothesis lies in the patent
fact that in the modern civilized world the rise and fall of men in
the social scale is due much more often to mental than to physical
peculiarities, and most of all to good or bad fortune occurring
during development. In the slums are, doubtless, some people
who have fallen because they are innately somewhat feeble-
minded ; that is, people whose mental capacity to profit by ex-
perience is so inferior to that of the average of their race that they
have sunk in consequence. A far larger number have sunk
through a mental susceptibility to the charm of alcohol which, on
the average, weighs alike on them and on their descendants. But
probably the largest number have descended, not through any
germinal inferiority, but through sheer misfortune, including the
great misfortune of a bad mental training. Owing to the growth
of machinery and population there is not enough work in the
land for all the hands that are capable of doing it. Therefore even
some of the capable must fail. Once a family has fallen into the
slums, it is exceedingly difficult for it to emerge again — partly owing
to the lack of opportunity which extreme poverty entails, and
partly because the physical and mental traits acquired in the slum
are such as tend to unfit the individual for successful life in any other
environment. The statistics hitherto compiled by biometricians
demonstrate the precise average degree of physical superiority or
inferiority present in one section of the population as compared
to another. But — if the thing must be done statistically — before
we can decide whether the difference is innate or acquired, a
further inquiry is needed in which the children derived from one
section are compared to those derived from another after all the

448 PHYSICAL DETERIORATION & MICROBIC DISEASE

children have been reared under identical conditions. This inquiry
might be made, though with difficulty ; for in the slums are any
number of people immediately derived from robust English and
Irish peasant stocks, and these, if biometricians are right, should
be physically superior to the rest of native slum population.

733. Medical men trace physical deterioration to the direct
effect on the germ-plasm of such agencies as insufficient food, bad
hygiene, disease, and alcoholism. They have discovered that
apparently no British families of a purely urban descent of four
generations are in existence, and believe, therefore, that the germ-
plasm is poisoned so rapidly under urban conditions that the town
renews itself from the country in every two or three generations.
But the very magnitude of the migration into the town, combined
with constant intermarriages between the urban and rural popula-
tions, renders practically impossible a purely urban descent of four
generations. The absurdity of attributing the rarity of families of
pure and ancient urban descent to germinal deterioration is seen
very clearly when we consider the case of the Jews. These people,
who intermarry amongst themselves, are often desperately poor,
and are not specially clean and sanitary in their habits and
dwellings. Indeed numbers of them inhabit the worst slums.
Derived by an almost pure descent from the inhabitants of those
terrible slums, the ghettos of the middle ages, and rarely inhabiting
rural parts, they are the most extremely urban type in the country,
and are, nevertheless, under town conditions, the most hardy and
prolific type of all. Medical writers attribute the relative immunity
of the Jews to the superior care bestowed by Jewish women on
offspring. But while Jewish mothers in slums are, on the average,
noticeably more healthy1 and temperate,2 and, therefore, better
able to rear and suckle children than English women in the same
surroundings, neither they nor their children are appreciably
cleaner, nor are their dwellings better than those of the natives.
The fact appears to be, then, that Jews are especially healthy and
temperate in towns, merely because they are derived from a race
which has been fitted by prolonged selection to urban conditions.
At any rate, if all the facts, including the recent evolution of
civilized races, are taken into account, I can think of no other
explanation ; and none other has been suggested except that the
Deity takes particular care of His chosen people, or that the
religious training of the Jews results in better maternal acquire-
ments than Christian training, and so forth. The Chinese appear
1 See § 435- * See § 501.

THE CURE OF PHYSICAL DETERIORATION 449

to be quite as resistant and prolific as the Jews, and it will hardly
be maintained that they are a specially favoured or well-trained
race.

734. It follows that urban conditions, except perhaps in rare
and isolated instances, do not cause deterioration of the germ-plasm,
but merely of the individual exposed to them. As far as the
evidence indicates, the child of peasant parents, if reared in the
slums, suffers quite as much as the offspring of a town-bred
family. Indeed the survival of the town family indicates some
degree of fitness to the environment. It must be borne in mind
that the physical dangers of urban life arise mainly from microbic
disease, which, though less concentrated, is by no means absent,
even in the most sparsely populated localities in Britain. The
great cities of the present day have grown from the hamlets and
villages of the past, and their slow increase has enabled the race to
adapt itself to the altered conditions. Even now our villages are
training the race for existence in cities.

735. The conclusion we reach, then, is that the physical
deterioration which accompanies urban life may be removed in a
single generation by improving the conditions of life under which
the poor dwell — by providing better food, housing, sanitation, and
greater opportunities for active games to the young. Much,
indeed, has been done already. The task before us is difficult,
but not nearly so difficult as is supposed by biometricians and
medical men. We need not resort to selection, unless we wish to
evolve rapidly a race capable of vigorous life in slums. It would
be an easier and quicker proceeding to abolish the slums. We
need not wait till the imaginary innate deterioration caused by
generations of degradation is remedied by generations spent in
better surroundings. Our main difficulties arise from the selfish-
ness of the governing classes, the intemperance of the poor, and the
ignorance of both. If all classes understood the causes to which
physical deterioration is due, desired its removal, and were willing
to work and spend with that object in view ; if we saw to it that
even the children of drunkards had proper food, care, housing, and
exercise, physical deterioration would cease to characterize sections
of the people, though we should still see it, as amongst the upper
classes at present, in individuals who were congenitally incapable
of attaining average physical development.

736. Microbic disease, the principal source of physical injury
and death amongst civilized peoples, affords several practical
problems of great interest and importance. In combating it, two

29

450 PHYSICAL DETERIORATION & MICROBIC DISEASE

methods of procedure are conceivable: (i) we may attempt, by
what may be termed external sanitation^ by rendering the
environment external to the human body unfavourable to the
microbes, to banish the organisms that cause disease, or (2) we
may strive to render human beings more resistant, and so practise
what may be termed internal sanitation. If we adopt the latter
course we may (A) raise the innate resisting power of the race by
altering the germ-plasm by artificial selection, or (H) that of
individuals by conferring artificial immunity such as that which is
acquired to smallpox through vaccination. Artificial selection,
even when pressed to a point to which Natural Selection is never
pressed, would merely increase the resisting power of the race.1
That is, it would mitigate the severity of disease, but would not
banish it. On the other hand, acquired immunity, if universally
acquired, would banish disease ; for the micro-organisms, deprived
of their nutritive supply, would become extinct. It must not be
forgotten, however, (a) that immunity to one disease does not
confer immunity to any other, and (U) that while it is possible to
acquire immunity to some diseases (e.g. diphtheria and smallpox),
it is not possible to acquire it to others (e.g. tuberculosis and leprosy).
Therefore, while we may hope to banish utterly the microbes of
such a disease as smallpox, either by external sanitation or by
internal sanitation, we can hope to banish the microbes of such
diseases as tuberculosis only by external sanitation. It is true that
by improving the surroundings we are able to increase the power
to resist tuberculosis (and its consequences) in people who have
lived under weakening conditions (e.g. in slums) ; yet, since many
people living under the best conditions take the disease, it is
impossible, merely by making people healthier and stronger,
to prevent frequent infection and therefore propagation of the
microbes.

737. Our power of banishing the microbes of the various
diseases by external sanitation is largely conditioned by the mode
in which they pass from one human being to another. The
contagious diseases, ophthalmia, various skin complaints, the
venereal maladies, and the like, are, for obvious reasons, particularly

1 Selection by any ill-condition merely increases the racial power of resisting
that ill- condition. It cannot procure absolute immunity for the reason that,
when the severity of selection is relaxed, retrogression tends to follow. Absolute
racial immunity to any ill-condition results only through selection by agencies
other than that condition. Thus the higher animals are not immune to the assaults
of spiders because they have undergone thorough selection by spiders. They are
immune because they were otherwise^selected.

WATER AND INSECT-BORNE DISEASES 451

controllable. Were the public sufficiently well-informed, intelligent,
and careful, they should disappear within a very few years. Even
as it is, with the exception of the venereal diseases, cleanly people
rarely suffer from them. The venereal diseases are prevalent
mainly because our systems of religion and morality are still so
primitive that effective sanitation, like personal cleanliness in the
early ages of Christianity, is regarded as morally reprehensible.
Wilful poisoning with arsenic is a criminal offence. Wilful
poisoning with syphilis, even of an innocent wife or an ignorant
boy, is not a legal crime.

738. The water-borne, the ' filth ' diseases, enteric fever, cholera,
dysentery, epidemic diarrhcea, and other maladies which affect
particularly the alimentary canal, are also very controllable by
external sanitation. Except under special conditions they do not
spread rapidly, and their mode of existence outside the human
body is such that they are extremely open to attack. Careful
sanitation has almost eliminated them from many areas where
they were formerly prevalent. There is no apparent reason why,
with increasing knowledge and efficiency of preventive measures,
they should not be banished altogether. As in the case of the
contagious diseases, artificial selection is unnecessary, and artificial
immunity only desirable in localities where sources of infection
outside the human body are yet too numerous and widespread to
be controlled by the system of sanitation practised or practicable.

739. In all probability insect-borne maladies, also, will be
banished in no very distant future by external sanitation. The
destruction of the intermediate hosts supplies a ready means of
attack. Already Europeans, owing to the conditions under which
they dwell, are rarely infected by plague in India, even when it is
raging amongst the natives. Malaria has been greatly diminished
in many parts of the world through the destruction of mosquitoes.
The same means have been effective against yellow fever in Havana.
Comparatively little as yet has been achieved against sleeping-
sickness, but the disease has not long been studied, and the life
history of the intermediate host, the tsetse fly, is not fully known.
If it be true that the malady is conveyed only by one species of
insect which is confined to the shady banks of streams, it may
prove possible to banish it more easily and effectively than has been
found possible in the case of any other insect-borne disease. In the
case of insect-borne diseases, then, selection is clearly out of place.

740. As far as we are able to judge at present, air-borne
diseases will never be banished by external sanitation. They

452 PHYSICAL DETERIORATION & MICROBIC DISEASE

pass from host to host through a medium, the air, which is essential
to human existence, and which, blowing where it listeth, cannot
be controlled nor efficiently disinfected. Speaking practically,
these maladies are independent of climatic or other local conditions
except density of population. Since they spread with a rapidity
which is proportionate to the number of susceptible individuals,
and since immunity to them is conferred by illness and recovery,
the more thoroughly they are banished from a community, the
greater grows the number of susceptible persons, and therefore the
liability to pestilence — to disease in its fearful epidemic form.
In England, for example, only the endemic prevalence of air-borne
disease, and the consequent acquired immunity of the major
portion of the population, preserves us from disaster. If air-borne
diseases were restricted to a single islet for a generation, the rest
of the globe would stand in danger of depopulation. When they
broke out from the island habitat they would sweep, as in ancient
times, over the whole world — not merely in one great and terrible
pandemic, but in many recurrent and devastating epidemics, each
with its attendant famine, till in the process of ages the epidemics,
growing more frequent, but less disastrous, at last settled again
into endemic disease. Therefore, even were it possible to banish
measles, and whooping-cough, for example, from our midst by
external sanitation, it would be disastrous to do so while they yet
lingered in any quarter of the globe, and it would always be hard
to ascertain with any degree of certainty that some such spot did
not exist. In civilized countries unavailing attempts are con-
stantly made to restrict the spread of measles and whooping-cough,
as by closing schools during such slight epidemics as occur
amongst us, but only with the result of aggravating future epidemics.
Isolation is quite impracticable except when the great majority of
the members of the community have already been infected and
thereby have acquired immunity.1

741. Clearly, then, in the case of air-borne diseases we have
nothing to hope from external sanitation. From artificial selection,
also, little or nothing could be gained. Already Natural Selection
is very stringent; only people resistant to measles, whooping-
cough, influenza, and probably such complaints as bronchitis,
pneumonia, and rheumatic fever, survive. Very prolonged and
effective artificial selection could only render air-borne maladies
somewhat milder to the mass of the population. There remains
internal sanitation — the production of acquired immunity by means

1 See § 454.

AIR AND EARTH-BORNE DISEASES 453

of vaccination ; that is, by means of an artificially attenuated form
of each disease. By such measures smallpox, the most dreaded of
all air-borne maladies, has been almost banished from various parts
of the civilized world, and would have quite disappeared from the
globe had the whole human species for the term of a generation
been vaccinated at intervals of a few years. Thereafter, the
virulent microbes, having become extinct, vaccination itself would
have become unnecessary. This conclusion may appear ex-
travagant ; but, if we take all the facts into account, it is difficult
to escape from it. In Germany, for example, smallpox seems
never to appear except as an importation from abroad. What
is possible in one country is possible in others.

742. Whether internal sanitation can be made as effective a
weapon against air-borne disease in general as it is against
smallpox in particular can only be known in the future. As yet
we have made no more than a beginning. It may be useful
only against such diseases as usually confer permanent immunity,
and perhaps it will ultimately prove impossible to attenuate many
air-borne diseases in the way smallpox has been modified — that
is, to bring about such an attenuation in the nature of the microbes,
that, unable to exist in the blood-stream, they are confined to a
single locality in the body, and so are incapable of reaching the
air passages and infecting the atmosphere. Antitoxins, since
they induce only a ' passive ' or temporary immunity, cannot serve
the same purpose. Moreover, in order to manufacture antitoxins,
it is necessary to keep alive the virulent microbes.

743. Immunity to leprosy and tuberculosis, the principal earth-
borne diseases, cannot be acquired by the individual. Therefore,
internal sanitation supplies no weapon against them. The
infectivity of leprosy, however, is very low. Owing apparently to
the isolation of sufferers, and the increase of personal cleanliness, it
has been banished from most civilized communities. There can
be little doubt that ultimately it will disappear altogether. On
the other hand, tuberculosis, principally a disease of the air passages,
is, relatively, highly infectious.1 External sanitation — improve-

1 1 have termed tuberculosis an earth-borne disease, because its bacilli rest
when outside the body mainly on the floor, walls, and furniture of dwellings.
But since they are inhaled with floating dust it is also in a real sense an air-borne
malady. To me the evidence that it enters the body in the vast majority of cases
through the lungs appears overwhelming. But many medical men, notably
Behring, favour the hypothesis that the alimentary canal is the main portal
of infection, and that the milk of tuberculous cows is the principal vehicle. It is
supposed that bacilli, imbibed during infancy, " remain latent until they find

454 PHYSICAL DETERIORATION & MICROBIC DISEASE

ments as regards light, ventilation and air-space — has somewhat
reduced its prevalence, and may continue to do so for a time. But
the power of resisting tuberculosis is a direct product of evolution.
A fall in the mortality due to it implies lessened stringency of
selection, which in turn, if carried far enough, implies retrogression.
Therefore to procure a permanent fall in the death-rate, it is not

their opportunity [whatever that may mean] for development, and that individual
predisposition is of little account." But how in that case is it possible to explain
the fact that consumption tends to run in families even when individuals are
separated by continents and generations ? It can hardly be that the members
of families of low resisting power are naturally prone to use tuberculous milk.
Besides, the very people who suffer most from tuberculosis when exposed to it in
infected dwellings are precisely those who have had no opportunities of being
infected during infancy ; who have never drunk any milk but their mother's
milk ; who, indeed, in many instances, have never seen a cow, let alone an infected
cow ; for example, Esquimaux, Tierra del Fuegians, Polynesians, and the like.
Deaths from the various forms of tuberculosis occur in about the same proportion
in Japan as in Europe ; but, according to Kitasoto, tuberculosis is unknown
amongst the Japanese cattle, infants are never fed on other than human milk,
and cow's milk is so little used that the daily per capita consumption by the
human population averages no more than three-quarters of a teaspoon. In fact,
cow's milk is not a general article of diet in Japan. Additional evidence that
tuberculosis is an air-borne disease is afforded by the fact that a sufferer with
phthisical lungs is apparently a much greater danger to his fellows than one who
suffers from tuberculosis of the skin (lupus). It is possible that some human
beings, especially infants, in whom the alimentary canal is the principal seat of
disease, have contracted the malady from tuberculous milk ; but, since tubercle
is always found in the bronchial glands of infected children, it is not at all probable
that the majority of sufferers are thus infected. More especially, it is improbable
that pulmonary tuberculosis occurring in adults is commonly due to bacilli imbibed
in milk during or after infancy. The Royal Commissioners " Appointed to Inquire
into the Relations of Human and Animal Tuberculosis," after conducting a long
series of experiments, maintain that human and bovine tuberculosis are similar in
kind. Since tuberculosis has never been observed in wild animals, it is practically
certain that the bovine disease is derived from human sources. Doubtless, there-
fore, they are right, but their labour was unnecessary. " The fact that the bacillus
of bovine tuberculosis can readily by feeding as well as by subcutaneous injection
give rise to generalized tuberculosis in the anthropoid ape, so nearly allied to man,
and indeed seems, so far as our few experiments go, to produce this result more
readily than in the bovine body itself, has an importance so obvious that it need
not be dwelt on " (Second Interim Report, p. 14). But the susceptibility of anthro-
poid apes only proves, as might have been expected, that their bodies furnish
an environment favourable to bacilli which have undergone evolution in the
allied human species. But apes, unlike Englishmen, have undergone no evolution
against tuberculosis. They are in the position of Polynesians. It does not
follow that Englishmen can be as readily infected as apes. Judging from analogy,
we have every reason to believe it probable (i) that bovine tuberculosis is derived
from the human disease ; (2) that the microbes of it are becoming adapted to the
new environment ; (3) that they are becoming less adapted to the old environ-
ment ; and (4) that consequently they are less virulent to human beings than the
microbes derived from the human disease.

TUBERCULOSIS 455

enough to improve the sanitation ; to balance the increasing
retrogression continuous improvement is necessary. Doubtless, if
the poor Jews of the slums, who as a class are probably the most
resistant in the community, were removed to better surroundings,
they would have lower death-rates from tuberculosis than before ;
but only for a few generations. Gradually the rate would rise
until the mortality balanced the retrogression. Even among our
wealthier classes consumption claims its toll of victims, and it is
difficult to believe that the environment in cold and crowded
England can ever be made so unfavourable to the bacilli as it
already is in the warm, sun-bathed, and sparsely populated
Polynesian Islands where the native races are undergoing ex-
termination. Isolation, such as that practised in sanatoria, is,
owing to the vast multitude of sufferers, impracticable as a general
preventive measure. Speaking practically sanatoria effect cures
only amongst highly resistant people who have been weakened in
worse surroundings A great number of those who improve in
them return to perish in their own homes. Consumption is never
detected in its earliest stages. The victim does not suspect his
disease until it is well advanced. Long before it has been recog-
nized, the bacilli have been disseminated by means of his cough —
not only in large masses of sputum, but in a fine spray. It is con-
ceivable of course that we shall one day discover a medicine which
will act as effectively in tuberculosis as mercury in syphilis and
quinine in malaria; but, since tuberculosis has so long been studied,
this is, at least, improbable. It would seem, then, that the only
hope of permanently reducing the mortality from tuberculosis lies
in selection — probably, in the first instance at least, not a selec-
tion enforced by legal penalties, but one due to the presence
of an enlightened public opinion which will regard as morally
reprehensible the fertile marriages of phthisical types.

CHAPTER XXIV

INTEMPERANCE AND INSANITY

Immunity to alcohol — Evolution and retrogression — Attempts to suppress
drinking in Mohammedan countries — In modern civilized states — In the United
States, Canada and Australasia — Failure of prohibition — Insanity — Two distinct
kinds — Lunacy — Feeble-mindedness — Definitions of idiotcy, imbecility and
feeble-mindedness — The Royal Commission on the Care and Control of the Feeble-
minded.

744. ~TTNTEMPERANCE. Alcohol is capable of bestowing
f keen pleasure on many, and probably some pleasure on
all people. But in England and many other countries
the amount of pleasure conferred by it is greatly outbalanced by
the suffering. In these countries, if no one drank, the gain would
be great, though not so great as if all men drank, as most men
smoke or as the Jews drink, in moderation. Like the microbic
poisons, it is a cause of disease through its action on the tissues of
the body. There is, however, this immensely important difference
between the microbic poisons and alcohol; people 'take' the
former in spite of their desires, the latter because of their desires.
They suffer from a microbic disease, because they have a certain
weakness of body ; from intemperance, because they have a certain
peculiarity of mind. It follows that the term 'immunity,' when
used in reference to microbic disease and alcohol, has unlike
meanings. Used in reference to disease, it implies that the
individual is physically incapable of being infected under the
normal conditions of life. But, though a given quantity of alcohol
is less poisonous to some men than to others, no man is physically
incapable of swallowing poisonous doses ; and many men, even the
most resistant physically, take it in such doses. Consequently,
Nature, taking as always the most direct course, evolves races
which are mentally, not physically, immune. Immunity to alcohol
implies, therefore, an incapacity to be tempted by the narcotic in
harmful quantities. A kind of immunity to alcohol may be
created by fostering a moral abhorrence of intemperance ; but
this voluntary avoidance of temptation bears no likeness to what
is termed immunity to disease — neither to the inborn immunity

456

IMMUNITY TO ALCOHOL 457

which prevents infection, nor the acquired immunity which results
from infection and recovery. It resembles more closely that ex-
ternal sanitation by means of which we endeavour to prevent the
infection of susceptible people.

745. Susceptibility to the charm of alcohol, like that to infection
by a disease, is an 'innate' character. It may be extended or
decreased by acquirement, by circumstances affecting the mental
state of the individual (e.g. misery or happiness), just as suscepti-
bility to microbic infection may be altered by circumstances
affecting his bodily state. But it may be, and often is, present in
people whose circumstances are otherwise of the happiest. As we
have seen, it is much more pronounced in some individuals and
races than in others. On the other hand, the actual craving for
alcohol is purely an acquirement, a mental growth, which occurs
only in susceptible persons who have had previous experience of the
poison. Within limits, which vary with the individual, the craving
tends to increase with added experience. Herein the disease of
alcoholism differs sharply from such a malady as measles, experience
of which gives origin to acquired immunity.1 It follows that internal
sanitation, the procurement of immunity through experience of the
poison, is impossible in the case of alcohol. Therefore, if we wish to
benefit the race, our choice of action is limited to the banishment of
alcohol or the elimination by selection of the susceptible individual.

746. Alcohol, a waste product of the yeast fungus, is derived
from sugar. Speaking practically, both sugar and yeast are pre-
sent in every part of the habitable globe. Their area of distribution
is much more nearly universal than that of any disease. Obviously,
it is impossible to eliminate either the one or the other. Alcoholic
fermentation occurs constantly in nature, but human art is neces-
sary to produce the narcotic in intoxicating quantities. The art
was discovered by savages at some period enormously remote in
human history, and has been preserved and improved ever since.
At the present day, in addition to its consumption as a beverage,
alcohol is useful as a fuel, a solvent, a preservative, and the like,
in many of our industries. Obviously again, it is practically
impossible to suppress the manufacture of intoxicating solutions.
The question then arises whether it is possible by legal means to

1 It will be noticed that I compare actual alcoholism, not the susceptibility
to it, to a disease. The term disease is often applied to the susceptibility. It
would be as reasonable to describe a person who had never been infected by measles
as suffering from that malady. Questions of nomenclature are not trivial when
a wrong use of words indicates confusion of thought in the speaker, and is a cause
of confusion in his audience.

458 INTEMPERANCE AND INSANITY

suppress its use as a beverage, or at any rate its immoderate use.
Probably every one will agree that purely moderate drinking can-
not be enforced by law in a race many members of which are capable
of enjoying immoderate drinking. Human nature is unable to
resist the strong, steady pull of a constantly nourished temptation.

747. There remains, then, the total suppression of alcohol as
a beverage. Suppose for a moment that this were possible, and
that a law enforcing it were passed. Then a race like the
British, which had undergone some evolution, would tend to retro-
gress towards that primitive state in which the average racial
susceptibility to the charm of alcohol was much greater than it is
at present. Therefore, if at any future period this law were
repealed or passed into abeyance, the last state of the race
would be worse than the first; for the race began its evolution
when alcohol was hard to procure, and, in any case, could be
obtained only in very dilute solutions. The longer the law was
effectually [enforced the worse would be the ultimate disaster.
Our literature, both ancient and modern, is full of references to the
delights of drinking, and the instinct of curiosity is strong in man.
Any one who could read and possessed fruit, sugar, or starch,
could manufacture alcohol for himself in secret. Many races, the
South Europeans, for example, derive great pleasure and little
suffering from alcohol. They could hardly be persuaded to pass
a self-denying law which forbade its use, and which benefited, not
themselves, but only distant races. The world grows increasingly
cosmopolitan every day. Merchants and travellers conveying
foreign products and habits pass more and more from every
quarter of the globe to every other. As surely as the sun shines,
travellers from lands where the use of alcohol has been suppressed,
would learn its use abroad, and seek, in the end successfully, to
reintroduce it to their own countries. Judging, then, from the
biological standpoint, external sanitation against alcohol cannot
be perpetually successful. Temporary success would merely
expose the race to dangers similar to those which would menace
it were a prevalent, lethal, and highly infectious disease banished
from the country but not from the world. Since alcohol cannot
be banished from civilized communities, great insusceptibility to
its charm, implying evolution and therefore selection, is essential
to the existence of a civilized race.

748. However, it may be argued that " Our business as
practical men is with the present, and not with a remote and
problematical future. In the past, men have rarely sought any-

PROHIBITION 459

thing more than immediate ends ; yet modern civilization has
arisen. Posterity may safely be left to redress its own evils.
Doubtless it will discover means of doing so at present unknown to
us." Is it possible, then, in the immediate future, if nothing more,
to suppress or considerably reduce excessive drinking by legal or
moral methods ? An immense body of evidence bearing on this
problem is available. All history indicates that as soon as any
race gains possession of considerable quantities of alcohol, that is
as soon as it reaches the earlier stages of civilization, it begins
attempts at temperance reform. Moderation was preached at
least 7000 years ago in Egypt. Prohibition was decreed more
than a thousand years before the Christian era in China. The
ancient Rechabites, the Gnostics, the followers of Montanism, and
the Manicheans were professed abstainers. It is probable that
every century in the history of every European and Asiatic
community, which had not already achieved moderation through
selection, has been marked by repeated temperance edicts, some
of them of savage severity. The final result is that the use of
alcohol is now less controlled and more nearly universal than at
any former period of the world's history.

749. Under very primitive conditions the human being enjoys
almost as much freedom as a wild animal. In fact he is a wild
animal. As society organizes itself, and the individual is brought
into closer and more constant contact with masses of his fellows,
his freedom is restricted till a point is reached when the nation is
regarded as the property of some person who is believed to have,
or at least claims and enforces, a divine right to deal with his
subjects as he pleases. Later, with advancing organization, there
is a return, towards the primitive condition of individual freedom.
In modern England, for example, the individual is in many
respects as free as the utter savage. The general tendency of
such legal restrictions as bind him is merely to prevent him
curtailing the liberties of his fellows, or breaking such engage-
ments as he has voluntarily contracted.

750. Some laws which are possible at one stage of civilization
are impossible at another. If incompatible with the spirit, the
general tendency of the times, they quickly pass into abeyance.
Thus during the Dark Ages of Europe edicts for the maintenance
of uniformity in religion were often terribly effective. They would
be absurd at the present day. A year or two ago a man was
forbidden to marry his deceased wife's sister ; it is probable that in
the future he will be permitted to marry his grandmother. Laws

460 INTEMPERANCE AND INSANITY

prohibiting drinking are just such interferences with individual
liberty as cannot be enforced in modern times. It will be observed
that I do not maintain that such laws are inherently wrong. I
insist merely that they cannot be enforced. It will be observed
also that I speak of prohibition, of attempts to prevent all drinking,
not of regulation, of attempts to place the consumption of alcohol
under such conditions that moderation is encouraged, so that, as
at an ordinary dinner table, the drinker does not interfere with
the rights and comforts of his fellows.

751. Under semi-civilized conditions prohibitive laws have
occasionally met with temporary success. In some Mohammedan
countries they have had prolonged success. Nevertheless, intem-
perance has been common among many, and especially among the
more enlightened Moslem communities. Others have substituted
opium for alcohol. Religious fanaticism has tended to keep some
Mohammedan communities both sober and barbarous ; but it
cannot now long resist the influences which are so swiftly chang-
ing the face of the modern world. Presently Nature will pass the
races of the near East through the fire which has hardened their
neighbours against the stringent conditions of civilized life. To-
day, the comparatively drunken Englishman and Russian are at
a disadvantage in the struggle for life and wealth as compared
to the temperate Jew. To-morrow the Mohammedans will face
a yet heavier handicap. This forecast may be disputed, but we
have the facts. Has a highly civilized community ever existed
which had not already passed through the fire ?

752. Prohibitory laws, when enacted, in highly civilized states,
have almost invariably failed, and as a rule worse than failed. I
say ' almost,' because in some very sparsely settled colonies where
temperance sentiment has been very strong, where each inhabitant
is known to all his neighbours for many miles round, and where
the channels of supply and communication with the outer world
are few and well known, prohibitory legislation appears to have
achieved a temporary, I had almost said a momentary, success.
I say, ' worse than failed,' because in places where the population
is dense, where men are acquainted with few even of their near
neighbours, and where many channels of supply and communica-
tion exist and more may easily be organized, attempts at repressive
legislation are always followed by increased intemperance, and
by even greater evils.

753. No modern civilized government has attempted the
gigantic task of abolishing the use of alcohol throughout its

PROHIBITION IN AMERICA 461

dominions. But various areas, possessing local self-government, in
the English-speaking settlements, have sought to enforce abstinence
on their working-classes by prohibiting, not drinking or the
importation of alcohol, but only the manufacture and sale of it.
This modified form of prohibition has been adopted at various
times by seventeen entire States of the American Union. " It is
now retained only by three, and in those it cannot be looked
upon as a success. Parts of prohibitory States have always been
in open rebellion against the law ; drinking has never been impos-
sible ; the sale of liquor has always been profitable, and seldom
disreputable in the eyes of the public. Violation of the law has
been open and avowed. Federal law requires the payment of a
special annual tax by retail liquor dealers; and most States,
including those under prohibition, provide that the payment of
the tax shall be prima facie evidence of a sale of liquor having
been made, thus utilizing the Federal officials in the detection of
illegal traffic. During the fiscal year ending June 3Oth, 1906, the
number of retailers in malt liquors were, in the State of Kansas,
4019 ; in Maine, 599 ; and in North Dakota, 1582 — these being the
three prohibition States.

754. "In urban districts, at any rate, it has not been found
possible to find any sound ethical basis for the law, or to persuade
the majority to regard its violation as immoral. Without the backing
of public opinion, no enforcement of prohibition has been obtained
except at the price of raising animosities between rival factions
of such intensity as seriously to disturb the community. Juries
have violated their oaths ; judges have hesitated to impose
statutory penalties ; blackmail and corruption have been directly
instigated, and the law in general has been brought into contempt.
Persistent disregard of the liquor laws is supposed to encourage
disobedience to other enactments, and an example is cited in
Kansas, where the fact that an anti-gambling law is almost a
dead letter has been attributed to the lax enforcement of
prohibition in the cities of the State.

755. " It should be mentioned that prohibition prevents a
community from passing any laws for reclaiming or protecting
its drunkards. Where in theory there is no drinking, in theory
there can be no intoxication ; but from the practical point of view
such arguments cannot be justified." l

1 Report on the Liquor Traffic Legislation of the United States, prepared by Mr
R. C. Lindsay, Second Secretary to His Majesty's Embassy at Washington, and
issued by the Foreign Office in April 1907.

462 INTEMPERANCE AND INSANITY

756. The difficulty of enforcing prohibition under the ordinary
conditions of civilized life is shown by the fact that only very
thinly populated states of the American Union have continued
the attempt. In 1890, North Dakota had four persons to the
square mile, Kansas seventeen, and Maine twenty. None of
these States had a town of 50,000 inhabitants. Speaking
practically, in no town, not even in what we in England should
term a village, was there more than a pretence of prohibition.
At that date the States that have abandoned prohibition had
on the average a population four or five times denser than the
population of those that have retained prohibition. Nineteen per
cent, of the inhabitants of the former dwelt in towns of more than
50,000 inhabitants. The difference has since increased. West-
moreland, the most sparsely populated English county, had, in
round numbers, in 1891, a population of eighty persons to the
square mile, Lancashire and Surrey had 2000, and Middlesex
1 1,500.!

757. Prohibition applied to more limited areas than entire
States is termed local option. Owing to the greater ease with
which alcohol may be obtained from neighbouring areas it is
correspondingly easy to enforce as regards the manufacture and
sale of drink, but is even less effective as regards the consumption
of drink. It has been enacted in many States of the American
Union, in Canada, and in Australasia. Like * total prohibition,' it
is possible that it has achieved partial and temporary success in
some very wild and sparsely inhabited districts such as parts of
Dakota. It is certain that it is a complete failure in every town
and densely inhabited rural district.2

758. Mere failure would leave matters no worse than before;
but here failure is accompanied by many evils. For open
drinking under the eyes of the public and police, whose business
it is to prevent excessive drinking, is substituted secret and
uncontrolled debauchery. The actual amount of intemperance
is increased ; men make sure of drinking their fill while they have
the opportunity ; they drink in surroundings where the greatest
possible amount of harm results, and are given every facility for
excessive indulgence. Drug stores, normally conducted by a
very respectable class of men, become drink-shops which sell
in addition immense quantities of such narcotics as morphia,

1 For evidence concerning the statements in this paragraph see The Temperance
Problem, by Messrs Rowntree & Sherwell, pp. 115-249.
8 Op. cit.t pp. 250-369.

PROHIBITION IN AMERICA 463

laudanum and cocaine.1 The police turn aside from an impossible
task. Successful evasion of one important law tends to produce
contempt for all law. Widespread demoralization follows. Crying
evils exist unredressed ; politics become merely a struggle between
prohibitionists and their opponents. Politicians, seeking place,
support one side or the other regardless of their private opinions
and practices. These statements are very sweeping, but they are
supported by any amount of evidence.2

759. Other things equal, large towns tend to be more in-
temperate than smaller towns, and floating populations than fixed
populations. In 1898, the latest year for which statistics are
available, the inhabitants of New York numbered 3,500,000, of
Chicago 1,850,000, of Boston 582,463, and of Portland, the capital
of Maine and the classic prohibition city, 41,508. Eighty per cent,
of the population of Portland were native-born. The convictions
for drunkenness per 1000 inhabitants were in New York 13, in
Chicago 23, in Boston 45, in Portland 42. New York, Chicago
and Boston permit the sale of drink ; but Boston is a * safety-valve '
in the midst of a prohibition area from which came 44 per cent, of
the inebriates convicted in its courts. Nor was drunkenness con-
fined to it. Cambridge, one of its suburbs, is the largest prohibi-
tion city in the States ; since it adopted ' no license ' it has doubled
its own convictions per thousand of population. When prohibition
was first introduced into Portland, the convictions for drunkenness
averaged 16 per iooo.3 General Neal Dow, to whom more than to
any other one man its establishment was due, stated in his evidence

1 " On August 3ist, 1899 — a week prior to our visit — another ' raid ' was made
on a few of the saloons (including one bottling factory), and more than a thousand
gallons of beer, wine and spirits, were seized, of which nearly one-half (47 5 £
gallons) was seized at one establishment — a so-called ' drug-store ' with a large
bar in the rear of the shop. This raid, however, like its predecessors, had to be
made over the heads of the city and county officials " (The Temperance Problem,
p. 195). "In the regular drug-stores, and in 160 of the 172 general stores in the
State of Vermont (then under prohibition), they sell every month 3,300,000 doses
of opium, besides what they dispense in patent medicines, and besides what the
doctors dispense (90 per. cent of the doctors dispense their own medicines), which
gives one and a half doses of opium to every man and woman in the State of
Vermont above the age of twenty-one years every day in the year. (By dose I
mean i grain of opium, | of a grain of morphia, £ ounce of paragoric, and 20 drops
of laudanum). And the amount consumed would average a dose to every man,
woman, and child in the State of Vermont every day in the year" (Dr Ashbel
P. Grinnell).

2 Readers desiring fuller evidence than I have space for will find it set forth in,
amongst other works, The Temperance Problem, and the Reports of the American
Committee of Fifty to Investigate the Liquor Problem.

3 The Temperance Problem, p. 701.

464 INTEMPERANCE AND INSANITY

before the Royal Canadian Commission, " When I was Mayor
(1851) every man who indicated he was drunk was arrested, but
now they do not do that unless the man is noisy and disturbing
the peace." Another witness, a " Past Most Worthy Patriarch of
the Sons of Temperance," on being told that evidence had been
given that men drunk but not disorderly were not arrested, and
that in the preceding year " men shook their fists in the face of the
Police in Portland, and dared them to arrest them," said, " I have
no doubt of it." " And that would naturally reduce the number
of arrests very largely in the city of Portland ? " " Yes." l The
following sums up the case very fairly : " Every word of Mr Morris'
(Rev. Phillip H.) arraignments of the prohibitory law is true. He
might have made it much stronger and still kept within the borders
of truth .... Prohibition has remained upon the Maine statute
books for half a century, for the single reason that it has never
been enforced. One year of genuine enforcement, and it would be
abolished as soon as the legislature could be got together . . .
' Make the law respected where it is a law,' said Mr Moore. There
is the solution. Make the law respected, and everybody except
the theorists who now sustain it will demand its repeal." 2

760. The evidence concerning the failure of prohibition and
local option in other parts of the United States, in Canada, and in
Australasia is similar in kind and quite as conclusive. Of Canada,
the Report (1895) of the Royal Commission says, " in short the law
as an aggressive weapon has been abandoned." In Australia one
' town,' the Moonta mines township, is said to be under ' prohibi-
tion.' Another, Mildura, has closed its public houses, but alcohol
is sold in clubs. " There is no haughty exclusiveness about these
clubs. The members appear to be anxious to extend the right
hand of good fellowship to all comers, so that no man need go
athirst." 3 New Zealand has a law of local option. At the election
of 1905 * no license ' was adopted by six out of sixty-five districts.
It has been in operation longest in the Clutha district, and the
King country, the inhabitants of which are aborigines. Its success
may be gauged by the following : " The Maori chiefs in the King
country, New Zealand, have asked the Government to substitute a
limited licensing system for the prohibition which is in force at

1 Quoted by Rowntree & Sherwell, op. cit., p.i6o.

* Biddeford (Maine) Daily Record, April 24th, 1899, quoted by Rowntree &
Sherwell, op. cit., p. 198.

3 The Report to the Victorian Board of Public Health, by Dr Robertson, quoted
by Edwin H. Pratt. The Licensed Trade, p. 141 (London, Murray).

THE KINDS OF INSANITY 465

present, and under which liquor of bad quality is being sold every-
where. Mr Seddon, the Premier, approves of the proposal. He
told a deputation that the chiefs and the police were unanimous in
stating- that prohibition had spread the evil it had been intended
to exclude. Sly grog-selling is rampant and could not be stopped.
The same thing was going on in the Clutha district in Otago, where
there were no Maoris, and where prohibition was enforced by
popular vote." 1

761. A law forbidding the use of alcohol is as much an
anachronism as one enforcing a belief in the Thirty-nine Articles,
or the Darwinian Doctrine of Descent. Prohibition merely deprives
the authorities of much of their power of controlling intemperance
and tends to make them partners, pensioners, or blackmailers of
law breakers. The whole habit of modern thought and behaviour,
the whole fabric of civilized society is against its effective adminis-
tration. But that which cannot be altogether prevented may to
some extent be regulated and diminished. Up to a certain point
it is possible to control the drink traffic ; attempts to pass that
point usually end in worse than failure. Drinking there is sure to
be, but the more openly it is conducted the less imperfect are the
facilities for control. If, were it possible, all public houses and
clubs had glass walls, intemperance would be reduced to a mini-
mum. Very little drunkenness occurs in the cafes of the French
Boulevards. If, then, we wish to benefit the race in the immediate
future our endeavour should be, not to prevent drinking, for that
is impossible, but to bring all places where excessive drinking is
likely to occur more thoroughly under the hand of the public
authorities. That is the only method of external sanitation with
respect to alcohol which, in civilised communities, has been at all
successful in the past or is likely to be successful in the future.

762. Insanity. Two very distinct kinds of insanity are observ-
able:— (A) The individual may possess, and usually does possess
in average degree, every mental faculty found in the normal
human being except one — memory. Thus he may have all the
human instincts, imitativeness, curiosity, sexual inclination, and
the rest ; but he is more or less incapable of storing experience —
incapable of filling his conscious memory with data which may
be recollected, and his unconscious memory with ' acquired '
dexterities and habits. If his lack of memory is very great, he
is an idiot, unable perhaps to learn to walk or speak. A lesser
degree of incapacity to learn constitutes imbecility. A still

1 The Morning Post, Oct. 29th, 1900.
3°

466 INTEMPERANCE AND INSANITY

lesser degree, feeble - mindedness. There is, however, no sharp
line of demarcation : imbecility and idiocy are merely graver
phases of feeble-mindedness. The defect of memory is usually
general : but in some cases it is more or less limited to particular
departments of mental acquirement. Thus there are * moral
imbeciles ' who, while able to make other mental acquirements,
are unable to acquire, in the form of imitation instincts, the code
of morals prevalent in the community in which they are reared.
The low tone of morality, especially sexual morality, so common
amongst the feeble-minded, however, is more often due to general
incapacity : the individual possesses normal instincts which, like
other animals, he tends to obey, but which he does not learn to con-
trol like the average human being. To lack of memory, also, is
attributable his deficiency in the 'higher faculties,' for example
intelligence and reason. Probably, in comparison to the rest of
our powers, we are all feeble-minded to some extent in one or more
particulars. Thus, while possessing fair capacity in most depart-
ments of mental acquirement, we may be relatively incapable
of accumulating musical, lingual, or mathematical efficiency. The
connection between weak-mindedness and incapacity to learn is
clearly seen when we consider that if we lacked, as some people
do, such an instinct as the sexual or the parental, the function
of which is not to impel us to make acquirements useful to
ourselves, we should not necessarily seem feeble-minded. But
lack of imitativeness or curiosity would almost necessarily
lead to a condition of mental dullness closely resembling
imbecility.

763. (Z?) The individual may be a ' lunatic,' quite normally
capable of recollecting experiences and learning dexterities and
habits. But the universe his mind constructs for him differs
markedly from that created by the minds of normal people. He
feels and thinks abnormally. His experiences impress his mind
in an unusual way, and he draws unusual inferences from them.
He has hallucinations and delusions. What to the normal person
is a shadow on the wall, may seem to him the devil. Common
sounds may have an awful significance,

" As the Lord were walking near,
Whispering terrible things and dear."

The sight of two people, perhaps strangers, in conversation may
create a conviction that they are plotting great good or harm to him.
The ordinary behaviour of his fellows may give rise to the notion

IMBECILITY AND LUNACY 467

that they are persecuting him, or on the other hand, to a belief
that they admit his claim to be monarch or deity.

764. Obviously, then, the difference between the two kinds of
insanity is very great. Idiocy is a condition in which there is
little or no capacity to learn ; lunacy a condition in which there
is capacity to learn but in which there is much ivrong learning.
Both kinds of insanity can be imitated in greater or lesser degree
by people who are quite capable of normal development. Thus
training may so close a man's mind as to render him more or
less unable to profit by experience, or it may endow him with
strange and what seem to non-believers absurd delusions, as in
the case of the adherents of many religions. Feeble-mindedness
may arise from injury to the brain at any period of life, and it
is not an unusual accompaniment of extreme old age ; but it is
seen typically most commonly in people who from birth forwards
are more or less incapable of making mental acquirements. On
the other hand, lunacy, at any rate clearly marked lunacy, almost
invariably manifests itself during or after adolescence.

765. Probably most alienists will accept my description of
lunacy as correct. There is nothing new in it except perhaps the
stress laid on memory in the statement that this form of mental
defect is due to wrong learning. But the description of feeble-
mindedness is new. If it be correct, then, the importance of the
part played by memory in human mental development has been
as insufficiently realized by alienists as by students of normal
psychology. However, when we study their descriptions of the con-
dition, we find that simple incapacity to learn is always implied,
though, owing to non-recognition of the fundamental truth, other
mental states which, on consideration, would be admitted as not
especially those of imbecility, are sometimes included. Consider,
for example, the following description supplied by the Royal
College of Physicians to the Royal Commission on the Care and
Control of the Feeble-minded.

766. " ' Idiots,' i.e. persons so deeply defective in mind from
birth or from an early age that they are unable to guard them-
selves from common physical dangers, such as, in the case of
young children, would prevent their parents leaving them alone.

" ' Imbeciles,' i.e. persons who are capable of guarding them-
selves against common physical dangers, but who are incapable of
earning their own living by reason of mental defect from birth or
from an early age.

" * Feeble-minded,' i.e. persons who may be capable of earning a

468 INTEMPERANCE AND INSANITY

living under favourable circumstances, but are incapable from
mental defect existing from birth or from an early age : (a) of
competing on equal terms with their normal fellows ; or (&) of
managing themselves and their affairs with ordinary prudence.

" ' Moral ' imbeciles, i.e. persons who from an early age display
some mental defect coupled with strong vicious or criminal
propensities on whom punishment has little or no deterrent
effect." l

767. Or consider " The very good definitions submitted to us
by Sir James Crichton-Browne, of the * imbecile ' and the ' feeble-
minded ' " which " do not turn on the ' capacity of earning a living,
but have in some measure to define the child by anticipation, by
standards applicable to a later time of life than early childhood,
such as prudence, independence, and self control,' or ' taking care
of himself in the common affairs of life.' " These definitions are :
— " An imbecile is a person who, by reason of arrested development
or disease of the brain dating from birth or early years, has the use
of his observing and reasoning faculties so restricted as to in-
capacitate him for education in the ordinary sense or for taking
care of himself in the common affairs of life, and who in appearance
and manner generally evinces his mental short-comings.

" A feeble-minded person is one who, by reason of arrested
development or disease of the brain dating from birth or from
some age short of maturity, has his reasoning faculties partially
weakened, so that he is slow or unsteady in his mental operations,
and falls short of ordinary standards of prudence, independence,
and self-control.

" The moral imbecile is a person who by reason of arrested
development or disease of the brain dating from birth or early
years displays at an early age vicious or criminal propensities
which are of an incorrigible or unusual nature, and are generally
associated with some slight limitation of intellect." 2

768. Both these descriptions imply incapacity to learn. Those
furnished by the Royal College of Physicians, however, merely
describe the social and material consequences of the defect rather
than the defect itself — consequences which might conceivably
arise from lunacy, or mere " backwardness " due to illness, or
exceptionally bad training. Sir James Crichton-Browne goes
deeper, for while he also describes the effects, he attributes them to

J Report of the Royal Commission on the Care and Control of the Feeble-minded,
vol. viii. p. 1 88.

2 Op. cit.y vol. viii. p. 189.

DEFINITIONS OF IMBECILITY 469

a weakening of the observing and reasoning faculties due to
disease of the brain or the arrested development (of a faculty not
mentioned, and due to a cause not named). There is, however, no
evidence that the observing faculties of imbeciles are defective ;
their senses are usually as acute as the normal, and, apparently,
they are as much guided by them as other animals. But they
cannot store their observations. Their reasoning faculties are
defective only because reason itself is an ' acquirement ' — only
because they cannot gather sufficient materials for complex thought
nor learn to use skilfully even such materials as they do gather. The
defect is, as I say, essentially an incapacity to profit by experience,
an initial lack or subsequent failure of memory, which prevents the
imbecile learning and retaining all that the normal person learns
and retains from infancy forwards. I include failure of memory
because there does not appear any good reason for the arbitrary
limitation of the term feeble-minded to " arrested development or
disease of the brain dating from birth or from some age short of
maturity." Take away, as by injury, from the normal adult all
that he has learned and at once he becomes an imbecile. Failure
of memory in the aged, whereby stored experience is lost, produces
precisely the same effects as congenital defect. The individual
becomes equally ' incapacitated for education or of taking care of
himself/ and, as a fact, is taken care of by his friends or the State
in just the same way as a congenital imbecile.

769. A better description occurs in a Statement on Heredity in
Relation to Feeble-mindedness, written by Sir E. Ray Lankester at
the request of the Commission. " There is every reason to regard
this condition as a case of atavism — a relapse to a primitive
animal condition of cerebral activity — memory, and with it self-
control (depending very closely as it does on memory), is defective.
Some savage races (e.g. Australian blacks) are — as compared with
more highly developed races — normally in a condition of feeble-
mindedness.1

"Such throwing back in brain character among the more
advanced races of man is certainly transmitted to offspring, and
there seems no properly based argument for the view that feeble-
mindedness is not always congenital. In most cases it can be
shown (90 per cent, of carefully examined cases) to be due to

1 I think it would be hard to prove this statement concerning Australian
natives. A school of native children once obtained the first place in an Australian
colony, and most people (e.g. Sir John Cockburn, who told me personally) who have
personal knowledge of the blacks rate their natural intelligence very high, and
suppose that training, not incapacity, has made them savages of a low type.

470 INTEMPERANCE AND INSANITY

hereditary taint, although, as in other cases of reversion, it may
from time to time appear as a c sport/ that is to say, without any
history of parental taint." l

770. In other words imbecility is both a reversion and a
mutation. "A little thought renders it evident that the feeble-
minded person is always one with a defective memory. ... In
effect and in fact the feeble-minded person is an instance of
reversion to a pre-human mental state. But the reversion is not
complete ; for while he loses some part of his power of profiting
by experience, he regains no part of the lost power of being guided
by instinct. Therefore he is correspondingly helpless as compared
with a lower animal. The instincts (e.g. sexual) which normal
human beings still possess often appear unduly prominent in him,
but only because he cannot learn to control them." 2

771. But if imbecility is a mutation, the reproduction should
tend to be Mendelian. It should be patent or latent in descendants.
It " is a sharp contrast to normality. Here, then, apparently we
have an explanation of the well-known fact that while the children
of a defective may all be normal, yet amongst the descendants
may appear individuals who are defective."3 The Royal Commission
states in its Report, " In this connection the probable nature of the
swamping is of some importance. Speaking generally, the trend of
the evidence indicates that the offspring of feeble-minded persons are
either apparently normal or distinctly feeble-minded. In the same
family occur both types, the same person may have both normal
and feeble-minded offspring and descendants ; the defect may
skip one or more generations and appear later. It would appear,
therefore, that the swamping may be due not so much to a gradual
obliteration of the defect by a blending with normality, as to its
becoming latent or overlaid by the latter. It would seem also
that the probability of its re-appearance amongst descendants is in
some degree proportionate to the frequency with which it has
occurred amongst ancestors." 4 It seems, then, that the inheritance
of imbecility is comparable to that of such a trait as eye-colour.
We saw that black eye-cplour is strongly dominant over one of a
lighter shade, but that after two or more infusions of the latter
(that is, after the lighter shade is derived in a patent or latent

1 Op. cit., Appendices, vol. v. p. 247.

2 Op. cit., Note on the Hereditary Transmission of Mental Deficiency, by G.
Archdall Reid, Appendices, vol. v. p. 247.

3 Note on the Hereditary Transmission of Mental Deficiency, by G Archdall
Reid, vol. v. p. 248.

4 Op. cit., vol. viii. p. 184.

THE INCREASE OF INSANITY 471

condition through both parents) it tends to be reproduced by
descendants. So also normality appears strongly dominant over
imbecility ; but, when the latter is derived through both parents,
normality, like black eye-colour, becomes less dominant and the
alternative condition tends to be reproduced — to become patent.

772. In every civilized country, during the last half century,
the number of persons registered as insane has increased out of
all proportion to the increase of the general population. For
example, in Ireland, "while one person in every 657 of the popula-
tion was registered as insane in the year 1851, the proportion had
risen to one in 178 in 1901." 1 There is now one officially known
lunatic to 301.32 individuals of the general population as against
one to 335 nine years ago, and one to 536 in 1859." 2 "From 1st
of January 1858 to 1st January 1908 the total number of lunatics
officially known to the Board . . . has increased from 5,824 to
16,288, showing an increase of 10,464. . . . Since 1858 the number
of lunatics under the protection of the Board has increased 180
per cent." 3 Opinions differ as to the cause of the increase. Some
of it, or most of it, is undoubtedly due to a more complete
registration.4 But probably some of it is due to actual multiplica-
tion.5 We possess no data on which it is possible to found a

1 Macpherson, Edinburgh Medical Journal, May, 1903, p. 398.

2 Fifty-fourth Report of the Commissioners in Lunacy, 1901, England and Wales.

3 Op. cit., Scotland.

4 See The Fiftieth Report of the General Board of Commissioners in Lunacy for
Scotland, pp. 9 et seq.

5 " Every one knows that a large number of the mothers of illegitimate children
are of weak intellect ; that their issue are frequently of the same type ; that a
large number of the habitual inmates of workhouses are of the same low standard
of mind ; that much of the petty crime of this country is committed by persons
below the average in intellectual power.

" One of the Poor Law inspectors saw in a workhouse in Somerset, an imbecile
woman with an illegitimate imbecile daughter, who had her own illegitimate
daughter in her arms. Precisely the same picture has been seen in the County
of Cornwall, and these are but pictures in small of a fact which is to be seen in
very many of our workhouses.

" But the ranks of the insane as well as of the imbecile are recruited from
the children of the feeble-minded. The fearful increase of late years of insanity
in this country has necessarily created alarm, and I cannot but believe that one
of the sources of this fact is to be found in the imbecility of the parents.

Sir James Crichton- Browne entirely agrees in this view. He has written to
me to the effect that a terrible increase of insanity is going on, and that it is un-
doubtedly not merely due to increased diligence or improved diagnosis, but in
some measure to the cause named, viz. propagation of the weak-minded, and
' I am confident,' he adds, that permanent provision for imbeciles of both sexes,
but especially girls, however costly it might be in the first instance, would
ultimately result in saving of the rates. In a word, imbecility, insanity, bastardy,

472 INTEMPERANCE AND INSANITY

sure conclusion. In any case, however, the number of the insane
is so large that their existence is a source of vast misery and
hardship to very many people and a considerable and constantly
growing burden to the State.

773. The problem of the causation of insanity — of the causation
of its first appearance in a line of descent — has been much debated.
Both imbecility and lunacy are so often reproduced in families in
which they have once appeared, that it is certain that there is
present, in some instances at least, an 'innate and transmissible'
weakness, a predisposition to one or other form of mental unsound-
ness.1 Since lunacy is due to wrong learning, since the individual
is a lunatic because he receives wrong impressions from his
surroundings, the direct influence of the environment must
necessarily, in a sense, always play a part in its causation. But,
since imbecility is due to no learning, or a lack of sufficient learn-
ing, since the individual is an idiot or an imbecile because he does
not mentally acquire anything or enough from his surroundings,
the environment need not play a part in the causation of his
weakness,2 for he may be defective through a spontaneous
variation which occurred in him or in a progenitor, and which

and crime are now paid for by the ratepayer, and any method of diminishing these
at reasonable cost must be to his benefit.

" In the ruder state of society which has passed away little heed was taken
of these unfortunate children, and many of them, no doubt, died comparatively
early in the struggle for existence. But we have learned to think more tenderly
of the inferior members of our race, and we seek to protect them from the
calamities and sufferings to which they are naturally exposed, and to preserve
their lives to the utmost. But in so doing, and in so doing rightly, we incur,
as it appears to me, another responsibility, namely, that of preventing, so far as
we reasonably can, the perpetuation of a low type of humanity, for otherwise
the beneficence of one generation becomes the burden and the injury of all succeed-
ing ones. The past increase in the number of lunatics in the country, to which
I have already alluded, demands our most serious consideration of every means
which can be legitimately used to protect the race from physical and mental
degradation, and I regard the segregation of imbeciles, first in childhood and in
youth, and subsequently throughout life, as one of the means which is most open
to us " (Sir James Fry, Evidence before the Royal Commission on the Care and
Control of the Feeble-minded, vol. i. p. 312).

1 " Undoubtedly those who have great experience in the care and supervision
of persons suffering from mental defect in these forms, such as ' idiots ' or
' imbeciles ' . . . state that in a very large proportion these persons are the
offspring of mentally defective parents or are members of families in which other
nearly related members are mentally defective. Op. cit., vol. viii. p. 181.

2 The reader must bear in mind that by the direct influence of the environment
we mean such influence as causes change in the individual or the germ-plasm
by acting directly on them. By indirect action we mean selection or cessation
of selection.

THE CAUSES OF INSANITY 473

renders him incapable of being so affected by the environment as
to learn from it.

774. But in another sense the environment — through violence,
disease, alcoholism, business worries, religious and sexual excite-
ment, and the like — may act directly as a cause of insanity by
injuring the brain of the sufferer, or by injuring the germ-plasm
contained in his germ-cells. That is to say, it may cause
immediate insanity, or be a cause of a tendency to insanity in
descendants. Cases of insanity, especially of lunacy which is a
disease of adult life, plainly traceable to injury or disease sustained
by the sufferer himself, are not uncommon. We need not dwell
on such instances, the causation being obvious ; the difficulty lies,
not in perceiving the right means of prevention, but in applying
them. Our interest centres in those more obscure cases in which
the individual is born insane (i.e. more or less incapable of learn-
ing), or born predisposed to become insane (i.e. to become a
lunatic.) Such cases are due either to injury sustained by the
germ-plasm, or to spontaneous variation.

775. Probably injury to the brain occurring during intra-uterine
life (especially from maternal disease or alcoholism) accounts for
some cases of filial insanity. Probably, however, such injury is
much more frequently a cause of death occurring before birth or
shortly afterwards. It may be that the high infantile mortality
of urban as compared to rural areas is due in a measure to this
cause.1 Cerebral injuries, whether acquired before or after birth,
are not transmissible. But germinal defects tend to be inherited.
If the variations which result in insanity are usually spontaneous, it
is beyond our power to diminish their frequency. We can only,
by controlling the output of offspring by the * innately ' insane,
prevent their perpetuation in descendants. If, on the other hand,
they are usually caused (on the occasion of their first appearance
in a line of descent) by the direct action of the environment on
the germ-plasm, it may be within our power, not only to prevent
their perpetuation, but also, by improving the environment, their
initial occurrence.

776. But every argument which tells against the hypothesis
that variations in general are due to the direct action of the
environment tells equally against the hypothesis that those

1 " It is not necessary to dwell upon some other causes of mental defect, such
as disease or accident in early life, or even before or at birth, operating through
injury to the brain. Cases of this kind are recognized by all ; and do not com-
plicate the present question. They occur in comparatively few instances (op. cit.,
vol. viii. p. 185).

474 INTEMPERANCE AND INSANITY

particular variations that cause insanity are due to it. As we
have noted, medical men have been accustomed to attribute all
sorts of filial defects to all sorts of parental and ancestral ill-
conditions.1 Such evidence has often been tendered to Royal
Commissions and other State inquiries, and has guided or mis-
guided them in their decisions. The Report of the Royal Com-
mission on the Care and Control of the Feeble-minded, the most
recent of such State inquiries, however, indicates a rapid and a
very remarkable change of medical opinion. After discussing the
evidence in detail and noting that the weight of evidence is entirely
in favour both of the spontaneous origin and subsequent inherita-
bility of feeble-mindedness, the Report continues : —

777. " The view that injurious conditions in the environment
which affect the parent or the child in utero or after birth are of
importance in the production of feeble-mindedness needs some
further practical comment. The Memoranda quoted in the pre-
ceding paragraph (549) 2 contain strong arguments against any
likelihood of such causes being in any way operative as causes.
Many races have been exposed to one or other of all the ill-condi-
tions which have been alleged as causes of filial deterioration. In
every case the only apparent effect has been to render these races
capable of dwelling comparatively unharmed under such conditions.
It is not to be conceived that a race which deteriorates in every
generation can emerge from the struggle not weakened, but
strengthened. Moreover, almost conclusive disproof of this
hypothesis is furnished by the facts submitted to us by the medical
investigators. These observers show that feeble-mindedness is
practically as common in rural as in urban districts, and probably
no less prevalent amongst the well-to-do than amongst the poor.
It is clear that if the contentions of these witnesses who place
predominant stress on adverse environmental influences as a cause
of feeble-mindedness were just, there would be an unquestionable
prevalence of this affliction among the urban poor — the chief
victims of poverty and disease." 3

1 Here is an example. " The Feeble-minded in Ireland. When a country with
few industries except agriculture has its life blood drained by the emigration of
the young and fit, and when those who remain are depressed by the discouraging
results of trying to keep their heads above water by tilling the soil, it is small
wonder that the commissioners charged with the task of deciding what steps
should be taken for the better care and control of the insane and feeble-minded,
should have found a grave state of things to exist." (Leading Article, British
Medical Journal, Sept. I2th 1908.)

2 The allusion is to contributions by Sir E. Ray Lankester and the present writer.

3 Op. cit., vol. viii. p. 184-5.

THE CONTROL OF THE FEEBLE-MINDED 475

778. Medical men have often declared that the insane tend to
be infertile, and that, therefore, the type tends to die out. The
Report states : — " With regard to the allegation of the small
fertility of mentally deficient persons, the reports of some of our
medical investigators and other witnesses, both medical and other-
wise, tend to show that although, as might be expected for several
reasons, there is great mortality among the children of these
persons, there is also a very marked degree of fertility and
survival to adult age, especially among those of the higher grades
who are termed feeble-minded. Miss Dendy, Honorary Secretary
of the Lancashire and Cheshire Association for the Permanent
Care of the Feeble-minded, a very experienced witness, has stated
elsewhere that from her personal knowledge she can show that the
higher grades of feeble-minded persons (who are the most
numerous and dangerous) tend to have very large families ; and
she can prove this from the detailed records of 1,000 cases." x

779. In conclusion, the Commission sums up the general effect
of the evidence as follows : —

" ( i) That both on grounds of fact and theory there is the highest
degree of probability that ' feeble-mindedness ' is usually spon-
taneous in origin— that is not due to influences acting on the
parent — and tends strongly to be inherited.

" (2) That, especially in view of the evidence concerning fertility,
the prevention of mentally defective persons from becoming parents
would tend largely to diminish the number of such persons in the
population.

"(3) That the evidence for these conclusions strongly supports
measures, which on other grounds are of pressing importance, for
placing mentally defective persons, men and women, who are
living at large and uncontrolled, in institutions where they will be
employed and detained ; and in this, and in other ways, kept under
effective supervision so long as may be necessary."

780. " The question naturally rises whether it is desirable and
practicable that any steps should be taken to place obstacles in
the way of the marriage of persons ascertained to be mentally
defective, over and above the restrictions on marriage and procrea-
tion which would ensue from the detention in institutions of
mentally defective persons in whose case such procedure is deemed
necessary ; and if there be a disposition to answer the question in
the affirmative, the problem must be faced, to which of the classes of
the mentally defective should such additional restriction be applied.

1 Op. cit.t vol. viii. p. 185.

476 INTEMPERANCE AND INSANITY

781. "Such legislation would not be an absolute novelty in
English speaking communities; but there is little or no reliable
information as to the practicable results of the tentative efforts in
this direction which have been made in New Jersey and elsewhere ;
and it is clear that such legislation however carefully restricted
would in effect operate less by imposing an easily enforceable
legal prohibition than by guiding and directing the advisory
functions of medical and other authorities and in other ways
educating public opinion to the proper consideration of a very
serious evil.

782. " We are of the opinion that it would be unwise to modify
or supplement the existing law with respect to the marriage of
1 persons of unsound mind ' [i.e. lunatics]. It is perhaps unnecessary
to refer to other objections to any such proposal ; it is clear that
the limited and often temporary nature of this particular mental
disability renders it impossible either to prohibit permanently the
marriage of such persons or to set out in practically useful legislative
proposals the conditions under which such marriages might take
place.

783. " No such obstacle, however, presents itself in the case of
those persons who exhibit the congenital and incurable forms of
mental defect [i.e. imbecility], and we believe that a legislative
prohibition affecting these classes would have useful direct and
indirect effects." *

1 Op. cit., vol. viii. p. 185.

CHAPTER XXV
EDUCATION

The most important practical problem of biology — Our power of influencing
mental growth — Self-education — Formal education — The three aims of the
school-master — Subjects taught, and methods of teaching them — The teaching
of young children ; of older children ; of young adults — Religious teaching —
The religious attitude is an acquirement — The antagonism between religion and
science — Methods of teaching religion — Prejudice and superstition — Economic
and social effects of methods of teaching religion — Inborn and acquired feeble-
mindedness and lunacy — The teaching of the classics — Scientific teaching — Science
teaching — Some sciences are founded on few and some on many facts — The former
are mainly interpretative, the latter mainly descriptive — Systematists — Darwin's
effort to make biology interpretative — Description is the warp and interpretation
the woof of science — The teaching of biology — The importance of the science —
Conclusion.

o

784. /^\F all the practical problems on which the study of
heredity sheds a light, by far the most important is
that of the education of the young, if only for the
reason that the solutions of all other problems, if soluble they be,
depends on the intelligence of the race that takes them in hand.
Here, since the mental growth which the normal human being
makes under the stimulus of experience is so vast, since according
to the stimulus supplied this growth may take any one or more of
a thousand different directions, and since the kind and amount of
stimulus is very greatly under the control of the guardians of the
child, our power for good and evil is at its maximum. Training
may endow the child with wide and useful knowledge, or with
knowledge which, though great, is narrow and useless, or it may
leave him very ignorant ; it may bestow on him habits, tones and
attitudes of mind which enable him to utilize such knowledge as he
acquires to the utmost limit of his capacity, or which render the
widest knowledge and the highest capacity unavailing. There is
abundant evidence that a child of normal capacity may be trained
to a degree of stupidity resembling innate feeble-mindedness, or to
a degree of wrong-headedness resembling insanity, or, on the other
hand, to a degree of intelligence which, relatively speaking,
resembles genius. We may differ, indeed men do differ very

477

478 EDUCATION

widely, in ideals of mental training ; we may not agree as to what
kinds of knowledge and mental habits are the best ; but no one
will deny that a knowledge of what may be, and has been achieved
by mental training, and of the means best adapted to achieve any
desired result, would be a great advantage to the teacher. Every
one will agree also, in theory at any rate, that wide and useful
knowledge and high intelligence are desirable qualities, and that
ignorance and stupidity are not. Unfortunately, useful knowledge
and high intelligence are eulogistic terms which are applied by
different men to very unlike things. For example, the terms would
hardly have had the same meaning for Huxley and the curates
whose * cackling ' he abhorred. In his opinion the curates were
ignorant and unintelligent ; in their view his knowledge was not
right knowledge, and his intelligence damnable.

785. We have seen that memory is nothing other than a power
of growing, of developing mentally under the stimulus of use, and
that on this faculty depends all thought, all intelligence, all mental
adaptability. Great intelligence must have for its basis a power,
correspondingly great, of profiting by experience; or, in other
words, a great memory. Man is intelligent because his memory is
very capacious. It contains not only such things as words, scenesj
events, and processes of reasoning, which can be recalled to
consciousness, but also dexterities, habits, bents, tendencies, tones,
and mental attitudes which cannot be consciously recalled or
pictured in the mind, but which are every whit as important. We
have seen also that, not only our * physical ' dexterities, such as
walking and the delicately co-ordinated movement of the lips and
tongue in speaking, but also such ' mental ' dexterities as are
involved in associating, comparing, discriminating, and reasoning
depend on memory. Lastly, we have to see that, just as the
instinct of sport impels the child to play with his limbs till he is
able to use them dexterously, so a homologous instinct impels him
to play with the contents of his conscious memory till he is able to
use them skilfully. Probably this impulse to play with the contents
of the conscious memory, to think, is the most imperious instinct
in our nature. At any rate, it is the one which is the most cease-
less in its promptings. A man may resist hunger, or thirst, or love,
or sleep, but not for a moment can he resist the impulse to think —
the impulse to learn to use the contents of his conscious memory
skilfully and thereby store his unconscious memory.

786. Prompted, then, by the instincts of play, curiosity, and
imitativeness, the child undertakes the earlier part of his own

SCHOOLROOM EDUCATION 479

education and performs its task supremely well. This phase of
education, because directed by instinct, is full of pleasure and
interest, and follows the same lines in the children of all races.
With the aid of the hunting instinct it bestowed on primitive man
almost all the acquirements that enabled him to maintain exis-
tence. But as soon as man became man, and more especially
when he became civilized, labour, a new mode of activity to which
he was compelled by the environment he himself had created but
to which he was not prompted by instinct, and which, therefore, was
not pleasurable, became necessary. Labour is seldom associated
with pleasure, unless interest is awakened by some element of
sport, curiosity, imitativeness, or some other instinct. At first,
doubtless, all labour was associated with some instinctive prompt-
ings, but as civilization advanced, as life grew more complex and
labour aimed at ends more and more remote, its instinctive
promptings withdrew further and further into the background, and
were replaced by motives derived from intelligence. Through
labour men learned new dexterities. They fashioned tools, and
learned to use them. They invented a mode of recording words
and thoughts by written symbols and learned to become skilful in
interpreting them. Ever, as the mental horizon widened, toil
played a greater and greater part in education. At present our
children spend many of their most receptive years at such labour ;
and when we speak of education we mean, as a rule, only the toil-
some part of it.

787. This laborious, or schoolroom, training is formally de-
signed to achieve two aims. An endeavour is made, on the one
hand, to impart knowledge of a kind that cannot be gathered by
the child during the course of his non-laborious education outside
the schoolroom, and, on the other, to train the mind to deal skil-
fully with the ordered knowledge thus acquired, and in this way
develop powers of thought (i.e. skill in thinking) more far-reach-
ing and accurate than could be otherwise attained. A third aim
to which the schoolmaster is supposed to devote attention while
he is the immediate guardian of the child is the formation of
' character.' ' Character,' however, is not acquired with the same
obvious toil as knowledge and skill in thinking. It arises, more
or less unconsciously, as a reaction between the child's capacities
and the total environment, of which ^ the schoolroom is only a
part, though it may be and often is, an important part.

788. The three aims of the schoolmaster are separable in theory,
but not in practice. If facts be taught to the pupil, he tends to

480 EDUCATION

think about them ; and, according to the way in which he thinks
his character will be influenced subtly and profoundly. All arrays
of facts do not afford equal facilities for acquiring skill in thinking.
Some, for example, the lengths of rivers, the heights of mountains,
the dates of history, and facts about the bones and muscles of
animals, may be useful as items of knowledge, but by themselves
they afford poor materials for the play of thought. Others, like
the data given in mathematical exercises, may be useless as items
of knowledge, but exceedingly well adapted as materials for mental
gymnastics.

789. Facts are relatively useful or useless as items of know-
ledge and as materials for creating powers of thought, not only
in proportion as they are true and afford exercise in hard thinking,
but in proportion as they do or do not link up with the subsequent
experiences of the learner. Thus, since the elementary truths of
arithmetic are used almost every day in our lives, they are remem-
bered and have a greater influence on the mental career of the
average individual than the higher mathematics he may have
learned ; for the latter, though they require more strenuous think-
ing, are seldom used, and, therefore, being forgotten, tend to lose
their influence. Again, facts as materials for thought derive their
value for the pupil very largely from the way in which they are
acquired ; for on this depends the way in which he will think
about them, and the way he thinks about them will in turn
influence his whole habits of thought. Thus the facts of geometry
are comparatively valueless if learned by rote, but excellent if the
chain of reasoning by which they are demonstrated be understood
and assimilated.

790. The teaching of bald collections of facts is comparatively
easy. Any man, who has a book of reference and means of
inflicting pain, may force his pupils to learn the dates of history,
the outlines of zoology, or the words of a language. Unfortunately
the ease and lack of intelligence with which this kind of teaching
may be conducted, the little labour entailed on the teacher, and
its effectiveness for purposes of examination or other displays of
mere knowledge, constitute a strong temptation for its employ-
ment. It is very widely used, not only for the tuition of little
children, but also for that of young men and women on the
threshold of independent life. Indeed little children are usually
better taught than older people. Their thinking processes are so-
simple, their instinctive curiosity and tendency to play mentally
with all they learn so strong, that even the inferior teacher, taking

THE SKILFUL TEACHER 481

the line of least resistance, finds himself joining in their play,
asking and answering questions, suggesting analogies and other
relations ; in brief, giving lessons in careful thinking. Anything
so good as the object lesson or the kindergarten system is rarely
found in the tuition of older boys and girls. Moreover, in England,
the majority of children attend the public elementary schools, the
teachers in which have been trained for their functions, are under
strict and competent supervision, and know how to make lessons
interesting. It is quite common for poor children to prefer the
school-term to the holidays.

791. A principal qualification of a good teacher lies in his power
of interesting his pupils, a thing that can be done only by arousing
their emotions, their instincts, or the imitation instincts which the
teacher helps to create. Rewards and punishments may be made
the means, but a much better way is to appeal to curiosity,
imitativeness, and, above all, to that strongest of instincts which
impels us to play with the contents of our memory, and so,
by ascertaining the relations, particularly the causal relations,
between the objects of thought, to unify the world our minds con-
struct. If the teacher is dexterous, curiosity will cause his pupils
to ascertain and store facts, imitativeness will cause them to copy
his own processes of thought, and the instinct to play with the
contents of memory will impel them to become skilful in thinking.
The best of all teachers is one who does not merely state, nor
even explain, the relations between facts, thereby doing little more
than add new facts to the rest, but who so guides his pupils that
they are led to do their own thinking and make their own dis-
coveries. Both facts and thinking then acquire enhanced value.
Not every subject affords full scope to his talents. But usually he
has some power of choice, if only between the parts of a subject,
and something may be done even with facts the relations of which
are so simple and obvious that they are perceived without effort
even by children. Unhappily, skill in teaching is rarely one of the
qualifications by means of which the tutors who train the children
of the governing classes secure their appointments. Doubtless
many tutors, through private study or because they are of a
thoughtful cast of mind, learn to teach well ; but this ability
is not, as in the case of teachers in public elementary schools
systematically fostered by compulsory training.

792. Probably, as a body, the least skilful teachers are those
who complete the training of young men of the professional classes.
As a rule they are people who have achieved success in the

31

482 EDUCATION

practice of some lucrative profession, for example, medicine.
They have knowledge, but they are seldom young, and, consequently,
in many cases they are not very capable of learning such a new
thing as how to teach. Indeed they rarely have any notion that
there is anything to learn. Doubtless there are amongst them
many ' natural ' teachers whose processes of thought, through
constant, if unconscious, self-training, combined perhaps with
superior capacity to learn to think well, have become so clear and
logical that they are able to present the objects of study interest-
ingly and suggestively to their pupils. But probably every
student of a profession hears lectures, attendance at which, though
compulsory, is not only a waste of time but is also positively
harmful to a developing and imitative mind. The method too
often adopted is, not the Socratic plan of teaching the student,
whenever possible, how to think in order that he may discover
what to think, but that of the Catechism which asks only stereo-
typed answers to stereotyped questions. Among the pupils are
future teachers, and in science, as in religion and other human
affairs, evil as well as good traditions tend to be perpetuated.

793. Except as regards a supply of facts, some professional
courses, for example the medical, hardly attempt to continue
intellectual development. It is not reasonable to suppose, however,
that the preparatory schools have already accomplished all that is
possible to stimulate the reflective powers, or that mere accumula-
tion of knowledge will do it. Men who have continued their
formal education for some years after leaving school, usually
possess much greater knowledge than their less fortunate fellows ;
but it is not equally obvious that their skill in thinking has
developed a corresponding superiority. In brief, the teachers who
direct the concluding stages of professional education, having been
trained by an imperfect method, are usually unable to do other
than train their pupils by it. They are compelled thereto, not only
by the requirements of examinations which have been framed by
men like themselves, but by their own attitudes of mind. When,
as is not unusual, they exclaim that they are able to supply their
pupils with knowledge but not with brains, they condemn their own
methods. On the average they deal with normal human beings ;
and since 'brains' grow under the stimulus of use, it should be a
main part of their business to develop them.

794. It is, of course, out of the question to select as teachers
to young men about to enter a profession any but its most
eminent practitioners. It is equally out of the question to expect

MENTAL HABITS 483

men who have achieved distinction in any important branch of
study, and who have, as is often the case, made considerable
additions to knowledge, to acquire in middle or old age the sort
of skill that is considered essential in good pupil teachers. More-
over, students who adopt a professional career must acquire the data
on which practice is founded ; and the array of facts which have to
be committed to memory is often so vast that little time is left for
thinking about them. Many of the subjects in the curricula are
such that the best of tutors are forced to restrict themselves to
teaching facts and habits of close observation. Nevertheless, a good
deal might be done to awaken science teachers to a conviction that
the function of higher education is to impart more than knowledge
and habits of observation. Some of the facts and subjects on which
students must pass examinations have no bearing on practice and
might be exchanged for others which place a greater strain on the
reflective faculties; or, at least, the teaching of them might be so
modified that the reflective faculties are more exercised than at
present.

795. If we train a man well in any department of ' physical '
activity, such as penmanship or cycling, he tends to become
particularly dexterous in it. But the influence of special training
does not altogether end with the acquisition of special dexterity.
Thus an individual who has learned to co-ordinate his muscles for
walking has made a step towards learning to co-ordinate them for
cycling. So, also, if we train an individual to think well in any
sphere of 'mental' activity, for example, chess, mathematics, or
physics, he will not only become especially skilful in it, but his
acquirement will tend to colour his whole mental state by exerting
a greater or lesser influence in other departments of thought — a
greater influence in kindred departments, a lesser influence in
departments that are psychologically more remote. By themselves
facts are isolated things ; each fact must be acquired separately, and,
unless linked by thoughts to others, held separately. But mental
dexterities, habits, attitudes, link together inevitably ; one furnishes
a stepping-stone to another. Nevertheless, just as we cannot
make a man a good cyclist by teaching him to walk, nor even by
providing him with plenty of bicycles, so we cannot insure that he
will be a good thinker in any department (e.g. the ordinary affairs
of life) by training him in another department (e.g. mathematics),
nor even by providing him with the materials of thought, the facts,
in the chosen department. To insure the best results our teaching
must be direct ; that is, we must not only provide the right facts,

484 EDUCATION

but we must also train our pupils to think about them in the right
way.

796. To sum up: skill in thinking, like other dexterities,
depends partly on innate capacity to learn, partly on the amount of
practice, and partly on the kind of practice. Innate capacity, though
it varies with individuals, is a fixed quantity in each individual. But
the amount and kind of practice is within our control. We deliber-
ately train young children to think skilfully, and the younger they
are the more direct is our teaching, the more closely adapted to the
end in view and the needs of the subsequent career. But as they
grow older and ripe for the attainment of higher grades of skill, we
tend to slacken our efforts, or to seek our ends in a very indirect and
ineffectual way. The human being tends to remember only impres-
sive things, or those which are hammered into his mind by repeated
experiences, and he tends to think only of that which interests him,
Often, by way of mental gymnastics, in the vague hope that the
youth will remember and think, we supply him with facts which,
rightly used, might furnish excellent materials for thought, but
which we do not impel him to use, and which he does not use of
his own initiative, because by themselves they are uninteresting and
of such a kind that his subsequent experiences do not keep them
in mind. We put him on the tread-mill and expect him to become
speedy in the race.1

1 1 remember a professor of zoology telling me some years ago, that though
he did his best to convince his pupils, principally medical students, that acquire-
ments were not transmissible, his teachings were ' spoilt ' by the physicians and
surgeons through whose hands the young men subsequently passed. He quite
recognized the importance of the matter, and alluded sorrowfully to the medical
evidence given before various Royal Commissions by former members of his
class. His lectures consisted in more or less detailed anatomical descriptions of
certain types — starfish, sea-urchin, earthworm, leech, cockchafer, lobster, dogfish,
cod, snake, rabbit, and so forth — animals which, by way of practical work, the
pupils were required to dissect. His examinations were designed to discover the
extent to which these teachings had been committed to memory. Once or twice
during a session he mentioned the theory of evolution and expressed his agreement
with it. Once or twice, also, he told his pupils that, though the matter was still
subjudice, he was convinced that acquirements were not transmissible, and added
an account of various experiments, such as the amputation of rats' tails. The
anatomical studies of his pupils were so conducted that nothing was learned but
facts, their co-existences and resemblances — that one species was related to another
because such and such structures were possessed by both, that the lobster had
certain organs and the rabbit certain others, that the dogfish had no bones but
only cartilages in such and such numbers and shapes, but that the cod had bones
of which there were just so many in his head, and that the precise shape and
spatial relations of these bones were this and that — facts that had no bearing,
or none at least that he made clear, on the problems of heredity which he
recognized as so important ; and, indeed, so little bearing on anything else in

A NEGLECTED PROBLEM 485

797. The extent to which thinking power may be influence! by
the formal training received during early manhood cannot easily
be observed in the individual. When trying to analyse the degree of
intelligence displayed by him, we do not know what part to attribute
to innate capacity, what to formal training, and what to various
other influences, such as those exercised by his companions, all of
which contribute to his intellectual development and status. If
we meet a clever man and approve the system by which he was
trained, we are apt to attribute his efficiency mainly to training ;
if we disapprove of the system, we tend to assign it to innate
capacity. Owing to lack of systematic inquiry, this question of
what is ' innate ' and what is ' acquired ' in the human mind, though
the most important of all practically, is yet the most neglected
problem of psychology. The consequent uncertainty, combined
with the difficulty of ascertaining the precise results of this or that
system of mental training and then comparing them with the results
obtained by other systems, has led to a vast diversity of opinion as
to which system is the best, some authorities advocating one, some
another, and some holding, apparently, that so much is innate that
all systems produce nearly the same results in the end.1 It is
possible, however, to overcome the difficulty in some measure.

798. We found that the solution of the problem of the causation

the medical curriculum or the affairs of everyday life that, when the examination
on them was over, they were promptly forgotten by all except the few students
who adopted zoology as a profession or as a hobby. The professor's convictions
were countered by the convictions of other professors — of physiology, patho-
logy, medicine, surgery, and the like. His experiments were met by accounts
of other experiments (extraordinarily misinterpreted), by details about cats,
almost as legendary as Bo-Peep's sheep, that had left their tails behind them in
traps and doorways and had borne tailless offspring ever afterwards, by stories
about human mothers who had seen moving sights and borne marked children,
and about consumptives, alcoholics, syphilitics, and imbeciles whose children
were similarly affected. Their reasoning was founded on credulity and confusion
of thought, but the students had been so trained that they were unable to per-
ceive its weakness. But, if the zoologist, instead of stating his convictions or
appealing to evidence which his pupils could not verify, had carefully explained
the distinction between variations and modifications, pointed out the difficulty
of believing that the latter could affect the germ-plasm in such precise ways as to
be reproduced in the child as ' innate ' characters, and had then appealed to the
facts of ordinary experience and of human evolution against disease, he would
have supplied his audience with data and thoughts pregnant and unforgettable
because they would have linked up with subsequent experiences, and with a
mental training which would have enabled them to appraise at their true worth
the puerilities of professors who argued, for example, that " acquirements must
be transmissible, for every character must have had a beginning, and therefore
must have been acquired by some one who handed it on to his descendants."
1 See § 708.

486 EDUCATION

of variations is impossible as long as we observe only individuals,
but that we are able to arrive at definite and almost certainly true
conclusions when we compare races that have evolved under
known but unlike conditions, and more particularly when we are
able to compare the present of a race with its known past. The
same method will serve in the endeavour to ascertain the effects
of mental training in early manhood. We shall thus, if only we
think carefully enough, be able to compare different systems of
mental training and separate the effects produced by them from
those produced by the other influences to which the individual is
exposed. All systems profess to teach, on the one hand, know-
ledge, and, on the other, right and efficient ways of thinking. The
amount and kind of knowledge imparted by any system is easily
observable. Our object, then> is to ascertain the intellectual effects
other than mere knowledge — the kinds and qualities of the thinking
resulting from the principal methods of teaching. We shall see more
clearly than ever that, while knowledge, as is very obvious, results
from the things that are taught, the quality of the thinking depends in
a degree that is rarely realized on the way in which they are taught.

799. The effects of religious teaching offer very favourable
materials for study. All sorts of religions have been taught, in
every variety of way, to races all over the world and in every stage
of culture and civilization. Some religions have been held by the
same races for many consecutive centuries. Other races have
rapidly and repeatedly changed their religions. Some religions
have been held by many diverse races, while in other cases sections
of the same race have followed two or more diverse religions. In
some countries the inhabitants are all of one religion, which is
taught to every one in much the same way ; in others, systems,
strongly contrasted in the things they teach and in the way they
teach, divide the inhabitants. In different times and places the
same religion has been taught by different methods. As in the
case of diseases, the range and diversity of the phenomena thus
presented enable us, through processes of analysis and comparison,
to reach conclusions otherwise unattainable.

800. At this stage I must beg the reader to bear in mind
constantly the fact that we are discussing, not the truth or untruth
of religious doctrines, but only the mental effects resulting from
methods of teaching. If we strictly limit the discussion to this
question, and if our reasoning be right, we may, however much
we may disagree as to religious doctrine, be able to reach an
agreement as regards method. At any rate, we shall have

RELIGIOUS TRAINING 487

gathered materials which may help us to agree ultimately. Even
if doctrines be regarded as Divine revelations, yet the ways in
which priests, parents, and schoolmasters teach them are neces-
sarily human devices, and therefore legitimate subjects of criticism.
It is admitted that good teaching tends more than bad teaching
to create intelligence ; and a religion like any other subject may
be well or ill taught. Again, since few people are able to think
without bias of their own faith, and since it is probable that the
reader is an average individual, may I beg him, if I happen to
mention his religion, to try to think in terms of some other.
Thus, if I make mention of the Christian sect to which he
belongs, let him try to conceive some corresponding Mohammedan
sect and suppose we are discussing that.

80 1. All religious knowledge is, of course, acquired, as are
also the kinds of thinking and the attitudes of mind that result
from religious teaching. It is because they are universally recog-
nized as highly important acquirements that so much care is
taken in teaching them. Since religion offers immense rewards
and punishments, covers the whole field of morals, inculcates par-
ticular views concerning the universe, influences the individual in
all his public and private relations, and tends, therefore, to be
revived in his thoughts more often than any other subject that is
formally taught, probably none other so profoundly affects his
intellectual status. But children, though they may be coerced to
religious thoughts and observances, are comparatively little affected by
them. They are too completely under the sway of strong instincts
which impel them to thinking which is, at least, non-religious ;
their minds are very ductile and therefore incapable of those
passionate convictions and unalterable mental attitudes which so
often characterize the adult, and which we term perverse and
fanactical in people who differ from us ; their stage of develop-
ment is such that they are but little capable of appreciating the
surpassing importance of 'religious truth,' or of being influenced by
religious motives in the way that the adult is influenced. To them
religion is but one of the many wonderful things that they learn
from the adult — the occasion of a story or a lesson, of a game or
of a labour. The fervour of the saint or the dervish, the stern
conviction of the puritan, and even the hysteria of some sects is
not for children. Only after adolescence is reached does religion
exercise its typical influence.

802. Speaking generally, in proportion as the mental influence
of a religion is wide, the intellectual status with which it is asso-

488 EDUCATION

ciated is low. This, of course, does not necessarily imply that the
doctrines of all religions are untrue and degrading. If the religion
is true, it may imply merely that many of the doctrines taught by
it have, through the advance of science, been established on
verifiable evidence, and, therefore, have passed from the category
of things believed to be true into that of things proved to
be true — into that category which it is the hope of all religious
people that their articles of faith will be found at the awakening
after death. They then become a part, not of ' religious ' truth, but
of that ordinary secular knowledge which, when systematized, is
termed science. For their acceptance an "act of faith" is no
longer needed. Thus, if all the doctrines of Mohammedanism
were verified, they would be distributed amongst the various
sciences, and, since no indisputably verified fact is ever regarded
as a religious truth, the religion, as such, would cease to exist.
It would be rejected, not by the irreligious, but only by the
ignorant, who, as a rule, would be prejudiced adherents of some
other faith. Probably, too, the emotional tone of true believers
would undergo change. Verified truth is not regarded with
that peculiar devotion to which the adherents of religions are
trained. There is no need for it. Thus, in science heated con-
troversies occur only about matters that are doubtful. No one
was ever fanatical about a mathematical demonstration. It follows,
that as verified truth accumulates, the area covered and emotionally
coloured by religion tends to shrink. For example, our ancestors
held as religious truth an immense body of belief concerning the
visible universe, but nobody claims any part of our present verified
knowledge as an item of faith, and, if any of our fellows now held
that the earth is flat, we should think them foolish, not wicked.
But " when we examine the general culture of the savage we find
that it is entirely religious. The savage not only has religion, but
apparently has nothing else." x The heavens and the earth, every
echo, rainbow, and lightning flash, every disease and accident, even
the things he eats, and the rocks and trees he dwells under, are
interpreted by him in religious terms. Compare the area covered
by his religious convictions with the shrunken area covered by the
modern Christianity of the more enlightened peoples. In one
sense, then, science is always antagonistic to religion. Whatever
is true it tends to render non-religious ; whatever is false it tends
to overthrow ; and invariably it tends to alter the emotional tone,

1 The Rev. A. E. Crawley, " The Origin and Function of Religion," Sociological
Papers, vol. iii. p. 245, Macmillan & Co., 1907.

METHODS OF TEACHING 489

the mental attitude. If the reader doubts this statement, it would
be well if he tried to think of a truth which has remained religious
after having been verified, or of a verified truth which he regards
with emotional devotion.

803. Most religions have, or had, doctrines about the shape of
the world. The ancient Christian belief that the world is flat has
been abandoned, and, therefore, may furnish a text, the discussion
of which, while permitting a measure of freedom, will arouse a
minimum of prejudice. This 'fact,' that the earth is flat, may be
taught in three distinct ways. First, it may be stated to the pupil,
after the manner of much science teaching, as an obvious truth,
which he may observe for himself by looking at the horizon all
around him ; so that, though he is supplied with material for
thought and not forbidden to think, no further attempt is made to
awaken thought or to influence its direction or quality. Or, to
speak more accurately, while the pupil is supplied with facts
which he usually learns to arrange according to their co-existences
and resemblances, he is not taught to classify them according to
their invariable or necessary sequences. Therefore, since his
notions as to what constitutes evidence and what proof are not
derived from his teacher, and since much of the thinking, indeed,
nearly all the difficult thinking, of human beings is in terms of
cause and effect, the main part of his intellectual development is
neglected. Examples of this kind of instruction, which is little
more than a storing of information, and which is regarded by
modern educationalists as a necessary evil that should be
reduced to a minimum, are seen when the lengths of rivers,
the dates of history, or the facts of systematic zoology and
botany are committed to memory. Facts concerning the shape
of the world are so impressive and suggestive and tend so to
link up with subsequent experiences that, unlike many 'scientific'
facts, they are sure to be remembered and thought about ; but
the use that is made of them by a pupil taught according to
this system is left more or less to chance. The mental
attitude created is such that, though the pupil is left free to learn the
actual truth from other people, he is not very likely to correct the
initial error himself.

804. Second, not only may the pupil be told that the world is
flat, but, as an essential part of the teaching, he may also be
made to proceed to a rigorous deductive inference of con-
sequences and a comparison of these consequences with reality.
In other words, he is taught to classify his facts not only accord-

490 EDUCATION

ing to their co-existences and resemblances, but more especially,
as in the ordinary teaching of mathematics and physics, he is
trained how to arrange them according to their sequences.
Acquiring definite ideas as to what constitutes evidence and
what proof, he values his facts and hypotheses in proportion
as they are capable of verification and of being linked with
other facts and hypotheses. Thus, given the flatness of the
world as an initial fact, he may be told that it follows
necessarily that, if armed with a powerful telescope he stands
in clear weather on the seashore, a ship will never sink below
the horizon but will be visible from truck to waterline all
the way to America, that a ship that sails continually to the
West will never come back by the East, that the sun and
stars must revolve round the earth, and that, since they are so
many, since they rise and set in slightly different places every day
of the year, and since their apparent positions in relation to one
another are more or less fixed, it is likely that they must pass
beyond the edge of the flat earth and not through holes in its
surface ; and so forth. The initial statement made to the pupil is
untrue. He will start his reasoning from false premises. But, at
least, he will reason and will treat his apparently established fact as
material for thought and as the starting-point for the acquisition,
examination, and systematization of more facts and thoughts.
Moreover, facts and the thinking founded on them are distinct
things. As was often the case in Pagan Greece, very good thinking
may be founded on false premisses — thinking so good that presently
the premisses are likely to be discerned as false, as not in accord
with reality. But, whether the premisses be true or false, the main
feature of this kind of teaching is that it tends to endow the pupil
with an acquisitive^ an open, a reflective habit of mind. Not only
is he left free to learn the real truth about the shape of the world
from others, but, because he will try to link up his belief with so
many phenomena, he is apt to discover it for himself. Not only
does he tend to think freely and carefully about his past experiences,
but he remains alive also to fresh experiences, which, again, he tends
to think about, and link up with, and use as a test for that which
he has already stored — a mental attitude which tends continually
to increase his store of material for thought and his skill in using
it. He learns to remain a learner and become a thinker. He
takes every possible means to avoid error. The universe his mind
constructs tends continually towards that organized whole which j
is the goal of all good thinking and all good science.

METHODS OF TEACHING 491

805. We have seen that a vast capacity and tendency to profit
by experience is the distinctive attribute of the human being, and
particularly of the child. Through this arises what we call
intelligence. In one sense the adult is more intelligent than the
child j for, having had greater opportunities, he has profited more
from experience ; but in another and a very real sense, the child
is the more intelligent ; for, as a rule, he is more receptive, more
capable of assimilating fresh experience to that already stored.
As may be seen by comparing a Darwin with a Mohammedan
ecclesiastic, or average men trained in modern Europe with those
trained in mediaeval Europe or in Thibet, the degree in which the

> adult preserves the youthful tendency to reach out the tentacles of
\ the -mind and knit together the materials thus gathered depends on
I the formation of a HABIT, which, in turn, depends, in great measure,
I on the kind of formal training he receives. The kind of teaching
! we are now discussing, though not especially employed for science
| subjects, is usually termed scientific by modern educationalists.
It was practised in its highest perfection by the Pagan Greeks, and
was, as it seems to me, the source of their greatness. We have
only to read, for instance, the dialogues of Socrates, to perceive
how strenuously they strove to create not only skill in thinking,
but also that open, receptive mind which is its necessary accom-
paniment. At any rate, every nation on earth is, and has been,
great in proportion as it has practised it. At the present day,
owing to the freedom of thought permitted by modern civilization,
we all tend to receive, in greater or lesser measure, this kind of
training from our general surroundings ; but in our formal education
it is used comparatively little except, as we have already noted, in
teaching young children.

806. It has been used only very rarely for religious teaching,
and can be used for it only when the religion is in no way opposed
to known truth, or when the teachers have no dread that newly dis-
covered truths — deceptions of the devil — will oppose it. If the
religion is in any way false, if it covers and colours a wide area
of the mental field, and if the contemporary science is rapidly
advancing, the two are apt to come into sharp conflict ; and then the
scientific method is liable to be abhorred by some, at least, of the
exponents of religion. On the other hand, when science has made
but small advances, the current religion, even if false, may offer as
good an interpretation of observed phenomena as can be con-
ceived, and therefore may be very tolerant. This, to an exceptional
degree, was the case in Pagan Greece. The excellence of Greek

492 EDUCATION

training in habits of thought was due, apparently, to an unusual
combination of accidents. There existed an enthusiasm for mental
development, the religion offered little or no opposition, the supply
of verified and systematized knowledge was small ; therefore the
teachers could train, and did train their pupils in little besides
methods of thought. In modern times the supply of facts is so
enormous that the tendency is to teach nothing else — facts of
language, history, geography, zoology, and the like.

807. Third, the * fact ' that the world is flat may be conveyed

to the pupil in such a way that he holds it, as an article of faith,

with a sentimental devotion that has for its correlate an active

dislike or blank disregard of all evidence that tends to controvert

it. Of course, all men do not hold their faiths in this way.

Faith, even religious faith, may be associated with an open mind.

But there is evidence all around us that men may be taught to

hold it thus. This kind of thinking is essentially sectarian, and

is very different from that which we have just considered. It, also,

deals with the relation of cause arid effect; but the criteria for

evidence and proof are not the same. The learner is taught to

appeal not to reality, but to authority, and to value his facts and

hypotheses not in proportion as they are capable of verification

and of being linked together by chains of reasoning, but in pro-

vcportion as the facts have been gathered in a particular field (e.g.

CT&ristian, Mohammedan, Hindoo, experimental) and the hypo-

thes^es have been formulated by particular persons. Under

the ^influence °f sucn teaching, not only is a given 'fact'

accepted by the pupil, but an attitude of mind is created which

co-reli£gionists (e.g. modern Mohammedans) describe as one of

simplep or steadfast faith, but which opponents (e.g. modern

Christians) term superstitious or fanatical. Both descriptions are

correct. A superstition is a religious prejudice which is fanatical

when/i the emotional bias is very strong. It is not necessarily

an ;vuntrue, but only an unverified belief held in a certain

obstinate, unreasoning way, which renders the mind more or

lejjss incapable of profiting from fresh experience. A faith that

via'ill be maintained in spite of evidence that it is untrue, is both

ysimple and steadfast, and superstitious and prejudiced. Obviously,

then, as regards mental habits, it is not the truth or untruth of

a doctrine that matters, but the attitude of mind. Doubtless, all

of us hold many untrue beliefs. They are not prejudices if founded

on ignorance or on mere bad judgment. On the other hand, a

truth, which its pioneers discovered because they had open minds,

THE EFFECTS OF TEACHING 493

may be held as a prejudice by followers whose minds are closed.
Thus, if evidence were now produced which conclusively proved
the flatness of the earth, it is very certain that many minds, even
minds of scientific men, are so trained that they would cling to the
notion that it is round with unalterable devotion. I think I have
met people who held the theory of natural selection in this way.
The kind of teaching which most commonly produces a faith,
that turns from opposing evidence with abhorrence or contempt,
is what is usually termed dogmatic. It is generally practised by
sects which take a pride in being ' orthodox' — in holding opinions
which are quite identical for all the members and every generation
of the communion.

808. It is interesting to note how readily we are able to
recognize as such superstitions and prejudices to which we
have not been trained and which conflict with our own beliefs.
Thus, every Mohammedan is able to perceive, not only how
slight is the foundation of fact, or how great the misinter-
pretation of fact, on which Hindoos have reared the monstrous
edifice of their faith, but also to perceive that nothing but
intense prejudice prevents, if not a recognition of the truth (the
doctrines of Mohammedanism), at least a recognition of false-
I hood (the doctrines of Hindooism). If we place irrefutable
I evidence before the ardent adult Mohammedan or Hindoo, and
i preach it for half a century, we shall not shake his faith in the
least. Moreover •, and this is the important point, his mental inertia,
his habit of thought ', extends beyond the articles of his faith. It
determines his whole attitude. It is hard to interest him in new
ideas or set him thinking on new lines. Thus, though he may be
l| forced to perceive the advantages of a new gun or some other
I mechanical device, he will seldom invent or improve one. He is
; capable of patient labour on traditional lines, and even of prolonged
i and passionate outbursts of energy when under the influence of
strong emotion ; but he is quite incapable of that other sort of
! patient thought and sustained effort, that wide appeal to ex-
i perience, that rigorous deductive inference of consequences, and
| that receptivity, which make individual men, or those collections
: of men we call nations, pre-eminently human, thinkers of new
I thoughts, learners and discoverers of new truth, and therefore
j progressive and successful over competitors who are worse
equipped mentally. Very rarely does his race produce a man
distinguished in any field of human thought and endeavour except
religion. Examples of his great men are Peter the Hermit and

494 EDUCATION

the Mahdi. Great men in fields of labour other than religion are
invariably thinkers of new thoughts ; and if, by chance, such a one
appears in an orthodox environment, he is apt to be treated with
derision or dislike as insane or wicked, and so to perish unrecognized,
ineffective, and inglorious. The children of the orthodox, on the
other hand, are quick and receptive, for, given the opportunity,
they are easily trained to recognize new truth. Plainly, then, the
adult has been made incapable of learning. He has acquired a
stupidity which is inborn in the lower animal and the congenital
imbecile. Contemporary Mohammedanism and Hindooism afford
examples of religions that cover and, since they are taught dog-
matically, colour so large a portion of the intellectual field, that
a habit of mind is created which is carried into every relation of
life. Hence the stagnation of their adherents.

809. As compared to the lower animal and the imbecile, the
normal human being is distinguished by his control over his
instincts and passions, which prompt him as strongly and less
imperiously. What is true of the normal man as compared to lower
types is true of the more reflective as compared to the less reflective
man. If only because the former is more far seeing, he tends, on
the average, to be more * reasonable/ more orderly and law-abiding.
Therefore, open-minded and progressive communities not only
tend to secure improved governments, but they are also more easy
to govern. Among them individual freedom, mild laws, and a
civil unarmed police tend to replace tyranny, savage laws, and a
military government. Compare the social states and the govern-
ments of Morocco, Turkey, Persia, Thibet and China, with the
domestic peace of many Christian communities, and of Japan
since its type of mental training changed. Compare modern
1 orthodox ' Christian communities with those in which a greater play
of the reflective faculties is permitted by the religious teaching.
Note the comparative statistics of murder and other crimes of
violence, the acts of brigandage and dacoity, the rebellions, civil
wars, and conspiracies against the established government, and the
acts of tyranny committed by the government1 Note, also, the

1 All sorts of hypotheses have been formulated to account for the relative
prevalence of crime. Here is a curious example from a particularly sane book
(Recollections, by David Christie Murray, p. 247). " My sympathies are with
the old exploded prize-ring. Rightly or wrongly I trace the growth of crimes
of violence to the abolition of that glorious institution. I want to see it back
again, with its rules of fair-play, and its contempt for pain, and its excellent
tuition in temper and forbearance." Students of the question should study
statistics. But they should not, as is so very common when it is desired to

THE OUTPUT OF GREAT MEN

495

output of great men whose labours have rendered their nations
illustrious. It will be found, no matter how fervently the priest-
hood inculcate a reverence for thrift, law and authority, that, of
any two communities, the more orthodox is almost invariably the
more poverty-stricken, the more turbulent, and the more savagely
governed. All orthodox communities are flourishing in proportion
to the number of heretics they include. Wherever the heretical
(e.g. Protestants) and the orthodox (e.g. Greek Churchmen) mingle
on equal terms, the former tend to be the more law-abiding and to
occupy the more responsible and lucrative posts, whereas the latter
tend to become hewers of wood and drawers of water. The great
men produced by orthodox communities are relatively very few,

demonstrate, for example, the injurious effects of secular education, compare
material derived from localities (e.g. new colonies) that are undergoing rapid
change with data gathered from places where an old order standeth. Nor should
the statistics of the country be compared without reservation with those of the
town. Rural populations always tend to be the more law-abiding (see § 523).
Here are some statistics of murder from an author (see Crime and its Causes, by
the Rev. W. D. Morrison) who attributes crime to climate, but who has neglected
to compare the relative amount of crime in Australasia and South America, both of
which have warm climates : —

Population over
tea years of age.

Tried.

Per

.000 in-

z.1 ii~.ui; -.

Convicted.

?-r

.000

habitants

Italy .
Austria .

France .
Belgium
England
Ireland .
Scotland
Spain .

Germany

23,408,277

11/144470

^.:--.S:;

I&S94053

1883-6

1882-6
1881-5

[0,321,558

:>>:-o
1883-6
[882-6
[882-6

3,606

wm

£

129
60

1,584

15^0

---5

3-35

2.II
11.91

1. 10

1.61

2,805
499
580
101

_:
1,085

"Is

476

11.98
2.90
3-87

0.76

1^0

0.74

8.16

5-78

0.88

The population of England and Wales is now in the neighbourhood of thirty-five
Probably the Anglicans number about fifteen millions, the Noncon-
formists about the same, while the Roman Church claims about a million and a half.
|The prison population, March 28, 1906, was 21,580. Of this total the Anglicans
'are returned as contributing 16,089, the Nonconformists 1,094, and the Catholics
(Parfa'mtmmtmt) Retttr* on Prisons t Religious Cnsds of Prisoners, April
1906). Doubtless, the numbers assigned to the Anglicans are too high and those
I to the Nonconformists too low. Prisoners, like soldiers, tend to " follow the band."
In Scotland, at the same date, Catholics, a small minority, contributed 971 to a
population of 2,812.

496 EDUCATION

and, with scarcely an exception, rebels against clerical authority or
actual defaulters from the faith. Such, for example, were Voltaire
and the men of the French Revolution, Garibaldi, Mazzini, Cavour,
de Lesseps, Renan, Victor Hugo, Jaurez the great President of
Mexico, and Tolstoi. If the reader will consider the matter he
will be able to recollect hardly a man, not a cleric^ who was both
orthodox and great. I can call to mind only Pasteur.

810. I feel sure that many people will dissent from the opinion
that such great social and intellectual differences as exist, for
example, between England and Morocco are due mainly to
differences in the way religion is taught ; or rather, since religious
instruction tends everywhere to be of the same dogmatic type, to
differences in the extent to which this method of teaching is
influential in moulding the minds of young adults and thus deter-
mining their final mental attitudes. I can only ask the reader —
while bearing in mind (i) that dogmatic teaching obviously tends
to close the mind and to create an unchanging outlook on life, (2)
that teaching of this kind is much more influential in such places
as Morocco where nearly all the formal and much of the informal
mental training is religious than in England where it preponderates
much less, where the many divergent sects adopt a tolerant atti-
tude towards one another, where much of the formal teaching of
other subjects is deliberately designed to create a receptive tone
of mind, and where indeed the whole surroundings are such that
they tend to a far greater degree to encourage independence of
thought, (3) that in proportion as dogmatic teaching has been
influential the adherents of each of the religions of the world have
tended to have much the same social and intellectual status,
though in other respects (e.g. climate) the environment has often
been very different, and (4) that in proportion as religious teaching
has excluded other subjects, races have been stagnant and bar-
barous— to try to conceive interpretations unlike the one I have
suggested. If the facts be granted, only two other suppositions
are conceivable, or, at any rate, have been conceived with any
degree of clearness.

8 1 1. First, there is the hypothesis that racial mental differences
are mainly innate, and, therefore, that the social state of Morocco
differs from that of England because Moors and Englishmen are
"naturally" as much unlike mentally as physically. We have
already discussed this hypothesis rather fully, but consider again
what it implies. It implies that Englishmen and Moors are incap-
able of becoming alike mentally, and, therefore, that there is no

DOGMATIC TRAINING 497

hope that Moors will form a civilized community except after ages
of selective elimination ; in other words, it implies that they are
now as a nation so incapable of learning as to be extremely
feeble-minded in the technical sense. All orthodox Mohammedan
communities, in proportion to their orthodoxy, in proportion as
their faith is steadfast and fanatical, exhibit much the same social
phenomena. Amongst them are descendants of the Pagan Greeks,
who, also, as well as most Hindoos and Buddhists, must be feeble-
minded. How, in that case, shall we explain the fact that a few
generations back, during the middle ages, the ancestors and co-
religionists of these same Moors were, in Spain, far more
enlightened, progressive, and orderly than our own contemporary
ancestors ? We derive the beginnings of modern science from them.
During our own Dark Ages Europe was in a state of social and
intellectual stagnation, perpetual foreign war, and domestic disorder
identical with that of Morocco of to-day. If, then, the social state
depends on innate racial characteristics, what caused the rapid and
tremendous change that occurred at the Reformation in some of the
countries of Western Europe ? At that time the various peoples
turned from the teachings of an infallible church to that of a book
which, it is true, they believed infallible, but on which each man
exercised his wits and which he interpreted in his own way.
Hence the diverging heresies, the clashing sects, which in them-
selves were indications of, and conduced to, divergent and
independent thought. Was the greatness of the Greeks and
Romans at a time when the teaching tended to develop the
reflective faculties due to race, and their decline when the teaching
tended to crush independent thought due to race also ? How did
it happen that the tiny community of Athens, which in the former
period produced more really great thinkers, poets, historians,
philosophers, and the like, and more great men of action — who of
necessity were men of great thought also — than all Europe during
its Dark Ages, never again produced any ? Did the Chinese achieve
civilization because they were less feeble-minded than their con-
temporaries ? Have they stagnated for centuries because they are
more feeble-minded ? Were the Japanese feeble-minded half a
century ago? Are they no longer so? How is it that, except
when the teaching is more liberal or less liberal than the ordinary,
the adherents of each religion, who may be of many diverse races,
are so much alike mentally, but so dissimilar from the adherents
of other religions even when of the same race ?

812. Whether, or not, connected as cause and effect, there can be
32

498 EDUCATION

no doubt that, in proportion as the prevailing religious teaching
tends to create a habit of prejudiced thinking, races are stagnant
and turbulent. Must we suppose, then, that inferior races tend
' naturally ' to follow ' orthodox ' religions ? But, if that is so, then,
once again, what was the origin of the astonishing germinal change
which caused the Pagan Greeks and Romans to embrace orthodox
Christianity and the progressive Protestant nations to abandon it ?
No one, not a fanatic, denies the sincerity of the great majority of
the ecclesiastics of every religion. How does it happen that
ecclesiastics, especially those of the more ' orthodox ' religions and
sects, have ever as a body resisted new truth more strenuously than
the laity ? They are of the same race, but they have been much
more carefully trained dogmatically.1 Most people place a high
value on religious teaching and education generally, but of what
value is any sort of teaching if ' nature ' be so powerful as to be
the main source of racial and social differences ? Moreover, if the
human being is so mentally blocked out by ' nature/ in what par-
ticular does he differ from the lower animal mentally ? It cannot
be by reason of superior educability.

813. Second, there is the hypothesis that the actual doctrines,
the actual ' facts/ taught by religions are the source of the mental
peculiarities of their adherents. Within limits, this is true, no
doubt. If a child be taught, for example, that the world is flat, he
will have, no matter how well trained, some difficulty, especially in
adult life when his receptive powers are beginning to wane, in
changing to a conviction that it is round. A man, who believes all
the fiction taught by Fetishism, cannot well be other than a

1 The whole atmosphere of modern civilization, like that of Pagan Greece
and Rome, is antagonistic to rigid orthodoxy. The various sects now mingle j
freely, almost every one can read, and to every one who is able to read is accessible !
a voluminous literature crowded with diverse opinions. Some freedom of thought :
is inevitable. Religion may flourish in this atmosphere, as witness the continual j
growth in England and America of ardent Nonconformist sects which, notwith- \
standing their fervour, permit considerable latitude of belief. But orthodoxy
perishes, as witness the enormous secessions from the Roman church amongst j
the more enlightened peoples of the Continent, and the fact that, in spite of a
stream of immigration which has been flowing for many years, the Catholic
population of Great Britain and the United States does not increase proportionately.
The doctrines of Catholicism are not demonstrably less true than those of Pro-
testant sects. It seems evident, then, that the mental atmosphere created by
the method of teaching is the cause of the decay of the former ; and the fact that
the ecclesiastics of the more rigid churches persist in maintaining a mental environ-
ment which renders the prevalence of their own doctrines difficult, is a conspicuous
instance of incapacity to profit from experience. The Greek church, also, is
beginning to suffer. Christianity loses fewer adherents through Anglican teaching.
Nevertheless, Nonconformity has'gained largely from this comparatively rigid sect.

HABITS OF MIND 499

savage. Therefore religions, in so far as they are false, are bars to
the discovery of truth. Nevertheless, false beliefs owe their
stability mainly to the way in which they are taught to the pupil.
For instance, it is possible to teach Mohammedanism and
Buddhism, as in the case of the Spanish Moors and the Japanese,
in such a way as to leave the mind open to fresh evidence. More-
over, it is not credible that the Pagan Greeks and Romans were
intellectually greater than their Christian descendants of the Dark
Ages merely because their religious beliefs were more true, or at
any rate less false. Nor is it credible that the comparatively
trifling doctrinal differences which separate Protestant races from
their mediaeval ancestors, and, in a lesser degree, from modern
Catholics and Greek Churchmen, are the causes of their considerable
i social superiority.

814. As in the case of susceptibility to alcohol, racial intel-
lectual peculiarities have been attributed to all sorts of causes.
For example, climate has been alleged as a cause. But both
stagnant and progressive races have existed in all the zones of
the earth, and while climates change only in geological time,
races may change their characteristics in a generation. Moreover,
the effect produced by climate is either germinal, or one which
is ' acquired ' by every generation in turn. If germinal, it comes
under the heading of innate ; if acquired, under that of mental
training. However, all thinking that has connected mental
peculiarities with climate has been excessively vague. Because
individuals, whose race has evolved in fitness to a cold or
temperate climate, have found a warm climate enervating, the
latter, in spite of natural selection, has been supposed to enervate

jjthe race that has evolved in it. On the other hand, hot climates
,nd fiery suns have been thought to conduce to 'hot' and
fiery' natures. Equally absurd is the notion that 'young'
•aces tend to be vigorous and * old ' races decrepit, or that there
s a law of nature that causes races to swing continually between
tates of high and low efficiency. Every human race is of the
ame age. Indeed, if it be true that living beings are genetically
elated, all species known to us are derived from an equal
mtiquity.

815. To sum up: — the method by which religion is taught
>rofoundly affects mental development. If it be such that the
)upil, as in the case of fanatical Mohammedans, is made to hold
lis beliefs as a mass of obstructive prejudices, then, no matter
vhat the truth of the religion, it becomes a cause of social

500 EDUCATION

stagnation and intellectual inefficiency. The results of such
teaching, observable as they are in every age and country, and
in connexion with almost every religion, are so universal and
manifest that the relation of cause and effect is certain. Precisely
in proportion as the prevailing religion is used to render the
mind incapable of estimating the value of conflicting evidence and
of assimilating new truth, the individual is rendered unintelligent
and the race stagnant and lawless. Such teaching, which every
trained teacher would condemn as abominable if used for a
secular subject, tends to produce a condition of feeble-mindedness
which differs from the congenital kind only in that it has a
different origin and is less profound inasmuch as it affects only
the reflective faculties — the unconscious, not the conscious, memory ;
skill in thinking, not ability in storing facts. Now, since children
are at that stage of mental development in which the individual
acquires the main part of his knowledge and mental habits, it is
impossible to close their minds permanently. Thus, while it is
easy to convince them of the truth of any set of religious doctrines
and prejudice them against any other set, it is almost as easy to
obliterate the impression. Habits of thought become permanent
only later when the youth develops into the man, when the
instinctive open-mindedness and receptivity of the child wanes,
and is replaced by a habit of being open-minded or the reverse.
Consider how small, speaking relatively, would be the intel-
lectual ill-effects of Mohammedanism, Hindooism, or any other
religion which we believe to be false, if the method of instruction,
even if faulty for children, were good when adults were taught.

816. I have discussed religious teaching only in order to
demonstrate the truth that it is as necessary to bestow attention
on the thinking faculties of young adults as on the increase of
their knowledge. The years during which the youth changes
into the man are, from the standpoint of mental development,
the most important of all ; for at that period the mental habits,
like the physical parts, tend to settle into relative stability.
To achieve the best results we must not only train little
children to think well, but we- must continue the process to the
latest stage possible. As we use the child's knowledge for a
foundation on which to build the larger knowledge of the adult,
so we should use his mental skill as a stepping-stone towards the
acquirement of greater powers of thinking. It is agreed on all
hands that a. good educational system must teach knowledge and
mental skill which will be useful in the widest sense to the pupil —

SCIENTIFIC TEACHING 501

useful not merely in this or that occupation, but in bestowing
general intellectual power. Knowledge, and skill in using it, are
useful only when they link up with the experiences of the sub-
sequent career ; that is, when they are actually useful in themselves,
or when they serve as a ladder towards the acquirement of a more
extended and directly useful knowledge and skill. It would be
folly, for example, to teach even elementary mathematics to one
who, were it possible, could never be helped by it in any way.
Therefore, since environments vary, the same instruction is not
always equally valuable. Thus an acquaintance with Latin and
Greek is not as useful to-day as it was four centuries ago, when the
former was a * bread-and-butter ' subject and the only path to know-
ledge, and the latter the sole means of reaching the higher planes
of thought. At present three principal systems of mental training
are advocated, the so-called classical, the so-called scientific, and
the scientific.

817. The first is classical in name only. It consists mainly in
a formal teaching of the words and the relations between the words
of two foreign languages which are no longer spoken ; a method of
acquiring a language so unnatural, and therefore uninteresting and
ineffective, that a decade of toil confers on the pupil less than was
acquired without labour by a Greek or Roman infant of two. The
Greek children and young adults studied no foreign language, and
the Romans only Greek, and that only when their greatness was
beginning to wane. It may be doubted whether the classical
system of verbal signs contributed appreciably to the quality of
the thoughts of which they were the means of expression. On the
contrary, it is probable that good thinking needed, and therefore
invented, good means of verbal expression. Classical literature can
teach modern man nothing about the universe his mind constructs
except some valuable human history. Its beauty is very great, and,
considering the limited knowledge of the ancients, the thinking it
reveals quite the most skilful known to us. But, judging from
results, such instruction in Greek and Latin as is given to boys, and
even to older pupils, does not very commonly awaken a very keen
appreciation of the beauty or bestow great skill in thinking. More-
over, the thoughts have all been expressed in English by scholars
with at least as much precision as is possible to the learner. Doubt-
less, since English is in part derived from Latin, a knowledge of the
latter helps us somewhat to an understanding of the former ; but
the benefit is hardly so marked as to justify years of labour ; and
just as it was anciently possible to speak and write good Greek

502 EDUCATION

and Latin without a profound knowledge of the derivations of the
words, so, in the case of English, it is still possible. While con-
structing Greek and Latin sentences or translating them into
English, the student is forced to think strenuously. Doubtless, he
derives benefit from this mental gymnastic ; but the skill achieved
is of a very special kind. It does not link up very obviously with
anything in the subsequent career of most students. That is to
say, the teaching is extremely indirect. In any case classical
teaching is as the poles apart from that which was practised when
Greece and Rome furnished examples of mental training for all
time. Modern classical scholars are often remarkably indif-
ferent to science ; but it is certain that the Pagans, active-
minded and filled with intense curiosity, would have hailed our
science with rapture, would have taught it to their young men,
and, above all, would have taught them how to think about it
in such a way as to turn it to the best intellectual and practical
account.

8 1 8. The expression 'scientific teaching' is used with two very
different meanings. On the one hand it implies tuition so given
that the pupil is stored with knowledge and skill that develop his
intellectual powers to the utmost. This kind of teaching, which
is scientific in the sense that means are consciously and effectively
adapted to achieve clearly recognized ends, need not deal with the
data of any of the sciences. But, since science is nothing other
than verified and classified truth, since it deals with reality, since
many of its problems are sufficiently abstruse to afford exercise in
strenuous thinking, and since the pupil who learns to think well
will be able to link up much of his scientific knowledge with the
experiences of his subsequent career, it probably affords the best :
materials for the general culture of young adults. On the other !
hand, the expression is often used to imply nothing more than j
instruction in the data of one or more of the sciences of such a
kind that little is required from the pupil save recollection and
observation. This kind of tuition is sometimes termed 'science j
teaching/ a description which is valuable as marking a distinction i|
of real importance.

819. We saw that some sciences, for example systematic zoo- i
logy and botany, are based on facts that are patent to observation, i
whereas nearly all the facts on which others, for example chemistry, I
are founded are so obscured by the conditions in which they occur |
that special devices must be adopted before they can be observed. .!:
No one will maintain formally that this difference in the way in

DESCRIPTION AND INTERPRETATION 503

which facts are gathered ought to make a difference in the kind of
thinking by means of which they are welded into sciences. There
is, however, a difference between sciences which is more important
in that to it is due a vast difference in the thinking by which they
are created. Some sciences are founded on a multitude of facts,
and some on a very few. The mathematical sciences are examples
of the latter class. Thus, " All the inductions involved in all
geometry are comprised in those simple ones, the formulae of
which are the Axioms, and a few of the so-called Definitions.
The remainder of the science is made up of the processes em-
ployed for bringing unforeseen cases within these inductions ; or
(in syllogistic language) for proving the minors necessary to
complete the syllogisms ; the majors being the definitions and
the axioms. In those definitions and axioms are laid down the
whole of the marks, by an artful combination of which it has been
found possible to discover and prove all that is proved in geometry.
The marks being so few, and the inductions which furnish them
being so obvious and familiar ; the connecting of several of them
together, which constitutes Deductions or Trains of Reasoning,
forms the whole difficulty of the science, and, with a trifling excep-
tion, its whole bulk; and hence Geometry is a Deductive Science." l
The definitions are precise descriptions. The axioms are laws.
We have defined a law as a description of a uniformity in the
sequence of phenomena, and we saw that it is usually possible
to deduce necessary consequences from it about sequences of
phenomena,

820. Physics in all its branches and throughout its whole vast
extent is another science that has been developed from a few
essential facts which have been welded into laws from which the
rest of the science has been deduced. Relatively speaking, very
little mere recollection is needed by the mathematician or the
physicist. His ' knowledge,5 however toilsomely acquired, con-
sists mainly in a special skill in thinking about sequences.

821. Astronomy is a science which is founded on an immense
number of facts. Thus there are millions of stars, only a few of
which the astronomer has named and attempts to recollect. If
he merely classified his facts according to co-existences and re-
semblances, for example if he classified the heavenly bodies accord-
ing to their apparent magnitudes, luminosities, and positions relative
to one another, astronomy would be a very incomplete science, and
the best astronomer would be a powerful photographic camera.

1 J. S. Mill, Logic, ii. iv. 4.

504 EDUCATION

But every astronomer is also a mathematician and physicist, and it
is the application of mathematical and physical laws to astronomy
that has given to this science all its intellectual splendour — that
has converted the astrologer into the astronomer, that has linked
together the facts of astronomy in chains of causation, that
has made it in great measure a deductive science founded on
laws.

822. Chemistry is based on an enormous number of facts, but,
as far as I am aware, has only one law of considerable importance,
Dalton's Atomic Theory, which is usually regarded by chemists
as their most valuable possession.

823. Systematic zoology, botany, anatomy, and the other
systematic sciences that relate to living beings are also founded
on a great number of facts, probably on a greater number of
recorded and described facts than any of the other sciences. But
they have no laws. They are descriptive not interpretative ; their
facts are classified according to co-existences and resemblances,
not in chains of causation. In effect, they consist of a multi-
tude of definitions. Thus a systematic zoologist will tell us no
more about a man than that he possesses certain characters, and
that therefore he is an animal belonging to the sub-kingdom
Vertebrata, class Mammalia, order Bimana, and so forth. The
faculties required by the young learner in these sciences are
mainly observation and recollection. No doubt, a great deal of
thought — comparison, discrimination, association, and the like —
is needed also ; but, as compared to the amount required in
physics and mathematics, it is very small in proportion to the
number of facts. Moreover, it is not the same kind of thought —
not deductive, not interpretative thought, not thought about the
sequences of phenomena, not a linking together of facts in the
relation of cause and effect, not a process of inferring the pre-
viously unknown as a necessary consequence from the previously
known, not ratiocination.

824. If a student has exceptional powers of recollection and
observation he may become an exceptionally good systematist.
But no such powers by themselves will enable him to become
a great mathematician or astronomer. The difference between
the interpretative and descriptive sciences is vividly illustrated
by the circumstance that I am able in a short time to ascertain
all that I want to know, indeed all that is known to the average
systematist, about any animal or plant, by turning to the books
on my shelves; whereas no number of books will enable me to

THE SYSTEMATISTS 505

understand the reasoning of the mathematician or astronomer

without a prolonged preliminary training in thinking. The mental

attitudes of the followers of the two kinds of sciences are markedly

different. Thus, I believe every student of the interpretative

sciences would regard it as better science if the theory that

the individual recapitulates the life-history of the race were first

inferred as a necessary consequence from the familiar truth that

\ offspring recapitulate with variations the development of their

'I parents, and then proved by an appeal to the less familiar facts

jj of embryology; whereas I think some biologists would regard

1 such a proceeding as unscientific, and would prefer to begin at

| the other end and found an untested hypothesis on the evidence

| furnished by embryology alone. Biology is remarkable for the

number of untested and often untestable hypotheses which its

followers have formulated. Witness the numerous hypotheses

concerning inheritance, sex, immunity, and cancer. On the other

hand, if a physicist formulates a hypothesis he is almost sure to

endeavour to furnish not only the evidence on which it is founded,

but also that by which he thinks it is proved. Witness Kepler's

rejection of nineteen of his own hypotheses, which he disproved

by a deductive appeal to reality, before he arrived at the true

statement of planetary motion, and Newton's suppression for

fifteen years of a true theory of the moon's motion, because it

did not accord with data which were subsequently found to

be wrong.1

825. Obviously, since the mathematician has only a few data
on which to found his thinking, his science must be deductive
from its very beginnings. On the other hand, the biologist, like
the astronomer, must begin by classifying his facts according to
co-existences and resemblances, and only afterwards, when they
have thus been rendered manageable, proceed to construct chains
of causation. At any rate, every science, the facts of which are
very numerous and which has passed beyond the descriptive
stage, has grown in this way.2

826. Darwin attempted to make this second step. In his theory
of Natural Selection he formulated that which, if true, is a real
law. He described a uniformity in the sequence of events from
which necessary consequences could be deduced. He strove to
interpret facts about living beings, and so to link them together
in chains of causation. Consciously or unconsciously he sought
to do for biology what Newton had already done for physics and

1 See § 72. 2 See § 69 (footnote).

506 EDUCATION

astronomy.1 If mathematics and physics are sciences, his work
also was scientific, for he formulated a hypothesis which was
capable of being tested. But this arranging of facts in sequence
was a kind of science to which systematists, as such, were
not accustomed, and which, therefore, some of them put aside
austerely as that which was not science but * speculation/
" Parenthetically we may notice that though scientific opinion in
general became rapidly converted to the doctrine of pure selection,
there was one remarkable exception. Systematists, for the most
part, kept aloof. Every one was convinced that Natural Selection,
operating in a continuously varying population, was a sufficient
account of the origin of species, except the one class of scientific
workers whose labours familiarized them with the phenomenon of
specific difference. From that time the systematists became, as they
still in great measure remain, a class apart. A separation has been
effected between those who lead theoretical opinion and those who by
taste or necessity have retained an acquaintance with the facts.2 The
consequences of that separation have been many and grievous. To it
are to be traced the extraordinary misapprehensions as to the funda-
mental phenomena of specific difference which are now prevalent." 3

1 " We claim for Darwin that he is the Newton of natural history, and that,
just so surely as that the discovery and demonstration by Newton of the law
of gravitation established order in place of chaos, and laid a sure foundation for
all future study of the starry heavens, so surely has Darwin, by his discovery of
the law of natural selection and his demonstration of the great principle of the
preservation of useful variations in the struggle for life, not only thrown a flood
of light on the process of development of the whole organic world, but also estab-
lished a firm foundation for all future study of nature " (A. R. Wallace, Darwinism,
p. 9). Nothing in the histories of scientific men is more remarkable than Dr
Wallace's attitude. No one would suspect from his own writings that he was
Darwin's co-discoverer of the theory of natural selection. He assigns the whole
credit to the elder thinker. I imagine that posterity will be more just.

2 Among those who ' lead theoretical opinion,' but who, to judge from
Bateson's language, have not ' retained an acquaintance with the facts/ are
Wallace, Hooker, Thiselton-Dyer, Lankester, Weismann, Osborn, and Poulton.

3 Bateson, Mendel's Principles of Heredity, p. 3. Bateson continues, " If
species had really arisen by the Natural Selection for impalpable differences,
intermediate forms should abound, and the limits between species should be
on the whole indefinite. As this conclusion follows necessarily from the premises,
the selectionists believe and declare. that it represents the facts of nature."
Bateson is mistaken. Selectionists believe that evolution has resulted, not from
the selection of impalpable, but from the selection of fluctuating differences.
The distinction is important. Natural selection amongst human beings is the
only instance of this process observable by us, and the reader is now in a position
to judge whether, for instance, the difference between a man who perishes of
consumption and one who survives in the same environment is ' impalpable.' If
selection amongst men were such that short and weak individuals were eliminated,
while tall and strong individuals survived, if men, for example, fought for their

BIOLOGICAL TRAINING 507

827. The question arises whether the attitude of those syste-
matists who have 'kept aloof from speculation can be justified.
Here speculation means nothing other than an attempt to link
together facts concerning animals and plants in chains of causation.
Of course, speculation may be what even students of other sciences
consider illegitimate ; that is, it may be founded on data which
have not been verified, or it may be conducted by thinking which
I is not tested. But no such considerations seem to have guided
the system atists that 'kept aloof; for, as their aloofness implies,
they did not attempt to impugn either the facts or the thinking,
and they preserved the aloofness even after the actual occurrence
of Natural Selection and of evolution consequent on it was
demonstrated amongst men, the only living beings with whose
lives they were at all intimately acquainted. It is not alleged that
their attitude was due to lack of time, or of interest, or of knowledge
of the facts. Apparently they have been guided by the more or
less clearly formulated notion that science is created, not by ascer-
taining chains of causation, but solely by classifying facts according
to co-existences and resemblances. Whether they are right or
wrong is, in the absence of any attempt at demonstration by them,
a matter of opinion ; but it is worthy of notice that that which is
condemned by them is, in effect, not merely the science of Darwin,
but also that of Bacon and Newton, not merely the theory of
Natural Selection, but also mathematics in its entirety, physics
almost in its entirety, and astronomy in the best part of its extent.
It is worthy of notice also, that unless human beings linked together
in chains of causation the facts they learn during the ordinary
course of their lives they would not be rational beings, and could
not maintain existence. The circumstance that they are able

mates, the differences selected would not be impalpable. It is true that, if we
arranged all the members of a variety in a row in the order of their heights or
strengths we should, as a rule, find the differences between each individual and
his next neighbours very small. But nature would do nothing of the kind. On
the contrary, she would simply select for survival, as a general rule, the especially
tall and strong, and for elimination the especially short and weak. Forms inter-
mediate between living types actually abound — forms that are intermediate
between one kingdom and another, one class and another, one order and another,
one species and another, or one variety and another. No selectionist believes that
all the links have survived or are known. The complete chain could be recon-
structed only if every generation were known to us. Mutationists do not doubt
that the organic world has arisen by evolution. But their links are missing
equally with those of the selectionists ; for none will maintain that the vast gaps
which exist between many living types and their nearest known relations, gaps
which involve thousands of co-ordinated changes, can ever have been crossed by
a single leap.

508 EDUCATION

usefully to employ this mode of thinking in ordinary life is, at
least, presumptive evidence that it can be usefully employed
in science where especial care is exercised.

828. My object, however, is not to assail the attitude of the
systematists. "The isolation of the systematists is one of the
most melancholy sequela of Darwinism." x They are doomed to
extinction ; for facts arranged in chains of causation are so very
much more interesting to normal human beings than facts arranged
in any other way, and normal people are so driven to think, are so
trained to think, in chains of causation, by the ordinary con-
ditions of their lives, that even the severest systematic training
can hardly repress, and rarely quite represses, the tendency, the
instinct, to think in that way. Pure systematists are now a small
minority, even among biologists, and as a type are unknown, and
have always been unknown, amongst the students of all other
sciences. The great weight of scientific practice and opinion has
ever been strongly against them. They are a peculiar product of
biological training which still remains almost purely systematic \
for, though Darwin greatly altered the course of biological thought,
his influence has not yet affected the method by which students
are instructed to nearly the same extent. Like monks and nuns,
systematists afford a remarkable example of the importance of
acquirement in human mental development, and of its power to
nullify even an instinct.

829. My object is to draw attention to the circumstance that,
while the majority of biologists, impelled by instinct and informal
training, think about biological facts in terms of causation, yet,
unlike mathematicians, physicists, and astronomers, they receive
little or no formal education which especially fits them to deal with
their data in that way. Here they are, in fact, untrained thinkers.
I make this statement with no offensive intention. It may be
verified in any centre of biological teaching. All biological cur-
ricula are designed to impart only " systematic " knowledge.
If it is unscientific to think in terms of causation, it is never
explained to learners why it is unscientific. The result is that
numbers of students are left with what can only be very misty
or wrong notions as to what constitutes science. The circum-
stance that biologists are divided by real sectarian differences —
that is, differences founded on an improper acceptance or rejection
of evidence or modes of thinking 2 — is, alone, sufficient proof that

1 Bateson, Darwin and Modern Science, p. 89 (footnote).

2 See § 45-

THE RESULTS OF BIOLOGICAL TEACHING 509

their training is defective. Systematists tacitly repudiate science
which is created by linking facts in chains of causation ; most
scientific men regard it as the most perfect form of science.
Experimentalists seek to secure accuracy in thinking by, in effect,
limiting the materials of thought to facts furnished by experiment ;
most men of science believe that one of the essential conditions of
accuracy is the careful taking of all authentic and relevant facts
into account. Medical men, whose professional thinking is entirely
in terms of causation, frequently denounce deduction ; most men
of science suppose that the truth of hypotheses can be tested only
by means of it. Even biometricians, who are mathematicians,
rarely test their thinking deductively. In biology they follow the
prevailing fashion, using mathematical formulae, but not mathe-
matical methods of securing accuracy in thinking. The science
they create is purely empirical. Judging by their work, they
appear to suppose that thinking which is founded on simple
enumeration and which, therefore, is isolated and untested, is
superior to thinking which is founded on a discovery of causes,
and which, therefore, is linked with other truth and can be tested
by it. Most scientific men believe the contrary.

830. Not only does the mathematician always endeavour to
test his thinking, but he invariably prefers a deductive to an
enumerative test. Thus, if he has multiplied one number by
another, he has a greater sense of certainty that he has thought
correctly when he has divided the product by one of the factors and
found that the quotient agrees with the other than when he has
repeated his multiplication a dozen times. In the former case he
thinks that he has proved the correctness of his thinking ; in the
latter he supposes that he has merely raised an expectation that
it is correct Yet, since the conditions of thought are usually
relatively simple in the mathematics, it is here, if ever, that testing
by simple enumeration should be useful ; for the simpler the con-
ditions the less likely it is that any essential factor has been
omitted or wrongly thought about, or that any non-essential factor
has been included. On the other hand, the conditions are usually
very complex in biology. We are constantly liable to confuse the
essential with the non-essential. Here, if ever, simple enumeration
should be dangerous and deduction comparatively safe and useful.
Nevertheless, many biologists, though professing admiration for
the mathematics as the type of all that is accurate, express or
imply the utmost contempt for testing (i.e. deduction) when used
in their own science. Thus, the fact that long lost ancestral traits

5io EDUCATION

sometimes appear in pure-bred individuals seems, according to the
mathematical conception of science, to furnish conclusive proof
that the Mendelian doctrine of segregation is erroneous. If,
however, we mention this test to a member of the experimental
school, we are sure to find that it carries no conviction. He will not
attempt to demonstrate that the supposed test is no test. He will
merely declare that the problems of heredity are not to be solved
in the arm-chair by essayists, logicians, or dialecticians, but only
by real men of science labouring in the laboratory or the
breeding pen. If we insist that the "dialectician" is utilizing
all the experimental facts and more besides, that it is needful
that even "real" men of science shall test their thinking, that
thinking can be carried on as well in an armchair as a breeding
pen, and that the experiments on which he relies prove, not
alternative inheritance, but only alternative reproduction, he will,
by way of retort, adduce similar experiments on rabbits. If
we raise the same objections to these, he will adduce like
experiments on fowls. And so on, and so on. Ultimately we
are left to wonder helplessly whether he is unaware of the true
nature of science, or whether every one who has both thought and
expressed himself clearly about it is unaware ; whether biology,
which, from the scientific standpoint of the mathematician and
physicist, seems so pregnant with great possibilities, so laden with
tremendous issues, is in truth so mean and narrow a thing, a
mere guessing about the abnormalities of sexual reproduction, or
at most no more than a study of the function of sex ; whether a
new and more accurate science is really being created by exclusive
devotion to experiments and abnormalities, or whether we are
spectators in a kind of confidence trick in which a display of
experiment is used to obtain a fictitious appearance of accuracy.

831. Whoever is right some one must be wrong ; and a teach-
ing which results in such a babble of opinions must be wrong also.
A mathematician will seldom affirm contradictories, and any
statement by him is usually accepted or rejected by his fellows
on grounds of pure fact and reason. The same is true of
physicists, chemists, and astronomers. But a biologist — as when
he upholds both the theory of recapitulation and the Law of
Ancestral Inheritance, both the theory of Natural Selection and
the notion that variations are caused by the direct action of the
environment, both the hypothesis that harmful conditions cause
races to decline and the hypothesis that such conditions cause
races to progress in the same characters at the same time — often

SUMMARY 511

displays a power of affirming contradictories which is not exceeded
by, and is much less excusable than that displayed by the
adherents of any of the creeds. The latter do not profess to be
guided solely by verified truth and pure reason. Moreover, in
many instances the statements of the biologist are judged on
grounds of pure prejudice by many of his fellows.

832. Biologists often insist that 'the time has come' when the
traditional education of young adults shall be replaced by a training
in science. But of all modern sciences the most fundamentally im-
portant is the science of education ; and the training accorded to
young biological students is precisely that kind which is most con-
demned by modern educationalists who denounce, for example, tradi-
tional, classical, historical, and geographical teaching as consisting
too much in a mere learning and comparison of words, dates, lengths
of rivers, and the like. They insist that it is not enough to store
the memory with facts ; intelligence must also be developed ; and by
intelligence they always mean skill in thinking in terms of causation.

833. Systematic knowledge is necessary to biologists, but, to
judge by what the students of other sciences consider essential,
it is not all that is necessary. If it be right that scientific men
shall have their powers of precise thinking about sequences
developed to the utmost by formal training ; if the most complete
science is created not merely by classifying facts according to their
co-existences and resmblances, but also by classifying them accord-
ing to their causal relations ; if the former method of classification
is the warp and the latter the woof of perfected science ; if facts
should be arranged not only according to one relation, but accord-
ing to every relation ; — then there ought to be a considerable change
in biological education, and learners should receive a formal training
in the method of classification which Darwin has done so much to
introduce as well as in the method of which Linnaeus was so great
an exponent.

834. It is not merely the education of biologists that is in question.
All education is in question. And very much more than education ;
for on its mental training depends almost absolutely, both in war
and in peace, the weal and woe of every human race. Whoever
has attempted to bring about any sort of reform — from that of a
slaughter-house to that of a state, from that of a nursery to that
of a religion — knows well that his chief difficulties lie, not in
the ignorance of those he would influence, for facts however
laboriously gathered are readily imparted, but rather in mental
states engendered by an education which does little to create a

512 EDUCATION

habit of open-mindedness to new ideas. Only biologists are in a
position to know the fundamental facts — to ascertain what is
"inborn" and what "acquired" in the human mind, and to
discover how any desired quality may best be evolved or
developed, and any defect eliminated. When we think about
what is good or bad in education, we think in terms of causation.
Not until biologists have trained their students by direct methods
to become skilful in the interpretation of evidence, and thus have
raised a body of workers capable of becoming effective thinkers
about education, not until their science teaching has become
scientific in method, will they be in a postion to speak with the
authority that is their right. And not until then will the mental
training of the general public receive a reform of which there
is urgent need, and the practical utility and intellectual splendour
of biology be recognized by all men.

835. In this book, now finished, I have tried, however un-
successfully, to follow the only method by which all thinkers
who have expressed themselves on the subject have supposed it
possible to trace sequences of cause and effect with any degree
of certainty — the method of using some (as many as possible)
of the available, authentic, and relevant facts for the foundations
of hypotheses, and the remainder (which of necessity are usually
by far the greater number) to test the correctness of the thinking
— the method of fitting each inference to all the facts, no matter
how numerous or how gathered, and so of never resting content
until every devisable test had been satisfied. "An hypothesis
is any supposition which we make (either without evidence, or on
evidence avowedly insufficient) in order to endeavour to deduce from
it conclusions in accordance with facts which are known to be real ;
under the idea that if the conclusions to which the hypothesis
leads are known truths, the hypothesis itself must be, or at least
is likely to be, true." l The reader has perhaps noted that, while I
have rarely, if ever, contradicted alleged facts, many of which in
common with all other people I have been obliged to accept at
second hand on what appeared good authority, I have often con-
troverted inferences, none of which we are obliged to accept at
second hand, which seemed to me, when tested, to conflict with
well-known and undisputed truths. " An opinion which stands in
need 'of much illustration can often receive it most effectually,
and least tediously, in the form of a defence against objections.
And on subjects concerning which speculative minds are still
1 J. S. Mill, Logic, iii. xiv. 4.

SUMMARY 513

divided, a writer does but half his duty by stating his doctrine,
if he does not also examine, and to the best of his ability judge,
those of other thinkers."1 However completely I may have
failed in all else, I am not without hope that I have demonstrated
at least that much evidence, hitherto neglected, particularly that
furnished by human diseases, is, if used in accordance with the
methods employed in the other sciences, valuable to the student
of heredity and evolution in his strivings to create a coherent
body of thought and knowledge, the various parts of which shall
interlock as smoothly and consistently as those of any other
deductive science.

836. We have journeyed in a wide and in parts untravelled
region of thought, and have ambitiously endeavoured to solve
the greater problems of heredity. If in any instance we have
succeeded, then in each such case a law of nature has been formu-
lated which, as far as I am able to judge, is as nearly fundamental
as can be discovered in the present state of our knowledge. Of
these laws, if any of them are real laws, the most important from
the scientific standpoint, because the most basic, is the generaliza-
tion that the vast majority of variations are under the immediate
control of natural selection, and therefore are spontaneous in the
sense that they arise independently of the direct action of the
environment, and that on these spontaneous variations only is
evolution built ; for they only are products of the normal growth
and change of the germ-plasm, all others being results of injury
to it. If this be a truth, the close and continuous adaptation of
persisting species to their environments necessarily follows. On
the other hand, the conclusion that the " acquirements " of the
individual are as much a part of his inheritance as his " inborn "
traits is, from the practical standpoint, the most important of all.
If this be a truth, we have a valid explanation* of the principal
line of evolution of the higher animals, and a potent means of
influencing our own species for good and evil.

837. The matters we have dealt with have been complex and
difficult, and I fear it is more than probable that the reader has
detected numerous errors and inadequacies of fact and reasoning.
For them I ask no sort of indulgence — more especially as I
have often challenged him to indicate material misstatements
and omissions, or, given the facts as true and comprehensive, to
indicate how any conclusions other than those reached are con-
ceivable. But I have the right to claim, either that I shall be

1 Op. cit., ii. vii. i.
33

514 EDUCATION

judged accordingly as I have, or have not, followed the established
rules under which all science has been created hitherto, or that
the reader shall plainly think out his reasons for rejecting them.
Conceivably these established rules are wrong. But in that case
they should be shown to be wrong. To imply, as is so often done,
that they are wrong merely by setting up private, unexplained,
and apparently indefensible standards for evidence and proof is to
destroy the distinction between scientific and sectarian thinking —
is to render scientific discussion as futile and scientific dissension
as unappeasable as the discussions and dissensions of religious
factions.

838. " Principles of Evidence and Theories of Method are not
to be constructed a priori. The laws of our rational faculty, like
those of every other natural agency, are only learnt by seeing
the agent at work. The earlier achievements of science were made
without the conscious observance of any Scientific Method ; and
we should never have known by what process truth is to be
ascertained if we had not previously ascertained many truths.
But it was only the easier problems that could be thus resolved :
natural sagacity, when it tried its strength against the more difficult
ones, either failed altogether, or if it succeeded here and there in
obtaining a solution, had no sure means of convincing others that
its solution was correct. In scientific investigation, as in all other
works of human skill, the way of obtaining the end is seen, as it
were, instinctively by superior minds in some comparatively simple
case, and is then, by judicious generalization, adapted to the
variety of complex cases. We learn to do a thing in difficult
circumstances by attending to the manner in which we have
spontaneously done the same thing in easier ones.

839. " This truth is exemplified by the history of the various
branches of knowledge which have successively, in the ascending
order of their complication, assumed the character of sciences ; and
will doubtless receive fresh confirmation from those of which the final
scientific constitution is yet to come, and which are still abandoned
to the uncertainties of vague and popular discussion. Although
several other sciences have emerged from this state at a compara-
tively recent date, none now remain in it except those which relate
to man himself, the most complex and most difficult subject of
study on which the human mind can be engaged.1 . ,/tM-

1 Mill was mistaken. He was thinking of the study of human mind and society
in terms of causation. But already Darwin had published his view of the origin
of species, and Wallace his famous companion essay. Stimulated by them,

SCIENTIFIC METHOD 515

840. " If, on matters so much the most important with which
the human intellect can occupy itself, a more general agreement
is ever to exist among thinkers ; if what has been pronounced
' the proper study of mankind ' is not destined to remain the only
subject which Philosophy cannot succeed in rescuing from Empiri-
cism ; the same process through which the laws of many simpler
phenomena have by general acknowledgment been placed beyond
dispute must be consciously and deliberately applied to those
more difficult inquiries. If there are some subjects on which the
results obtained have finally received the unanimous assent of all
that have attended to the proof, and others on which mankind
have not yet been equally successful ; on which the most sagacious
minds have occupied themselves from the earliest date, and have
never succeeded in establishing any considerable body of truths,
so as to be beyond denial or doubt ; it is by generalizing the
methods successfully followed in the former inquiries, and adapting
them to the latter, that we may hope to remove this blot on the
face of science." l

841. To sum up: whether we consider the histories of indi-
viduals, or peoples, or sciences, or religions, or peace, or war, or
education, or commerce, or invention, or legislation, indeed of
almost any field of human endeavour, one truth is seen to stand
forth vividly and unmistakably the moment our attention is drawn
to it — the truth that human progress and success depend, and have
ever depended, chiefly on a power acquired through antecedent
training, a habit, of thinking skilfully about causes and their
effects. Thus only have men, by studying the present, been able
with any degree of certainty, to realize the past and anticipate'
the future. This kind of thinking is skilful only when it is
carefully tested and comprehensive. Beginning with general-
izations from experience, it proceeds, therefore, to establish
these generalizations and extend the area covered by them by
a thorough and relentless appeal to reality. Only those indi-
viduals have achieved enduring success that have thought in this
way. Only those nations have been great and progressive that

many other men besides were at work to discover the causal relations that link
together the different kinds of plants and animals that have appeared on earth.
As we have seen, all Mill wrote was then, and is now, strictly applicable to the
whole study of causation in relation to living beings — that is, to the whole study
of heredity and evolution, and all that it implies. To this day, because of funda-
mental differences concerning evidence and method, biological thinkers, however
right they may be, can, as a rule, convince only minorities of their fellows,
i Op. cit., vi. i. i.

5i6 EDUCATION

have trained their youth to think in it. Only those religions that
have not greatly obstructed this method of reaching truth have
been associated with growing civilizations. Only those sciences
have become interpretative in which it has been systematically
recognized and followed. The races that have been barbarous, the
religions that have caused stagnation and disorder, the systems of
education that have been futile, the sciences that have been cock-
pits of factions and tumbling grounds of whimsies, the armies that
have been defeated in war, the individuals that have laboured in
vain — these have all owed their misfortunes to lack of thorough-
ness in thinking ; that is, to an insufficient testing of suppositions,
and, therefore, to an incomplete survey of the facts.

APPENDIX

AN ATTEMPT TO REPRESENT DIAGRAMMATICALLY SOME OF
THE IDEAS CONNECTED WITH INHERITANCE

BY

HERBERT HALL TURNER, D.Sc., LL.D., F.R.S.

Savilian Professor of Astronomy, Oxford

i. 'W'NTRODUCTORY.— The perusal of Dr Archdall Reid's Prin-
t ciples of Heredity -, and of the present work, suggest that there is a
-^- closer resemblance between biological and geometrical reasoning
than might be supposed. Starting from certain axioms in geo-
metry, a considerable superstructure is erected by following necessary laws
of thought. In biology, there are no axioms of the same kind ; but there
are some fundamental truths which may to some extent take their place ;
as, for instance, that children resemble their parents. The precision of an
axiom is absent : so is the self-evidence : but the universality of the truth
and its universal acceptance, when once the limits of application are
understood, are comparable with those of a geometrical axiom. Every
one knows that the offspring of an elephant will be an elephant, of a dog
a dog, of a butterfly a butterfly similarly marked. The resemblance
between parent and child only extends to broad features and breaks down
at details, and hence the necessity for specifying limits of application.
But there is no difficulty about this unless we try to be too precise. We
know with equal confidence that children differ from their parents ;
i.e. that no two beings are ever precisely alike ; each of these two appar-
ently contradictory propositions is undeniably true within its own limits
of application : and though these limits cannot be precisely defined, they
are well understood.

2. Now, Dr Archdall Reid has shown that we may build upon such
truths as these in a manner not very different from that in which
geometers build upon their fundamental truths. For instance, he deduces
Recapitulation from the two principles just quoted, and little more; he
insists that we need not have derived it from independent observation,
but could have deduced it (as a necessity of thought) from other principles
already known and more familiar.

3. To a mathematician such a view is fascinating, and his impulse is
immediately to seek mathematical analogies or diagrammatic representa-
tions, which help him to picture the process of thought. Thus, he may
think of the resemblance between the growth of a child and that of its
parent as represented by two similar tracks — let us say the tracks of the
front and hind wheel of a bicycle. They are nearly, but not quite, the
same. If a third, fourth, fifth wheel followed in similar sequence, we

517

5i8

APPENDIX

should have a representation of ancestry by the successive tracks which
would appeal specially to a mathematician, who is accustomed to curves and
their properties. Given this tendency of one wheel, or say of one cyclist,
to follow the preceding, it is suggested at once that the general path will
remain much the same unless there is some persistent disturbing cause —
say the gradual wearing away of a bad patch on the road. Further, it
is possible that each cyclist, though following the path of his predecessor,
may ride just a little quicker and farther ; so that what was once the
whole extent of the ride becomes ultimately only an early stage of it passed
over with great rapidity : and we thus arrive very simply at a conception
nearly related to that of Recapitulation in biology.

4. Nothing is proved by this : but when Dr Archdall Reid challenges
his readers to think of any possible alternative to Recapitulation, such
analogies help the mathematician by presenting the corresponding diffi-
culty of travelling from one point to another without passing through
intermediate positions. One may " go round," but this is to lose time :
and for living beings, natural selection makes it important to save time —
to reach strength and maturity early. The cyclist we have pictured above
can save time in two ways only : by going quicker or by shortening the
route. If their predecessors had laid down a circuitous route, those
following later may shorten it by " cutting across " : but we must
remember that time was important for the predecessors also, since they
too were naturally selected : and hence they were forced into the most
direct route they could find. The path is thus constantly tending to
become straight, and to be ridden quicker.

5. This illustration will serve to show the kind of temptation which
besets a reader, whose training has been mathematical, to think in his
own terms ; and to feel that ideas are clearer, to him at any rate, when
expressed in those terms. It will thus explain the origin of the following
essay in diagrammatic representation of biological conceptions. The
crudity and imperfections of the attempt are too obvious to be covered
by any apology: but they may stimulate some abler pen to a more
successful endeavour.

6. Diagrammatic representation. — Let the size of an organ or feature

(length of arm, weight of brain,
etc.) or its degree (clearness
of vision measured in some
selected manner) be repre-
sented in the familiar way by a
diagram, in which one ordinate
is the time scale measured
along OX in any convenient
units, i, 2, 3, 4, 5, etc., which
may be years for a man, or
days for an insect; the other
axis, OY, being devoted to the
size or degree of the organ. Then the growth of the organ will be
represented by a path, ORPQS, of some kind, which has the follow-

GENERAL FEATURES OF GROWTH

519

FlG- 2-

ing properties : (a) It starts from O, since all organs must have a beginning.
(b) It ends at some point, T, when the animal dies, (c) The ordinates
RL, PM, QN, SV, etc., tend generally y
to increase. There is nothing im-
possible in a decrease such as PQ
(Fig. 2), much less in a stationary
period such as PR in Fig. 2 ; but the
general rule in Nature is growth, and
for the present the exceptions may be
left out of consideration.

7. Resemblance to parents. — Now
let the path for a certain organ in a
parent be OQP, PD being the size at
a time OD selected for observation or
measurement. At a corresponding time
in the life of one of the offspring let
the corresponding organ be observed or
measured, and found to be pD. Then
we know from experience that — chil-
dren resemble their parents — (I.),
and hence that pD will not be very
different from PD on the average. But
also we know that — children are not
exactly like their parents^ and may
differ from them either way — (!!.)>

and hence pD will usually differ from PD ; and the difference may be in
either direction.

8. But the two elementary principles just stated tell us more than
this. The resemblance and the difference are not applicable to a single
moment only such as OD ; they extend throughout life, and consequently
if we observe the corresponding organs at any previous time Od, we shall
find that dq is not very different from dQ, though, as a rule, not exactly
equal to it.

It is easily seen that the path Oqp for the child will thus lie near to

that OQP for the parent throughout
its whole length ; or in other words —
the development of the child is a
recapitulation of the parental develop-
ment—(III.).

9. The tendency to diverge. — Let
us now suppose that the path OA is
followed by a certain individual. (For
convenience it and other paths are
• drawn straight, but this in no way
affects the argument at present.) His

FIG. 3.

M

FIG. 4.

children may, and generally will,
follow paths near this, such as OB and Ob, which may differ from
OA in opposite directions. The children of OB will similarly, in

52o APPENDIX

general, follow either a path Oc, which is a return towards the
ancestral path OA, and may even go on the other side of it, or
a path OC, which is a further deviation from the ancestral. We are
not yet in a position to say anything of the relative chances of these
two possibilities, but experience of a wide kind tells us that both are
possibilities ; and similarly it is possible for the children OD, Od of Ob
either to return towards the ancestral type (as OD) or to diverge further
from it as Od. Hence there is a continual tendency to produce descen-
dants differing more and more from the original type in both directions,
and if this tendency were unchecked we should get animals of all sorts
of miscellaneous shapes. There are, however, three important checks to
this tendency which may not be entirely independent, but which we will
consider separately in the first instance; they are (a] the sexual, (b)
the ancestral, (c) the retrogressive. The first two we can deal with at
once : the third is more conveniently deferred until we come to natural
selection (§ 55).

10. Influence of Two Sexes. — Most living forms are the children not
of one individual but of two. Let the path of one parent be OQ, and

of the other OS. What will be the path
of the child? We know from wide ex-
perience that — as a rule children resemble
both parents — (IV.), and thus the child's
path will, as a rule, be intermediate between
the paths OQ and OS ; not necessarily
half-way between them, but somewhere
intermediate. The child's path may be
such as OC nearer to OQ, or OD nearer
— r^ to OS. There might, for instance, be a
tendency for the child to resemble the
father rather than the mother ; and if OQ

be the path of the father, the child's path would be like OC. But if
for every pair of 'parents ; OQ OS, in which OQ represents the father there
exists another pair in which OQ represents the mother (V.), then for every
child OC above the half-way path we shall have another child OD equally
below the half-way path, and on the average the children will follow the
half-way path.

11. The condition italicized is roughly in accordance with experience.
There are tall men with short wives and short men with tall wives.
Whether there are more of the former than the latter we cannot say
without statistical inquiry : but it is easily seen that the condition
must be roughly fulfilled. For take any ten married couples : divide
the men into tall and short — five of each : the women also into tall and
short — five of each. Suppose three tall men marry tall women : then two
tall men marry short women. There are thus left five short men married
to three short and two tall women.

12. The argument is quite general. If we take n tall men and n
short men : n tall women and n short women : and if x of the tall men
have tall wives : then n - x have short wives. And since x tall women are

EFFECT OF SEX ON TYPE 521

already disposed of, the remaining n - x tall women must have short
husbands, just as many as there are tall men with short wives. Hence
the generality of the proposition is only limited by two assumptions
tacitly made, viz. : —

(1) That there are equal numbers of tall and short. We can always
secure this by arranging the individuals in series and counting to the
half-way. But the separation will in general be rather arbitrary since
many men (and women) will be closely of medium height, and there will
be other striking features of distribution which are neglected in this
rough assortment.

(2) We have assumed quite independent standards for men and
women. This is an assumption already familiar in statistical work.
Sir Francis Galton at the outset of his essay " Natural Inheritance "
adopts the artifice of "never dealing with female measures as they
are observed, but always employing the male equivalents in the place of
them " : and without this artifice he declares that he " hardly knows how
we should have succeeded in making a fair start."

13. With these qualifications the condition (V.) is seen to be in
accordance with general experience : and hence it follows — that on the
average the child's path will fall just midway between those of its
parents — (VI.).

14. But we must remember that this result is only the extension to
the case of two parents of the law assumed for one parent — i.e. that a
child resembles its parent. It is therefore liable to modifications due to
any departure from this law such as we shall presently consider.

15. Sexual restriction of deviation from type. — Now suppose OP is
the general type of a species, and some individual follows the path
OQ differing from OP. The path of the

mate may be on either side of OP, but
will on the average be along OP: and
hence the children will on the average
follow the midway path OR, which
diverges from OP only half as much as
OQ. Hence we see how the deviations
of the parents are reduced in their off-
spring, and the tendency to diverge
indefinitely, noticed in § 9, is checked.
We shall presently show that definite
limits are assigned to the divergence, but

first there is a special point calling for notice, which might modify the
conclusion just reached.

1 6. Assortative mating. — An assumption (italicized) was made in the
last paragraph, namely, that the mate is chosen indifferently from the
community at large : and that there is no systematic tendency, for
instance, for the parents to resemble one another. This is in rough
accordance with our experience : a tall man does not as a rule choose a
tall wife ; indeed there are often ludicrous exceptions, which strike the
attention so much that we should say that the tendency was the contrary.

522 APPENDIX

It is doubtful, however, whether ordinary impressions are sufficient to
decide with accuracy what is the general rule. We should probably be
equally surprised to find on careful inquiry, that tall men chose tall
wives in as large a percentage of cases as they chose short wives : though
a small percentage would not be surprising. We should probably admit
that the matter was essentially suitable for statistical inquiry, though we
should not expect any very startling results. If "like on the whole
chooses like," then the divergences of parents are not reduced by so
much as one half : if " like chooses unlike," then the reduction is greater.
Now each parent has many qualities, and the deviations are not all in the
same direction. A tall man may have long arms and long legs, but he
may be short in temper : and his choice of a mate may depend as much
on his short temper as on his long arms. Hence, on the whole, though
statistical inquiries may give interesting results in special cases, we should
reasonably expect to find that the path of the child was that of the " mid-
parent," and that the deviations of the parents from the type were halved
in each generation.

T 7. Definite limits for divergence. — Now suppose that a snail were to
start crawling away from a wall, and were to crawl one foot per hour. If
it were undisturbed it would ultimately reach an indefinite distance from
the wall. But suppose at the end of each hour some one put it back
just half-way to the wall. Then the course of events is as follows : —
After i hour it has crawled to 1 2 inches : put back to 6
„ 2 „ „ 1 8 inches: „ 9

;, 3 „ „ 21 inches: „ ioj

„ 4 „ „ 22 \ inches: „ nj

„ 5 „ „ 23j inches: „ nf

and so on. Those who have mathematical knowledge will see at once
that the snail never gets two feet away from the wall, although it gets
continually nearer and nearer to that distance : and indeed without
mathematical knowledge the facts are fairly obvious : for so long as the
snail does not reach the two foot mark he must be put back behind the one
foot mark, and thus has more than a foot to go. This proves the first
part of the proposition — that he never reaches the two foot mark. The
second part (that he gets continually nearer) follows from the fact that
his failure is halved each time. At the end of the first hour he fails by a
whole foot : at the end of the second by six inches : at the end of
the third by three inches : and so on. The defect is halved each
hour.

1 8. The application of this illustration is also tolerably clear.
Children have a tendency to deviate from their parents, and if unchecked
the deviations from the ancestral type might accumulate (like the distance
of the snail from the wall) to any amount. But if the deviation is halved
every generation, a certain limit cannot be surpassed, though it is con
tinually approached. If the case were as simple as that of the snail this
limit would be twice the deviation of any generation from the preceding —
(VII.) : but the problem is really much more complicated. Nevertheless,
we may reasonably anticipate a result of about the kind indicated.

ALTERNATIVE SEXUAL INHERITANCE

523

FIG. 7.

1 9. Limits of deviation. — The limits thus assigned will be of course
on both sides of the ancestral type. They are not necessarily at equal
distances from it, for (owing to natural selection or other causes) there
may be more tendency to diverge on one side than on the other : and
the limit will be proportionately greater. But it will be seen that we have
arrived at an important conception of

the path followed by a descendant. If

OP be the ancestral type, then the

paths of the descendants are confined

between certain limits, OQ, OR, on

opposite sides of the ancestral type.

These limits are not actually defined

so sharply as we have drawn them ;

they are more like the edges of a

shadow ; and an accurate mathematical

expression for them would express a

gradual shading off — a fall rapid at

first and very gradual afterwards. But

if for simplicity we think of actually well defined limits, we shall not be

far from the truth, and the results arrived at will have corresponding exact

propositions, differing from them only in detail.

20. Transmission of sexual characters. — The general law of trans-
mission above considered has however a class of important exceptions,
applying to cases where the differences between parents are not small,
and are not continuously graded. The most conspicuous and important
of these is presented by the sexual characteristics themselves. The child
of male and female parents is not something midway between (with
possible extremely rare exceptions), but either the one or the other. We
are clearly in the presence of a totally different law of transmission.

2 1 . We can illustrate the difference graphically by adopting separate
planes for the representation of the two sets of characters. Our diagrams

have hitherto been drawn in
one plane, OXY : if we devote
this plane to paths such as OP,
representing the growth of a
female organ, we shall not in
general be able to represent
the growth of the correspond-
ing male organ on the same
diagram, as the definitions
would not apply. But we
could take another plane, OXZ,
in which OX still represented
the time scale, and OQ the
FIG. 8. growth of the male organ. In

so far as the organ in one sex

is rudimentary in the other, we could of course represent it by a line
near OX in the other. Thus if OP represents the growth of breasts

524 APPENDIX

in a female, the corresponding growth for a male might be a path Op,
very close to X, since the growth is slight. And if the organ of
one sex were actually non-existent in the other, it could nevertheless
be represented by the line OX itself, which represents zero growth
throughout.

22. So that each sex would be represented by two sets of sexual
characters, "patent" and "latent" as Dr Archdall Reid calls them.
" Patent " female characters would be represented by paths such as OP
far from OX, in the special female planes : and " latent " female characters
would be represented by paths near OX (or coinciding with it) in the
special male planes such as XOZ.

23. Now we know that our principle (IV.) no longer applies in this
case. From wide experience we know that — in sexual characters the
children represent either one parent or the other : not both — (VIII.).
Let us see how this principle can be represented diagrammatically.
To avoid the complexities of solid geometry, let us make a cross section
of Fig. 8 through the lines PTQ, as represented in Fig. 9. The

point T represents rudimentary or
zero characters, P well developed
female, and Q well developed male,
Now the child has two sets of
qualities : we may represent him by
a pair of points, AB, connected to-
gether, or rather kept separate by a
rigid rod. (The notion of keeping
Q separate is appropriate, because he
has one set patent and the other
_ latent : not both patent or both latent,

A^ Bz i.e. A and B must not coincide.)

FIG. 9. Experience then tells us that there

are two possible positions of AB, as

crudely represented in Fig. 9 : either A falling on P and B on T, or
A on T and B on Q.

24. This result would follow at once if we conceive of P, T, and Q
as centres of attraction for the ends, A,B, of the rod. And this conception
would be quite in keeping with what has gone before: thus in Fig. 7
we might regard the type path, OP, as attractive, so that other paths would
be attracted near it. If we took a cross section of the path as we did
for those of Fig. 8, we should get a single point, P, representing the parent,
attracting the single point, R, representing the child. When we come to
sexual characters we must represent the child by two points as above :
and we then get a new interpretation.

25. It is scarcely necessary to say that the diagrammatic analogy
proves nothing whatever. It is merely a convenient summary of facts
which we learn from wide experience. But it may help us to realize
the connexion, with these fundamental and well known facts, of others
which are not so well known.

26. For instance, it may help us to realize how Mendelian inheritance

B,

ANCESTRAL INFLUENCE

525

FIG. 10.

is analogous to sexual inheritance, as Dr Reid has argued. Mendelian
inheritance deals with the combination of two characters, one of which
is patent and the other latent or non-existent. It could be represented
graphically by the same artifice used for sex. But properly to develop
the consequences requires a more careful study of the phenomena than
the present writer has been able to undertake.

27. Ancestral resemblance. — Let us now return to those qualities
which are transmitted non-sexually. We have hitherto dealt simply with
the resemblance of children to their
immediate parents ; but we know that
inheritance is not from parents alone.
From wide experience we know that —
a child has a tendency to resemble,
not only its immediate parents, but its
ancestors, even when the parents differ
from them—(\^.

Hence if OP be the ancestral type,
and OQ the path of a parent, the
path of the child, Oq, will tend to lie
between OQ and OP : but there is
no reason why it should be midway between OQ and OP : probably it
lies nearer OQ, though we may not be able to deduce the numerical law
from theoretical considerations. Sir Francis Gal ton found in 1889 that
in certain cases Pq = 2 Qq : or Pq = f PQ : i.e. the deviation of a child
was § of the deviation of a parent : and this may quite possibly be a
general law deducible from theoretical considerations. On the ocher
hand, the numerical factor may differ in every case. For the present, we
shall merely use Sir Francis Galton's result for the purpose of illustration
without attempting to explain it, or inquire into its generality.

28. Corrected statement of sexual
effect. — Thus if one parent alone (OQ)
were concerned, the child would tend to
follow the path Oq, where Pq = | PQ.
If the other parent (OR) were alone
concerned, the child's path would tend
to be Or, where Pr=f PR. When
both parents are concerned, the child's
path will therefore tend to lie midway
between Oq and Or, not midway be-
tween OQ and OR as previously stated.
The deviation from OP will consequently
be f of that previously stated, which
we found was, on the average, one half that of the parents. Hence the
deviation will be reduced every generation, not in the ratio \ which is
the sexual effect, but in the ratio f X J = J, which is the combined sexual
and ancestral effect. Returning to the analogy of the snail, if at the end of
each hour one person sets him back to half his distance, and another
person to f of that half, he will always be set back to J of his total

FIG. ii.

526

APPENDIX

distance : and it is then clear that his limit will be reduced from 24 inches
to 1 8 inches. So long as he is short of the 18 inch mark he will be
set back behind the 6 inch mark, and will thus have more than a
foot to do to reach 18 inches. He will thus never get there, though
he will continually approach it. The effect of ancestral inheritance
is to reduce the limits of deviation from type which we arrived at
in § 10.

29. Stability of type. — We have thus arrived at a very definite notion
of the stability of a type when no cause such as natural selection interferes
with it. Mating alone would suffice to prescribe certain limits of
deviation from the ancestral type which could not be exceeded.

30. These limits are narrow — a simple analogy suggests as average
limit twice the average deviation of a single generation : and though a
more suitable but more complex calculation might give a rather different
result, the limits are not likely to be many times greater than the
deviations from one generation to the next.

31. Similarly the tendency of descendants to resemble their ancestors
causes a reversion to the type in each generation, which narrows the
limits still further.

32. We shall presently point out an important difference between

the action of these two agencies, the
sexual and the ancestral ; but at present
we are concerned with their con-
currence. Together they restrict the
deviation within narrow limits and
render the type stable.

3 3 . Paring down of irregularities. —
It is perhaps worthy of note that the
two agencies combine to destroy, not
only deviations of the whole path OV
— £ from OP, but also irregular deviations
such as OSQR, which may cross the
type path. The portion, OSQ, which

lies above OP, will tend to be replaced in the next generation by OsQ, still

above but less above : at Q there is no

tendency to change, and in the portion,

QTR, the influence is to raise the path

towards OP. Thus the path of the child

tends to straighten out irregularities

in those of the parents. Indeed it is ,.

easily seen that irregularities of this

kind have, owing to the sexual effect,

far less chance of surviving than have

deviations of the path as a whole,

either above or below, for the paths of

the parents may easily both deviate

in one direction as a whole, but their

irregularities would be unlikely to coincide, and would tend to annul one

FIG. 12.

FIG. 13.

PROGRESS MEANS EARLY DEVELOPMENT 527

another. Hence if OP be the type-path, we may take as representative
individual paths OKR and OMQ, lying near OP, but not as a rule
crossing it — (X.).

34. Earlier development. — Now this has an important consequence.
Instead of drawing, as hitherto, ordinates such as QPRT, parallel to the
OY axis, draw one NMLK parallel to the OT axis. Then NM or OV
represent the time at which the child, OQ, has the organ under consideration
of the same size (MV or LX) as the parent at the time OX. The child,
OQ, reaches this stage earlier than the parent ; and since the same is true
throughout the curve we see that this child passes through all the successive
stages (in regard to the organ in question) earlier than its parent.
Similarly the child, OR, develops more slowly than its parent, throughout.
We may say generally that — individuals strong in any organ develop early ;
those weak develop late — (XI.).

35. Relation of organs. — But we have so far considered one organ
alone, whereas the characteristics of any animal depend on the relation of
its parts — small head and long neck

in a giraffe : large head and short
neck in a lion. What is true of an
isolated organ may not be true of a i
combination, and we must consider
how the relationship of one to another
enters into the questions before us.
In the first instance, take any two
organs such as length of leg and
weight of brain : and, dropping any
question of time for the moment, let
us make a diagram to represent their
relationship, setting off the length of
leg along OZ, and the weight of brain along OY. Thus the point P repre-
sents the fact that when the length of leg is 4 feet, the weight of brain is
3 ounces or pounds, or any other suitable unit. Previously (at Q) the

length of leg was 2 feet, and the weight
of brain was i oz. or Ib. Since the
dimensions are all zero at first, the path
PQ will start from O, just as that repre-
senting the relation between any organ
(say Y) and the time.

36. Now it will easily be seen that
most of the considerations already
advanced in the case of the paths for
Z the growth Y of an organ, with the
time T, will apply equally well to the
path for the growth of one organ

relatively to another. If OQP is the path for a parent, and Oqp that of
a child, the facts that children roughly resemble parents, but that they
may differ from them in either direction, and so on, still apply to these
new paths. Hence we get the same rules about sexual and ancestral

Length of Leg
FIG. 14.

Z

FIG. 15.

528

APPENDIX

FIG. 16.

effect, and we are led in the same way to the limits of deviation from the
type.

37. If OP be the type-path it may indeed be a more devious curve
than those we have considered. But the descendants will have paths lying

within narrow limits, such as OQ
and OR. And the same will be
true of any pair of organs : so that
the infinite complexities of growth
and structure of the whole animal
will all be reproduced within
narrow limits in the developments
of their descendants.

38. Earlier and later develop -
ment. — But now let us reinsert the
time element. Of the individuals
which follow any given path, OQ,
reaching any stage, L,on the average
at a given time, some will have developed rather more rapidly and
reached K ; others more slowly only and reached M. We could
represent the time scale in the same diagram by marking off various
epochs on the curve. But we should always have to remember that some
individuals, while still keeping near the type, arrived at any given stage
early, and some arrived late. It is not difficult to see that the rule XII.
specified in § 34 applies, not to a
single organ alone, but to the whole Y
complexities of animal structure. We
can thus return to our curves repre-
senting the variations of a single organ
with the time, knowing that the results
obtained can be extended in this way.

39. Order of the quantities. — It is
perhaps worth while to consider for
a moment the size of the quantities
involved — what a mathematician calls
their " order." Thus if PT represents
the height of a parent, say 6 feet, then the average deviation, PQ, is

something like an inch or two — say
i in 50 : and SP will be nearly the
same fraction of OT. If OT be the
time taken to grow to full height, say
25 years, then SP will be about
6 months. The child who is going to
be taller than his parent by ^th part
will, on this computation, reach a
similar height about 6 months earlier.
But usually growth is rapid at first
and slow nearer maturity, so that the
figure should be like Fig. 18 rather than Fig. 17. It is easily seen that

FIG. 17.

FIG. 18.

NATURAL SELECTION

529

he child will under these conditions anticipate the parent by more
still. This anticipation, or early development, is of importance as will
be seen presently.

40. Natural selection. — We now come to the agency that modifies
the above conclusions, natural selection, which works by the destruction of
the defective. Let us represent the

growth of the particular character
which, by defect, renders the animal
liable to destruction by paths be-
tween OQ and OR, in the manner
already familiar. Then if the animal
does not reach a certain lower limit,
OD, in this character, it is liable
to destruction — for simplicity let us
say it is actually destroyed. But
this liability does not commence at

birth: animals are usually protected FIG. 19.

by their parents, sometimes for long

periods, after birth. The period of protection may be represented in
the time scale by OM, so that the animal is not liable to be destroyed
until its path has reached the ordinate MV. If then all who have
not reached the limit, OD, are destroyed, the survivors will be those
following paths between OVW and OLQ. This is the main argument
stated in its most elementary form : but in this form it is scarcely
applicable to real life : we must generalize the details.

41. Period of protection. — First let us consider the period of parental
protection, which is often evanescent. If the argument were no longer
applicable in such cases, we should have a serious difficulty. But
parental protection is only one form of a more general protection in
which chance plays a conspicuous part. Let us first consider a number
of seeds scattered on the ground and liable to be eaten by birds. A seed
may be snapped up directly it is scattered, or it may never be eaten at
all : and though there is thus no definite protection, there will, according
to the laws of probability, be an " expectation of life " of a seed — an
average period for which it may expect to survive. And this period will
not be determined by inherent qualities of the seed, but by external
circumstances, such as the number of depredating birds, the nature of
the soil, and the skill of the sower. There is something very similar in
the case of young animals too feeble to depend on their own exertions for
escape from destruction. In later life an animal may depend on its
speed fo • escape, and the speediest will have advantages over those less
speedy : but the speed of the very young may not suffice in any case to
protect them : slow and speedy may be open to similar risks, like two
seeds or two eggs in the same nest.

42. Hence the notion of the period of protection when generalized
will be somewhat complex : it will include not only the period before
birth (for viviparous animals), or the period in the egg and in the nest
after hatching : but also an additional period before the powers are

34

530 APPENDIX

sufficiently developed to give one individual sensible advantages over
another : the protection will in general be only partial, and the period
will vary greatly in length for different individuals. It will be definite
only in the sense in which an average is definite : and its essential
characteristic is that it is not determined by differences between
individuals, but by external causes : so that it is properly represented by
a vertical ordinate, MKL in Fig, 19, which cuts all paths at an equal
distance from OY.

43. The destructive limit. — Let us now consider the destructive limit,
represented by a line, DV, cutting all the paths at an equal distance from
the other axis. One criticism which may be made is that this representa-
tion is not always appropriate, since the quantity of any character required
for escaping destruction may vary during the life-time of the individual.
Thus if an animal depended for escape on length of leg, doubtless shorter
legs would suffice in its youth to carry it into safety than when it became
older and heavier : hence it might be said that the line, DV, ought to
slope upwards. But we can make a horizontal line suit such cases by
changing the character represented in the diagram. Instead of length of
leg, let us take actual speed : then the speed required in all cases would
be the same (namely, that which outstrips the enemy), and hence the
horizontal line would be appropriate. By choosing the right variable, we
can make our diagram suit other cases.

44. Effect on next generation. — We may now consider the effect of
this destruction on the next generation. The survivors represented by
paths between OVW and OQ in Fig. 19, are stronger in the particular
quality than those destroyed, and their children will tend to be like them.
We shall have to take account, in this connexion, of sexual and ancestral
influences ; but let us omit these in the first instance, for separate con-
sideration later. We thus simplify the problem to the case in which
children merely tend to resemble their parents.

45. By a slight extension of the significance of the diagram we can
use it to represent the members of one generation in all stages of growth.
Thus those destroyed in a generation are represented by the figure
VWRK, the survivors by LVWQ, and those who are still being
protected by the triangle OKL. These last may in general be dismissed
from consideration when we are discussing the next generation : for
usually breeding does not commence until the period of protection is
over, and the animal is thrown on its own resources. The parents of
the next generation will thus be represented simply by the figure LVWQ,
and their children will thus tend to follow paths between OW and OQ.

46. Thus the primary result of destroying the unfit is to improve the
next generation. The type-path tends to rise, and will continue to rise
as the destruction is repeated until the paths all clear the point V in Fig.
1 9 : that is to say the character represented will gradually improve. It
will probably go on improving even after the point V is cleared : for V
itself will tend to rise, since one animal is often the prey of another, and
the struggle between them will tend to improve both.

47. The point V may also move to the left. For the children of the

MATURITY 531

survivors run through the stages when they need protection more quickly

than the generation before them. Now

the protection itself is a product of natural

selection, and will not be maintained

without reason. Hence as each generation

needs it for a shorter period (on the

average) it may shorten automatically.

Hence O moves to the left and upwards

v»

M2

FIG. 20.

from a position such as V1 to another
such as V2; and the path representing
the growth of the character which deter-
mines destruction or survival will move
from O?! to OP2 : that is, its gradient
will become steeper, at any rate until it
has surmounted the point V. As to what happens after this we will
inquire presently.

48. Now in § 1 5 it was pointed out that this means earlier develop-
ment of the organ or character ; and thus we see the effect of natural
selection is to make organs on which it acts develop early.

49. Other organs. — Again there is nothing impossible in the associa-
tion of an early development of organ Y with retarded development of
organ Z. But if Y and Z are both acted on by natural selection there
will be a tendency for both to develop early ; and the relative proportions
of the animal, so far as these two organs are concerned, will tend to be
preserved while at the same time its development is accelerated. But
natural selection acts on an immense number of characters in a complex
animal, and the same argument will extend to them all. Hence there is
a continual tendency to preserve those individuals which run quickly
through the copies set them by their parents, at any rate until they reach
the destructive limit.

50. Modification of curve. — But now what happens after reaching this
limit ? We return to the case of a single organ for simplicity. Once the

limit is attained, and the individual is
secure of survival, he may, so to speak,
please himself whether he goes further.
Those who survive at V may go on
to Q or only to R, and their children
will be equally numerous. Now we
have hitherto dealt with straight paths
and regarded such a path as OVR as
unusual: but this was before the idea

of natural selection was introduced ; and

we shall presently see reasons for modi-
fying the results previously arrived at. We
shall find in fact that influences tending to depress the portion VQ to VR ;
so that after a certain point the growth is slower than at first. This is a well-
known feature of the growth of all animals and plants : after a certain point
they reach " full growth," and further development is comparatively slow.

M

FIG. 21.

532

APPENDIX

51. Sexual effects combined with natural selection. — We now turn to

the modifications introduced by mating. Let us suppose that the destruc-
tion of the unfit has produced a
rise from the ancestral type OP to
Op. Then the reasoning of § 15
shows how mating sets certain limits
OQ, OR for deviation from the type
Op : but suggests no general tendency
to return towards OP.

52. But there is a particular
tendency of this kind arising from
the sexual effect, in connexion with
the paring down of irregularities. If
OP be the type, then we have re-
marked that such irregular paths as

OrKR tend to disappear because in effect there are equally likely paths,

OqKQ, with which they may be

mated. But under natural selection

the paths are not equally likely.

The path OrKR climbs over the

V and indicates survival : the paths

OqKQ does not surmount V, and

means destruction. Thus paths such

as OrKR get the advantage and

survive. This is the first cause for

the depression of path noticed in

§ 5°-

53. Ancestral inheritance and

FIG. 22.

FIG. 23.

natural selection. — Let us now consider ancestral inheritance. As before,

let OP be the ancestral type, DV
the destructive limit, and suppose
the type has risen, under the
influence of natural selection, to
OQ. Then by virtue of ancestral
inheritance there is a continual
tendency for every point of OQ
to return to OP; and this acts
in the contrary direction to
natural selection, and, at any
rate, checks indefinite departure
from the original type.

54. But is it sufficient to arrest
it ? In whatever form we think of

ancestral influence, we cannot avoid contemplating it as becoming weaker
in each succeeding generation. Suppose for a moment that for a particular
generation the tendency of natural selection to raise the type were just
counterbalanced by the tendency of ancestral influence to depress it.
For the next generation the depressing influence would be weaker, and

FIG.

RETROGRESSION 533

the type would rise : there seems no escape from the continual rising at
any rate so far as the critical limit D V. But beyond this limit, natural
selection ceases to work, and ancestral influences act unchecked. Hence
LQ will tend to move nearer OP, i.e. in the direction LR. This is the
second cause for the depression of the path noticed above.

55. Retrogressive tendency. — But as yet we have found nothing to
arrest continual and indefinite departure from the original type up to
the point V. There is nothing which can permanently balance natural
selection, so that the type may remain stable in the presence of its natural
enemies. And yet our experience is that such stability is reached. If
we admit the existence of such stability, then we may put the inference
as follows : Let any generation consist of A individuals who are destroyed
before breeding, and B individuals who survive and have offspring. If a
condition of stability is reached the next generation will be the same —
A unfit and B fit. But all these are by hypotheses the offspring of the
B members only of the preceding generation. These B members do not,
therefore, produce offspring B, fit like themselves (on the average), but
partly B and partly A ; the average of the offspring is lower than that of
the parent : and this goes on continually. The parents are of a constant
type B : the children are of a constant inferior type between B and A.
If the difference remains really constant, ancestral resemblance cannot
explain it, for this is all the time growing weaker. We seem to be thrown
back on some innate tendency to retrogression, which may possibly be a
universal tendency. We assumed at the outset that children might deviate
from their parents in either direction : but the deviations may not be
equal. We should have a vera causa of the kind we are looking for if the
tendency to retrogression were the stronger. It is not necessary that it
should be always stronger; it would suffice if it became stronger with growth.

56. Dr Archdall Reid has, however, no hesitation in stating the
principle in a universal form. He wrote to me on July 16, 1909: "In
all structures retrogressive variations tend to predominate, and do in the
long run predominate over progressive variations. Therefore we get —

(a) Retrogression on relaxation of selection, and more especially on
cessation of selection.

(b) Stability of type when selection balances the tendency to
retrogression.

(c) Progression when the strin-
gency of selection is sufficient to
overcome the tendency to retro-
gression (reversion)."

He adds that —

" Retrogressive variations tend
to be prepotent in a blend, i.e. the
retrogressive parent is on the average °
better represented in the blend."

57. I am not clear whether this is really an additional effect.
Suppose OPX and OP2 to represent the parents, OP2 being the retro-
gressive. Then according to the law of individual retrogression the child

534 APPENDIX

of OPj would in any case regress, say to Opj : and the child of OP2 to
Op2. Hence without any additional effect due to blending the child of
both parents would tend to be midway between OPl and OP2, which
is nearer to OP2 than to OPX : so that the retrogressive parent would be
better represented in the blend in any case. Is the prepotency intensified
by the blending ? It is clear that we are now on totally different ground,
where we no longer depend on our every day experience, but require the
guidance of specialists, who have observed the phenomena more closely.

58. This essay then comes to a natural termination. But if the
reasoning is correct, we have been able to show that we can deduce from
well known laws, combined with the principle of natural selection.

(1) The value of sex in restricting deviation from type.

(2) The tendency to run through early development more and more
quickly, thus compressing the past history and leaving time for adding
to it.

(3) The cessation of growth, or comparative slowness of growth, on
reaching maturity.

(4) The probable existence of an inherent tendency to retrogression,
other than the ancestral.

It follows then that such facts as (2) and (3), which we can independ-
ently verify from wide experience, are independent verifications of the
wide working of natural selection.

GLOSSARY

ACQUIRED, acquirement; terms intended by biologists to indicate alterations in the
individual caused by the action of environment on his mind and body. Since, however,
all characters arise as a reaction to the environment the terms are misleading. They
really designate traits that arise under the stimulus of use and injury.

ALLELOMORPH ; an ' alternative ' unit, believed by the followers of the Mendelian
hypothesis to exist in the germ-plasm, which is supposed to be compounded of such
units.

BIOMETRY ; the measurement and statistical treatment of biological phenomena.
BI-PARENTAL ; see cell.

CELL ; a living entity, usually microscopical, typically possessing a cell-wall, with living
protoplasmic contents (the cytoplasm} in which is embedded a nucleus. Within the nucleus
is a substance termed chromatin, which is differentiated from the rest of the nucleo-plasm.
Cells multiply by self-division, the mother-cell constricting itself and dividing into two
daughter-cells. Before division occurs the chromatin of the nucleus usually gathers itself
into masses termed chromosomes, the number of which is definite for each species. On the
nucleus depends, apparently, the nature of the cell, and therefore the nature of the in-
dividual that develops from the germ-cell. Consequently, it is probable that the nucleus
contains all or most of the germ-plasm, the substance which is the ' bearer of heredity,'
which carries the hereditary tendencies or developmental potentialities. The germ-plasm
has been identified with some show of reason with the chromatin. Unicellular animals
and plants consist each of a single cell, the daughter- cells of which separate and become
distinct individuals. Each cell therefore performs all the functions of life. On the other
hand, a multicellular organism is compounded of two or more cells. It takes origin in
a single cell (which is usually a fertilized ovum). The daughter-cells in the successive
generations do not separate. Consequently the individual may consist of billions of cells,
all of which are differentiated to perform special functions — e.g. locomotion, secretion,
reproduction of new individuals (cell-comm^tnit^es). The cells of the multicellular organ-
ism which are immediately concerned with the reproduction of new individuals are
termed germ-cells. All the others (e.g. muscle, skin, and nerve cells) are termed somatic
cells, and together constitute the soma, the main mass of the body of the individual.
Since unicellular organisms are, in effect, germ-cells, they have, of course, no soma. The
germ-cells of multicellular organisms are termed sperms (spermatozoa] and ova. In the
case of plants they are termed pollen-grains and ovules respectively. Sperms are derived
from the male, ova from the female reproductive organs. A fertilized oviim is formed
by the union of a sperm with an ovum. Apparently this act of conjugation consists
essentially in a union of nuclei which involves a more or less intimate union of the contained
chromatin. In some species each individual is an hermaphrodite ; that is, it possesses
both male and female organs and produces both sperms and ova. In the great majority
of species, including of course all those types the individuals of which are male or female
and produce only sperms or only ova, the germ-cells of the individual conjugate only
with germ-cells from another individual. The reproduction is then bi-parental. In some
species, however, there is self-fertilization ; that is the sperms and ova of the same
hermaphrodite conjugate. Some species produce only ova, which, without being fertilized,
develop into individuals. This mode of reproduction is termed parthenogenesis. Between
the germ-cell, fertilized or not, whence a multicellular individual is derived and the germ-
cells contained in his (or her) own body, lie generations of cells, the ancestors of the germ-
cells, which, like the cells of the soma, do not conjugate with other cells. These are the
generations of the germ-tract. When reproduction is by means of germ-cells it is
termed sexual; when it is by means of slips, buds, suckers, and the like, it is a-sexual.

CELL-COMMUNITY ; see cell.

CHARACTER ; any trait of an individual — e.g. his head, a hair, the colour of a hair.

CHROMATIN ; see cell.

CHROMOSOME ; see cell.

CONJUGATION ; see cell.

CYTOPLASM ; see cell.

535

536 THE LAWS OF HEREDITY

DARWINIAN ; a term sometimes used to designate that school of evolutionists which denies
the transmission of acquirements, and sometimes to designate the school which supposes
that evolution is founded, not on mutations, but on fluctuations.

DAUGHTER-CELL ; see cell.

DEDUCTION ; the chain of reasoning, the inverse process to induction, by means of which we
pass from a consideration of general notions to a consideration of particular facts. It is
most useful when employed to test the correctness of inductions and bring within their
range facts not previously included.

DEVELOPMENT ; the growth or unfolding of the individual from the germ.

EMBRYO ; the individual in his earliest stages of growth after development from the ovum.

ENDEMIC disease ; strictly speaking a local malady which has no tendency to spread.
Usually, however, the term implies the continuous presence of a disease in a locality.

ENZYME ; a ferment secreted by living cells.

EPIDEMIC ; a term applied to a considerable outburst or increase of a disease.

EVOLUTION ; an adaptive change undergone by a race.

EXCRETION ; a term applied both to the act of eliminating waste or used up material from
the organism and to the waste material itself.

FERTILIZED ovum ; see cell.
FLUCTUATION ; an unstable variation.

FCETUS ; the individual in that stage of development that intervenes between the embryonic
condition and birth.

GAMETE ; a germ-cell before conjugation.

GERM-CELL ; see cell.

GERM-PLASM ; see cell.

GERM-TRACT ; see cell.

GERMINAL ; pertaining to the germ-cell, or having origin in the germ-plasm.

HAEMOPHILIA ; a disease or state in which the blood lacks coagulating power.
HEREDITY ; the organic relation between progenitors and descendants.
HEREDITARY tendencies ; see cell.
HERMAPHRODITE ; see cell.

HYBRID ; an offspring or descendant derived from the union of individuals belonging to
distant species.

HYPOTHESIS ; an inference not yet proved to be true.

INBORN or innate ; a term employed to designate characters which are supposed to differ
from acquirements in that they are especially rooted in the constitution of the individual.
Really it designates traits that develop under stimuli other than use and injury.

INDIVIDUAL ; see cell.

INDUCTION ; the process of thought by means of which we found general notions on a
consideration of particular facts. Thus, having observed that offspring recapitulate the
parental development, we reach through induction the notion that they recapitulate the
life-history of the race.

INHERITABLE ; a term used to designate characters that arise under a stimulus other than
use or injury. Really no characters are inheritable, or all are equally inheritable.

LAMARCKIAN doctrine ; the doctrine that offspring tend to reproduce miraculously under
the stimulus of nutriment traits which evolution fitted progenitors to acquire under the
stimulus of use or injury.

LARVA ; an insect in that stage of development which precedes the final stage.

LAW, natural ; an established theory ; a description of a uniformity in the sequence of events
the actual existence of which has been proved.

LIFE-HISTORY ; the stages of the evolution of the race.

MATERNAL impression ; a term having origin in the popular belief that maternal mental
impressions are apt to produce analogous physical peculiarities in the child.

GLOSSARY 537

MENDELISM ; a biological doctrine founded by Mendel.

MICROBES ; unicellular animals and plants which cause infectious disease in higher types.

MODIFICATION ; a term commonly used to designate a character which has resulted from use
or injury ; an acquirement.

MONGREL ; the offspring or descendant of parents that were derived from distant varieties.
MONSTER ; an individual that diverges very greatly from the type of his race.
MOTHER-CELL ; see cell.
MULTICELLULAR ; see cell.

MUTATION ; according to de Vries, a wide departure from the normal type, a ' sport ' ;
according to Punnett and others, a stable variation.

MUTATION hypothesis ; the doctrine that evolution is founded on mutations.

NUCLEUS ; see cell.
NUCLEO-PLASM ; see cell.

OVUM ; see cell.
OVULE ; see cell.

PANDEMIC ; a very wide-spread epidemic.

PARASITE ; an organism that obtains its nutriment from the tissues of living beings.

PARTHENOGENESIS ; see cell.

PATHOGENIC ; disease-producing.

PLACENTA ; the organ which connects a mother with her unborn child.

POLLEN-GRAIN ; see cell.

PROGRESSION ; an increase, due to variation, of one or more of the qualities of a character
— e.g. size, complexity, power.

PROTOPLASM ; the physical basis of life.

RECAPITULATION ; the recapitulation (always with variations) by the individual of the
parental development and the racial life-history.

REGRESSION ; the tendency displayed by the progenitors or descendants of exceptional
individuals to be nearer the racial mean.

RETROGRESSION ; a decrease, due to variation, of one or more of the qualities of a character.
REVERSION ; a return to the ancestral type.

SAPROPHYTE ; an organism that obtains its nutriment from non-living matter.

SELECTION ; is of several kinds ; artificial, when man consciously chooses the progenitors
of a race : natural, when unconscious nature exercises the choice ; reversed, when the
selection " affects not increase of an organ, but decrease of it " ; germinal, when (as
has been supposed) the selection occurs among the units of the germ-plasm.

SELECTIONIST ; an adherent of the doctrine that evolution is founded on the selection of

fluctuations.

SELF-FERTILIZATION ; see cell.
SEXUAL ; see cell
SOMA ; see cell.

SOMATIC ; pertaining to the soma.
SPERM or spermatozoa ; see cell.
SPONTANEOUS ; a term used to designate alterations in the germ-plasm caused, not by

external, but by internal conditions.

TELEGONY ; a term having origin in the popular belief that if a mother has offspring by two

mates, the children of the second father will exhibit the influence of the first.
THEORY ; an inference or hypothesis which has been proved to be true.
TOXIN ; a poison, offensive or defensive in function, secreted by a living being.

538 THE LAWS OF HEREDITY

UMBILICAL cord ; the structure which passes from the navel of the child to the placenta.
UNICELLULAR ; see cell.
UTERUS ; the womb.

VARIABILITY ; the tendency to vary.

VARIATION ; a filial departure, founded on a germinal change, from the parental type.

WASTE-PRODUCTS ; the final products of tissue metabolism. They are excreted by living
beings, and are comparable to the ash, carbonic acid, water, etc., which result from the
combustion of coal.

ZYGOTE ; the fertilized ovum.

INDEX

ABILITY, biometric investigation of, 136-7,
428 et seq. ; nature of, 421-2

Abnormalities, 22

Aborigines, decay of, 279

Abrin, toleration of, 247

Abstinence from Alcohol, ancient, 459

Acclimatization, meaning of term, 263

Acquired, right use of term, 20

Acquirements, real nature of, 14 et seq. ;
importance of, n et seq., 245, 424, 485 ;
superiority to inborn traits, 69 et seq., 401,
424 ; mental, 379, 401

Actions, protoplasmic, 371 ; reflex, 371 ; instinc-
tive* 373 1 rational, 373 etseg.; voluntary, 373
et seq. ; deliberate, 376 ; automatic, 400

Adaptation, universality of, 21, 56-7, 106,
182, 187, 206, 219, 236, 324-5, 373, 390-2,
396 ; of microbes, 238 ; of the individual,
57 ; test of, 222 ; mental, 324, 388 et seq.

Adaptability of man, 381, 428

Africa, West, malaria in, 234-5 ; alcohol in,
299, 302 et seq.

Alcohol, a waste product, 243 ; effect on
health, 286-7, 3J7 et se<7' > immediate and
remote effects, 306-7 ; craving for, 288 et
seq,, 457; variations in craving for, 289
et seq. ; influence of environment on con-
sumption, 292-3 ; as agent of natural selec-
tion, 294 et seq. ; artificial selection for,
457"8 ; evolution caused by, 297, 308 et
^.,458; compared to tuberculosis, 308;
civilization, 313 ; climate, 311-2 ; occupa-
tion, 314 */j^. ; strength of beverages, 313 ;
ancient use of, 299 et seq. \ laws prohibit-
ing use of, 300, 306, 458 et seq. ; average
racial consumption of, 311; convivial and
industrial drinking, 314 et seq. ; suscepti-
bility to charm of, 289, 293-4 ; susceptibility
^iot a disease, 457 ; alleged cause of racial
deterioration, 322 ; antiquity of drinking,
299 ; drinking of Jews, 299, 301-2 ; Greeks,
300 ; Italians, 301 ; West Africans, 302-3 ;
Germans, 304-5 ; British, 305 ; Chinese,
305-6; savages, 306; Mohammedans, 460

Alcoholism, and disease, 457 ; chronic, 318 ;
altruistic, 318 et seq. ; impossibility of pre-
venting, 457, 465

Alison, on drinking of savages, 306

Allelomorphs, 155 ; compound, 161 ; non-
existence of, 1 88

Alternation, of generations, 23 ; of progres-
sion and retrogression, 25 ; of sexual traits,
190

Alternative reproduction, conditions of, 178

Anatomy, systematic, 33, 504

Ancestral Inheritance, Law of, 126 et seq.

resemblances, 523

Andalusian Fowls, 155

Ani, maxims of, 300

Animals, lower, minds of, 380, 398, 415, 425 ;

dreams of, 418 ; social, 382
Ant, mental operations of, 382-3 ; brains of,

405

Anthrax, lethal dose of for rabbit, 86 ; attenua-
tion of, 240
Antitoxin, preparation of, 240; mixed with

toxin, 241, 243-4
Aphides, latency of male characters, 113;

variability of, 148 ; cause of disease in

vines, 276

Aptitudes, mental, 422
Areopagus, laws against drinking, 300
Aristophanes, on drinking, 300
Arsenic, toleration of, 247
Astronomy, scientific method in, 503
Athens, great men in, 496
Attention, area of, 412-3 ; concentration and

diffusion of, 413-4 ; association with the

will, 414

Attractions, sexual, 145, 189
Australia, temperancejegislation in, 462, 464
Automatic actions, 400 et seq. ; compared to

reflexes, 410-1 ; characteristics of, 411-12
Automaton hypothesis, 356 et se.q
Axioms, mathematical, 346

B

BACON, Francis, on the power of words,
19-20 ; service to science, 50 ; on know-
ledge by causes, 343

Bacot, Mr A., on repertoire patterns, 60

Baldwin, Prof. Mark, on use-acquirements,
72 ; on plasticity, 408

Bantam, Sebright, 146, 165, 189

Baring, Mr Maurice, on drinking in Russia,
320

Bateson, Mr W., on dandelions and hawk-
weeds, 148 ; on segregation, 153, 154 ; on
central doctrine of Mendelism, 154; on
imperfect dominance, 155 ; on compound
allelomorphs, 161 ; on discontinuous origin
of Mendelian characters, 162 ; on ferments,
164; on limitations experimentation, 172;
on scientific method, 184-5 > on fertility
and Mendelian inheritance, 190 ; on Men-
delian inheritance of sexual characters, 191 ;
on inheritance of stature, 193 ; on systema-
tists, 506 ; on origin of species, 506

Bathmic hypothesis, 60

Beauty, appreciation of, 423-4

Bees, latency of male characters, 113 ; diseases
of, 275

Berberis vulgaris, repertoire patterns of, 60

Berkeley, on Idealism, 334

Bible, exhortations against intemperance, 299

539

540

THE LAWS OF HEREDITY

Biologists, as essayists, 184-5 > contrasted
with students of other sciences, 509-10 ;
education of, 510 et seq.

Biometry, 36, 133 et seq., 226, 261, 409, 428
et seq.t 443, 447, 509; wasted labours of,
136 et seq.

Black Death, the, 271-2

Blending, abnormal, of sexual traits, 146 ;
normal, 195; of Mendelian traits 160-1, 196;
of crossed human races, 173-4 ; of fluctua-
tions, 189; meaning of term, 194-5; the
only exception to, 195; of mutations, 196 ;
effects of, 197

Bosanquet, Dr W. C., on immunity, 238 ; on
virulence, 238

Botany, systematic, 33, 504; method of,

39. 5°4

Brain, relation to mind, 362 et seq. \ evolu-
tion of, 396-7 ; redation of size to intelli-
gence, 434-5

Branthwaite, Dr, on alcoholism and feeble-
mindedness, 316

British, the, intemperance of, 305 ; alleged
mental deterioration of, 430

British Medical Association, investigation on
alcoholism, 295-6

Brown-Se"quard, on transmission of acquire-
ments, 73

Bumpus, on Natural Selection, 136

Bushmen of New Zealand, drinking habits
of, 288

CANADA, temperance legislation in, 462
Canaries, varietal crossings of, 156
Cancer, 103
Capacity, for growth, 6 ; mental, 421 et seq. ;

variations in, 425 ; definition of, 438
Carnivora, immunity to septic poisoning, 89
Casas, las, Bishop, philanthropic efforts, 280
Castle, Prof. W. E. , on dominance, 157 ; on
gametic purity, 161 ; on mutation hypo-
thesis, 170 ; on Mendelian inheritance of
sexual traits, 191

Caterpillar, development of, 120; instincts
of, 376-7, 379 ; lack of memory, 379, 422 ;
mental growth of, 421

Catholics, Roman, mental traits of, 427, 495
Causation, chain of, 47-8, 349 ; circle of, 350
Cause and effect, 343, 350
Cells, in uni- and multicellular organisms,
i ; multiplication of, i ; daughter-, i ;
specialization of, i ; contractility of, and
mind, 368-70
Cell-community, i
Cephalic index, 429

Cerebrum, association with memory, 396
Chapters in development, missing, 27
Characters, relation to germ-plasm, 8 ; inborn
and acquired, 15-16 ; changes during evolu-
tion, 118 ; non-adaptive, 219, 391-2
Chauveau, Prof., on immunity, 243
Chemistry, study of compared with that ot

biology, 31, 34, 504
Chicken-pox, deaths due to, 260 ; compared

to tobacco, 308

Child, mental peculiarities of, 394 ; education
of, 480 ; effects of religious training on,
487

Chinese, drunkenness among, 306 ; brains of,

435

Chloroform, craving for, 289
Chromatin, as bearer of heredity, 3
Chromosomes, numbers of, 131
Civilization, effects of, 222 et seq.; and

disease, 269 et seq. , 278 ; and alcohol, 298 ;

and prohibition, 459 et seq.
Civilized man, distinction from savage, 397
Classical, teaching, 501
Classification of facts, 36 et seq.; of feelings,

330-1

Clayton, experiments on beans, 84, 97
Clifford, on science, 37 ; on idealism, 335 ;

on relation of mind to body, 357
Climates, healthy and unhealthy, 263 ; and

intemperance, 311

Cocaine, use as substitute for alcohol, 463
Cochin fowl, 155
Cockburn, Sir J., on intelligence of Australian

Blacks, 469

Coherence of thought, 329 et seq., 340
Colour-blindness, inheritance of, 189
Columbus, voyage of, 278
Committee of Fifty, investigation by, 463
i Common sense, definition of, 324

Conception, mental, 326
I Confidence trick in science, 510
| Conjugation, not a necessary antecedent of

reproduction, 2, 142 ; effects of, 144, 188 ;

function of, 202

Contributions, ancestral, 126 et seq.
Controversy, utility of, 45
Cope, Prof., on evolution, n
Correlation, 70-1, 182, 261 ; between size of

brain and mental capacity, 434
Cowpox, 238
Crabs, changes of sex, 114; blind, 123; lack

of memory in, 407
Crawley, Rev. A. G. , on religion of savages,

488
Crichton-Browne, Sir J. , on mental defects,

468

Crime, causation of, 494
Criteria, for facts and thinking, 32, 505-6, 512
Crucial instances, 165
Cuba, imported disease, 280
Cue"not, Prof., theory of factors and deter-
miners, 164, 166

Curiosity, instinct of, 385 ; in education, 478-9
Cypris reptans^ stability of, 201

D

DANDELIONS, parthenogenesis in, 148

Darbishire, Mr A. D., experiments on mice,
163

Darien, British colony in, 235

Dark Ages, diseases in, 269 ; mental training
in, 497

Darwin, Charles, hypothesis of pangenesis,
5, 66 ; belief in the transmission of acquire-
ments, 61 ; on retrogression, 112 ; on
latency, 113-4, 165, 177 ; belief in blended
inheritance, 150 ; on reversion in pure-bred
races, 165-6 ; on artificial selection, 176 ;
method of work, 185, 214-5 '< on effects of
crossing, 198 ; use of deduction by, 212-3,
346 ; his teaching, 212, 391, 505 ; on
memory, 405 ; the Newton of biology, 506

INDEX

Darwin, Mr Francis, on the transmission of
acquirements, 74

Daughter-cells, i

Davenport, Prof. C. B., on Mendelian traits
of poultry, 155, 172 ; on blending of
Mendelian traits, 160-1

Deaf-mutism, inheritance of, 189

Death certificates, 295

Deduction, nature of, 42-3 ; function of, 46,
51-2 ; medical condemnation of, 30, 211,
509 ; in physics, 47, 49, 211, 214-5, 503 ; in
mathematics, 47, 211, 344, 355, 503, 505,
509 ; in biology, 49-50, 345, 509 ; Darwin's
use of, 212-3 I when necessary, 509

Deductions, from fact of immunity, 257-8

Dendy, Miss, on fertility of the feeble-minded,
475

Desire, emotion of, 373-4

Deterioration, physical, 446 et seq. ; cure of, 449

Determinants, 109

Determiners, 164

Development, method of, 23 ; of human
beings, 26-6 ; periods of slow and rapid,
120-1 ; independent, 154, 160.

Devotion, to truth, 41 ; to beliefs, 488

Devotional faculty, 325

Dexterities, physical and mental, 419

Diets, human, 440

Digitalis, hybrids of, 157

Dimorphism, sexual, 142, 144, 188-9

Diphtheria, antitoxic treatment of, 240, 248 ;
effects of sanitation on, 450

Discrimination, 377

Diseases, regarded as experiments, 39-40,
216, 261 ; evidence furnished by, against
mutation hypothesis, 199; in England,
224 ; selection by, 225 ; list of microbic,
227 ; frequency of, 227 ; air-borne, 228,
239, 272, 278, 451-3; contagious, 229,
270, 450-1 ; earth-borne, 229, 274-5, 453 \
insect-borne, 229, 271-2, 451 ; water-borne,
228, 274, 451 ; general, 230, 239 ; cause of
duration, 233-4 ; spread of, 236 ; epidemic
and endemic, 257, 275, 277, 279, 452 ; as
material for study of heredity, 261 ; resist-
ance of human races to, 263, of lower
animals, 275-6 ; evolution of, 266 et seq. ;
extinction of, 268 ; places of origin, 269 ;
migration of, 270-1 ; antiquity of, 269, 275 ;
conditions of prevalence, 275 ; invasion of
Western Hemisphere, 2.^etseq.\ as empire-
builders, 281 et seq.

Disuse, as criterion of nature of growth, 7 ;
alleged as cause of retrogression, 108

Dogs, deterioration in India, 84, 98 ; dis-
temper of, 275 ; crossing of large and small
breeds, 198

Dominance, 153 ; imperfect, 155; of recessive
characters, 155 ; influenced by sex, 156 ; by
environment, 156 ; by race, 157 ; by idio-
syncrasy, 157 ; a phenomenon of sexual re-
production, 192

Dominants, pure, impure, and extracted, 153,

158

Donkin, Dr H. B., on cirrhosis of liver, 295
Dow, General Neal, on prohibition in

Maine, 463-4
Dreams, 416 et seq.

Drelincourt, on speculations about sex, 199
Drift racial, caused by environment, 92

Drinkers, the three classes of, 285, 286
Dyer, Sir W. Thiselton, on latency in a
natural species, 176 ; method of work, 185

EARTH, shape of, 489 et seq.

Education, and alcohol, 312 ; importance of,
477; in early life, 478-9; in school-room,
479-80; of young adults, 481 et seq.

Educability, 398, 428

Efficiency, 422

Egypt, disease in, 269 ; intemperance in, 300,
459

Ehrlich, hypothesis of immunity, 251 et seq.

Embryo, prototypes of, 27; adaptations of,
119

Emotions, acquired, 410

Enumeration, simple, 54, 342-3, 509

Epidemic and endemic diseases, 272, 452

Error, sources of, 36

Esquimaux, effects of vaccination on, 239

Essayists in biology 184-5

Europe, use of alcohol in, 299

Evidence, when admissible, 35; neglect of,
59. 136

Evolution, universal belief in, 4; recapitula-
tion of, 24 ; theories of, 59-62, 258 ; of
toxins, 88 et seq. ; of human races, 180 ;
against disease, 224-5 < against alcohol, 297

Ewart, Prof. J. Cossar, on causation of varia-
tions, 81-2, 85 ; on retrogression, 112 ; on
horse-zebra hybrid, 156

Exact methods of inquiry, ^etseq. ; sciences,
36, 211

Exclusive inheritance, 151

Exodus, book of, on leprosy, 269

Experience, stored in mind, 377

Experiment, object of, 33 ; two ways of using,
43; scope in biology, 45, 50, 51, 510;
failure of, 44-5, 81-5, 87-91, 98-9, 171-3, 184,
204-5, 22I> 264, 409; as cause of contro-
versy, 45

Experimental, sciences, 36, 502 ; evidence in
favour of Lamarckian doctrine, 73 ; school,
30-1, 184

Explanation, nature of, 349

Extracted dominants and recessives, 158

Eye-colour, reproduction of, 145-6, 149, 174,
178, 428 et seq.

Eyes, retrogression of, 123, 223 ; protected and
unprotected, 418

FACTS, admissible, 32 ; patent and obscured,
33 ; scientific value of, 38, 480 ; teaching of,
480

Factors, colour-, 164

Faith, 488

Family life, 380

Fashion, influence of, 204, 292, 386

Feeble-mindedness, 425, tf>$et seq.

Female characters, reproduced by male, 114

Fe're", on alcoholized eggs, 264

Fertility, biometric investigation of, 137-8,
430-1 ; evolution of, 137-8 ; of the insane,
475

Fertilization, not essential condition of repro-
duction, 2, 142

542

THE LAWS OF HEREDITY

Filial regression, law of, 134

Fluctuations, 150, 506 ; blending of, 176 ; as

causes of racial change, 179, 183-4
Food-supply, 269 ; in manufacture of alcohol,

298

Fovea centralis of eye, 412 ; of attention, 413
Fowler, I. , on knowledge by causes, 54
Fowls, Mendelian traits of, 155, 156, 157, 160,

165, 167, 172
Frog, instincts of, 381
Froude, on disease in West Indies, 280
Fry, Sir J., on increase of insanity, 471-2
Function, of cells, i ; of sex, 197 ; definition

of term, 188

GALTON, Sir F., on Law of Ancestral Inheri-
tance, 126 et seq. ; on kinds of inheritance,

^1SI
Gamete, 153

Gametic purity, 157

Garden plants, variability of, 100

Gartner, on latent characters, 176

Genetics, new science of, 188

Geniality, 429

Genius, 426

Geology, systematic, 33

Geometry, 343, 347, 480, 503

Germans, ancient drinking customs, 304-5

Germ-cells, 2 ; potential immortality of, 5 ;
cause of numbers of, 96 ; alleged in-
violability of, 264

Germ-plasm, nature of, 3 ; continuity of, 5,
124, 134 ; quantitative and qualitative
division of, 17-8 ; necessity of thinking in
terms of, 15, 25 ; causation of variations in,
80 et seq. ; resistance to direct action of
environment, 92 et seq. ; as living entity, 98

Germinal selection, 109 ; changes, 221-2

Gibbon, on drinking customs of Ancient
Germans, 304

Gilbey, Sir A., on race-horses, in

Gordon, Dr H. Laing, on drinking in Italy,
301

Gout, transmission of, 74

Gravitation, law of, 47, 352, 360

Greece, drinking in, 300 ; teaching in, 490-1

Growth, factors of, 6, 422, 438 ; of mind and
body compared, 420, 477

Growth-force, 60

Guinea-pigs, susceptibility to tuberculosis,

255
Gulick, Rev. J. T., on snails, 202

H

HABITS, 401 et seq. ; 483, 515
Habituation to toxins, 247, 253
Haemophilia, alleged transmission of, 75
Hair-colour, 145, 428
Hair-texture, 174-5
Halteridium, 81
Hapsburgh lip, 181
Hare, Dr F., on deduction, 30
Hartog, Prof. M., on transmission of acquire-
ments, 74

Harveian Society, on alcoholism, 295
Hawkweeds, parthenogenesis in, 148'
Heart's-ease, evolution of pansy from, 112

Henslow, Prof. G. , on transmission of
acquirements, 74

Hereditary tendencies, definition of, 3 ; altera-
tion of, 79

Heredity, material for study of, 34 ; not an
exact science, 35-6 ; experimental study of,
34 et seq., 184, 510; greater problems of,
216-7

Hermaphrodite, 143, 146 ; human, 146

Herschell, on science, 37

Hewitt, on variations in ducks, 83; on rever-
sion in bantams, 165

Hinny. 157

Hipparion, hoofs of, 123

Hippuris, 60

History, life-, 24

Historians, on disease, 276-7

Hodgson, Dr, on Idealism, 336

Hoffmann, experiments on plants, 83

Homer, on drinking, 300

Horse, retrogression in, 123 ; American trot-
ting, 179 ; latent traits in, 196

Human beings, mutations of, 175, 179 ; racial
differentiation, 180-1 ; racial crossings, 173
et seq., 200-1 ; as subjects for study, 216,
220-1 ; errors about racial changes of, 223 ;
lack of instinctive movements, 378-9 ; distin-
guishing peculiarity, 424 ; adaptability,
381, 428; ways of improving, 438-9; arti-
ficial selection of, 439

Hume, on mind, 335

Hunger, instinct of, 384

Hunter, Dr W., on maternal impressions, 75

Hurst, Mr C. C. , experiments on poultry,
156 ; on rabbits, 163

Huxley, method of work, 185 ; on necessary
truth, 349 ; on science, 351 ; on relation of
mind to body, 356-7 ; on curates, 478

Huxley lecture, 428

Hybridization, almost confined to artificial
varieties, 176

ffydroitte, 27

Hypotheses, 39-40 ; untested, 49-50 ; of
chemists and physicists, 50 ; bathmic, 60 ;
nature of, 512

IDEALISM, definition of, 324 ; thorough going,
333 ; futility of, 334, 336, 338, 360

Idiot, mind of, 389, 425, 465 et seq.

Imagination, the scientific, 52, 89

Imbecility, 53 ; as variation, 425 ; nature, 425,
465 ; in slums, 447 ; causation, 472-3 ; pre-
vention, 475

Imitativeness, 385

Immunity, inborn and acquired, 233, 235, 253,
254, 257 ; conditions of, 237, 248 ; active
and passive, 241 ; Pasteur's hypothesis
243 ; Cheauveau's, 243 ; Behring's, 243 et
seq.; Ehrlich's, 251 et seq.; in acute and
chronic disease, 257 ; inference of conse-
quences from, 258-9 ; evolution of, 225 ;
meaning of term, 309 ; artificially de-
veloped or evolved, 450, 453, 455

Impure dominants, 153

Inborn and acquired characters, true distinc-
tion between, 16-7 ; general failure to dis-
tinguish between, 439-40

INDEX

543

Individual, derivation from ovum, 5-6

Induction, nature of, 42

Inertia, mental, 493

Insanity, the two kinds, 465 ; increase of,
471 ; causation of, 472-3

Instinct, definition of, 374 ; human, 374-5,
383; imitated by acquirements, 400-1,
410 ; extended by acquirements, 422 ; dis-
tinguished from acquirements, 423 ; modi-
fied by acquirements, 423-4 ; for food, 440 ;
to think, 403, 478

Intelligence, and fertility, 138, 478 ; defined,
377 ; measure of, 378 ; distinguished from
reason, 378 ; substituted for instinct, 380
et seq. \ adaptiveness of, 398 , 478 ; Pearson
on, 431 ; relation to size of brain, 434; of
adult compared with that of child, 491

Isolation, physiological, 143, 178, 181

Italy, drinking in, 300-1

JAMES, Prof. W., on science, 351, 360; on
Idealism, 336 ; on separateness of mind
and body, 361 ; on memory, 395

Japan, social and intellectual changes in,
445> 497 5 tuberculosis in, 454

Jealousy, instinct of, 424

Jennings, Mr H. S., on paramoecium, 94
evons, on framing of hypotheses, 42 ; on the

Newtonian method, 52

Jews, ancient intemperance of, 299 ; modern
sobriety, 301 ; mental peculiarities of, 428 ;
effects of urban life on, 448

K

KANT, on mind, 335

Kemp, Rev. D., on drinking in West Africa,

303-4

Kepler, on planetary motion, 43, 48
Kindergarten system, 481
Kingsley, Miss M., on malaria, 235; on

drinking in West Africa, 303
Knowledge, sources of, 338 ; traditional, 381 ;

useful, 478

LABOUR, 479 ; laborious mental training, 479
Laboratory methods, when useful, 33, 35 ;

scope in physics and biology, 49
Lake dwellers, use of alcohol by, 299
Lamarckian hypothesis of evolution, n, 61,
62, 76 ; controversy, 15-6 ; strongest evi-
dence against, 73 ; applied to disease, 259
Landois and Stirling, on ciliary action, 369
Lankester, Sir E. Ray, on retrogression, 22 ;
method of work, 185 ; on alcohol, 297 ; on
size of brain and intelligence, 434 ; on im-
beciles, 469-70

Latency, distinguished from retrogression,
113, 115; temporary, 113; permanent, 114;
of sexual traits, 145, 159, 195 ; of Mendelian
traits, 160 et seq. ; of eye-colour, 174 ; Dar-
win on, 177 ; de Vries on, 177 ; occurs only in
artificial varieties, 176

Latent characters, alternation of, 115-6;
common in artificial varieties, 161 et seq. ;
absent in natural varieties, 275 et seq.

Law, natural, definition of, 47, 348 ; of
Ancestral Inheritance, 126 et seq. ; of filial
regression, 134 ; laws of heredity, 213

Laws, against excessive drinking, 300, 305,
306,458^^^., 465

Leprosy, antiquity of, 269

Lewes, idea of evolution, n ; on intelligence,
406

Life insurance and alcohol, 287, 296

Linnaeus, scientific method, 511

Lobster, lack of memory, 407

Local option, 462, 464

Lock, Mr R. H., on experiment, 31 ; mulat-
tos, 174 ; on study of human species, 180 ;
on claims of Mendelians, 188

Locomotion, power of, effects on number of
varieties, 202

Logic, Port Royal, 42

Love, sexual and parental, 386

Lubbock, on wasps, 418

Lunacy, 466 et seq. , 471

Lycurgus, punishment of drinkers by, 300

M

MACAULAY, on scientific method, 42

M'Gregor, Sir W., on drinking in West
Africa, 302

Mach, on scientific facts, 47

Macpherson, Dr J., on increase of insanity,
47i

Malaria, in pigeons, 81 ; an insect-borne
disease, 229 ; duration of, 234 ; racial re-
sistance to, 235, 309 ; migrations of, 271 ;
evolution against, 309

Male characters, alternation with female
traits, 145 et seq. \ reproduced by female,

113. l65

Man, crossed races of, 173 et seq. ; neglect of,
by biologists, 216, 218 ; place of origin, 269 ;
helplessness at birth, 381 ; differences be-
tween savage and civilized, ancient and
modern, 397; distinction from lower ani-
mals, 404; mental differences between
individuals, 426 et seq.
Manipulation, association with brain, 396
Maoris, mental traits of, 398 ; social state,

427 ; and alcohol, 464
Maspero, on intemperance in Ancient Egypt,

300

Maternal, impressions, 75, 76 ; love, 378, 386
Mathematics, not an experimental science,

36 ; method of, 343 et seq., 503, 509, 517
Mathematical knowledge, factors of, 422
Matter, meaning of term, 324, 354 ; in

motion, 362

Mauritius, invasion of malaria, 271
Medical men, and deduction, 30, 509 ; Royal
Commission on, 74 ; belief in Lamarc-
kianism, 75, 255, 443 ; belief in direct
action of environment on germ-plasm, 81,
84, 264, 448 ; on Jewish mothers, 448 ;
evidence before Royal Commissions, 474 ;
study of heredity, 74

Medical statistics, 81, 84, 264; certificates of
death, 295 ; education, 482

544

THE LAWS OF HEREDITY

Memories, concentrated, 396

Memory, importance of, 325, 330, 338, 377,
380 ; defined, 377, 379, 394, 478 ; evolution
of, 380, 394, 405 ; neglected study of, 389;;
superiority in youth, 394 ; systems for im-
proving, 395 ; organ of, 396 ; conscious and
unconscious, 399 ; range of, 404 ; variations
of, 404, 422 ; in Crustacea, 407 ; in wasps,
418 ; abolished in dreams, 416 ; bearing in
mind, 418 ; distinguished from "memories,"
421 ^defective in the feeble-minded, 425,465 ;
instinct to play with contents of, 403, 478

Mendel, experiments on peas, 152, 158

Mendelian hypothesis, chief points of, 154-
158 ; exceptions to, 159 ; central doctrine
of, 154 ; disproof of, 160 et seq. \ propor-
tions, 153, 158, 167 ; exceptions to propor-
tion, 158 ; inheritance, right interpretation
of, 163, 165, 167 ; inheritance of mutations,
169 ; traits of poultry, 172 ; of peas, 153 ;
sexual and Mendelian traits compared,
189-91 ; Mendelian inheritance a human
creation, 192 ; deductive inference of con-
sequences, 193

Mendelism, not tested by experiment, 184 ;
concerned only with problems of sex, 188 ;
and disease, 280 ; and science, 510

Mental traits, co-adaptation of, 388 et seq.

training, importance of, 435 ; of child,

401, 478 ; of young adults, 481 et seq.

Mercier, Dr C. , on transmission of acquire-
ments, 74 ; on craving for alcohol, 290 ;
on separateness of mind and body, 361

Method, of development, 22, 24 ; of science,
42, 185,345, 351, tfxtetseq.

Methods, exact, 34, 35, 184; experimental
and biometric, 140

Metzger, experiments on maize, 83

Mice, crossed varieties of, 162, 163

Microbes, variations of, 87 et seq. ; cause of
disease, 227 ; evolution of, 88, 266 ; our
power of banishing, 450

Microbic diseases, effects of sanitation, 450

Middle Ages, physicians of, 269 ; social state
of, 497

Migrations of negroes, 265 ; of human races,
181, 270 ; of disease, 270 etseq.

Mill, John Stuart, on deductive method, 48,
213-5, 502> 5T4: on l^e statistical method,
140 ; on matter, 335 ; on knowledge, 343 ;
on the use of hypotheses, 512 ; on con-
troversy, 512-3

Millais, Sir E., on breeding of Basset hounds,
126

Millardet, on false hybrids, 159

Mind, uniqueness of, 325 ; alleged super-
natural origin of, 325 ; not comparable with
matter, 327 et seq. ; growth of in infant,
329 et seq. ; relation to body, 362 ; the work
of the brain, 362 ; relation to expenditure
of energy, 363-4 ; evolution of, 364 ; a pro-
duct of evolution, 369 ; but not a direct
product, 365 ; association with nervous
tissue, 367 ; utility of, 367 ; beginnings of,
368-9, 378, 393 ; a product of Natural
Selection, 368 ; alleged universal presence
of, 368 ; order of evolution, 370, 387, 393,
409; of man, 374 et seq., 377, 426, 444 et
seq. ; bearing in mind, 418 ; development
of, 419 ; growth compared with that of

body, 420, 426 ; effects of training on,
444

Minds, of other people, 333 et seq. ; closed
and open, 492 et seq.

Miracle, 59, 65, 90, 325

Missionaries and disease, 280 ; and alcohol,
302 et seq.

Mitchell, Sir A., on dreams, 417

Modesty, 423

Modifications, 15, 21 ; distinguished from
variations, 79

Mohammedans and alcohol, 460

Monks, cranial capacity of, 435

Morality, 423 ; effects on of temperance legis-
lation, 462 ; of imbeciles, 466

Morgan, Prof. Lloyd, on use acquirements,
72 ; on plasticity, 408

Prof. T. H., on experimentation, 30-1 ;

on latency of Mendelian traits, 160; on
evolution and adaptation, 391

Morocco, social state of, 497

Morrison, Rev. W. D., on crime, 495

Mosaic inheritance, 155

Mothers, Jewish, 448

Mulatto, skin colour, 174

Mule, 157

Multicellular organisms, i

Murray, David Christie, on crime, 494

Mutilations, alleged transition of, 75

Mutation, meaning of term, 170

Mutations, 22, 151 ; alleged stability of, 150,
169-70, 171, 179, 183; human, 175, 179,
181; in wild nature, 179; ofO. lamarckiana,
179 ; inutility of, 179 ; reproduced in the
mode of sexual traits, 189 et seq. ; blending
of, 195-6 ; retrogression of, 171, 196

Mutation hypothesis, 150, 169 ; grounds for
maintaining, 175-6 ; grounds for rejecting,
181 et seq. , 199 ; not tested by experiment.
184 ; inference of consequences from, 194 ;
and reflexes, 373 ; and mind, 388 ; and
palaeontology, 392

Mutationists and biometricians, 150

N

NAMES, importance of, 18

Narcissus, from cross between jonquil and

daffodil, 156

Narcotics, immediate and remote effects, 306
Natural Selection, theory, contrasted with

Lamarckian hypothesis, 66 et seq. ; objec-
tions to, 107, 185, 391
Natural varieties, blending of when crossed,

176 ; lack of latent traits, 176
Nature and Nurture, 421, 429
Naudin, on crossed artificial varieties, 177
Necessary truth, 47, 346, 349
Negro, teeth of, 224 ; and malaria, 234 ; and

alcohol, 302 et seq. ; migrations of, 265
Nervous tissue, association with mind, 367 ;

evolution of, 370
Neutralization of toxins, hypothesis of, 243

et seq.
New Zealand, aborigines of, 427 ; temperance

legislation in, 464
Newton, on orbit of moon, 43 ; scientific

method, 52 ; on gravitation, 352 ; compared

with Darwin, 505-6

INDEX

545

Nicotine, a toxin, 243, 307

Nucleus, of cell, the bearer of heredity, 3

Nutriment, as material for growth, 6 ; as

stimulus, 7 ; and inborn traits, 14-16 ;

alleged cause of variations, 99

O

OBSCURED facts, 33

Offspring, relation to parent, 5

Old age, mind in, 421

Opium, a toxin, 243, 307 ; toleration of, 247 ;

racial susceptibility to, 306-7 ; evolution

against, 309 ; compared to malaria, 308 ;

substituted for alcohol, 460, 462
Organisms, unicellular and multicellular, i ;

primitive, 9
Orthodoxy, in religion, mental influence of,

492 et $eq.

Orton, Mr J. H., on hermaphroditism, 114
Osborn, Prof. H. F., on acquirements, 72 ;

method of work, 185 ; on plasticity, 408

PAGANS, ancient, social state and religion,
427 ; mental training of, 490, 500

Palaeontology, 392

Palm wine, 299

Pandemics, 272, 275, 452

Pangenesis, hypothesis of, 5, 66

Pansy, evolution of, 112

Parasites, evolution from saprophytes, 87

Parental affection, 386, 424.

Parsimony, law of, 60, 100, 166 ; of nature,
96, 138, 196, 202, 402; how caused, 118 et
seq., \wetseq.

Parthenogenesis, 2, 142 ; variations occurring
in, 147 ; and Mendelian reproduction, 188 ;
conditions of occurrence, 204

Parthenogenetic types, stability of, 201

Particulate inheritance, 151

Pasteur, on rabies, 240 ; on anthrax, 240 ; on
immunity, 243

Patency of sexual traits, 159 ; of Mendelian
traits, 60 et seq.

Pearl, Dr, on paramoecium, 93

Pearson, Prof. Karl, on science, 37 ; on
variability, 94, 149 ; on Filial Regression,
134 ; on metaphysicians, 335 ; on natural
law, 351 ; inheritance of mental and moral
traits, 428

Peas, Mendel's experiments on, 152 ; Men-
delian characters of, 153 ; sweet, compound
characters of, 161

Perception, 326 ; limits of, 340

Pestilence, 276

Phagocytes, functions of, 231-2, 247

Phylloxera, 276

Physics, study of, compared to biology, 30,
34, 51, 211, 505 ; as exact science, 35, 48,
50, 345 ; as deductive science, 214, 503

Physiological isolation, 143, 178, 181

Pictet, experiments on butterflies, 83

Pigeons, Ewart's experiments on, 81, 85;
latent traits in pure breeds, 165

Pittacus, on drunkenness, 300

Plague, human, 271, 276; rabbit, 275

35

Plants, regeneration in, n; stability when
propagated by cuttings, 94; retrogression
in, 121 ; reversion in, 156

Play, function of, 384, 403, 478

Pleasure in obeying instincts, 479

Pleasure and pain, evolution of, 371 ; associa-
tion with the will, 373

Pliny, on drunkenness in ancient Rome, 301

Poisoning, by microbes, 230 ; by alcohol,
306, 456

Polar bodies, 131

Polish fowls, 146, 189

Population, pressure of, 269

Poultry, Mendelian traits of, 155, 156, 157,
160, 167, 172 ; blending of Mendelian traits,
160

Predominance of retrogressive variations, 109,
in, 197, 220

Prejudice, denned, 492

Prejudices, biological, 32, 511 ; religious, 492

Prepotency, meaning of term, 195

rimitive organisms, 9
I Primrose, evening, 179

Probity, inheritance of, 429

Problems of heredity, the greater, 217 ;
practical, 446

Progression, conditions of, in ; of human
races, 223

Progressive traits, 22

Prohibition in China, 306, 459 ; among Mo-
hammedans, 460 ; in United States, 461

Properties of objects, 339-341

Protoplasmic movements, 371

Prototypes of embryo, 27, 119 et seq.

Public health, statistics of, 136, 264, 281

Punnett, Mr R. C., on stability of mutations,
169-170

Pure dominants, 153, 157; recessives from,
158

Pure races, Mendelian traits in, 165

Purim, feast of, 299

Purity, gametic, 154

R

RABBITS, Ewart's experiments on, 82, 85 ;
effects of crossing, 162 ; lethal dose of an-
thrax, 86

Rabies, cure of, 239, 245, 246

Races, human, differentiation of, 181 ; rapid
mental change of, 427, 497

Racial, change, definition, 221 ; inferiority,

497

Reality, deductive appeal to, 41

Reason, defined, 377 ; distinguished from
instinct and intelligence, 378

Reasoning, nature of, 340

Recapitulation, of parental development, 21 ;
of the evolution of the race, 24 et seq., 116
et seq., 250, 268, 387 ; occurs only amongst
multicellular types, 23 ; inaccuracy of, 25,
118 et seq. ; evidence furnished by embryo,
28 ; correct method of proving, 54, 505 ;
utility of, 57 ; of ancestors, 125 ; Prof.
Turner on, 517 et seq.

Recessives, 153 ; dominants from, 158

Reduction of chromosomes, 131

Reflexes, 371 ; imitated by automatic actions,
411 ; distinguished from instincts, 374

Reformation, the Protestant, 427, 497

546

THE LAWS OF HEREDITY

Regeneration, 10

Regression, filial, 134

Reid, Archdall, on Mendelian hypotheses,

174, 180; on imbecility, 470; on mental

deterioration, 474 ; on scientific method,

S.I7

Rejuvenescence, 147
Relations between facts, 38, 46
Religion, mental effects of, 427 ; and science.

488
Religious teaching, mental effects of, 486,

488

Renaissance, the, 427
Reproduction, alternative, 145, 149 ; blended,

149, 193, 195

Resemblance between parents and offspring,
21

Retrogression, explanations of, 108 ; con-
ditions of, no; the cause of total loss of
traits, 115 ; identical with reversion, 116 ;
utility of, 119 ; part played in evolution by,
121 . 533 I causation of, 122 ; of mutations,
171, 196; caused by blending, 197 et seq. ;
of human races, 223 ; of instincts, 380, 384 ;
in relation to alcohol, 458

Reversion, the two kinds, 117 ; masking of,
117 ; in pure races, 165 ; of imbeciles, 425,
470

Reversed, selection, 108 ; function of, 123

Revitilization by conjugation, hypotheses of,
147

Richet, on memory, 406

Ricin, acquired toleration of, 247

Ridge, Dr J. , on alcohol, 296

Rinderpest, 275

Romans, rise and fall of, 427

Romanes, on evolution, n ; on transmission
of acquirements, 62 ; on memory, 406-7

Roux, experiments on serum, 240

Rowntree and Sherwell, on temperance legis-
lation, 462 et seq.

Royal College of Physicians, description of
the feeble-minded, 467

Royal Commission, medical evidence before,
74, 444, 484 ; on tuberculosis, 454 ; Canadian,
on intemperance, 464 ; on Care and Control
of the Feeble-minded, 467 et seq,

Russia, drinking in, 320

SAMUELSON, on drinking in Greece, 300 ; in

West Africa, 304 ; in Germany, 304-5 ; in

China, 306

Sanders, Miss, on segregation, 154
Sanitation, improvement of, 227, 273, 277 ;

external and internal, 450
Saprophyte, evolution into parasite, 88, 266 ;

retrogression from parasite, 88
Savages, food supply of, 269 ; and alcohol,

298, 306 ; English child trained by, 420,

430 ; instincts of, 423 ; religion of, 488
Scarlet fever, infectivity of, 228
Schools, epidemic disease in, 273 ; influence

on children, 430, 433, 481 ; biological, 31,

School-master, aims of, 479
Schopenhauer, on mind, 335
Science, nature of, 36 et seq. ; warp and woof
°f> 355. 511 ; antagonisms to religion, 488

Sciences, differences between, ^etseq., 502 et
seq.; exact, 35 et seq. ; the most scientific, 47,
345; deductive, 47, 213 et seq., ^o^efseq.,
514 ; systematic, 354, 502

Scientific distinguished from science teaching,
502

Scott, Dr D. H., on adaptation, 392

Sebright bantam, 146, 165, 189

Sectarian differences, definition of, 32 ; in
biology, 32, 508-9

Segregation of allelomorphs, 153 ; the central
doctrine of Mendelism, 154; disproof of,
165, 173 et seq.

Selection, natural distinguished from artificial,
r77 I by violent death, 66 ; by slow decay,
67 ; when operative, 92 ; among germ-cells,
96 ; varyirig stringency of, no et seq., 256,
296 ; experimental evidence, 73 ; by disease
and alcohol, 98 ; by alcohol and opium,
309 ; in slums, 447 ; effects attainable by,
450 ; test of, 222 ; germinal, 109 ; reversed,
108, 123 ; function of, 202, 529 ; human,
224

Selection theorist, 151, 390 et seq.; inference
consequences from, 194-5

Selective breeding, human, 439

Self-control, 290, 425

fertilization, 2, 194, 204

Sensations, 370 ; caused by alcohol, 285, 287
et seq.

Senses of civilized man, 223

Sense-impressions, 332 et seq. , 338

Serum, antitoxic, preparation of, 240 ; nature
of, 248

Sex, an adaptation, 144 ; effects of, 188, 193 ;
function of, 144, 148, 149, 193, 197, 199,
202, 204, 209, 389 ; diagrammatic repre-
sentation of, 517 et seq.

Sexual traits, latency of, 113, 145 ; trans-
ference to opposite sex, 146 ; alternation
of, 145, 159, 189 ; dominance of, 189 ;
normal blending of, 195 ; abnormal blend-
ing of, 146 ; transmission of, 523

dimorphism, 142

beauty, appreciation of, 423

Sherwell and Rowntree, on temperance legisla-
tion, 462 et seq.

Sight, sense of, 327

Skill in thinking, 339, 342, 400, 401 et se-/..
485 et seq., 500 et seq., 504, 511

Skin colour, reproduction of, 174

Sleeping sickness, 229, 271

Slums, 39 ; prevalence of disease in, 257, 275 ;
alcoholism in, 296 ; physical deterioration
in, 446 et seq.

Small-pox, 273 ; change to cow-pox, 238

Smith, Mr Geoffrey, on Rhizocephala, 114

Snails, differentiation of, 181, 202

Snake venom, attenuation of, 242, 247

Sneezing, 371

Solon, condemnation of intemperance, 300

Somatic cells, relations to germs, 3, 5 ; re-
sisting power of idio-plasm, 94 ; function
of, 124

Space, knowledge of, how acquired, 330, 341

Spanish plantations in West Indies, 280;
empire in America, 282

Spartans, drinking customs, 300

Species, ever-sporting, 180

Specific mean, 66

INDEX

547

Speculation, 355, 506; legitimacy of, 507

Speech, 396, 422

Spencer, Herbert, theory of evolution, n ;

on living body as crystal, 65 ; on evolution

of higher animals, 72 ; on memory, 406
Sperms, union with ova, 2 ; equivalent with

ova as bearers of heredity, 2 ; traits of, 143
Sports, or large variations, 22
Sporting instinct, 384
Stability of type, 526
Stag, horns of, 10
Stagnation, mental, 427
Starvation, effects of on mother and foetus, 441
Statistics, vital, 224
Sterility, on blending of alternative traits in,

190
Stimulus for growth, 6, 7, 8, 438 ; nutriment

as, 8 ; use as, 7, 11-13 5 injury as, 7, 9-11
Stone age, diseases in, 275
Stupidity, natural, 381, 425 ; artificial, 439,

477, 494
Succession, invariable, 336 ; necessary, 337,

343

Sucking in infants, 383
Sugar, in manufacture of alcohol, 457
Sullivan, Dr W. C., 315 et seq., 318 et seq.
Superficial thinking, 15, 76
Superstition, defined, 492
Susceptibility of germ-plasm to environment,

66 ft seq., 98 ; to charm of alcohol, 289,

293» 457

Sutton & Co., on culture of plants, 112
Symbolism, mental, 327
Syphilis, alleged inheritance of, 75, 242 ;

duration of, 234 ; recovery from, 249 ;

antiquity of, 269 ; migrations of, 270
Systematists, rejection of Darwin's work by,

506
Systematic sciences, 39, 354, 504

TEACHER, the skilful, 481

Teaching, for the professions, 482 et seq.\
biological, 484, 510 et seq. ; religious, 486 et
seq. ; classical, 501 ; science, 502 ; scientific,
489,502

Teeth, human, 223

Telegony, 75-6

Tests, for hypotheses, 39, 345

Texas, fever of cattle, 82, 275

Think, instinct to, 403, 478

Thinking, in terms of germ-plasm, 15, 25 ;
means for securing accuracy, 42 et seq.\
coherent, origin of, 330, 340 ; skill in, 339,
342, 400, 401, 485 etseq., yx>et seq., 504, 511

Thirst, 285, 286, 384

Thought, limits of, 340

Tickling, 371

Tobacco, racial effects of, 308

Toleration, of poisons, 245, 247 ; of opinion,

497

Tonga, morals in, 423
Towns of Europeans in Asia and Western

Hemisphere, 280
Toxins, evolution of, 88 et seq. ; counter-, 231 ;

intra- and extra-cellular, 232, 237, 253 ;

produced by plants and higher animals,

242 ; toleration of, 245, 247

Traditional knowledge, 381, 397

Training, mental, possibilities of, 477, 483 ;
in school-room, 479

Transmission or transmutation of acquire-
ments, 19, 61 et seq., 251, 258

Truths, necessary, 344, 346 et seq., 349

Tse-tze fly, 275

Tuberculin, 253

Tuberculosis, microbes of, 229 ; recovery
from, 233 ; spread of, 274, 279 ; compared
to alcohol, 308; effects of sanitation, 450,
453 ; human and bovine, 453

Tugwell, Bishop, on drinking in West Africa,

303

Turner, Prof. H. H., on New Euclidians,
344; on resemblance and divergence from
parents, 517 ; on the influence of sex, 520
et seq. ; on assertive mating, 521 ; on trans-
mission of sexual traits, 523 ; on stability
of type, 526 , on abbreviation of life-history,
527 ; on natural selection, 529 ; on retro-
gressive tendency, 533

Twins, identical, 17

U

UEBERWEG, on crucial instances, 165

Understanding, nature of, 349

Unicellular organism, i

United States, temperance legislation in, 461
et seq.

Units, ancestral, 124

Urban conditions, 448

Use, as stimulus for growth, 7, n et seq.t
442-3 ; mistaken idea about, n et seq. ;
not stimulus for growth of all characters,
12, 89 ; hypertrophy of brain from, 396

Use-acquirements, utility of, 69 et seq. , 389 ;
magnitude of, 7, 71 ; limited to higher
organisms, 12, 90 ; in disease, 247, 253

Utility, of old-established traits, 112

VACCINIA, 239, 248, 273

Variability, 98 et seq. ; an adaptation, 100 el
seq. ; established by Natural Selection, 102 ;
biometric investigations, 138 ; occurring
apart from conjugation, 147 ; diagram-
matic representation of, 518, et seq.

Variations, from parents, 21, 80, 196; pro-
gressive and retrogressive, 22, 220 ; con-
tinuous and discontinuous, 22, 150 ; nature
of, 21-22 ; interpolated, 26 ; difficulty of
accounting for, 58 ; distinguished from
modifications, 22, 78 ; spontaneous, 79 ;
caused by direct action of environment, 79,
92, 96 ; of unicellular organisms, 89 et seq. \
place of occurrence, 102-3 ; bud-, 103 ; cause
of, 105, 147-8, 259, 474 ; elimination of use-
less, 118; in parthenogenesis, 147-8; defini-
tion of, 438

Varieties, crossings of natural and artificial,
173 et seq. ; relative numbers of, 202

Veil of familiarity, 13

Vernon, Dr H. M., on correlated traits, 70 ;
on experiments on beans, 84 ; on Law on
Ancestral Inheritance, 128, 130 ; on Natural
Selection, 136; on reversion in plants, 156

THE LAWS OF HEREDITY

Vestigial structures, 27, 108

Virulence, evolution of, 88

Voluntary action, 371 et seq. ; defined, 376

Vries, Prof. H. de, on variations of dandelion
and hawk weed, 148, 201 ; on mutation
theory, 151 ; on Mendelian phenomena,
166 ; on latency, 177 ; on mutations of O.
lamarckiana, 179 ; on correlated mutations,
182

W

WALCHEREN, British expedition to, 261
Walker, Mr C. E., experiments on hens, 114;

on chromosomes, 131
Wallace, Alfred Russel, on transmission of

acquirements, 61 ; method of work, 185 ;

on snails, 202 ; on evolution of mind, 397 ;

on Darwin, 506

Wallace, Mr J.^Sims, on teeth, 224
Warren, Dr E., on variations in Daphnia

magna and aphides, 148
Wasp, memory in, 418
Waterton, on male traits in hens, 113
Weismann, experiments on butterflies, 83 ; on

continuity of germ-plasm, 124 ; on criminal

selection, 109 ; on revitilization, 147; method

of work, 185
Weldon, Prof. W. F. R., on the Law of

Ancestral Inheritance, 130
Welton, Prof. J., on universe as systematic

unity, 37 ; on hypothesis and proof, 39-40 ;

on scientific method, 42 ; on proof, 46 ; on

natural law, 46, 348, 352 ; on crucial

instances, 164

West Indies, disease in, 280

Whewell, on scientific method, 41 ; on hypo-
theses, 48 ; on gravitation, 49 ; on mathe-
matical axioms, 347

Whichura, on crossed natural varieties, 177

Wicking, on latent traits in pigeons, 116

Will, the, 373, 374 et seq. ; association with
attention, 414

Williams, The Hon. Mr Sapira, on drinking
in West Africa, 302

Wine, sacramental, 304

Working hypotheses, 39

Wright, Dr Strethill, on Hydraidae, 27

Written symbols, 397

Wundt, on origin of mind, 368

YEAST, production of alcohol by, 457

Yellow fever, 272

Youatt, on sheep, 70

Yule, Mr Udney, on Law of Ancestral Inheri-
tance, 129-30; on experimental crossing,
205

ZEBRA, crossed with horse, 156, 196
Zoology, systematic, 33 ; method by which~.it

is created, 504
Zygote, 153
Zymotic disease, 227

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FICTION

29

The Novels of Alexandre Dumas.

Medium Svo. Price 6d. Double Volumes, it.

ACTS!.

THE ADVENTURES OF CAPTAIN PAMPHILK,

AMAURY.

THE BIRD OF FATB.

THE BLACK TULIP.

THB CASTLE OF EFPSTEW.

CATHERINE BLUM.

CECILS.

THE CHATELET.

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CHICOT THE JESTER.

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THE CONVICT'S SON.

THE CORSICAN BROTHERS; and OTHO THB
ARCHER.

CROP-EARED JACQUOT.

DOM GORENFLOT.

THE FATAL COMBAT.

THE FENCING MASTER.

FERNANDE.

GAHRIEL LAMBERT.

GEORGES.

THE GREAT MASSACRK.

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ROBIN HOOD.

SAMUEL GELB.

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I KNOW A MAIDEN.
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Austen (J.). PRIDE AND PREJUDICE.

Bagot (Richard). A ROMAN MYSTERY.
CASTING OF NETS.
DONNA DIANA.

Balfour (Andrew). BY STROKE OF
SWORD.

Baring-Gould (S.). FURZE BLOOM.

CHEAP JACK ZITA.

KITTY ALONE.

URITH.

THE BROOM SQUIRE.

IN .THE ROAR OF THE SEA.

NOEMI.

A BOOK OF FAIRY TALES. Illustrated

LITTLE TU'PENNY.

WINEFRED.

THE FROBISHERS.

THE QUEEN OF LOVE.

METHUEN AND COMPANY LIMITED

ARMINELL.

BLADYS OF THE STEWPONEY.

Barr (Robert). JENNIE BAXTER.
IN THE MIDST OF ALARMS.
THE COUNTESS TEKLA.
THE MUTABLE MANY.

Benson (E. F.). DODO.
THE VINTAGE.

Bronte (Charlotte). SHIRLEY.

Brownell (C. L.). THE HEART OF
JAPAN.

Burton (J. Bloundelle). ACROSS THE
SALT SEAS.

Caffyn (Mrs.). ANNE MAULEVERER.

Capes (Bernard). THE LAKE OF
WINE.

Clifford (Mrs. W. K.). A FLASH OF

SUMMER.
MRS. KEITH'S CRIME.

Corbett (Julian). A
GREAT WATERS.

BUSINESS IN

Croker (Mrs. B. M.). ANGEL.
A STATE SECRET.
PEGGY OF THE BARTONS.
JOHANNA.

Dante (Alighierl). THE DIVINE

COMEDY (Cary).

Doyle (A. Conan). ROUND THE RED
LAMP.

Duncan (Sara Jeannette). A VOYAGE

OF CONSOLATION.
THOSE DELIGHTFUL AMERICANS.

Eliot (George). THE MILL ON THE
FLOSS.

Findlater (Jane H.). THE GREEN
GRAVES OF BALGOWRIE.

Gallon (Tom). RICKERBY'S FOLLY.

Gaskell (Mrs.)- CRANFORD.
MARY BARTON.
NORTH AND SOUTH.

Gerard (Dorothea). HOLY MATRI-
MONY.

THE CONQUEST OF LONDON.
MADE OF MONEY.

Gisslng (G.). THE TOWN TRAVELLER.
THE CROWN OF LIFE.

Clanville (Ernest).

TREASURE.
THE KLOOF BRIDE.

THE INCA'S

Gleig (Charles). BUNTER'S CRUISE.

Grimm • (The Brothers). GRIMM'S
FAIRY TALES.

Hope (Anthony). A MAN OF MARK.

A CHANGE OF AIR.

THE CHRONICLES OF COUNT

ANTONIO.
PHROSO.
THE DOLLY DIALOGUES.

Hornung (E. W.). DEAD MEN TELL
NO TALES.

Ingraham (J. H.). THE THRONE OF

igranan
DAVID.

Le Queux (WA THE HUNCHBACK
OF WESTMINSTER.

Levett-Yeats (S. K.). THE TRAITOR'S

WAY.
ORRAIN.

Linton (E. Lynn). THE TRUE HIS
TORY OF JOSHUA DAVIDSON.

Lyall (Edna). DERRICK VAUGHAN.

Malet (Lucas). THE CARISSIMA.
A COUNSEL OF PERFECTION.

Mann (Mrs. M. E.). MRS. PETEB

HOWARD.
A LOST ESTATE.
THE CEDAR STAR.
ONE ANOTHER'S BURDENS.
THE PATTEN EXPERIMENT.
A WINTER'S TALE.

Marchmont (A. W.). MISER HOAD^

LEY'S SECRET.
A MOMENT'S ERROR.

Marryat (Captain). PETER SIMPLE.
JACOB FAITHFUL.

March (Richard). A METAMORPHOSIS,
THE TWICKENHAM PEERAGE.
THE GODDESS.
THE JOSS.

Mason (A. E. W.). CLEMENTINA,

Mathers (Helen). HONEY.

GRIFF OF GRIFFITHSCOURT.

SAM'S SWEETHEART.

THE FERRYMAN.

Meade (Mrs. L. T.). DRIFT.

Miller (Esther). LIVING LIES.

Mitford (Bertram). THE SIGN OF THE

SPIDER.
Montresor (F. F.). THE ALIEN

FICTION

Morrison (Arthur). THE HOLE IN
THE WALL.

Nesbit (E.). THE RED HOUSE.

Norris (W. E.). HIS GRACE.
GILES INGILBY.
THE CREDIT OF THE COUNTY.
LORD LEONARD THE LUCKLESS.
MATTHEW AUSTEN.
CLARISSA FURIOSA.

Oliphant (Mrs.). THE LADY'S WALK.
SIR ROBERT'S FORTUNE.
THE PRODIGALS.
THE TWO MARYS.

Oppenheim (E. P.). MASTER OF MEN.

Parker (Gilbert). THE POMP OF THE

LAVILETTES.

VVHENVALMOND CAME TO PONTIAC.
THE TRAIL OF THE SWORD.

Pemberton (Max). THE FOOTSTEPS

OF A THRONE.
I CROWN THEE KING.

Phillpotts (Eden). THE HUMAN BOY.
CHILDREN OF THE MIST.
THE POACHER'S WIFE.
THE RIVER.

TH#E£oLQFUl"er C°Uehl- THE

Ridge (W. Pett). A SON OF THE STATE.

LOST PROPERTY.

GEORGE and THE GENERAL.

ERB.

Russell (W. Clark). ABANDONED.
A MARRIAGE AT SEA.
MY DANISH SWEETHEART.
HIS ISLAND PRINCESS.

Sergeant (Adeline). THE MASTER OF

BEECHWOOD.
BALBARA'S MONEY.
THE YELLOW DIAMOND.
THE LOVE THAT OVERCAME.

c (Mrs. Alfred). THE KINS

Surtees (R. S.). HANDLEY CROSS.
MR. SPONGE'S SPORTING TOUR.
ASK MAMMA,

Watford (Mrs. L. B.). MR. SMITH.

COUSINS.

THE BABY'S GRANDMOTHER.

TROUBLESOME DAUGHTERS.

Wallace (General Lew). BEN-HUR
THE FAIR GOD.

Watson (H. B.SMarriott). THE ADVEN

TURERS.

•CAPTAIN FORTUNE.

Weekes (A. B.). PRISONERS OF WAR.

Wells (H. G.). THE SEA LADY.

White (Percy). A PASSIONATE PIL-
GRIM.

PRINTED BY

WILLIAM CLOWES AND SONS, LIMITED
LONDON AND BECCLES.

Reid

The laws of heredity

431
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