Animal Behaviour

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Title: Animal Behaviour
Author: Morgan, C. Lloyd (Conwy Lloyd)
Language: English
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ANIMAL BEHAVIOUR

BY
C. LLOYD MORGAN, F.R.S.

AUTHOR OF “THE SPRINGS OF CONDUCT,” “HABIT AND INSTINCT,”
“PSYCHOLOGY FOR TEACHERS,” ETC. ETC.

_ILLUSTRATED_

SECOND EDITION
THIRD IMPRESSION

LONDON
EDWARD ARNOLD
1920
(_All rights reserved_)

PREFACE TO THE FIRST EDITION

My book on “Animal Life and Intelligence” being out of print, I
undertook to revise it for a new Edition. As the work of revision
proceeded, however, it appeared that the amended treatment would not
fall conveniently under the previous scheme of arrangement. I therefore
decided to write a new book under the title of “Animal Behaviour.” A
few passages from the older work have been introduced, and some of the
observations and conclusions already published in greater detail in
“Habit and Instinct” have been summarized. But it will be found that
these occupy a relatively small space in the following pages.

C. LL. M.

UNIVERSITY COLLEGE, BRISTOL,
OCTOBER 1_st_, 1900.

CONTENTS

CHAPTER I

_ORGANIC BEHAVIOUR_

PAGE

I. BEHAVIOUR IN GENERAL 1
II. BEHAVIOUR OF CELLS 3
III. CORPORATE BEHAVIOUR 14
IV. THE BEHAVIOUR OF PLANTS 24
V. REFLEX ACTION 31
VI. THE EVOLUTION OF ORGANIC BEHAVIOUR 35

CHAPTER II

_CONSCIOUSNESS_

I. THE CONSCIOUS ACCOMPANIMENTS OF CERTAIN ORGANIC CHANGES 42
II. THE EARLY STAGES OF MENTAL DEVELOPMENT 48
III. LATER PHASES IN MENTAL DEVELOPMENT 56
IV. THE EVOLUTION OF CONSCIOUSNESS 61

CHAPTER III

_INSTINCTIVE BEHAVIOUR_

I. DEFINITION OF INSTINCTIVE BEHAVIOUR 63
II. INSTINCTIVE BEHAVIOUR IN INSECTS 71
III. THE INSTINCTIVE BEHAVIOUR OF YOUNG BIRDS 84
IV. THE CONSCIOUS ASPECT OF INSTINCTIVE BEHAVIOUR 98
V. THE EVOLUTION OF INSTINCTIVE BEHAVIOUR 106

CHAPTER IV

_INTELLIGENT BEHAVIOUR_

I. THE NATURE OF INTELLIGENT BEHAVIOUR 117
II. INTELLIGENT BEHAVIOUR IN INSECTS 123
III. SOME RESULTS OF EXPERIMENT 134
IV. THE EVOLUTION OF INTELLIGENT BEHAVIOUR 155
V. THE INFLUENCE OF INTELLIGENCE ON INSTINCT 168

CHAPTER V

_SOCIAL BEHAVIOUR_

I. IMITATION 179
II. INTERCOMMUNICATION 193
III. SOCIAL COMMUNITIES OF BEES AND ANTS 205
IV. ANIMAL TRADITION 220
V. THE EVOLUTION OF SOCIAL BEHAVIOUR 225

CHAPTER VI

_THE FEELINGS AND EMOTIONS_

I. IMPULSE, INTEREST, AND EMOTION 235
II. PLAY 248
III. COURTSHIP 258
IV. ANIMAL “ÆSTHETICS” AND “ETHICS” 270
V. THE EVOLUTION OF FEELING AND EMOTION 282

CHAPTER VII

_THE EVOLUTION OF ANIMAL BEHAVIOUR_

I. THE PHYSIOLOGICAL ASPECT 295
II. THE BIOLOGICAL ASPECT 305
III. THE PSYCHOLOGICAL ASPECT 315
IV. CONTINUITY IN EVOLUTION 324

INDEX 338

ILLUSTRATIONS

FIG. PAGE

1. _Paramecium_. (From “Animal Biology.” Longmans) 4

2. Behaviour of Paramecia. (After Jennings, _American Journal of
Psychology_) 8

3. Cell-division. (From “Animal Biology.” Longmans) 13

4. Wapiti with antlers in velvet. (Drawing by Mr. Charles Whymper,
after photograph by Miss Reynolds) 16

5. Wapiti with velvet shredding off. (Drawing by Mr. Charles Whymper,
after photograph by Miss Reynolds) 17

6. Sun-dew leaf and tentacles. (From Darwin’s “Insectivorous Plants.”
Murray. By kind permission of Mr. Francis Darwin, F.R.S.) 26

7. Venus’s Fly-trap. (From Darwin’s “Insectivorous Plants.” Murray. By
kind permission of Mr. Francis Darwin, F.R.S.) 27

8. Flower of _Valisneria_ 28

9. Flower of _Catasetum_ 30

10. Flower of _Catasetum_ dissected. (From Darwin’s “Fertilization
of Orchids.” Murray. By kind permission of Mr. Francis
Darwin, F.R.S.) 31

11. Solitary Wasp stinging Caterpillar. (After Plate III. in Dr. and
Mrs. Peckham’s “Solitary Wasps”) 75

12. Solitary Wasp dragging a Caterpillar to its Nest. (After Plate IV.
in Dr. Peckham’s “Solitary Wasps”) 76

13. Insect Larvæ: _Sitaris_, _Argyromœba_, and _Leucopsis_. (After
Fabre “Souvenirs”) 80

14. Yucca Flower and Moth 83

15. Newly-hatched Chick swimming. (Drawn by Mr. Charles Whymper, after
instantaneous photographs and a sketch by the author) 85

16. Nestling Megapode. (From Dr. R. Bowdler Sharpe’s “Wonders of the
Bird World.” Wells Gardner) 87

17. Cuckoo ejecting Meadow Pipit. (From Mrs. Hugh Blackburn’s sketch
in “Birds from Moidart.” David Douglas) 91

18. Leaf-case of Birch-weevil 121

19. Solitary Wasp using a stone as a tool. (After Plate V. in Dr.
Peckham’s “Solitary Wasps”) 127

20. Spiders placed by Solitary Wasps in crotches of branching stems.
(After Plate X. in Dr. Peckham’s “Solitary Wasps”) 133

21. Fox-terrier lifting the latch of a gate. (Drawn by Mr. Charles
Whymper, after a photograph by Miss Alice Worsley) 145

22. Cage used by Dr. Thorndike. (After figure in “Animal
Intelligence,” _Psychological Review_, 1898) 148

23. Diagram illustrating Dr. Thorndike’s Experiments. (Based on
data given in his monograph on “Animal Intelligence”) 150

24. Wood ant. (From Shipley’s “Invertebrates.” A. & C. Black) 207

25. Beetle soliciting food from Ant. (After Wasmann. Enlarged) 213

26. Honey-pot Ant. (Enlarged) 215

ANIMAL BEHAVIOUR

CHAPTER I

_ORGANIC BEHAVIOUR_

I.--BEHAVIOUR IN GENERAL

We commonly use the word “behaviour” with a wide range of meaning. We
speak of the behaviour of troops in the field, of the prisoner at the
bar, of a dandy in the ball-room. But the chemist and the physicist
often speak of the behaviour of atoms and molecules, or that of a gas
under changing conditions of temperature and pressure. The geologist
tells us that a glacier behaves in many respects like a river, and
discusses how the crust of the earth behaves under the stresses to
which it is subjected. Weather-wise people comment on the behaviour
of the mercury in a barometer as a storm approaches. Instances of
a similar usage need not be multiplied. Frequently employed with a
moral significance, the word is at least occasionally used in a wider
and more comprehensive sense. When Mary, the nurse, returns with the
little Miss Smiths from Master Brown’s birthday party, she is narrowly
questioned as to their behaviour; but meanwhile their father, the
professor, has been discoursing to his students on the behaviour
of iron filings in the magnetic field; and his son Jack, of H.M.S.
_Blunderer_, entertains his elder sisters with a graphic description of
the behaviour of a first-class battle-ship in a heavy sea.

The word will be employed in the following pages in a wide and
comprehensive sense. We shall have to consider, not only the kind
of animal behaviour which implies intelligence, sometimes of a high
order; not only such behaviour as animal play and courtship, which
suggests emotional attributes; but also forms of behaviour which, if
not unconscious, seem to lack conscious guidance and control. We shall
deal mainly with the behaviour of the animal as a whole, but also
incidentally with that of its constituent particles, or cells; and we
shall not hesitate to cite (in a parenthetic section) some episodes of
plant life as examples of organic behaviour.

Thus broadly used, the term in all cases indicates and draws attention
to the reaction of that which we speak of as behaving, in response
to certain surrounding conditions or circumstances which evoke the
behaviour. The middy would not talk of the behaviour of his ship as
she lay at anchor in Portland harbour; the word is only applicable
when there is action and reaction as the vessel ploughs through a
heavy sea, or when she answers to the helm. Apart from gravitation the
glacier and the river would not “behave in a similar manner.” Only
under the conditions comprised under the term “magnetic field” do iron
filings exhibit certain peculiarities of behaviour. And so, also, in
other cases. The behaviour of cells is evoked under given organic or
external conditions; instinctive, intelligent, and emotional behaviour
are called forth in response to those circumstances which exercise a
constraining influence at the moment of action.

It is therefore necessary, in a discussion of animal behaviour, that we
should endeavour to realize, as far as possible, in every case, first,
the nature of the animal under consideration; secondly, the conditions
under which it is placed; thirdly, the manner in which the response is
called forth by the circumstances, and fourthly, how far the behaviour
adequately meets the essential conditions of the situation.

II.--BEHAVIOUR OF CELLS

From what has already been said it may be inferred that our use of
the term “behaviour” neither implies nor excludes the presence of
consciousness. Few are prepared to contend that the iron filings in a
magnetic field consciously group themselves in definite and symmetrical
patterns, or that sand grains on a vibrating plate assemble along
certain nodal lines because they are conscious of the effects of the
bow by which the plate is set in sounding vibration. But where organic
response falls under our observation, no matter how simple and direct
that response may be, there is a natural tendency to suppose that the
behaviour is conscious; and where the response is less simple and
more indirect, this tendency is so strengthened as to give rise to a
state of mind bordering on, or actually reaching, conviction. Nor is
this surprising: for, in the first place, organic responses, even the
simplest, are less obviously and directly related to the interplay of
surrounding circumstances; and, in the second place, they are more
obviously in relation to some purpose in the sense that they directly
or indirectly contribute to the maintenance of life or the furtherance
of well-being. Now where behaviour is complex and subserves an end
which we can note and name, there arises the supposition that it may
well be of the same nature as our own complex and conscious behaviour.

Take for example the behaviour of the Slipper-animalcule, Paramecium,
one of the minute creatures known to zoologists as Protozoa. The
whole animal is constituted by a single cell, somewhat less than
one-hundredth of an inch in length, the form and behaviour of which
may be readily studied under the microscope. Thousands may be obtained
from water in which some hay has been allowed to rot. The surface of
the Paramecium is covered with waving hair-like cilia, by which it is
propelled through the water, while stiffer hairs may be shot out from
the surface at any point where there is a local source of irritation,
as indicated at the top of the accompanying figure. Two little sacs
expand and contract, and serve to drain off water and waste products
from the substance of the cell. Food is taken in at the end of the
funnel, shown in the lower part of the figure. The cilia here work
in such manner as to drive the particles into and down the tube, and
on reaching its inner end these particles burst through into the
semi-fluid substance, and circulate therein. Just above the funnel
there are two bean-like bodies, the larger of which is known as the
macronucleus, the smaller as the micronucleus.

[Illustration: FIG. 1.--Paramecium.]

The process of multiplication is by “fission,” or the division of each
Paramecium into two similar animalcules. Not infrequently, however,
two Paramecia may be seen to approach each other and come together,
funnel to funnel; and in each the nuclei undergo curious changes. The
macronucleus breaks up, and is scattered. The micronucleus in each
divides into four portions, of which three break up and disappear;
while the fourth again divides into two parts, one to be retained and
the other to be exchanged for the similar micronuclear product of the
other Paramecium. The retained portion and that received in exchange
then unite to form a new micronucleus. M. Maupas concludes from his
careful observations that, in the absence of such “conjugation” in
the mid-period of life, Paramecia pass into a state of senility which
ends in decrepitude and death. If this be so, conjugation is in them
necessary for the continuance of a healthy race.

Here we have what a zoologist would describe as a specialized mode of
behaviour of the nuclei; and we have also the behaviour of the minute
creatures (which contain the nuclei) as they approach each other and
come together in conjugation. Can one wonder that the latter, at any
rate, has been regarded as an example of conscious procedure? In
truth we do not know in what manner and by what subtle influences the
Paramecia are drawn together in conjugation. But it is scarcely logical
to base on such ignorance any positive assertion as to conscious
attraction. It is better to confess that here is a piece of organic
behaviour, the exact conditions of which are at present unexplained.

We may take from the writings[1] of Dr. H. S. Jennings, of Harvard,
some account of other modes of behaviour among Paramecia. They largely
feed upon clotted masses of bacteria. If a number are placed upon a
glass slip, together with a small bacterial clot, they will be seen to
congregate around the clot and to feed upon it. All apparently press in
so as to reach it, or get as near it as possible. And if a number be
placed on another slide without any clot, they soon collect in groups
in one or more regions, as in Fig. 2, III. It appears as if they were
actuated by some social impulse leading them to crowd together and shun
isolated positions. Nay, more; it seems as if, after thus collecting
and crowding in to some centre of interest, the attractive influence
gradually waned; the group spreads, and the Paramecia are less densely
packed; the assembly scatters more and more, but still seems to be
retained by an invisible boundary beyond which the little creatures do
not pass.

[Illustration: FIG. 2.--Behaviour of Paramecia (after Jennings).]

Furthermore, if kept in a jar, the Paramecia crowd up towards the
surface where the bacteria clots are floating; and if, beneath the
cover glass of a slip on which they are under microscopic examination,
a drop of liquid be introduced through a very fine tube, they will seem
either to be attracted to it, as in Fig. 2, I., or repelled from it,
as in Fig. 2, II., according to its nature. From alkaline liquids they
are repelled; to slightly acid drops they are attracted, unless the
acidity be too pungent. Heat and cold are alike repellent, and even a
drop of pure distilled water forms an area into which the Paramecia do
not enter.

With such facts before him, the incautious observer may be led to
the conclusion that Paramecia are not only conscious, but endowed
with intelligence and volition. Even M. Binet,[2] who occupies a
position which should lead him to exercise more caution, tells us
that there is not a single infusorian which cannot be frightened,
and does not manifest its fear by rapid flight; he speaks of some
of these unicellular animals as “endowed with memory and volition,”
and possessed of “instinct of great precision;” and he describes the
following stages:--

“(1) The perception of an external object;

“(2) The choice made between a number of objects;

“(3) The perception of their position in space;

“(4) Movements calculated either to approach the body and seize it, or
to flee from it.”

But when we seem to have grasped his point of view, when we have
catalogued the memory, fear, instinct, perception, choice and
volition, the whole intelligent edifice crumbles; for we are told that
“we are not in a position to determine whether these various acts
are accompanied by consciousness, or whether they follow as simple
physiological processes.” To most of us fear, memory, choice, volition,
imply something more than simple physiological processes; they imply
not only consciousness, but highly elaborated consciousness.

Dr. Jennings’s researches show that no such implication can be accepted
unless we are prepared to cast aside the trammels of reasonable
caution. In the first place, the whole matter of feeding appears to
be referable to simple organic behaviour not necessarily involving
consciousness. The cilia in the mouth-groove and funnel constantly
wave in such a manner as to drive a current of water, together with
any particles which float therein, towards the interior; and the
particles are then engulphed, no matter what their composition may be.
Digestible or indigestible, in they go. There is no selection of the
one or rejection of the other. But, as we have seen, the Paramecia
collect around a bacterial clot and feed upon it. Surely here there
is selection of the nutritious! Apparently not. They collect in just
the same way towards a piece of blotting-paper, cotton-wool, cloth,
sponge, or other fibrous body, and remain assembled round such an
innutritious centre just as long as round a bacterial clot. There seems
to be no choice in the matter; contact with any substance gives rise,
as an organic response, to the lessening or cessation of the regular
movements in all the cilia except those of the mouth-groove and funnel.
As the Paramecia swim hither and thither, first one, then another,
then more, chance to come in contact with the bacterial clot, the
blotting-paper, or other substance, and since the lashing of the cilia
is then automatically lessened, there they stay; others find their way
to the same spot in the course of their random movements, and they,
too, stay; thus many soon collect.

But this does not account for the seemingly social assemblages of
Paramecia where there is no such substance to arrest their progress.
Dr. Jennings attributes this to the fact that a dilute solution of
carbon-dioxide has, what we may call for the present, an attractive
influence. If a bubble of air and a bubble of carbon dioxide be
introduced into the water in which Paramecia are swimming beneath a
cover-glass, the animalcules collect around the carbonic dioxide, but
not around the air bubble. At first they press up close to the bubble
of carbon dioxide, but gradually form a ring farther and farther from
its limiting boundary. This is held to be due to the fact that it
is only the dilute solution of carbonic acid that has the peculiar
“attraction”--a stronger solution has a different effect. And, as the
gas dissolves, the Paramecia collect in a ring just where the solution
is sufficiently dilute.

Now carbon dioxide is a product of the organic waste of living
substance; it is given off by active Paramecia. Where therefore many
are collected together they form a centre of the production of this
substance; and when other Paramecia come, in the course of their random
movements, into such a centre they remain there and help to swell the
numbers in the cluster. If Paramecia be placed in water to which a
distinctly reddish tinge is given by mixing it with a small quantity
of rosol--a substance which is decolourized by carbon dioxide, and is
not injurious to Paramecia--it will be seen that, where the groups
are collected, the reddish tinge fades and disappears. As the groups
expand, and are less densely packed, the colourless area expands too:
and the limits within which the group is circumscribed are also the
limits of decolourization. Dr. Jennings considers it beyond question
that the assembling of Paramecia is due to the presence in such
assemblages of carbonic acid produced by the animals themselves. The
first beginning of the crowd may be some small fragment of bacterial
clot or other substance.

It would seem, then, that Paramecia are attracted by faintly acid
solutions; and here at least there is, it may be urged, an element of
choice. But even here, according to Dr. Jennings, there is not only
no real choice, but not even any real attraction. What takes place,
according to his observations, is briefly as follows. Suppose a faintly
acid drop be inserted beneath the cover-glass. Paramecia may almost
graze its boundary without being in any way affected by its presence.
But in their random movements some, and eventually many, perhaps most,
of the little animals chance to enter the faintly acid region; but
there is no sign of reaction or response; they swim on across the
drop until they reach its further margin. Here a reaction does take
place. Instead of proceeding onwards, slowly revolving on its long
axis, a Paramecium thus situated jerks backwards by a reversal of
all the cilia, at the same time revolving on its axis in a direction
opposite to that in which it was before turning. But the cilia of
the mouth-groove resume their normal mode of working sooner than the
others, and this causes the Paramecium to turn aside. It then goes
ahead until it again reaches the boundary at another point, when the
same behaviour is seen. The course of such a Paramecium is shown in
Fig. 2, IV.

If, instead of a faintly acid drop, a little alkaline liquid be
introduced beneath the cover-glass, the Paramecium similarly jerks
backward and turns aside on reaching its outer boundary. The turning
may carry it away from the alkali, as shown in Fig. 2, V.; but it just
as often brings it again towards the drop, especially a large one. It
seems to be a matter of chance which result follows. But eventually
the little creature sails off, since each time it comes within the
influence of the alkaline fluid it jerks back and turns. It appears,
then, that when it is swimming in a normal solution a faintly acid
liquid does not much modify its behaviour, but an alkaline fluid
evokes a reversal of the cilia; and that when it is a slightly acid
solution, not only does stronger acid cause reversal, but normal fluid
produces a similar result. A reaction of essentially the same kind is
in fact called forth by such different stimuli as chemical substances,
water heated above the normal temperature, or cooled considerably
below it, and fluids which cause changes of internal pressure within
the substance of the cell. Nor does it matter where the stimulus is
applied. If it be applied at the hinder end the infusorian still jerks
backward, though this may drive it into a destructive solution and thus
cause death. There is, however, some evidence of different behaviour in
some infusorians according as the stimulus is here or there. In other
words, the behaviour is to some extent related to the position of the
part stimulated.

Furthermore, it may be gathered from Dr. Jennings’s account that there
is nothing to lead us to suppose that such free living cells show
any indication of what may be regarded as the keynote of intelligent
behaviour. They do not profit by experience. They exhibit organic
reactions which may be accompanied by some dim form of consciousness,
but which do not seem to be under the guidance of such consciousness,
if it exist.

One of the first lessons which the study of animal behaviour, in its
organic aspect, should impress upon our minds is, that living cells
may react to stimuli in a manner which we perceive to be subservient
to a biological end, and yet react without conscious purpose--that is
to say, automatically. The living cell assimilates food and absorbs
oxygen, it grows and subdivides, it elaborates secretions, produces
a skeletal framework or covering, rids itself of waste products,
responds to stimuli in a definite fashion, moves hither and thither at
random, its functional activities being stimulated or checked by many
influences; and yet this varied life may give no evidence of a guiding
consciousness: if purpose there be, it lies deeper than its protoplasm,
deeper than the dim sentience which may be present or may be absent--we
cannot tell which.

And when the cells are incorporated in the body of one of the higher
animals, instead of each preserving a free and nomad existence; when
they become the multitudinous constituents of an organic republic with
unity of plan and unity of biological end, then the behaviour of each
is limited in range but perfected within that range, in subservience to
the requirements of the more complex unity. The muscle cell contracts,
the gland-cell secretes, the rods and cones of the retina respond to
the waves of light, and all the normal responses of the special cells
go on with such orderly regularity that the term behaviour seems
scarcely applicable to reactions so stereotyped. But the physiologist
and the physician know well that such uniformity of response is
dependent on uniformity of conditions. A little dose of some drug
will profoundly modify and render abnormal the procedure which was
before so mechanical in its exactitude; and we are thus led to see how
dependent the orderly behaviour really is on the maintenance of certain
surrounding conditions.

Moreover, the existence of every cell in the body corporate is the
outcome of a process of division involving a special mode of behaviour
in the nucleus, of which we are only beginning to guess the meaning
and significance, and of which we seek in vain to find an explanation
in mechanical terms. And when we trace these divisions back to their
primary source in the fertilized ovum, we find changes and evolutions
in the nuclear matter of which it can only be said that the more they
are studied the more complex and varied do they appear.

The egg, or ovum, is a single cell produced by the female, and varying
much in size, according to the amount of food-yolk with which it is
supplied. Like other cells, it has a nucleus, and this undergoes
changes which are definitely related to the fertilization of the ovum,
which we describe as the biological end. Such preparatory changes
for a future contingency are especially characteristic of organic
behaviour. There is nothing like it in the mineral kingdom. The nucleus
divides into two parts, one of which passes out of the ovum and is
lost. The nucleus again divides, and again one part passes out and is
lost. Thus only one quarter of the original amount of nuclear matter
remains. Now, division of the nucleus occurs whenever an animal cell
divides; but in this case (apart from details which would here be out
of place) there is this difference. During the ordinary division of
cells there are found in the nucleus a definite number of curved rods,
and this number is constant for any given species; but in the nucleus
which remains in the ovum after three parts of its substance are lost,
the number of rods has been reduced to half that which is common to the
species. The egg is now ready for fertilization. A minute active cell,
which is produced by the male, and which also has only half the normal
number of rods, enters the ovum. The two nuclei approach each other,
and give rise to the single nucleus of the fertilized ovum, which thus
has the full number of rods--half of them derived from one parent, half
from the other parent. The sperm cell of the male adds little to the
store of protoplasm in the ovum; but it introduces a minute body, which
seems to initiate subsequent divisions of the cell. The nature of these
divisions may be seen in the accompanying diagrammatic figure. In A
the cell is just preparing to divide. Above the nucleus is the minute
body (centrosome) just spoken of, which has already divided. In the
nucleus the matter of which the rods will be constituted is net-like.
In B this net-work has taken on the new form of a coiled thread, while
the divided body above is associated with a spindle of delicate fibres.
In C the membrane round the nucleus has disappeared, and the coiled
thread has broken up into curved rods (chromosomes), four of which are
shown. The two halves of the minute body form the centres of radiating
stars. In D each curved rod has split along its length, and the two
parts are being drawn asunder towards the centres of the two stars;
the cell itself is beginning to divide. In E the process is carried a
step further, while in F the cell has completely divided into two: the
rods have disappeared as such, and are replaced by a net-work; a new
nuclear membrane has been formed, and the minute body has again divided
preparatory to the further division of the cell.

[Illustration: FIG. 3.--Cell-division.]

Such, stripped as far as possible of technicalities, are some of the
facts concerning the behaviour of cells and their nuclei during the
process of cell-multiplication. No good purpose would be subserved by
pretending that we fully understand them. The splitting of the rods
does indeed seem an efficient means to the end of securing a fair
division of the nuclear substance, which, according to many biologists,
is the organic bearer of hereditary qualities in the cells. But that
is nearly all that we can say. Is the process accompanied by some form
of sentience? We do not know. That it is controlled and guided by any
consciousness in the cell is most improbable. But if it be a purely
organic and unconscious process it should at least impress on our
minds the fact that such organic behaviour may reach a high degree of
delicacy and complexity.

III. CORPORATE BEHAVIOUR

The word “corporate” is here applied to the organic behaviour of
cells when they are not independent and free, but are incorporated
in the animal body, and act in relation to each other. If the
behaviour of the individual cell during division impresses us with the
subtle intricacy of organic processes, the behaviour of the growing
cell-republic during the early stages of organic development must
impress us no less forcibly. We place the fertilized egg of a hen in
an incubator, and supply the requisite conditions of warmth, moisture,
and fresh air. Before the egg is laid cell-division has begun. A
small patch of closely similar cells has formed on the surface of
the yolk. Further subdivision is then arrested until the warmth of
incubation quickens again the patch into life. But when once thus
quickened no subsequent temporary arrest is possible--life will not
again lie dormant. If arrest there be it is that of death. And from
that little patch of cells, which spreads further and further over
the yolk, a chick is developed. Into the intricate technicalities
of embryology this is not the place to enter. But it is a matter of
common knowledge that, whereas we have to-day an egg such as we eat
for breakfast, three weeks hence we shall have a bright active bird,
a cunningly wrought piece of mechanism, and, more than that, a going
machine. During this wonderful process the cellular constituents take
on new forms and perform new functions, all in relationship to each
other, all as part of one organic whole. Here bones are developed
to form a skeletal framework, there muscles are constituted which
shall render orderly movements possible; feathers, beak, and claws
take shape as products of the skin; gut and glands prepare for future
modes of nutrition; heart and blood-vessels undergo many changes,
some reminiscent of bygone and ancestral gill-respiration, some in
relation to the provisional respiration of the embryo by means of a
temporary organ that spreads out beneath the shell, some preparatory to
the future use of the lungs,--some, again, related to the absorption
of food from the yolk, others to subsequent means of digestion;
nerve, brain, and sense-organs differentiate. A going machine in the
egg, the chick is hatched, and forthwith enters on a wider field of
behaviour. Few would think of attributing to the consciousness of the
embryo chick any guiding influence on the development of its bodily
structure, any control over the subtle changes and dispositions of its
constituent cells. But no sooner does the chick, when it is hatched,
begin to show wider modes of instinctive behaviour, than we invoke
conscious intelligence for their explanation, seemingly forgetful of
the fact that there is no logical ground for affirming that, while the
marvellous delicacies of structure are of unconscious organic origin,
the early modes of instinctive behaviour are due to the guidance of
consciousness. Such modes of behaviour will, however, be considered in
another chapter. Here we have to notice that the unquestionably organic
behaviour of the incorporated republic of cells may attain to a high
degree of complexity, and may serve a distinctly biological end.

[Illustration: FIG. 4.--Wapiti with antlers in velvet.]

There is, perhaps, no more striking instance of rapid and vigorous
growth than is afforded by the antlers of deer,[3] which are shed
and renewed every year. In the early summer, when growing, they are
covered over with a dark hairy skin, and are said to be “in velvet.”
If you lay your hand on the growing antler, you will feel that it is
hot with the nutrient blood that is coursing beneath it. It is, too,
exceedingly sensitive and tender. An army of tens of thousands of busy
living cells is at work beneath that velvet surface, building the bony
antlers, preparing for the battles of autumn. Each minute cell, working
for the general good, takes up from the nutrient blood the special
materials it requires; elaborates the crude bone-stuff, at first soft
as wax, but ere long to become hard as stone; and then, having done
its work, having added its special morsel to the fabric of the antler,
remains embedded and immured, buried beneath the bone-products of its
successors or descendants. No hive of bees is busier or more replete
with active life than the antler of a stag as it grows beneath the
soft, warm velvet. And thus are built up in the course of a few weeks
those splendid “beams,” with their “tynes” and “snags,” which, in the
case of the wapiti, even in the confinement of our Zoological Gardens,
may reach a weight of thirty-two pounds, and which, in the freedom of
the Rocky Mountains, may reach such a size that a man may walk, without
stooping, beneath the archway made by setting up upon their points the
shed antlers. When the antler has reached its full size, a circular
ridge makes its appearance at a short distance from the base. This
is the “burr,” which divides the antler into a short “pedicel” next
the skull, and the “beam” with its branches above. The circulation in
the blood-vessels of the beam now begins to languish, and the velvet
dies and peels off, leaving the hard, bony substance exposed. Then is
the time for fighting, when the stags challenge each other to single
combat, while the hinds stand timidly by. But when the period of battle
is over, and the wars and loves of the year are past, the bone beneath
the burr begins to be eaten away, through the activity of certain large
bone-absorbing cells, and, the base of attachment being thus weakened,
the antlers are shed; the scarred surface skins over and heals, and
only the hair-covered pedicel of the antler is left.

[Illustration: FIG. 5.--Wapiti with velvet shredding off.]

We have no reason to suppose that this corporate cellular behaviour,
involving the nicely adjusted co-operation of so vast an army of
organic units, is under the conscious guidance of the stag. And yet
how orderly the procedure! how admirable the result! Nor is there an
organ or structural part of the stag or any other animal that does not
tell the same tale. This is but one paragraph of the volume in which
is inscribed the varied and wonderful history of organic behaviour in
its corporate aspect. Is it a matter for wonder that the cause of such
phenomena has been regarded as “a mystery transcending naturalistic
conception; as an alien influx into nature, baffling scientific
interpretation”? And yet, though not surprising, this attitude of
mind, in face of organic phenomena, is illogical, and is due partly
to a misconception of the function of scientific interpretation,
partly to influences arising from the course pursued by the historical
development of scientific knowledge. The function of biological science
is to formulate and to express in generalized terms the related
antecedences and sequences which are observed to occur in animals and
plants. This can already be done with some approach to precision. But
the underlying cause of the observed phenomena does not fall within
the purview of natural science; it involves metaphysical conceptions.
It is no more (and no less) a “mystery” than all causation in its last
resort--as the _raison d’être_ of observed phenomena--is a mystery.
Gravitation, chemical affinity, crystalline force,--these are all
“mysteries.”

If the mystery of life, lying beneath and behind organic behaviour, be
said to baffle scientific interpretation, this is because it suggests
ultimate problems with which science as such should not attempt to
deal. The final causes of vital phenomena (as of other phenomena) lie
deeper than the probe of science can reach. But why is this sense
of mystery especially evoked in some minds by the contemplation of
organic behaviour, by the study of life? Partly, no doubt, because
the scientific interpretation of organic processes is but recent, and
in many respects incomplete. People have grown so accustomed to the
metaphysical assumptions employed by physicists and chemists when they
speak of the play of crystalline forces and the selective affinities
of atoms, they have been wont for so long to accept the “mysteries”
of crystallization and of chemical union, that these assumptions have
coalesced with the descriptions and explanations of science; and
the joint products are now, through custom, cheerfully accepted as
natural. Where the phenomena of organic behaviour are in question, this
coalescence has not yet taken place; the metaphysical element is on
the one hand proclaimed as inexplicable by natural science, and on the
other hand denied even by those who talk glibly of physical forces as
the final cause of the phenomena of the inorganic world.

So much reference to the problems which underlie the problems of
science seems necessary. It is here assumed that the phenomena of
organic behaviour are susceptible of scientific discussion and
elucidation. But even assuming that an adequate explanation in terms
of antecedence and sequence shall be thus attained by the science of
the future, this will not then satisfy, any more than our inadequate
explanations now satisfy, those who seek to know the ultimate meaning
and reason of it all: What makes organic matter behave as we see it
behave? what drives the wheels of life, as it drives the planets
in their courses? what impels the egg to go through its series of
developmental changes? what guides the cells along the divergent course
of their life-history? These are questions the ultimate answers to
which lie beyond the sphere of science--questions which man (who is a
metaphysical being) always does and always will ask, even if he rests
content with the answer of agnosticism; but questions to which natural
science never will be able, and should never so much as attempt, to
give an answer.

Enough has now been said to show that organic behaviour is a thing _sui
generis_, carrying its own peculiar marks of distinction: and further,
that, for science, this is just part of the constitution of nature,
neither more nor less mysterious than, let us say, crystallization or
chemical combination. But associated and closely interwoven with all
that is distinctively organic there is much which can to some extent be
interpreted in terms of physics and chemistry.

The animal[4] has sometimes been likened to a steam-engine, in which
the food is the fuel which enters into combustion with the oxygen taken
in through the lungs. It may be worth while to modify and modernize
this analogy--always remembering, however, that such an analogy must
not be pushed too far.

In the ordinary steam-engine the fuel is placed in the fire-box, to
which the oxygen of the air gains access; the heat produced by the
combustion converts the water in the boiler into steam, which is made
to act upon the piston, and thus set the machinery in motion. But
there is another kind of engine, now extensively used, which works on
a different principle. In the gas-engine the fuel is gaseous, and it
can thus be introduced in a state of intimate mixture with the oxygen
with which it is to unite in combustion. This is a great advantage. The
two can unite rapidly and explosively. In gunpowder the same end is
effected by mixing the carbon and sulphur with nitre, which contains
the oxygen necessary for their explosive combustion. And this is
carried still further in dynamite and gun-cotton, where the elements
necessary for explosive combustion are not merely mechanically mixed,
but are chemically combined in a highly unstable compound.

But in the gas-engine, not only are the fuel and the oxygen thus
intimately mixed, but the controlled explosions are caused to act
directly on the piston, and not through the intervention of water in a
boiler. Whereas, therefore, in the steam-engine the combustion is to
some extent external to the working of the machine, in the gas-engine
it is to a large extent internal and direct.

Now, instead of likening the animal as a whole to a steam-engine, it
is more satisfactory to liken each cell to an automatic gas-engine
which manufactures its own explosive. During the period of repose
which intervenes between periods of activity, its protoplasm is busy
in construction, taking from the blood-discs oxygen, and from the
blood-fluid carbonaceous and nitrogenous materials, and knitting these
together into relatively unstable explosive compounds, which play the
part of the mixed air and gas of the gas-engine. A resting muscle may
be likened to a complex and well-organized battery of gas-engines. On
the stimulus supplied through a nerve-channel a series of co-ordinated
explosions takes place: the gas-engines are set to work; the muscular
fibres contract; the products of the silent explosions are taken up
and hurried away by the blood-stream; and the protoplasm prepares a
fresh supply of explosive material. Long before the invention of the
gas-engine, long before gun-cotton or dynamite were dreamt of, long
before some Chinese or other inventor first mixed the ingredients of
gunpowder, organic nature had utilized the principle of controlled
explosions in the protoplasmic cell, and thus rendered animal behaviour
possible.

Certain cells are, however, more delicately explosive than others.
Those, for example, on or near the external surface of the body--those,
that is to say, which constitute the end-organs of the special
senses--contain explosive material which may be fired by a touch, a
sound, an odour, the contact with a sapid fluid or a ray of light.
The effects of the explosions in these delicate cells, reinforced in
certain neighbouring nerve-batteries, are transmitted down the nerves
as waves of subtle chemical or electrolytic change, and thus reach
that wonderful aggregation of organized and co-ordinated explosive
cells, the brain. Here it is again reinforced and directed (who, at
present, can say how?) along fresh nerve-channels to muscles, or
glands, or other organized groups of explosives. And in the brain,
somehow associated with the explosion of its cells, consciousness,
the mind-element, emerges; of which we need only notice here that
it belongs to a _wholly different order of being_ from the physical
activities and products with which we are at present concerned.

We must not press the explosion analogy too far. The essential thing
seems to be that the protoplasm of the cell has the power of building
up complex and unstable chemical compounds, which are perhaps stored
in its spongy substance; and that these unstable compounds, under
the influence of a stimulus (or, possibly, sometimes spontaneously),
break down into simpler and more stable compounds. In the case of
muscle-cells, this latter change is accompanied by an alteration
in length of the fibres, and consequent movements in the animal,
the products of the disruptive change being useless or harmful, and
being, therefore, removed as soon as possible. But very frequently
the products of explosive activity are made use of. In the case of
bone-cells, one of the products of disruption is of permanent use to
the organism, and constitutes the solid framework of the skeleton. In
the case of the secreting cells in the salivary and other digestive
glands, some of the disruptive products are of temporary value for the
preparation of the food. It is probable that these useful products
of disruption, permanent or temporary, took their origin in waste
products for which natural selection has found a use, and which have
been gradually rendered more and more efficacious in modes of organic
behaviour increasingly complex.

In the busy hive of cells which constitutes what we call the animal
body, there is thus ceaseless activity. During periods of apparent
rest the protoplasm is engaged in constructive work, building up fresh
supplies of unstable materials, which, during periods of apparent
activity, break up into simpler and more stable substances, some of
which are useful to the organism, while others must be got rid of as
soon as possible. From another point of view, the cells during apparent
rest are storing up energy to be utilized by the animal during its
periods of activity. The storing up of available energy may be likened
to the winding up of a watch or clock; it is when an organ is at rest
that the cells are winding themselves up; and thus we have the apparent
paradox that the cell is most active and doing most work when the organ
of which it forms a part is at rest. During the repose of an organ, in
fact, the cells are busily working in preparation for the manifestation
of energetic action that is to follow. Just as the brilliant display
of intellectual activity in a great orator is the result of the silent
work of a lifetime, so is the physical manifestation of muscular power
the result of the silent preparatory work of the muscle-cells.

It may, perhaps, seem strange that the products of cellular life should
be reached by the roundabout process of first producing unstable
compounds, from which are then formed more stable substances, useful
for permanent purposes as in bone, or temporary purposes as in the
digestive fluids. It seems a waste of power to build up substances
unnecessarily complex and stored with an unnecessarily abundant supply
of energy. But only thus could the organs be enabled to act under the
influence of stimuli, and afford examples of corporate behaviour. They
are like charged batteries ready to discharge under the influence of
the slightest organic touch. In this way, too, is afforded a means
by which the organ is not dependent only upon the products of the
immediate activity of the protoplasm at the time of action, but can
utilize the store laid up during preceding periods of rest.

Sufficient has now been said to illustrate the nature of some of the
physical processes which accompany organic behaviour in its corporate
aspect. The fact that should stand out clearly is that the animal body
is stored with large quantities of available energy resident in highly
complex and unstable chemical compounds, elaborated by the constituent
cells. These unstable compounds, eminently explosive according to
our analogy, are built up of materials derived from two different
sources--from the nutritive matter (containing carbon, hydrogen, and
nitrogen) absorbed during digestion, and from oxygen taken up from the
air during respiration. The cells thus become charged with energy that
can be set free on the application of the appropriate stimulus, which
may be likened to the spark that fires the explosive.

Let us note, in conclusion, that it is through the blood-system,
ramifying to all parts of the body, and the nerve-system, the
ramifications of which are not less perfect, that one of the larger
and higher animals is knit together into an organic whole. The former
carries to the cell the raw materials for the elaboration of its
explosive products, and, after the explosions, carries off the waste
products which result therefrom. The nerve-fibres carry the stimuli
by which the explosive is fired, while the central nervous system
organizes, co-ordinates, and controls the explosions, and initiates the
elaboration of the explosive compounds. Blood and nerves co-operate to
render corporate behaviour possible.

IV.--THE BEHAVIOUR OF PLANTS

A short parenthetic section on the behaviour of plants may serve
further to illustrate the nature of organic behaviour. We have seen
that Paramecium is apparently attracted by faintly acid solutions,
and have briefly considered Dr. Jennings’s interpretation of the
facts disclosed by careful observation. In the ferns the female
element, or ovum, is contained in a minute flask-shaped structure
(archegonium), in the neck and mouth of which mucilaginous matter, with
a slightly acid reaction, is developed; and this is said to exercise
an attractive influence on the freely swimming ciliated male elements,
or spermatozoids, which are necessary for fertilization. “Now, it
has been shown by experiment that the spermatozoids of ferns are
attracted by certain chemical substances, and especially by malic acid.
If artificial archegonia are prepared (consisting of tiny capillary
glass-tubes) and filled with mucilage to which a small quantity of this
acid has been added, they are found, when placed in water containing
fern-spermatozoids, to exercise the same attraction upon them which
the real archegonia exercise in nature. The malic acid gradually
diffuses out into the water, and the spermatozoids are influenced by
it, so that they move in the direction in which the substance is more
concentrated, _i.e._ towards the tube. Although it cannot be proved
that the archegonia themselves contain malic acid, as they are too
small for a recognizable quantity to be obtained from them, yet there
can be little doubt that the natural archegonia owe their attractive
influence to the same chemical agent which has proved efficacious
in experiment.”[5] In the light of Dr. Jennings’s observations, it
is perhaps not improbable that this so-called attractive influence
is similar to that seen in Paramecium; and that the spermatozoids
enter the organic acid in the course of their random movements, and
there remain. Be that as it may, the male elements collect in the
mucilaginous mass, and pass down the neck of the flask until one
reaches and coalesces with the female element, or ovum, and effects its
fertilization. Here we have organic behaviour unmistakably directed to
a biological end--behaviour which may indeed be accompanied by some dim
form of consciousness, but which is due to a purely organic reaction.
It is scarcely satisfactory to say that the spermatozoids “possess a
certain power of perception, by which their movements are guided.”[6]
If consciousness be present, it is probably merely an accompaniment
of the response, and has no directive influence on its nature and
character.

In the higher plants, as in the higher animals, the differentiation
and the orderly marshalling of the cell-progeny arising from the
coalescent male and female elements, afford, during development,
examples of corporate organic behaviour which can be more readily
described than explained, but which not less clearly subserve definite
biological ends, and in many cases, such as the direction of growth
in radicles and roots, the curling of tendrils, and the reaction to
the influence of light and warmth, are related to and evoked by the
environing conditions. More closely resembling familiar modes of
behaviour in animals are such movements as are seen in the “tentacles”
which project from the upper surface and margin of the Sun-dew leaf.
Their knobbed ends secrete a sticky matter, which glistens in the
sun, and to which small foreign bodies readily adhere. If particles
of limestone, sand, or clay, such as may be blown by the wind, touch
and stick to these knobs, there follows an exudation of acid liquid,
but no marked and continuous change occurs in the position of the
tentacles. But should an insect alight on the leaf, or a small piece
of meat be placed upon the tentacles, not only is there a discharge
of acid juice, but a ferment is also produced, which has a digestive
action on the nitrogenous matter. Slowly the tentacle curves inwards
and downwards, as one’s finger may bend towards the palm of one’s
hand; neighbouring tentacles also turn towards and incline on to the
stimulating substance; then others, further off, behave in a similar
way, until all the tentacles, some two hundred in number, are inflected
and converge upon the nitrogenous particle. Nay, more: “When two little
bits of meat are placed simultaneously on the right and left halves
of the same Sun-dew leaf, the two hundred tentacles divide into two
groups, and each one of the groups directs its aim to one of the bits
of meat.”[7]

[Illustration: FIG. 6.--Sun-dew (_Drosera_). Leaf (enlarged) with the
tentacles on one side inflected over a bit of meat placed on the disc.
(From Darwin’s “Insectivorous Plants.”)]

The movements, though slow, are orderly, methodical, and effective,
the secretions of many glands being brought to bear on just those
substances which are capable of digestion and absorption by the
plant. The seemingly concerted action is moreover due to an organic
transmission of impulses from cell to cell--a transmission accompanied
by visible changes in a purple substance contained within the cells. In
the Sun-dew any tentacle may form the starting-point of the spreading
wave of impulse. But in the Venus’s Fly-trap there are six delicate
spines, the slightest touch on any one of which causes the two halves
of the specially modified leaf-end to fold inwards on the midrib as a
hinge. The transmission of impulse is more rapid, the trap closing in a
few seconds; and electric currents have been observed to accompany the
change. Tooth-like spines at the edge of the trap interlock, and serve
to prevent the escape of small insects, while short-stalked purple
glands secrete an acid digestive juice. Division of labour has been
carried further; and organic behaviour, not less purposive, is carried
out in a manner even more effective.

[Illustration: FIG. 7.--Venus’s Fly-trap (_Dionæa_). Leaf viewed
laterally in its expanded state. (From Darwin’s “Insectivorous
Plants.”)]

In other plants adaptive movements are well known. “Few phenomena
have such a peculiar appearance as the movements which occur in the
sensitive Oxalis when rain comes on. Not only do the leaflets on which
the finest rain-drops fall fold together in a downward direction, but
all the neighbouring ones perform the same movement, although they have
not themselves been shaken by the impact of the falling drops. The
movement is continued to the common leaf-stalk bearing the numerous
leaflets. This also bends down towards the ground. The rain-drops now
slide over the bent leaf-stalk and down over the depressed leaflets,
and not a drop remains behind on their delicate surfaces.”[8] The
waves of impulse are said to be transmitted along definite lines, and
to cause the expulsion of water from certain cells at the point of
insertion of the leaflets or leaf-stalks, rendering them flaccid.

[Illustration: FIG. 8.--Flower of _Valisneria_.]

Appealing even more strongly to the popular imagination, though
probably not of deeper biological significance, is the behaviour of
plants in relation to the essential process of fertilization. Only two
examples can here be cited. _Valisneria spiralis_ is an aquatic plant,
with long submerged strap-like leaves, which grows in still water in
Southern Europe. The female flower is enclosed in two translucent
bracts, which form a protective bladder so long as the flower is
beneath the surface of the water; but the flower-stalk continues to
grow until the flower reaches the surface, when it becomes freely
exposed by the splitting of the bracts. There are three boat-shaped
sepals, which act as floats; three quite minute petals; and three large
fringed stigmas, which project over the abortive petals in the space
between the boat-like sepals. The flower is now ready for fertilization.

The male flowers, which are developed on different individuals from
those which produce the female flowers, grow in bunches beneath an
investing bladder. The stalk does not elongate, so that the bladder
never rises far above the bottom, and remains completely submerged.
Here the bladder bursts, and the male flowers, with short stalks, are
detached. Each has three sepals, which enclose and protect the stamens.
The separated flower now ascends to the surface, the sepals open and
form three hollow boats, by means of which the flower floats freely,
while the two functional stamens project upwards and somewhat obliquely
into the air, exposing the large sticky pollen-cells. Blown hither
and thither by the wind, these little flower-boats “accumulate in the
neighbourhood of fixed bodies, especially in their recesses, where
they rest like ships in harbour. When the little craft happen to get
stranded in the recesses of a female Valisneria flower, they adhere to
the tri-lobed stigma, and some of the pollen-cells are sure to be left
sticking to the fringes on the margins of the stigmatic surface.”[9]

This is a good example of purely organic behaviour admirably adapted to
secure a definite and important biological end. Few will be likely to
contend that it is even accompanied by, still less under the guidance
of, any conscious foresight on the part of the plant. And the lesson it
should teach is that, in the study of organic behaviour, adaptation to
the conditions of existence is not necessarily the outcome of conscious
guidance.

It is well known that the orchids exhibit, in their mode of
fertilization, remarkable adaptations by which the visits of insects
are rendered subservient to the needs of the plant. In the Catasetums,
for example, the male flower may be described as consisting of two
parts--a lower part, the cup-like labellum (Fig. 9, _l_), which
constitutes a landing-stage on which insects may alight; and an upper
part, the column (Fig. 9, _c_), surrounded by the upper sepal and
petals. In the upper part of the column the pollen-masses are borne at
one end of an elastic pedicel, at the other end of which is an adhesive
disc, and the rod is bent over a pad so as to be in a state of strain.
The disc is retained in position by a membrane with which two long
tubular horns (Figs. 9, _h_; 10, _an_) are continuous. These project
over the labellum, where insects alight to gnaw its sweet fleshy walls,
and if they be touched, even very lightly, they convey some stimulus to
the membrane which surrounds and connects the disc with the adjoining
surface, causing it instantly to rupture; and as soon as this happens,
the disc is suddenly set free. The highly elastic pedicel then flirts
the disc out of its chamber with such force that the whole is ejected,
sometimes to a distance of two or three feet, bringing away with it the
two pollen-masses. “The utility of so forcible an ejection is to drive
the soft and viscid cushion of the disc against the hairy thorax of
the large hymenopterous insects which frequent the flowers. When once
attached to an insect, assuredly no force which the insect could exert
would remove the disc and pedicel, but the caudicles [by which the
pollen-masses are attached] are ruptured without much difficulty, and
thus the balls of pollen might readily be left on the adhesive stigma
of the female flower.”[10]

[Illustration: FIG. 9.--Flower of _Catasetum_; _c_, column; _h_, horns;
_l_, labellum.]

Here again we have adaptive behaviour of exquisite nicety, and we
have the transmission of an impulse very rapidly along the cells of
the irritable horns, followed by the sudden rupture of a membrane.
Beautiful, however, as is the adaptation, effective as it is to a
definite biological end, the organic behaviour does not afford any
indication of the guidance of consciousness. Among plants we have many
interesting and admirable examples of organic behaviour; but nowhere so
much as a hint of that profiting by individual experience which is the
criterion of the effective presence of conscious guidance and control.

[Illustration: FIG. 10.--_Catasetum_; C, diagram of column; _a_, anther;
_an_, horn; _d_, adhesive disc; _f_, filament of anther; _g_, ovarium;
_ped_, pedicel; D and E, pollinium; _p_, pollen-mass. (From Darwin’s
“Orchids.”)]

V.--REFLEX ACTION

It is sometimes said that the tentacles of the Sun-dew leaf indicate
a primitive kind of reflex action in plants, and that they afford
evidence of discrimination. “It is,” says Romanes, “the stimulus
supplied by continuous _pressure_ that is so delicately perceived,
while the stimulus supplied by _impact_ is disregarded.”[11] And,
comparing this with what is observed in the Venus’s Fly Trap, he
says: “In these two plants the power of discriminating between these
two kinds of stimuli has been developed to an equally astonishing
extent, but in opposite directions.”[12] It is well, however, to
avoid terms which carry with them so distinctively a conscious
implication as “discrimination” and “perception” do for most of us.
Just as the photographer’s film reacts differently according to the
quality of light-rays, violet or red, which reach it, so do many
organic substances react differently to stimuli of different quality,
irrespective of their intensity. The “discrimination” of plants and of
some of the lower animals is of this kind, and it is better to speak of
it simply as differential reaction. There can then be no chance of its
being confused with conscious choice.

Nor should the movements of the Sun-dew tentacles or of those of the
Sea-anemone be termed in strictness reflex action. As originally
employed by Marshall Hall, and, since that time, by common consent,
_reflex action_ involves a differentiated nervous system. There is,
first, an afferent impulse from the point of stimulation passing
inwards to a nerve-centre; secondly, certain little-understood changes
within this centre; and thirdly, an efferent impulse from the centre
to some organ or group of cells which are thus affected. In plants
there is no indication of anything analogous to this specialized mode
of response. The impulse passes directly from the point of stimulation
to the part affected without the intervention of anything like a
nerve-centre. In the sensitive Oxalis the impulse passes directly to
the point of insertion of the leaflet or leaf-stalk; in Catasetum, from
the horn to the retaining membrane; in the Sun-dew, from the affected
tentacle to those in its neighbourhood. Even in the Sea-anemone, though
there is a loosely diffused nervous system, the passage of the impulse
from one part of the circlet of tentacles to other parts, seems to
follow a direct rather than a reflex course, and there do not appear to
be any specialized centres by which the impulses are received and then
redistributed.

In all animals in which well-differentiated nervous systems are found,
in which there are distinct nerve-fibres and nerve-centres, reflex
actions, simple or more complicated, occur. They form the initial
steps leading up to the highest types of organic behaviour. So long
as the nervous arcs--afferent fibres, nerve-centre, and efferent
fibres--remain intact reflex acts may be carried out with great
precision and delicacy, even when the higher centres, which we believe
to be those of conscious guidance and control, have been destroyed.
When, for example, the whole of the brain of a frog has been extirpated
and the animal is hung up by the lower jaw, if the left side be touched
with a drop of acid the left leg is drawn up and begins to scratch
at the irritated spot, and when this leg is held, the other hind leg
is, with seemingly greater difficulty, brought to bear on the same
spot. “This,” says Sir Michael Foster, “at first sight looks like
an intelligent choice.... But a frog deprived of its brain so that
the spinal cord only is left, makes no spontaneous movements at all.
Such an entire absence of spontaneity is wholly inconsistent with
the possession of intelligence.... We are therefore led to conclude
that the phenomena must be explained in some other way than by being
referred to the working of an intelligence.”[13] But if we concede that
intelligence is absent, may there not at least be some consciousness?
Sir Michael Foster’s reply to such a question goes as far as we have
any justification for going, even when we give free rein to conjecture.
“We may distinguish,” he says, “between an active continuous
consciousness, such as we usually understand by the term, and a passing
or momentary condition, which we may speak of as consciousness, but
which is wholly discontinuous from an antecedent or from a subsequent
similar momentary condition; and indeed we may suppose that the
complete consciousness of ourselves, and the similarly complete
consciousness which we infer to exist in many animals, has been
evolved out of such a rudimentary consciousness. We may, on this view,
suppose that every nervous action of a certain intensity or character
is accompanied by some amount of consciousness which we may, in a
way, compare to the light emitted when a combustion previously giving
rise to invisible heat waxes fiercer. We may thus infer that when the
brainless frog is stirred by some stimulus to a reflex act, the spinal
cord is lit up by a momentary flash of consciousness coming out of
the darkness and dying away into darkness again; and we may perhaps
infer that such a passing consciousness is the better developed the
larger the portion of the cord involved in the reflex act and the more
complex the movement. But such a momentary flash, even if we admit its
existence, is something very different from consciousness as ordinarily
understood, is far removed from intelligence, and cannot be appealed to
as explaining the ‘choice’ spoken of above.”[14]

These sentences indicate with sufficient clearness the distinction,
more than once hinted at in the foregoing pages, between consciousness
as an accompaniment, and consciousness as a guiding influence. We
shall have more to say in this connection in subsequent chapters. The
experiment with the frog shows, at any rate, that reflex actions, of
a distinctly purposive nature, may be carried out when the centres,
which are believed to exercise conscious control and guidance have
been destroyed. It is said that in man, when, owing to injuries of
the spine, the connection between the brain and the lower part of the
spinal cord have been severed, tickling of the foot causes withdrawal
of the limb without directly affecting the consciousness of the
patient. But in all such cases we are dealing with a maimed creature.
The living frog or man, healthy and intact, is, presumably in the one
case, certainly in the other, conscious of these reflex actions, and
can exercise some amount of guidance and control over them. In man this
is unquestionably the case. But granting that the brain is the organ
of conscious control, granting that it can receive impulses from and
transmit impulses to the reflex centres, no more is here implied, and
no more can be legitimately inferred, than that the kind of organic
behaviour we call “reflex action” is in the higher animals in touch
with the guiding centres. We have no ground for assuming that in
reflex action there is any power of intelligent guidance independent
of that which is exercised by the brain or analogous organ. In brief,
reflex acts, in animals endowed with intelligence, may be regarded as
specialized modes of organic behaviour; which are in themselves often
characterized by much complexity; which subserve definite biological
ends; which are effected by subordinate centres capable of transmitting
impulses to, and receiving impulses from, the centres of intelligent
guidance; and which, as responses confined to certain organs or parts
of the body, form elements in the wider behaviour of the animal as a
whole.

VI.--THE EVOLUTION OF ORGANIC BEHAVIOUR

The interpretation of organic behaviour in terms of evolution mainly
depends on the answer we give to the question: Are acquired modes
of behaviour inherited? A negative answer to this question is here
provisionally accepted. But the premisses from which this conclusion is
drawn are too technical for discussion in these pages. It must suffice
to state as briefly as possible what this conclusion amounts to, and to
indicate some of the consequences which follow from its acceptance.

The fertilized egg gives origin, as we have seen, to the multitude
of cells which build up the body of one of the higher animals. There
are, on the one hand, muscle-cells, gland-cells, nerve-cells, and
other constituents of the various tissues; and there are, on the
other hand, the reproductive cells--ova or sperms, as the case may
be. Now, every cell in the developed animal is a direct descendant of
the fertilized egg. But of all the varied host only the reproductive
cells take any direct share in the continuity of the race. Hereditary
transmission is therefore restricted to the germinal substance of
these reproductive cells. Trace the ancestry of any cell in the adult
body, say a nerve-cell, and you reach the fertilized ovum. Trace back
the ancestral line yet further, and you follow a long sequence of
reproductive cells, or, at least, of cells which have undergone but
little differentiation; but never again will you find, in the course of
a genealogy of bewildering length, a nerve-cell. Such a tissue-element
is a descendant, but cannot become an ancestor; it dies without direct
heirs.

It is universally admitted that the bodily structures are subject
to what is termed _modification_ under the stress of environing
circumstances. The muscles may acquire unusual strength by use and
exercise; the nerve-centres may learn certain tricks of behaviour
in the course of individual life; and other structures may be
similarly _accommodated_ to the conditions which affect them. To such
modifications of structure or function in the organs or parts the term
_acquired_ is primarily applied. The tissues have thus a certain amount
of organic plasticity, through which they are adjusted to a range of
circumstances varying in extent. They are able to acquire new modes of
behaviour. But the cells of which they are composed are off the line
of racial descent. They leave no direct heirs. When the body dies the
modifications of behaviour acquired by its parts perish with it. Only
if in some way they exercise what we may term a homœopathic influence
on the germinal substance can the accommodation they have learnt be
transmitted in inheritance. By a _homœopathic_ influence is here
meant one that is of such a nature as to communicate to the germinal
substance, the seeds of similar changes of structure or function.
And of the occurrence of any such homœopathic influence there is no
convincing evidence.

Logically contrasted with the modifications of the tissues, dependent
on organic plasticity, are the _variations_ which arise from the
nature and constitution of the reproductive cells. How they arise
cannot here be discussed. But they are, it is believed, subject to
the influence of natural selection, which has guided them, throughout
the ages of organic evolution, in the directions they have taken;
disadvantageous variations having been eliminated, and favourable
variations surviving in the struggle for existence. Such modes of
behaviour as are congenital and are due to hereditary transmission are
therefore the outcome of variations which have been selected generation
after generation. And the fit adjustment of this congenital behaviour
to the needs of life is termed _adaptation_. It is here assumed that
modifications of behaviour in one generation are not inherited, and
therefore contribute nothing to the store of adaptive behaviour in the
next generation.

It must not, however, be supposed that the provisional acceptance of
this conclusion involves the denial of all connection of any sort
between accommodation and adaptation. When we remember that plastic
modification and germinal variation have been working together,
in close association, all along the line of organic evolution to
reach the common goal of adjustment to the circumstances of life,
it is difficult to believe that they have been throughout the whole
process altogether independent of each other. Granted that acquired
modifications, as such, are not directly inherited, they may none the
less afford the conditions under which _coincident variations_ escape
elimination. By coincident variations I mean those the direction of
which coincides with that taken by modification. The survival of an
animal depends on its adjustment to the circumstances of its life, no
matter how this adjustment is secured. And this survival would in the
long run be better secured, we may suppose, where the two methods of
adjustment were coincident and not conflicting;[15] just as a man who
not only acquires by his own exertions a fortune but also inherits
one, is better off than his neighbour, of equal business capacity,
who is entirely dependent on his own exertions. The inheritance of a
small capital may, indeed, make just the difference between success
and failure. Even with it, if he had no power of acquiring more, he
might remain a poor man. Inheritance and acquisition combined may
best lead to survival in competition. Thus modification may supply
the conditions under which coincident variations are favoured, and,
given time, to reach step by step, through natural selection, a fully
adaptive level. If this be so we may accept many of the facts adduced
by the transmissionist in favour of the direct inheritance of acquired
characters, and at the same time interpret them on selectionist
principles.

If, however, acquired characters are not hereditary the method of
natural selection in racial progress is curiously indirect. Apart from
the preservation of their fecundity, the cells on which the continuity
of life, in all the higher animals, depends, have themselves taken
little part in the struggle for existence. Just as in the forest tree,
the firmly implanted roots, the sturdy stem, and the strong branches
have to bear the stress of the winter storm, that the flowers of
spring may ripen the seeds which contain the potentiality of all this
strength; so do muscle, sinew, and brain secure the survival of the
animal, that his descendants may carry on the struggle. One may liken
the cellular constituents of the animal to a hive of bees with fertile
drones and queen, and sterile workers. It is on the exertions of the
latter that, in the struggle for existence, the continued existence
of the swarm depends, while it is by the pairing of the fertile drone
and queen that the continuity of the race is secured. No worker can
transmit the qualities which are so essential to the well-being of
the community. But in the eggs of their sister the queen-mother these
qualities lie dormant. And since the race is one race, the workers
by their exertions contribute indirectly to the maintenance of those
hereditary aptitudes to which they are unable to contribute directly.
For it is essential to bear in mind that they not only work for their
own generation, but they determine the course of heredity. Picture two
such communities set in an environment which intensifies the struggle
for existence. The one is strong, healthy, and vigorous; the other in
all respects the reverse. The incidence of the battle of life falls
mainly on the workers. If they succumb in the one group their fertile
queen either perishes, or gives rise to a poor stock, certain in the
long run to be eliminated. But the vigorous workers in the other group
survive and secure, too, the survival of their queen, who, since she is
also their sister, bears, in her ovaries, the good seed from which a
new generation of vigorous workers shall be developed. Thus though the
sterile bees contribute nothing directly to the heredity of the race,
they indirectly determine the direction which that heredity shall take.
So, too, in the higher animals, the reproductive cells are the fertile
sisters of a host of sterile body cells, on which the main incidence
of the struggle for existence falls. Their sterility precludes their
directly contributing to the success of future cell-generations; but
in protecting their fertile sisters, the reproductive cells, they are
really determining the lines along which the evolution of the race
shall continue.

Acquired characters may thus be regarded as the results of those
accidents, fortunate or the reverse as the case may be, which happen
to the body, and more or less modify its outward form or hidden
structure, and its modes of organic behaviour; but which, as such, have
no direct effects for better or worse on the germinal substance. All
that the plant or animal can be is due to heredity; all that it _is_,
to heredity and circumstance. Even the ability to yield to circumstance
is part of heredity’s dower. Fortunate, then, the plant or animal
that inherits such definiteness of structure and behaviour as may fit
it to its station, together with such plasticity as may enable it to
accommodate itself to those changes of environing conditions which may
fall to its lot.

One more point must be noticed in connection with this difficult and
puzzling subject. The acceptance of the conclusion that acquired modes
of behaviour are not hereditary nowise commits us to the belief that
heredity has nothing whatever to do with them. Though what is acquired
may not be transmitted, what one may term the acquisitiveness is
unquestionably inherited. Though this, that, or the other acquired mode
of behaviour may have no direct descendants, the power of acquiring
any one of them under the appropriate circumstances is handed on as an
invaluable legacy. Just as the mirror which has reflected a fleeting
scene retains no lasting image of the bygone events, so heredity may
retain no impress of acquired characters; but just as the mirror
keeps its power of reflecting such scenes, so does heredity transmit
the power of acquiring such characters. As the leaves of the oak are
renewed each successive spring, so may acquired modes of behaviour be
repeated in each successive generation if only the requisite conditions
recur in due season.

From what has preceded it may, therefore, be inferred that organic
behaviour may arise either through modifications occurring in the
plastic tissues, or through variations having their origin in the
germinal substance. Broadly speaking, however, we may regard as
predominantly due to adaptation those congenital modes of behaviour and
those organic responses which on their first occurrence are relatively
definite in character, and which are directed to a biological end, for
whose attainment the tissues have had no preparatory training; and we
may regard as predominantly due to accommodation those responses which
are, so to speak, learnt by the tissues in the course of individual
life. Both are dependent on heredity, but in different ways. What the
animal owes to heredity may, indeed, as I have elsewhere said,[16] be
classified under two heads. Under the first will fall those relatively
definite modes of behaviour which fit the animal to deal at once, on
their first occurrence, with certain essential or frequently recurring
conditions of the environment. Under the second head will fall the
power of dealing with special circumstances as they arise in the
course of a varied life. The former may be likened to the inheritance
of specific drafts for definite needs which are sure to arise in the
conduct of life; the latter to the inheritance of a legacy which may
be drawn upon for any purpose as occasion may demand. If the need
becomes habitual the animal may, so to speak, instruct his banker to
set aside a specific sum to meet it as it arises. But this arrangement
is a purely individual matter, dictated by experience, and in no wise
enjoined by the original terms of the bequest. And both types are
fostered by natural selection which develops (_a_) such congenital
definiteness of response, and (_b_) such innate plasticity, as are
advantageous under the conditions of existence; uniform conditions
tending to emphasize the former, variable conditions the latter.

Difficult as it may be to earmark the items of the organic bequest--to
say that, of the sum of energy expended in any given case of organic
behaviour, so much is due to a specific draft definitely assigned in
heredity for this particular purpose, and so much is contributed from
the general legacy of innate plasticity,--it none the less conduces
to clear thinking to emphasize the logical distinction between them,
so long as it is steadily borne in mind that logical distinction does
not imply biological separation. The animal, with all its varied modes
of behaviour, is an organic whole, and as an organic whole it has
been developed from the fertilized egg. The very same tissues which
exhibit congenital modes of behaviour are capable also of acquiring new
responses and playing their part in accommodation. We have not one set
of organs which are the products of variation and another set which
result from modification. Our study would no doubt be simplified if
this were the case; but it is not so. And we must take the animal as we
find it, presenting varied behaviour of complex origin. Even the reflex
nervous centres, which are concerned in responses so automatic as to
suggest a stereotyped structure of distinctively germinal origin, are
also, as we saw at the close of the last section, in close touch with
those centres of control which are associated with the supreme power of
accommodation arising from the possession of consciousness.

CHAPTER II

_CONSCIOUSNESS_

I.--THE CONSCIOUS ACCOMPANIMENTS OF CERTAIN ORGANIC CHANGES

It is possible that all organic behaviour is accompanied by
consciousness. But there is no direct means of ascertaining whether
it is so or not. This is, and must remain, a matter of more or less
plausible conjecture. We have, indeed, no direct knowledge of any
consciousness save our own. Undue stress should not, however, be laid
on this fundamental isolation of the individual mind. We confidently
infer that our fellow-men are conscious, because they are in all
essential respects like us, and because they behave just as we do when
we act under its guiding influence. And on similar grounds we believe
not less confidently that many animals are also conscious. But how far
we are justified in extending this inference it is difficult to say.
Probably our safest criterion is afforded by circumstantial evidence
that the animal in question profits by experience. If, as we watch
any given creature during its life-history, we see at first a number
of congenital or acquired modes of behaviour, we may not be able to
say whether they are accompanied by consciousness or not; but if we
find that some of these are subsequently carried out more vigorously
while others are checked, we seem justified in the inference that
pleasurable consciousness was associated with the results of the
former, and disagreeable consciousness with those of the latter. When
we see that a chick, for example, pecks at first at any small object,
it is difficult to say, on these grounds, whether it is a sentient
animal or only an unconscious automaton; and if it continued to behave
in a similar fashion throughout life, our difficulty would still
remain. But when we see that some objects are rejected while others are
selected, we infer that consciousness in some way guides its behaviour.
The chick has profited by experience. But even this is clearly only a
criterion of what we may term _effective_ consciousness. There may be
sentience which is merely an accompaniment of organic action without
any guiding influence on subsequent modes of behaviour. In that case it
is not effective; and whether it is present or not we have no means of
ascertaining.

We seem also to be led to the conclusion, both from _a priori_
considerations and from the results of observation, that effective
consciousness is associated with a nervous system. Its fundamental
characteristic is control over the actions, so that some kinds of
behaviour may be carried out with increased vigour, and others checked.
And it is difficult to see how this can take place unless the centres
of control are different from those over which they exercise this
influence. If we are to understand anything definite by the guidance
of consciousness, we must conceive it as standing apart from and
exercising an overruling influence over that which it guides. This
is unquestionably an essential characteristic of consciousness, as
generally understood by those who take the trouble to consider its
relation to behaviour; and though some would seek to persuade us
that a mere accompaniment of consciousness can somehow determine the
continuance or discontinuance of organic behaviour, it is difficult
to see how this can be the case. The accompaniment of air-tremors
can no more influence the vibrations of a sounding string than an
accompaniment of consciousness can affect the nature of the organic
changes in the tentacles of the Sun-dew leaf.

And if, instead of trusting to such general _a priori_ considerations,
we study with attention the conditions under which an animal so behaves
as to lead us to infer that it profits by experience, we find that it
is not the consciousness that accompanies the behaviour which leads to
future guidance, but the consciousness that arises from the results of
the behaviour. Let us willingly grant that the newly hatched, and as
yet inexperienced chick, when it pecks at a small object is conscious
of a visual impression, and is conscious also of movements of its
neck and beak. These do not constitute the experience by which it
profits. This is provided by the results of the pecking, according as
the morsel seized is nice or nasty. We may say, in popular language,
that the little bird remembers when it sees a similar object that the
former results were pleasant or distasteful, as the case may be; and
that it is through this remembrance that future guidance is rendered
possible. But all the evidence that we possess goes to show that the
sensory centres, stimulated by what we will assume to be the taste
of the morsel, are different from those which are affected by sight,
and the movements concerned in pecking. So that the consciousness
which is effective in guiding future action is an accompaniment of the
stimulation of centres that are different from those concerned in the
behaviour over which guidance is exercised. And if this interpretation
of the observed facts be correct, it supports the conclusions reached
from _a priori_ considerations. It seems further to show that, not
only is a nervous system necessary for the occurrence of controlled
behaviour, but that no little complexity in its intercommunications is
essential.

It may be urged that the chick’s behaviour which has been selected
for purposes of illustration, and the interpretation we have put upon
it, throws too much stress on remembrance, so called, and further
gives the false impression that all experience must be for _future_
guidance. There are surely numberless cases, it will be said, in which
nothing of the nature of distinct memory is involved, and in which the
guidance of consciousness is exercised at once over present behaviour,
without any postponement to the future. Even omitting for the present
the former point, the formula implied--that present experience is
for future guidance--cannot be accepted in view of the familiar fact
that present experience is constantly influencing present behaviour.
Practically speaking, this is perfectly true: because, practically,
under the term present we include quite an appreciable period of
time--say, a few seconds, or even minutes. If we narrow our conception
of the present, as is commonly done in philosophical discussions, to
the boundary line between past and future, then it will be seen that
even the guidance of what in popular speech is called present behaviour
is really exercised on the _subsequent_ phases of that behaviour. At
the risk of some technicality our position must be explained a little
more fully. It is assumed that the data of consciousness are afforded
by afferent impulses coursing inwards from the organs of special sense,
or those concerned in responsive movements. This conclusion rests on
such a wide body of psychological inference that it may be accepted
without discussion, at any rate for our immediate purpose. The efferent
impulses, those which effect the orderly contraction of the muscles,
are unconscious; but when the movement is produced afferent impulses
course inwards from the parts concerned in the behaviour, and these may
then contribute data to consciousness.

Now let us suppose that a chick, which has been hatched in an
incubator, be removed some twelve hours after birth, held in the hands
for a few minutes until its eyes have grown accustomed to the light,
and placed on a table near some small pieces of hard-boiled egg.
Let us watch its behaviour and endeavour to interpret it. We shall
have occasion to consider hereafter whether the conscious experience
of parents and ancestors is inherited as such; for the present we
will assume that it is not. The chick has to acquire for itself its
own experience. A piece of egg catches the eye of the little bird,
which then pecks at it, and just fails to seize it. Here is a piece
of congenital organic behaviour. Taken by itself one might find it
difficult to say whether it is accompanied by consciousness or not,
just as one finds it difficult to say whether the closure of the
Venus’s Fly-trap is conscious. But the subsequent behaviour of the
chick leads us to infer that it is a sentient animal; and we may,
therefore, fairly assume that it is sentient from the first. Dividing
the course of the observed behaviour into stages, we may say that the
first stage is that in which the chick receives a visual stimulus
accompanied by a sensation of sight. Upon this there rapidly follows
the second stage, when the bird pecks, and its experience is widened
by new data of consciousness derived from a group of motor sensations;
and upon this, again, there follows the third stage, when sensations
come in from the morsel of egg which the chick touched but just failed
to seize. After a pause the chick strikes again. But we have not a mere
repetition of the former sequence of stages. The visual stimulus at
first fell upon the eye of a wholly inexperienced bird; now it falls
upon the eye of one that has gained experience of pecking and tasting.
What we may call the _conscious situation_ has completely changed, at
all events if we assume that the items of consciousness, including
as essential the consciousness of behaviour, do not remain separate
and isolated, but have coalesced into a group through association.
And in this group the consciousness of behaving is perhaps the most
important element in the situation, making it of practical value.
What psychologists term the _presentative_ visual stimulus, now calls
up _re-presentative_ elements, motor and gustatory; and these place
the situation in a wholly new aspect. They give it what Dr. Stout
terms “meaning.” On the second or third attempt the chick seizes and
swallows the morsel of egg. Its experience is yet further widened; and
thereafter the situation has other new elements. Later it pecks at
some nasty grub; shakes its head, and wipes its bill on the ground.
The conscious situation has for the future become more complex, and
the behaviour is henceforth differentiated into that of acceptance and
that of rejection, in each case determined by the acquired meaning
in the coalescent conscious situation: the sight of a nice piece of
egg being one situation, that of a nasty caterpillar another, each
associated with its specific behaviour-consciousness. We need not
carry the illustration further on these lines: the essential feature
is that experience grows by the coalescence of successive increments,
and that each increment modifies the situation which takes effect on
the _succeeding_ phases of behaviour, even if they succeed within the
fraction of a second. That is what is meant by saying that present
experience is for future guidance. The future need not be remote, but
may be so immediate that in popular speech we may say that it is not
future but present guidance which is rendered possible.

We may now turn for a moment to the criticism that there are
numberless cases in which nothing of the nature of distinct memory
is involved. We may now substitute for the word remembrance, which
was used above, the more technical term _re-presentation_. Profiting
by experience, regarded as a criterion of the presence of effective
consciousness, involves re-presentative elements in the conscious
situation which carry with them meaning. Let us for the moment assume
an ultra-sceptical attitude with regard to any conscious accompaniment.
The chick when it pecks, let us say, is an unconscious automaton. It
seizes a piece of egg; this affords an unconscious stimulus, which sets
agoing unconscious acts of swallowing; or it seizes a piece of meal
soaked in quinine, which sets agoing unconscious acts of rejection and
touches the hidden springs which make the automaton wipe its bill.
So far we find no great difficulty. It is when we have to consider
subsequent behaviour that a severe strain is felt on this method of
interpretation. One can understand an automatic action repeated again
and again as often as the stimulus is repeated. But the chick may shake
its head and wipe its bill on the mere sight of the quinine-soaked
meal, which, on the hypothesis of conscious experience, has already
proved distasteful. So that if we accept the unconscious automaton
theory we must assume an organic association which closely simulates
the conscious association to which our own experience testifies. But
the associations which take part in the guidance of behaviour in the
chick are so varied and delicate, so closely resemble those which in
ourselves imply conscious guidance, that a sceptical attitude throws
more strain upon our credulity than the acceptance of the current
belief in conscious control. We shall therefore assume that evidence
for such coalescent association is also evidence of the presence of
effective consciousness.

It may still be said, however, that in selecting an example from so
highly organized an animal as a bird, we are taking for granted that a
complex case of controlled behaviour may fairly be accepted as a type
of more simple cases. Unfortunately the only being with whose power
of conscious control we have any first-hand acquaintance is possessed
of a nervous system even more complex than that of the chick. Our
psychological interpretations are inevitably anthropomorphic. All
we can hope to do is to reduce our anthropomorphic conclusions to
their simplest expression. The irreducible residuum seems to be that
wherever an animal, no matter how lowly its station in the scale of
life, profits by experience, and gives evidence of association, it must
have some dim remembrance, or, let us now say, some re-presentation,
of the results of previous behaviour which enters into and remodels
the conscious situation; that through the re-presentative elements
behaviour is somehow guided; and, further, that the centre of conscious
control is different from the centre of response over which the control
is exercised.

II.--THE EARLY STAGES OF MENTAL DEVELOPMENT

We use the phrase “mental development” in its broadest acceptation as
inclusive of, and applicable to, all phases of effective consciousness.
We shall assume that throughout this development there is a concomitant
development of nerve-centres and of their organic connections. And we
shall further assume that experience, as such, is not inherited.

The nature of the grounds on which the latter assumption is based must
first be briefly indicated. It is commonly asserted that fear of man,
the inveterate hunter and sportsman, is inherited by many animals, as
is also that of other natural enemies. This is, however, questioned,
or even denied, by many careful observers. Mr. W. H. Hudson has an
excellent chapter on “Fear in Birds” in his “Naturalist in La Plata,”
and concludes that fear of particular enemies is, in nearly all
cases, the result of experience individually acquired. I have found
that pheasants, partridges, plovers, domestic chicks, and other young
birds, hatched in an incubator, show no signs of fear in the presence
of dog or cat, so long as the animal is not aggressive. It should be
mentioned, however, that Miss M. Hunt[17] asserts that chicks do show
inherited fear of the cat. Dr. Thorndike’s[18] observations, on the
other hand, support my own, which I have since repeated with the same
results. Neither birds nor small mammals show any signs of fear of
stealthily moving snakes. My fox terrier smelt, nose to nose, a young
lamb which was lying alone in a field. I was close at hand, and could
detect no indication of alarm on the part of the lamb till the mother
came running up in great excitement. Then the lamb ran off to her dam.
Whenever opportunity has arisen, I have introduced young kittens to my
fox terrier, and have never seen any sign of inherited fear. He was a
great hunter of strange cats, but was trained to behave politely to all
birds and beasts within the precincts of my study. It is true that he
was on good terms, or at least terms of permissive neutrality, with the
kittens’ mother. And it may be said that this was inherited; but such
an argument cannot apply in the case of pheasant or lamb.

Here, as throughout our study of animal behaviour in its conscious
aspect, we have not only to conduct observations with due care, but
to draw inferences with due caution. Douglas Spalding described how
newly hatched turkeys showed signs of alarm at the cry of a hawk; and
he inferred that, since this sound was quite new to their individual
experience, the alarm was due to the inheritance of ancestral
experience of hawks. But since young birds show signs of alarm at any
sudden and unaccustomed sound--a sneeze, the noise of a toy horn, a
loud violin note, and so forth--the safer inference seems to be that
they may be frightened by strange sounds of many kinds. But this
does not imply the inheritance of experience, which is essentially a
discriminating process. There is no sufficient evidence that a peculiar
cry suggests the hawk, of which the progenitors have acquired bitter
experience; nothing to justify the belief that the sound carries
with it inherited meaning. And as with hearing, so with sight. Young
birds may be frightened by many strange objects. I have seen a group
of several species, filled with apparent alarm at a large white jug
suddenly placed among them, at balls of paper tossed towards them, at a
handkerchief dropped in their midst. It is, in fact, their inexperience
which is often the condition of such fear. As Mr. Hudson says:[19] “A
piece of newspaper carried accidentally by the wind is as great an
object of terror to an inexperienced young bird as a buzzard sweeping
down with death in its talons.”

Until recently it was commonly asserted that birds avoid gaudy but
nauseous or harmful insects through the inheritance of experience
gained by their ancestors through many generations. But here again
the inference seems to have been incautiously drawn. Of the hundreds
of young birds I have had under observation, not one has avoided the
peculiarly distasteful cinnabar caterpillar, until it had gained for
itself experience of its nauseous character. So too of wasps and bees.
Only through experience are these avoided. It is true that chicks may
shrink from them if they buzz or even walk rapidly towards them. But a
large harmless fly will inspire just as much timidity. As the result of
careful observations, Mr. Frank Finn[20] concludes “that each bird has
to separately acquire its experience, and well remembers what it has
learnt.” And with this conclusion my own observations are entirely in
accord.

Such is some of the observational evidence on which is based the
provisional hypothesis that experience, as such, is not inherited.
What, then, is inherited? Clearly the organic conditions under which
experience can be acquired. Since a young bird inherits a tendency
to peck at small objects, especially, in the case of some birds such
as plovers or partridges, at small moving objects, opportunities
are afforded for discrimination in accordance with the results of
experience. Since its inherited timidity leads the chick to shrink
from many things seen or heard, a wide range of conscious data is
supplied. Inheritance provides the raw material of organic behaviour
for effective consciousness to deal with in accordance with the results
which are its data.

Having thus cleared the ground and laid bare some at least of the
assumptions which we accept as foundations on which to build, we may
now follow up the line of treatment which was suggested in the first
section of this chapter. Remembering that our aim is to understand the
influence of consciousness on behaviour--or, in more accurate, if more
cumbrous phraseology, the influence of certain nerve-centres which have
for their concomitant what we have termed effective consciousness--the
questions which present themselves in any given case are: What is the
conscious situation which is effective in guidance? what elements
enter into the situation, whence are they derived, and how were they
introduced? how do they take effect in behaviour?

If it be true that, in many of the lower forms of life, consciousness
or sentience, though presumably present in some dim form, is merely
an accompaniment of organic behaviour without reaching the level of
recognizable effectiveness; and if, during the development of one
of the higher animals from the fertilized ovum, the early stages of
organic behaviour are in like manner merely sentient; it follows
that, when effective consciousness enters upon the scene (who can say
at what exact stage of evolution?), it finds itself a partner in a
going concern. Much organic business is being transacted with orderly
regularity; preparations have been made for more extensive operations;
and energies lying dormant, or expending themselves aimlessly in starts
and twitches, await the guidance which shall direct them to higher and
wider biological ends. Or, to vary the analogy, consciousness is the
heir to a wide estate, over which he has no control until he comes of
age. Up to that time the estate is managed in strict accordance with
the dictates of the hereditary bequest. He may be aware of what is
going on, but merely as a spectator without power of interference. And
when he comes into possession his first business is to gather up the
threads. He must learn bit by bit how the estate is being managed, that
he may have data for the guidance of his own management within the wise
limits of the hereditary entail.

Now, when a mammal is born, a bird is hatched, an insect emerges from
the chrysalis, we have, if not the beginning, at any rate a great and
sudden extension of the range of effective consciousness. In the case
of the mammal and bird the experience gained in the womb or within the
egg-shell is presumably of little value for the wider life upon which
an entrance is made. It is true that an insect has passed through a
previous stage of active and no doubt consciously guided existence as
a caterpillar. But we do not know whether the experience thus acquired
is effectual for use in the later imago stage. And we may perhaps
infer from the extensive remodelling of the nervous system, which
occurs during the chrysalis sleep, that this itself serves to break
the continuity of experience. In any case the newly hatched chick, if
it inherit no experience, and can have gained little of guiding value
in the egg, enters upon a situation which from the number and variety
of the data supplied may well seem to us bewildering. If we picture
ourselves in such a position, with sights, sounds, motor sensations,
touches, and pressures raining in upon a virgin experience, we wonder
how we should make a beginning; how we could possibly decide on
the first step towards reducing this multiplicity and diversity to
something like unity and order. And perhaps we wonder how we ourselves
made a beginning when we were pink newly born babies.

If it may be said without paradox, we never did make a beginning. The
beginning was made for us. For we habitually associate ourselves with
the control centres, and regard our bodies, like our watches, as ours
and not us. We wind the bodily watch, and set its hands from time to
time; but we did not make it, and it was already going when heredity
handed it to us over the counter of birth. The first step towards
reducing the seeming chaos of sensory experience to something like
order is not due to the selection by consciousness of this or that
element for prominence among the rest, but to the thrusting forward
of certain modes of behaviour by the conditions of organic life. The
differentiation of the field of vision in the chick is not effected
by any conscious determination to fix the attention on that wriggling
maggot, but through the congenital response it calls forth. This serves
not only to make the grub stand out clearly amid its surroundings, but
also to emphasize a motor group, called into vigorous action in the
midst of other motor sensations, and, in rapid sequence, to lay stress
on a sensation of taste suddenly called into prominence.

Nor, as we have seen, do the organic effects cease here. The functional
action of three sensory centres is thus called into play. But they are
constituent parts of one nervous system. The direct stimulation of each
by nerve impulses from eye, motor organs, and beak, gives temporary
predominance to certain sensory data which are termed presentative. But
the several centres are connected with each other. And thenceforward,
in subsequent stages of experience, the direct stimulation of the
visual centre indirectly calls into play the other two, so that the
presentation through sight evolves re-presentations of the motor group,
and of taste. Hence sentience is not sufficient for guidance; there
must be _consentience_ involving the presence of several elements. But
these elements must not be regarded as separate save in our analysis;
they form constituent parts of the coalescent situation as a whole,
of which alone the chick is presumably conscious, without analysis of
detail.

It is just because the chick is a going concern when consciousness
comes of age and begins to assume control--just because a wide range
of congenital behaviour is part of the organic heritage--that the
early stages of the acquisition of experience proceed so rapidly and so
smoothly. The animal has not to make and fashion the early conscious
situations; it has only to accept them. It has not at first to
enforce order on the multiplicity of sensory data raining in upon the
conscious centres; it has only to take note of the existing order among
them. It has not painfully to learn how to co-ordinate the efferent
impulses proceeding to the many muscles concerned in some simple
response; it has only to be sensitive to the response as a whole. It
has not to select the association of this, that, and the other group
of data within a coalescent situation; organic behaviour provides it
with predetermined sequences ready made--sequences which have for
generations received the emphatic sanction of natural selection.
Congenital tendencies which it has inherited but not acquired determine
all its earliest behaviour, determine what elements in the sensory
complex shall be thrust into conscious prominence, determine in what
manner these data shall be associated; determine, in fact, what salient
points in the developing situations shall stand out clearly from the
rest, and how these salient points shall be grouped and linked by the
connecting threads of association and shall coalesce into effective
wholes.

And if in the comparatively helpless human infant the congenital modes
of response seem less organized than those of the chick, if there is a
larger percentage of random and apparently aimless movements, if the
organic management of the bodily estate is less definitely ordered
by the terms of the hereditary bequest, if there is more of maternal
guidance and fosterage; still the data are provided in a substantially
similar way. The situations are indeed destined to become more complex,
the distinctions which arise in consciousness are more numerous, the
coalescence and association include a wider range and succession of
salient points; a longer time is required to become acquainted with
the transactions of a business conducted in a far greater number
of centres: but, at least in the early stages, the data are of the
same kind, and are emphasized in the same way. Presentation and
re-presentation play a similar _rôle_; and the chief difference lies
in the fact that less stereotyped congenital behaviour is supplemented
by some guidance, probably far less than is generally supposed, from
those who lovingly minister to the course of infant development.

No attempt can here be made to trace even in outline (an outline
which must in any case be imaginary and conjectural) the sequence of
situations which marks the course of mental development in its earlier
stages. An example may, however, serve to show how the exercise of
congenital tendencies may give rise to a new situation, and lead to a
further development of behaviour.

I kept some young chicks in my study in an improvised pen floored
with newspaper, the edges of which were turned up and supported, to
form frail but sufficient retaining walls. One of the little birds,
a week old, stood near the corner of the pen, pecking vigorously and
persistently at something, which proved to be the number on the page
of the turned-up newspaper. He then transferred his attention and his
efforts to the corner of the paper just within his reach. Seizing this,
he pulled at it, bending the newspaper down, and thus making a breach
in the wall of the pen. Through this he stepped forth into the wider
world of my study. I restored the paper as before, caught the bird, and
replaced him near the scene of his former efforts. He again pecked at
the corner of the paper, pulled it down, and escaped. I then put him
back as far as possible from the spot. Presently he came round to the
same corner, repeated his previous behaviour, and again made his escape.

Now, here the inherited tendency to peck at small objects led, through
the drawing down of the paper, to a new situation, of which advantage
was taken. The little drama consisted of two scenes, which may be
sufficiently described as “the corner of the pen,” and “the open way,”
this being the sequence in experience. Subsequently the first scene
was again enacted in presentative terms, and there followed first
a re-presentation of scene ii., with its associated behaviour, and
then the presentative repetition of this scene. We may take this as
a sample of the nature of a conscious situation which is effective
in guidance. We have seen the nature of the elements (sensory data,
including as essential those supplied by the behaviour itself, with a
pleasurable or painful tone) which enter into such a situation; we have
seen that they owe their primary origin to direct presentation, but
that they may be subsequently introduced indirectly in re-presentative
form; we have seen that the situation as a whole results from the
coalescence of the data. There only remains the question how the
felt situation takes effect on behaviour. And to this question,
unfortunately, we can give but a meagre and incomplete reply. All
we can say is, that connections seem to be in some way established
between the centres of conscious control and the centres of congenital
response; and that through these channels the responsive behaviour may
be either checked or augmented (as a whole or in part), according to
the tone, disagreeable or pleasant, that suffuses the situation. How
this is effected we do not fully know.

III.--LATER PHASES IN MENTAL DEVELOPMENT

Some surprise may be felt that in our brief discussion of the early
stages of mental development nothing has been said of percepts and
concepts, nothing of abstraction or generalization. The omission
is not only due to a desire to avoid the subtle technicalities of
psychological nomenclature. It is partly due to the wish not to
forejudge a difficult question of interpretation. Spirited passages of
arms from time to time take place between psychologists in opposing
camps, as to whether animals are or are not capable of forming abstract
and general ideas; and untrained camp followers hang on the skirts
of the fray, making a good deal of noise with blank-cartridge. The
question at issue turns partly on the definitions of technical terms;
partly, when there is agreement on this point, on the interpretation
to be put on certain modes of behaviour. Nothing seems at first sight
much easier than to say what we mean by an abstract idea or by a
general idea. We are thinking about colour, which is both abstract
and general--abstract, because in itself it is a special quality of
visible objects floated off, so to speak, from other qualities, such
as hardness and weight, shape and size; general, because it includes
many different colours in one group. Looking up at the bookshelves, we
see a volume with a red back. We neglect the shape, the contents, the
lettering; it is the colour with which we are immediately concerned,
which forms an important feature in the present thought-situation;
and this is, in virtue of that situation, abstracted from the rest.
But a chick a few days old may have acquired experience of several
kinds of caterpillars much alike in shape and size; of which, one kind
is ringed with orange and black. And while the others are eagerly
seized, caterpillars of this kind are left untouched. It is not the
size or the shape which is an effective element in the situation; it
is the peculiar coloration of the cinnabar caterpillars. Now, does the
effectiveness of this quality in the stimulus justify the inference
that the chick forms an abstract idea of colour? That clearly depends
on our definition of abstract idea, and on our inferences concerning
the nature of the chick’s mind.

A dog lies dozing upon the mat, and hears a step in the porch without.
His behaviour at once shows that this enters into the conscious
situation. There is, moreover, a marked difference according as the
step has the familiar fall of the master’s tread, the well-known
shuffle of the irrepressible butcher’s lad, or an unfamiliar sound.
These several situations are, without question, nicely distinguished.
Let us suppose the situation of the moment is introduced by a strange
footfall. It seems to suggest man; but this cannot be any particular
man, since he is as yet invisible and is a stranger. Does the dog,
then, frame a general idea of man? Does the chamois do so when,
bounding across the snow field, he stops suddenly on scenting the
distant footprints of a mountaineer? Do you do so when you hear the
bleating of an invisible lamb in the meadow behind yonder wall? Here,
again, the answers we give to these questions depend partly on the
exact meaning of the term “general idea;” partly on our interpretation
of what passes through the mind of the being concerned. We have sought,
so far, rather to avoid than to answer these questions. We seem to be
on safe ground so long as we content ourselves with saying that the
orange and black of the cinnabar caterpillar, the strange footfall,
or the trail of the mountaineer, enter as effective elements into the
immediate conscious situation.

But when we pass to the higher phases of mental development we can
no longer wholly ignore such questions. When we are dealing with
intellectual human beings, there can be no doubt that they at least
are capable of framing, with definite intention, and of set purpose,
both general and abstract conceptions. And how do they reach these
conceptions? By reviewing a number of past situations, analyzing them,
intentionally disentangling and isolating for the purposes of their
thought certain elements which they contain, and classifying these
abstracts under genera and species--that is to say, into broader and
narrower groups. The primary and proximate object of this process is to
reach a scheme of thought by which the scheme of nature, as given in
experience, can be _explained_. And, no doubt, underlying this primary
object is the purpose of guiding future behaviour in accordance with
the rational scheme which is thus attained. Man is sometimes described
as _par excellence_ the being who looks before and after. All his
greatest achievements are due to his powers of reflection and foresight.

What share the symbolism of speech takes in the process briefly
indicated in the last paragraph is the subject of much discussion.
Without going so far as to urge that the very beginnings of reflective
thought are inexplicable without its aid, it may be accepted as
obviously true that words are a great assistance. They may be regarded
as intellectual pegs upon which we hang the results of abstraction
and generalization. It may be said that we often think in pictures
or images, and not in words, but the more abstract and general our
thought, the more it is dependent on the symbolic elements.

We may say, then, that the higher phases of mental development are
characterized by the fact that the situations contain the products of
reflective thought, presumably absent in the earlier stages; they are
further characterized by a new purpose or end of consciousness, namely,
to explain the situations hitherto merely accepted as they are given
in presentation or re-presentation; they require deliberate attention
to the relationships which hold good among the several elements of
successive situations; and they involve, so far as behaviour is
concerned, the intentional application of an ideal scheme with the
object of rational guidance. We shall follow Dr. Stout in terming
this later stage of mental development the _ideational stage_; and in
speaking of the simpler situations considered in the preceding section
as belonging to the _perceptual stage_.

It should be observed that we are not attempting to determine just
where, in the scale of organic existence, the line between the
perceptual and the ideational stages of mental development is to be
drawn. We are certainly very far from asserting that the one does not
give rise to the other in the course of an evolution which is orderly
and progressive. We are merely contrasting the rational guidance
of effective consciousness at its best with the earlier embryonic
condition out of which it has arisen by natural genesis. In doing this
we have been forced to make some reference to the difficulties of
technical nomenclature. And some further reference is necessary lest
our point of view be misunderstood.

We shall regard these abstract and general ideas as the products of
an intentional purpose directed to the special end of isolating the
one and of classifying the other; we shall reserve the term _rational_
for the conduct which is guided in accordance with an ideal scheme or
deliberate plan of action; while for behaviour to the guidance of which
no such reflection and deliberation seems to have contributed we shall
reserve the term _intelligent_. If, for example, the rejection of a
cinnabar caterpillar by the chick is the direct result of experience
through the re-presentation in the new situation of certain elements
introduced during the development of a like situation, we shall call
it an intelligent act. But if we have grounds for supposing that the
situation is reflectively considered by the chick in relation to an
ideal and more or less definitely conceived plan of action which is
(perhaps dimly) taking form in its mind, we shall regard it as so
far rational. And so, too, in other cases of animal behaviour. Now,
with regard to the control through which consciousness is effective
in the guidance of behaviour, it is necessary, in view of these
considerations, to distinguish its intelligent from its rational
exercise. And this is of importance since we generally speak of control
in the latter sense in reference to human conduct. Intelligent control
(on the perceptual plane) is due to the direct operation of the results
of experience without the intervention of any generalized conception or
ideal. In rational control (on the ideational plane), such conceptions
and ideals exert a controlling influence. If, to prevent a boy sucking
his thumb we administer bitter aloes, we trust to intelligent control
through the immediate effects of experience; but if he be induced to
give up the habit because it is babyish, he so far exercises rational
control. What we call self-control is of this type. Only one more
distinction need be drawn. Intelligent behaviour, founded on direct
association gained through previous experience, we shall attribute to
_impulse_; but for rational conduct, the outcome of reflection and
deliberation, we seek to ascertain the _motive_. In human affairs our
motives are referred to certain categories each of which presupposes
an ideal scheme, prudential, æsthetic, ethical, or other. To act from
motive and not from impulse is to act deliberately, because we judge
the action to be expedient, seemly, or right, as the case may be. If,
then, we contrast the lower perceptual stages of mental evolution with
the higher ideational phases, the former includes behaviour due to
impulse; but from it conduct due to motive is excluded.

IV.--THE EVOLUTION OF CONSCIOUSNESS

The origin of consciousness, like that of matter or energy, appears
to be beyond the pale of scientific discussion. The appearance of
effective consciousness on the scene of life does indeed seem to
justify the belief in the prior existence of sentience as the mere
accompaniment of organic behaviour. _Ex nihilo nihil fit._ And
since effective consciousness must, on this principle, be developed
from something, it is reasonable to assume that this something is
pre-existing sentience. Again, we may assume that this sentience is a
concomitant of _all_ life-processes, or only of some. But we have no
criterion by which we can hope to determine which of these alternatives
is the more probable.

We appear, however, at all events to have evidence that when effective
consciousness does enter on the scene and play its part in the guidance
of behaviour, its progress is, in technical phraseology, marked by
that differentiation of conscious elements, and that integration of
these differentiated items, which are seemingly the correlatives of
the differentiation and integration of nervous systems. There is thus,
presumably, a progressive development of orderly complexity in the
conscious situations of which controlled or guided behaviour is the
outcome. And when this has reached a certain stage--what stage it is
most difficult to determine--the relationships, at first implicit in
the conscious situations, as they naturally arise in the course of
experience, begin to be rendered explicit with the dawn of reflection.
Intentional abstraction and generalization to which data are afforded
by the reiterated emphasis in experience of the salient features in
successive situations, supply new elements to the more highly developed
situations of rational life. Ideal schemes and plans of action, the
products of reflection and foresight, take form in the mind and enter
into the conscious situation. And the intelligent animal, hitherto the
creature of impulse, guided only by the pleasurable or painful tone
which gives colour to experience, becomes a rational being, capable of
judging how far his own behaviour and that of others is conformable to
an ideal.

If, then, we were asked to characterize in the briefest possible
terms the stages of conscious evolution, we should say that in the
first stage we have consciousness as accompaniment; in the second,
consciousness as guide; in the third, consciousness as judge. And if
we were pressed to apply distinctive terms to these three, we should
adopt St. George Mivart’s term _consentience_ for the mid-phase,
and speak of mere sentience in the first stage; consentience in the
second; and consciousness, with restricted signification, in the
third and highest stage. Such a distinction in terms is, however, a
counsel of perfection, and we shall not attempt to preserve it in the
following pages, in which the word “consciousness” will be used in a
comprehensive sense.

Ever since the publication of Darwin’s “Origin of Species,”
evolutionists have been divided into two sections where consciousness
in the narrower sense is under discussion. The members of the one
have contended that, though the physical and perhaps the lower mental
nature of man is the outcome of evolutionary process, his higher mental
attributes are of other origin. The members of the second section have
urged that the higher not less than the lower characteristics of the
mind of man have been evolved. It is somewhat strange that naturalists
who accept the latter position are not infrequently impatient when
any serious attempt is made to discuss it from the standpoint of
psychology. It is, however, becoming more and more clearly evident that
the discussion of the relation of the animal to the human mind, if it
is to be made a subject of scientific inquiry, must be conducted on
psychological lines by those who have devoted years of study to the
subject. In this work such a discussion will be attempted, and animal
behaviour will be treated as the precursor of human conduct, and as
affording evidence of the germs from which the distinctively human
mental attributes may have been evolved.

CHAPTER III

_INSTINCTIVE BEHAVIOUR_

I.--DEFINITION OF INSTINCTIVE BEHAVIOUR

There are probably few subjects which have afforded more material for
wonder and pious admiration than the instinctive endowments of animals.
“I look upon instinct,” wrote Addison in one of his graceful essays,
“as upon the principle of gravitation in bodies, which is not to be
explained by any known qualities inherent in the bodies themselves,
nor from any laws of mechanism, but as an immediate impression from
the first Mover and the Divine Energy acting in the creatures.”[21] In
like manner Spence said: “We may call the instincts of animals those
faculties implanted in them by the Creator, by which, independent of
instruction, observation or experience, and without a knowledge of
the end in view, they are all alike impelled to the performance of
certain actions tending to the well-being of the individual and the
preservation of the species.”[22] According to such views, instinct is
an ultimate principle the natural genesis of which is beyond the pale
of explanation. But similar views were, at the time these passages
were written, held to apply, not only to animal behaviour, but also
to animal structure. The development of the stag’s antler, or of the
insect’s wing, was also regarded as “an immediate impression from
the first Mover and the Divine Energy acting in the creatures.” This
view, however, is, neither in the case of structure nor in the case
of behaviour, that entertained by modern science. It is indeed an
expression of opinion concerning the metaphysics of instinct. Leaving
the question of ultimate origin precisely where it stood in the times
of Addison and of Spence, modern science seeks to trace the natural
antecedents of all natural phenomena, and regards structure and
behaviour alike as the products of evolution, endeavouring to explain
the manner of their genetic origin in terms of progressive heredity.

Omitting, therefore, all reference to problems which, however
important, are beyond the limits of scientific inquiry,[23] we may
take as a basis for further discussion Spence’s definition, according
to which the instincts of animals are those faculties by which,
independent of instruction, observation, or experience, and without
a knowledge of the end in view, they are all alike impelled to the
performance of certain actions tending to their own well-being and the
preservation of the species.

Let us first consider the reference of instinctive actions to
a _faculty_ by which animals are said to be impelled to their
performance. Paley also defined instinct as “a _propensity_ prior to
experience.” And unquestionably in the popular conception it is usual
to attribute instinctive acts to some such conscious cause. But it
will be more convenient, for the present, to consider instinctive
behaviour from the objective point of view, as it is presented to
our observation; we may then proceed to the further consideration of
the conscious concomitants which may be inferred. From the objective
point of view, therefore, we may agree with Professor Groos, who
says[24] that “the idea of consciousness must be rigidly excluded
from any definition of instinct which is to be of practical utility,”
since “it is always hazardous in scientific investigation to allow an
hypothesis which cannot be tested empirically.” In this we have the
support of Dr. and Mrs. Peckham, whose studies of the life-histories
of spiders and wasps are models of careful and patient investigation.
“Under the term Instinct,” they say, “we place all complex acts which
are performed previous to experience, and in a similar manner by all
members of the same sex and race, leaving out as non-essential, at
this time, the question of whether they are or are not accompanied by
consciousness.”[25]

It may be said, however, that some reference to the conscious aspect
of instinctive behaviour is implied by saying that the acts are
performed without instruction or experience. But the reference at
present is wholly negative. We may say, as the result of observation,
that instinctive acts are performed under such circumstances as exclude
the possibility of guidance in the light of individual experience, and
render it in the highest degree improbable that there exists any idea
of the end to be attained. But this is a very different position from
that of asserting the presence of a positive faculty or propensity
which impels an animal to the performance of certain actions. This it
is which, from the observational point of view, is unnecessary. For
the reference of a given type of observed behaviour to a “propensity”
so to behave or to a “faculty” of thus behaving, is no more helpful
than the reference of the development of any given type of structure
to a “potentiality” so to develop. We may, therefore, without loss of
precision, simplify Spence’s definition by stating that instinctive
behaviour is independent of instruction and experience, and tends to
the well-being of the individual and the preservation of the species.

Let us next consider the clause which affirms that instinctive
behaviour is prior to experience. This is well in line with the
distinction now drawn by biologists between congenital and acquired
characters. It refers them to the former category, and implies that
the organic mechanism by which they are rendered possible is of
germinal origin. This is not, however, universally admitted. Professor
Wundt, for example, approaching the subject from the point of view
afforded by the study of man and the higher animals, gives to the
term a wider meaning, and so defines instinct as to include acquired
habits. “Movements,” he says,[26] “which originally followed upon
simple or compound voluntary acts, but which have become wholly or
partly mechanized in the course of individual life, or of generic
evolution, we term _instinctive_ actions.” In accordance with this
definition, instincts fall into two groups. Those “which, so far as we
can tell, have been developed during the life of the individual, and
in the absence of definite individual influences might have remained
wholly undeveloped, may be called _acquired_ instincts.” They have
become instinctive through repetition. “To be distinguished from these
acquired human instincts are others which are _connate_.” Now, there
can be no question that behaviour which has become habitual through
frequent repetition is frequently, in popular speech, described as
instinctive. We hear it said that the experienced cyclist guides his
machine instinctively. And the word is similarly used in many like
cases. But we shall find it conducive to precision and clearness of
thought to emphasize the distinction between what is acquired in
the course of life and what is congenital in the race. And to this
end we shall regard behaviour which has “become mechanized in the
course of individual life” as due to acquired habit, reserving the
term _instinctive_ for such behaviour as is independent of individual
experience. We shall, in short, so far accept Spence’s definition.

In this definition, as in those of the majority of naturalists,
it seems to be further implied that instinctive behaviour is of a
relatively definite kind, though it is no doubt subject to such
variation as is found in animal structure and organization. Mr.
Rutgers Marshall, however, in a recent work,[27] protests against any
such implication, and urges that “this variableness is so wide that
definiteness of reaction cannot for a moment be used as a differentia
in relation to instinct without narrowing our conception of the bounds
of instinct in a manner to be deplored.” “The actions,” he says,
“connected with the preparation for self-defence, those connected with
protection of the young, with nest-building, with migration, etc.,
these actions are surely to be classed as instinctive; and yet they
are exceedingly variable and unpredictable in detail; all that we can
predict is the general trend of the varying actions which result from
varying stimuli under varying conditions, and which function to some
determinate biological end.”

Mr. Marshall then proceeds to argue that we are “warranted in speaking
of the ethical instincts, of the patriotic instincts, of the benevolent
instincts, and of the artistic instincts;” and thus leads up to the
position, to be further elaborated in his work, that there exists in
man a religious instinct which has fulfilled a function of biological
value in the development of our race. Now, here again there is much in
popular usage of the words _instinct_ and _instinctive_ which lends
support, for what it is worth, to Mr. Marshall’s very broad conception
of the range of instinct. Again and again we hear, in the pulpit and
elsewhere, of the religious instinct; we hear, too, of the benevolent,
patriotic, and artistic instincts, and more besides. But what we are
endeavouring to define is a type of behaviour which, as such, is
prior to instruction and experience. Can we affirm that patriotic and
religious behaviour conforms to such a type? Is it unquestionably
congenital and not acquired? If we are forced to give negative answers
to these questions we must regard Mr. Marshall’s conception of instinct
(one inclusive of multifarious tendencies which have a biological
value) as too broad and too vague to be of any service to us at this
stage of our study of animal behaviour.

What, then, shall we understand by Spence’s phrase that instinct
involves the performance of “certain actions”? And how far shall
we accept it? We shall take it as implying so much definiteness of
behaviour as renders instinctive acts susceptible of scientific
investigation, and in this sense shall accept it with some modification
of phraseology. We shall freely admit, however, the existence of
variations of instinctive behaviour analogous to variations in animal
structure. It is the occurrence of such variations that renders the
natural selection of instinctive modes of behaviour conceivable.
We shall also admit some, nay much, variation in detail. Take, for
example, two of the cases which Mr. Marshall cites--nest-building
and migration. Both involve, not merely a simple response to a given
stimulus, but a complex sequence of actions. In detail there may be
much variation even among members of the same species. And yet, can it
be questioned that the behaviour as a whole is in each case relatively
definite? May we not even say that it is remarkably definite? May we
not even go further, and assert that only on the assumption that any
given instinctive act is relatively definite, can we regard it as a
subject for scientific investigation, and can we hope to distinguish it
from other modes of behaviour?

The next point for consideration in Spence’s definition, which we
have taken as our text, is his characterization of instinctive acts
as “tending to the well-being of the individual and the preservation
of the species.” Here we have Mr. Marshall with us, for he too lays
stress on the fact that instinctive behaviour has reference to a
definite biological end. But in saying that the biological end is _the_
objective mark of an instinct,[28] he seems to be in error. Because,
in the first place, there are other “objective marks,” and because, in
the second place, this objective mark is not restricted to instinctive
behaviour. According to Spence, a further characteristic of instinctive
acts is that they are independent of instruction or experience; and
this serves to differentiate them from other modes of behaviour which
are also subservient to a biological end. Intelligent behaviour, not
less than that which we term instinctive, has reference to a biological
end. Many intelligent acts, for example, have for their object the
well-being of the individual; many subserve race preservation; these
bear, every whit as much as instinctive acts, the “objective mark”
which Mr. Marshall regards as characteristic of instinct. And if we
turn to his subjective criterion--the absence of any conception of
the biological end which the behaviour subserves--Mr. Marshall’s
position is equally untenable. There are thousands of acquired modes of
behaviour, dependent on instruction or experience, in which there is,
on the subjective side, so far as we can judge, no conception of the
biological end to be attained. What can the animal in the early stages
of intelligence know of biological ends? Mr. Marshall’s subjective
criterion applies just as much to a wide range of intelligent behaviour
as it does to instinctive actions.

In accepting, therefore, Spence’s statement that when animals
behave instinctively they perform, without a knowledge of the end
in view, certain actions tending to their own well-being and the
preservation of the species, we must take it in connection with the
preceding limitation, remembering that they are also performed without
instruction and experience.

A further point for very brief consideration is suggested by the
phrase in which Spence says that animals are _all alike_ impelled to
the performance of certain actions. As it stands it is too sweeping
and general. Still, we do require some explicit statement of the
facts which he had in mind when he wrote the words “all alike.” And
we find it with sufficient exactness in Dr. Peckham’s definition,
where he comprises under the category of instinctive behaviour “all
complex acts which are performed previous to experience, and _in a
similar manner by all members of the same sex and race_.” This places
congenital behaviour in line with morphological structure as a subject
for comparative treatment.

One more question remains. What shall we understand by “complex acts”?
In the first place, it is well to restrict the term instinctive
to _co-ordinated_ actions; and this implies the presence of
nerve-centres by which the co-ordination is effected. We thus exclude
the organic behaviour of plants, since there is no evidence in the
vegetable kingdom of co-ordinating centres. In the second place, the
co-ordination is, as we have seen, congenital, and not acquired in the
course of individual experience. Young water-birds, and indeed young
chicks, as soon as they are born, and have recovered from the shock
of birth, can swim with definite co-ordination of leg movements. Here
the definiteness is not only congenital, but _connate_, if we use the
latter term for an instinctive activity which is performed at or very
shortly after birth. On the other hand, young swallows cannot fly at
birth; they are then too immature, and their wings are not sufficiently
developed. But when they are some three weeks old, and the wings have
attained functional size and power, little swallows can fly with
considerable if not perfect skill. The co-ordination is congenital,
for it is not acquired in the course of individual experience; but it
is not connate, since it is not exhibited at or shortly after birth.
The term _deferred_ may be applied to such congenital activities as
are thus carried out when the animal has undergone a certain amount of
further development after birth.

In the third place, it is customary to distinguish between such reflex
actions as have already been briefly exemplified,[29] and instinctive
behaviour. It is, however, by no means easy, if indeed it be possible,
to draw any sharp and decisive line of demarcation. Instinct has indeed
been well described by Mr. Herbert Spencer as compound reflex action;
hence the distinction between instinctive and reflex behaviour turns in
large degree on their relative complexity. It would seem, however, that
whereas a reflex act--such as the withdrawal of the foot of a sleeping
child when the sole is tickled--is a restricted and localized response,
involving a particular organ or a definite group of muscles, and is
initiated by a more or less specialized external stimulus; instinctive
behaviour is a response of the animal as a whole, and involves the
co-operation of several organs and of many groups of muscles. Partly
initiated by an external stimulus or group of stimuli, it is also,
seemingly, determined in part, in a greater degree than reflex action,
by internal factors which cause uneasiness or distress, more or less
marked, if they do not find their normal instinctive satisfaction. This
point, however, may be more profitably discussed in connection with
the conscious aspect of instinct. If, then, we say that reflex acts
are local responses of the congenital type due to specialized stimuli,
while instinctive activities are matters of more general behaviour,
usually involving a larger measure of central (as opposed to local or
ganglionic) co-ordination, and due to the more widely-spread effects
of stimuli in which both external and internal factors co-operate, we
shall probably get as near as is possible to the distinction of which
we are in search. But it must be remembered that there are cases in
which the distinction can hardly be maintained.

We are now in a position to define instinctive behaviour as comprising
those complex groups of co-ordinated acts which are, on their first
occurrence, independent of experience; which tend to the well-being
of the individual and the preservation of the race; which are due to
the co-operation of external and internal stimuli; which are similarly
performed by all the members of the same more or less restricted group
of animals; but which are subject to variation, and to subsequent
modification under the guidance of experience.

II.--INSTINCTIVE BEHAVIOUR IN INSECTS

Since instinctive behaviour is, by definition, independent of
experience, and since the animals which act instinctively are also, in
many cases, able to act intelligently, it is clear that, apart from
hereditary variations, we must expect to find acquired modifications
of instinct. As Huber said of bees, their instinctive procedure often
indicates “a little dose of judgment.” It is, indeed, exceedingly
difficult, as a matter of observation, to distinguish between
hereditary variation and acquired modification. For the _rôle_ played
by these two factors in any given behaviour can only be determined if
the whole life-history of the individual be known, and if there be
opportunities for comparing it with the complete life-histories of
other members of its race. And this is seldom possible.

These considerations must be borne in mind as we proceed to a brief
study of some of the instinctive modes of behaviour in insects.

Dr. and Mrs. Peckham’s investigations on the instincts and habits of
the solitary wasps have been described in a volume[30] worthy to be
placed by the side of Fabre’s “Souvenirs.” Their descriptions seem to
glow with the warm sunshine, and are redolent of the fresh air which
afforded the conditions under which the observations were conducted. We
can but regret that, in extracting from their bright pages some of the
salient facts, the natural delicacy and grace of their treatment must
be lost. For we can only give the dry skeleton which they have clothed
with the flesh of lively detail. They enumerate the following primary
modes of instinctive behaviour:--

1. Stinging.

2. Taking a particular kind of food.

3. Method of attacking and capturing prey.

4. Method of carrying prey.

5. Preparing nest, and then capturing prey, or the reverse.

6. The mode of taking prey into the nest.

7. The general style and locality of the nest.

8. The spinning or not spinning of a cocoon, and its specific form when
one is made.

When the young _Pelopœus_ emerges from the pupa-case and gnaws its
way out of the mud cell, with limp and flaccid wings, it responds
to a touch by well-directed movements of the abdomen with thrusts
of the sting, as perfect as those of the adult. There is clearly no
opportunity here for either instruction or experience to afford any
intelligent guidance. Stinging is an instinctive act. And it is an act
of which great use is made in the capture of prey which shall serve for
food to the young--it has a biological end. But the wasps of different
species do not have to learn by experience what prey to attack. It
is by instinct, too, that they take their proper food-supply, one
caterpillars, another spiders, a third flies or beetles. So deeply
seated, indeed, is the hereditary preference, that no fly-robber ever
takes spiders, nor will the capturer of spiders change to caterpillars
or beetles. Some keep to a few species or genera, while _Philanthus
punctatus_ preys chiefly or entirely on bees of the genus _Halictus_.

Romanes[31] thought that the manner of stinging and paralyzing their
prey might “be justly deemed the most remarkable instinct in the
world.” Spiders, insects, and caterpillars are stung, he says, “in
their chief nerve-centres, in consequence of which the victims are not
killed outright, but rendered motionless; they are then conveyed to a
burrow and, continuing to live in their paralyzed condition for several
weeks, are then available as food for the larvæ when these are hatched.
Of course the extraordinary fact which stands to be explained is that
of the precise anatomical, not to say also physiological knowledge
which appears to be displayed by the insect in stinging only the
nerve-centres of its prey.” Eimer[32] thought that it “is absolutely
impossible that the animal has arrived at its habit otherwise than by
reflection upon the facts of experience.” “At the beginning,” he says,
“she probably killed larvæ by stinging them anywhere, and then placed
them in the cell. The bad results of this showed themselves; the larvæ
putrified before they could serve as food for the larval wasps. In the
mean time the mother wasp discovered that those larvæ which she had
stung in particular parts of the body were motionless but still alive,
and then she concluded that larvæ stung in this particular way could be
kept for a longer time unchanged as living motionless food.”

Now, since these wasps, when they have stored their nests and laid an
egg on one of the victims, close it up once and for all, and take no
further interest in it or its contents, there seems no opportunity,
at any rate in the existing state of matters, for the acquisition of
that experience on which Eimer relied. But both his explanation and
Romanes’s difficulty are based on the following assumptions: first,
that the victims are instinctively or habitually stung in the chief
nerve-centres; secondly, that when thus stung they are not killed
but remain paralyzed for weeks; and thirdly, that the marvellously
definite and delicate instinctive behaviour is in direct relation to
the uniform result of prolonged paralysis and consequent preservation
of the food in the fresh state. But Dr. Peckham’s careful observations
and experiments show that, with the American wasps, the victims stored
in the nests are quite as often dead as alive; that those which are
only paralyzed live for a varying number of days, some more, some
less; that wasp larvæ thrive just as well on dead victims, sometimes
dried-up, sometimes undergoing decomposition, as on living and
paralyzed prey; that the nerve-centres are not stung with the supposed
uniformity; and that in some cases paralysis, in others death, follows
when the victims are stung in parts far removed from any nerve-centre.
“We believe,” he says, “that the primary purpose of the stinging is to
overcome resistance, and to prevent the escape of the victims, and that
incidentally some of them are killed and others are paralyzed.”

If, therefore, as will probably be shown to be the case, these
conclusions are found to be generally true for this interesting group
of insects, the mystery of “the precise anatomical, not to say also
physiological knowledge which appears to be displayed” by these wasps
turns out to be one of our own fabrication. It melts away in the light
of fuller and more searching investigation.

[Illustration: FIG. 11.--Solitary Wasp stinging Caterpillar (after
Peckham).]

It must not be supposed, however, from what has been said, that the
behaviour in the act of stinging is altogether indefinite. On the
contrary, each species proceeds in a relatively definite manner with
some variation or modification of method. _Philanthus punctatus_, for
example, stings the bees, on which she preys, under the neck, and the
thrust is at once fatal. Dr. Peckham further notes that he was only
successful in getting the wasps to sting when they were hunting; those
that had not yet begun to store the nests paid no attention to the
bees. This is an example of that internal factor to which reference was
made in the last section. Marchal observed that _Cerceris ornata_ runs
the end of her abdomen along the under surface of the thorax of the
bee, and delivers her thrust at the division of the segments--that is,
where the sting can enter. The action does not imply any physiological
knowledge. In general she begins at the neck. Spiders are usually, but
not always, stung on the ventral surface. To give but one more example,
Dr. Peckham observed in three cases the procedure of _Ammophila
urnaria_ which preys on caterpillars, and often, after stinging, bites
the neck in several places, this process being termed malaxation. In
three observed captures, all the caterpillars being of the same species
and alike in size, the thrusts were given on the ventral surface near
the middle line, between the segments. In the first, seven stings were
given at the extremities (there being thirteen segments), the middle
segments being left untouched, and no malaxation was practised. In the
second, seven stings were again given, but in the anterior and middle
segments, followed by slight malaxation. In both these cases the first
three thrusts were in definite order, behind the third, the second, and
the first segments successively. In the case of the third caterpillar,
only one thrust was given, between the third and fourth segments--that
is to say, in the position of the first stab in the other cases,--and
after this one thrust there was prolonged malaxation. Of fifteen stored
caterpillars examined, some lived only three days, others a little
longer, while a few showed signs of life at the end of a fortnight. In
more than one instance the second of the two caterpillars stored in
each nest died and became discoloured before the first one was entirely
eaten. The larva under such circumstances ate it with good appetite,
and then spun its cocoon as if nothing unpleasant had occurred.

[Illustration: FIG. 12.--Solitary Wasp dragging a Caterpillar to its
Nest (after Peckham).]

The mode of carrying their booty is in these wasps instinctive, and
relatively uniform. _Ammophila urnaria_ grasps the caterpillar, near
the anterior end, in her mandibles, and carries or drags it beneath her
legs, walking forwards. It is generally but not always with the ventral
surface uppermost. _Pompilus_ takes hold of her spider anywhere, but
always drags it over the ground, walking backwards. _Oxybelus_ clasps
her fly with her hind legs; _Bembex_ with the second pair. Each works
after her own fashion in a way that is relatively uniform for each
species.

The general style of the nest, its mode of construction, and its method
of closure, are always performed, says Dr. Peckham, by each species
in a similar manner, not indeed in circumstantial detail, but quite
in the same way in a broad sense. Variation or modification is always
present, but the tendency to depart from a nest of a given type is not
excessive. Some dig in the ground curved tunnels, with or without one
or more chambers. Others bore into decaying wood; others use straws,
or make tunnels in bramble stems; while the mud-daubers build cells in
which to store the food and lay the egg. This is sometimes deposited
on the first, sometimes on the last, sometimes on some intermediate
victim, but generally in much the same place and position. _Ammophila_,
for instance, lays it on the side of the sixth or seventh segment--that
is to say, in about the mid position.

Some species first capture their prey, and then make the nest in which
it is to be entombed. Others first prepare the nest, and then carry
or drag their prey to it--often from considerable distances--quite
irrespective of what seems to us the more appropriate method of the
two under the particular circumstances of the case. And the way in
which the victim is dragged into the nest is similarly a matter of
inheritance. Each way is characteristic of the species concerned, and
would be an important part of any definition of the animal based upon
its modes of behaviour. For example, a _Sphex_ places her grasshopper
just at the entrance of the nest, which she then enters herself before
dragging in her prey by the antennæ. When the wasp was in the hole,
Fabre moved the victim a little way off; the wasp came out, brought
the grasshopper to the entrance as before, and went in a second time.
This was repeated about forty times, each time with the same result,
until the patience of the naturalist was exhausted, and the persistent
wasp took her booty in after her appropriate fashion. She must place
the grasshopper close to the opening; she must then descend and examine
the nest, and, after that, must drag it down. Nothing less than the
performance of these acts in a certain order satisfies her instinctive
impulse.

In a private letter, from which he kindly allows me to quote, Dr.
Peckham says: “We have recently made some experiments on this wasp
(_Sphex ichneumonea_). First we allow her to carry in her prey
undisturbed, to see how far she was faithful to the traditions of her
ancestors, and to observe her normal methods. On the next day, when she
had placed her grasshopper just at the opening of the nest, and while
she was below, we drew it back to a little distance. She came out, and
we both repeated our operations four times--she running down into the
nest, always after getting the grasshopper into position, and we as
regularly drawing it away. The fifth time she changed her plan, seized
it by the head and backed into the nest with it. The next day, at the
fourth trial, she straddled it and walked head first into the nest with
it; and on the fourth day, at the eighth trial, she backed in with it
as on the second day.” These interesting observations show that the
wasp has sufficient intelligence to modify her procedure in accordance
with an unwonted situation. The “consecutive necessity,” as it has been
termed, has a potent influence, but is not absolute.

Fabre notes a case of similar consecutive necessity in the case of the
mason bee, _Chalicodoma_. If while a bee is provisioning its nest with
honey and pollen the structure be destroyed, she sometimes breaks open
a completed cell, and, having done so, goes on bringing more provision,
though the cell already contains a sufficient store of food; and only
when she has completed the superfluous storing does she deposit her egg
and seal up the cell. So, too, when the cell is removed in an early
stage of construction, and another completed cell already partially
stored is substituted, the bee, instead of simply adopting the new
cell, goes on building until the cell is as much as one-third beyond
the usual height; then, and not till then, does she proceed in due
course to the next stage of the instinctive procedure, the provisioning
of the cell.

From our general knowledge of animal nature, we should expect to
find parasitic forms ready to take advantage of the material stored
by such insects as the solitary wasps and the mason bees. It is said
that _Chalicodoma_ provides nourishment to the larvæ of some sixteen
unbidden guests. A parasitic bee (_Stelis nasuta_) breaks open a
closed cell, and, after depositing its eggs, seals it up again with
mortar. Since her eggs and larvæ develop more rapidly than those of
the mason bee, they are first served with the store of provision,
while the rightful owner is done out of its inheritance. By a curious
act, of what appears to us like retributive justice, these parasitic
larvæ sometimes fall a prey to another parasite, also a hymenopterous
insect named _Monodontomerus_, the larvæ of which prey on the young
of both bees. Another genus of the same family, _Leucopsis_ (Fig. 13,
F), also succeeds in piercing with its ovipositor, at a suitable spot,
the walls of the _Chalicodoma_ cell, and suspends its curious hooked
egg (Fig. 13, G) on the delicate cocoon within which the chrysalis
lies. Fabre found in some cases as many as five of these parasitic
eggs on a single cocoon. But he never found more than one larva in any
cell that he examined. The following is an epitome of his conclusions
and inferences. From the parasitic egg is hatched a minute arched
grub, with relatively large head and mandibles, and provided with
a number of bristles, which aid it in progression (Fig. 13, H). It
does not, however, at once attack the bee larva, but makes a series
of excursions, the object of which is to reach and destroy any other
parasitic eggs. This was not actually observed, but the eggs were
found to have been destroyed, and there was seemingly no other means
of destruction under the conditions maintained. The larva, this done,
changes its skin and takes on a new form, destitute of bristles, with a
very small head and minute mandibles (Fig. 13, I). In this new form it
attacks the _Chalicodoma_ larva, making a very small incision, through
which the juices of the host are transferred to the guest without
further injury to the grub. It is interesting to note that, if the
facts are accurately described and the inferences are correct, there
are associated with two types of instinctive behaviour two distinct
types of structure. The creature can have no conscious control over its
structural development, and there is no ground for assuming that it has
any control over its instinctive behaviour.

[Illustration: FIG. 13.--Insect Larvæ. A, B, of _Sitaris_; C, D, E, of
_Argyromœba_; G, H, I, of _Leucopsis_; F, imago of _Leucopsis_ (after
Fabre).]

The specialization of structure and of instinctive behaviour, in
accordance with a definite sequence of life-conditions, is even more
remarkable in another of the many parasites which _Chalicodoma_
unwittingly labours to nourish. This time it is a fly (_Argyromœba_),
which lays a minute egg on the outside of the cell. From this egg is
hatched a slender threadlike worm, barely one-twentieth of an inch in
length (Fig. 13, C). It has three pairs of longish bristles near the
anterior end, and a single yet longer pair at the hinder extremity.
These aid it in creeping over the wall of the cell. Its small head
is armed with short, stiff bristles. For many days it wanders over
the surface of the cell, inserting its bristly head into each minute
cranny and crack. Throughout this long period it has never a bite nor
sup. Probably many of them never succeed in finding a crevice by which
they can effect an entrance, but those that do manage to wriggle in
undergo a change, lose their bristles, and develop a minute suctorial
mouth, through which the contents of the larva are absorbed into their
swelling bodies (Fig. 13, D). When fully grown they are quite helpless,
and unable to get out from the cell in which they are now imprisoned.
For months they lie quiescent, but in the succeeding spring they pass
into a pupal condition very different from that of most flies. The
relatively large head is armed with strong spines; the middle region
bears bristles directed backwards; the posterior end has short spines
(Fig. 13, E). Fixing itself to the interior of the cell by the latter,
it strikes with its armoured head repeated blows on the walls of its
prison until a breach is at last made, and sufficiently enlarged to
form a suitable exit. Then the pupa-skin bursts, and the imago insect
emerges and flies off. At each stage of life there is the closest
relation between structure and behaviour, and each is equally adapted
to a biological end of which the creature has never had an opportunity
of gaining any experience.

Exceedingly multifarious are the ways in which insects thus provide
for the future of young they will never see. _Antherophagus_ lives
in flowers, and is believed to seize with its mandibles humble bees,
which then unwittingly bear the parasitic beetle to the nests in which
alone the larvæ have been found. The larvæ of our common oil-beetle
(_Meloë_) are parasitic on the bee, _Anthophora_. It deposits its ten
thousand eggs without observable discrimination; but the active young
larva instinctively seizes and attaches itself to any hairy object.
Thousands must go astray. They have been found on hairy beetles, flies,
and bees of the wrong genus. Some, however, become thus attached to
the one suitable species, and are conveyed by the _Anthophora_ to her
nest, where they promptly eat the egg she lays. It is not difficult
to picture to one’s self how this incompletely evolved instinct might
be further perfected by natural selection, through the survival of
those females which laid their eggs in the haunts of the bee-host. And
such an advance in instinctive behaviour is seen in another and rarer
beetle--_Sitaris_. Her eggs are laid in August near the entrance to a
nest of the _Anthophora_. In September they hatch to form larvæ, which
hibernate in groups till the following spring. Then they become active
(Fig. 13, A), and attach themselves to hairy objects. Being near the
_Anthophora_ nest, there is an increased chance of their fastening upon
this bee. The chance is still far from good, for if this were so, we
should not find that the _Sitaris_ laid as many as two thousand eggs.
Still, on these grounds, we may presume that its chance of survival is
about five times as good as that of _Meloë_, which lays ten thousand
eggs. The larva is said generally to attach itself to a male bee, which
is hatched earlier than his mate, and to pass on to the female at the
nuptial period; but in any case it eventually slips on to the egg that
she lays. This forms the food of the larva during the remainder of this
stage of its existence. It then moults and assumes a new form, capable
of feeding on the honey (Fig. 13, B); and, after further changes,
becomes a pupa, and then assumes the imago condition.

In these cases the advantage is wholly on the side of the parasite. But
there are cases of close relationship between insects and flowering
plants where the instinctive behaviour gives rise to reciprocal
benefit. The Yucca is a genus of American Liliaceous plants, with large
pale sweet-smelling flowers; and these are dependent for fertilization
on the instinctive behaviour of a small straw-coloured moth of the
genus _Pronuba_. Just when the Yucca plant blossoms in the summer,
the moths emerge from their chrysalis cases. They mate; and the
female then flies to a flower, collects a pellet of pollen from the
anthers, proceeds to another flower, pierces the pistil with her sharp
ovipositor, lays her eggs among the ovules, and finally darting to the
stigma stuffs the pollen pellet into its funnel-shaped extremity (Fig.
14). If the flower be not thus fertilized the ovules do not develop;
and if the ovules do not develop the grubs which are hatched from the
moth’s eggs die of starvation. There are enough ovules to supply food
to the grubs, and leave a balance to continue the race of Yuccas.

[Illustration: FIG. 14.--Yucca Flower and Moth.]

Whether the female moth is attracted to the flower by sight or smell,
we do not know. And whether the male finds the female, in the case
of the Yucca moth, through scent, we are not in a position to state
with certainty. It has, however, been shown that in certain moths[33]
some odour emitted by the female is the attractive stimulus, affecting
sense-organs situated on the antennæ of the male. To females confined
in an opaque vessel over the mouth of which gauze was tied, the males
came in numbers; but when a clear glass vessel was inverted, and sand
was packed round the mouth, so as to prevent the escape of air from the
interior, no males came, though the imprisoned females were clearly
visible. If the antennæ of the males were either removed or coated with
shellac the moths failed to notice the females even when close to them.
In what way the intact male is made aware of the direction from which
the scent comes, we do not know--possibly by differential stimulation
in the antennæ, the moth instinctively turning in the direction of
greater stimulation. It will be seen, therefore, that in the case of
the behaviour of the Yucca moth--behaviour which is essential to the
biological end of reproduction--there is much detail concerning which
we are ignorant. But for our present purpose the important point to
notice is that the procedure of the female cannot be due to imitation;
nor can it be the outcome of individually acquired experience; for
the method of procedure is not gradually learnt, but is carried out
without apparent hesitation the first and only time the appropriate
occasion presents itself. Not only does the moth take no heed of her
grubs, but they are so placed that she could not in any case ascertain
by observation that only if the ovules are fertilized do her offspring
thrive. She cannot possibly know what effect the stuffing of the pollen
on to the stigma exercises, or indeed whether it have any effect at
all. And yet generation after generation these moths collect the pollen
from the anthers and bear it to the stigma. Spence’s words “without
knowledge of the end in view” are amply justified in this case, as in
other cases of typically instinctive behaviour.

III.--THE INSTINCTIVE BEHAVIOUR OF YOUNG BIRDS

Since it is easy to hatch birds of many species in an incubator, and
to rear them under conditions which not only afford facilities for
observation but exclude parental influence, their study has special
advantages. One can with some approach to accuracy distinguish the
instinctive from the acquired factors in their behaviour.[34]

[Illustration: FIG. 15.--Newly-hatched Chick swimming.]

The callow young of such birds as pigeons, jays, and thrushes are
hatched in a helpless condition, and require constant and assiduous
ministration to their elementary organic needs. Most of their instincts
are of the deferred type. But pheasants, plovers, moor-hens, domestic
chicks, and ducklings, with many others, are active soon after birth,
and exhibit powers of complex co-ordination, with little or no
practice of the necessary limb-movements. They walk and balance the
body so soon and so well as to show us that this mode of procedure is
congenital, and has not to be gradually acquired through the guidance
of experience. Young water-birds swim with neat and orderly strokes the
very first time they are gently placed in water. Even little chicks a
day or two old can swim well. Dr. Thorndike, who draws attention to
this fact,[35] appears to accept the view, suggested by Dr. Bashford
Dean, that the movements are not those of swimming but only of running.
I have carefully watched the action through the glass walls of a tank
and compared it with that of a young moor-hen. In the two cases it
is quite similar in type, and the type appears to be different from
that of running, though it is perhaps hard to distinguish the two.
In any case, the hand over hand action is well co-ordinated, and is
very different from a mere excited struggle. Chicks twenty-six hours
old taken straight from the incubator drawer, before they had taken
food, made directly for the side of the tank and tried to scramble out.
They gradually sank deeper through the wetting of the down, but could
keep afloat for from two to three minutes. I have made observations on
chicks of various ages from twenty-four hours to a month, and find in
all cases similar results; but with the older birds the flapping of
the wings and more vigorous action cause them to get water-logged more
rapidly. There is some apparent distress with cries; but less than one
might expect under the circumstances. For the purposes of the above
illustration Mr. Charles Whymper had before him a sketch I made of the
leg-action, and instantaneous photographs of the chicks swimming for
which I am indebted to my colleague Mr. George Brebner. I have not
observed the behaviour of an adult hen when placed in the water. Dr.
Thorndike says, “there is no vigorous instinct to strike out toward the
shore,” she “will float about aimlessly for awhile and only very slowly
reach the shore.” But Mrs. Foster Wood informs me that she has seen a
hen leap into a pond after her brood of ducklings and swim to the other
side, a distance of twenty feet.

Diving, in water-birds, is also an instinctive mode of behaviour; and
this is obviously a more difficult procedure than swimming, one further
removed from reflex action. And careful observations have placed beyond
question the fact that flight is also instinctive. A swallow, for
example, taken from the nest under conditions which made it practically
certain that it had never yet taken wing, exhibited guided flight, and
attempted to alight on a suitable ledge. Of course flight is generally
a deferred instinct, and is not performed until the wings have reached
a suitable state of development. An instinctive response, which may
perhaps be regarded as one of its initial stages, is seen in quite
young chicks. If placed in a basket, and rapidly lowered therein
through a foot or two, the chick will extend its skinny and scarcely
feathered wings. But though, from the usual conditions of development,
flight in birds is a deferred instinct, yet in exceptional cases it
may be connate. The mound-builders (_Megapodes_) of the Australian
region are hatched from large eggs in warm earth or sand, and are not
tended by the parents. So well fledged are these birds that they can
fly the day they emerge from the egg. Dr. Worcester, while digging in
one of their mounds, made an unsuccessful attempt to seize one which
was newly hatched; but it flew several rods into thick brush, and this
notwithstanding the fact that it had probably never before seen the
light of day.

[Illustration: FIG. 16.--Nestling Megapode, to show the well-developed
wings. (From Dr. R. Bowdler Sharpe’s “Wonders of the Bird World.”)]

It must not be supposed that, in adducing flight as an example of
instinctive behaviour in birds, we are contending that it is this and
nothing more throughout life. The inference to be drawn from the facts
of observation is rather that instinct provides a general ground plan
of behaviour which intelligent acquisition, by enforcing here and
checking there, perfects and guides to finer issues. Few would contend
that the consummate skill evinced in fully developed flight at its
best, the hurtling swoop of the falcon, the hovering of the kestrel,
the wheeling of swifts in the summer air, the rapid dart and sudden
poise of the humming bird, the easy sweep of the sea-gull, the downward
glide of the stork--that these are, in all their exquisite perfection,
instinctive. A rough but sufficient outline of action is hereditary;
but the manifold graces and delicacies of perfected flight are due to
intelligent skill begotten of practice and experience.

There are many little idiosyncracies and special traits of flight
which are probably instinctive--such as enable an ornithologist or a
sportsman to recognize a flying bird from a distance. And the same is
true of other modes of behaviour. The observer of young birds cannot
fail to note and to be impressed by many of these. The way in which a
little moor-hen uses its wings in scrambling up any rough surface is
very characteristic; so, too, is the manner in which a guinea-chick
runs backwards and then sideways at a right angle when one attempts to
catch him. If suddenly startled, moor-hens and chicks scatter and hide;
plovers drop and crouch with their chins on the ground; pheasants stand
motionless and silent. Knowledge of the ways of birds enables one to
predict with tolerable accuracy how each kind will behave under given
circumstances. That the actions are always precisely alike cannot be
said with truth; but that the behaviour is so relatively definite as to
be readily recognizable can be confidently asserted. That a moor-hen
will flick its tail, that a chick will dust itself in the sand, that
pheasants and partridges will scratch the ground, that a jay will go
through certain actions in the bath, that the preening of the down will
be carried out in particular ways--moor-hens, for example, wringing out
the water in a peculiar manner,--and that all these, and many other
modes of behaviour, will be presented in relatively definite ways: all
these are, to borrow a phrase of Dr. Peckham’s, so characteristic of
the several groups of birds, that they would be an important part of
any definition based upon behaviour. And there can be no question that
they are instinctive. They may indeed seem trivial and commonplace,
scarcely worthy of special note; but they serve to show in how many
details organic heredity lays the foundation for future behaviour, and
affords groups of data for effective consciousness to utilize.

To show the instinctive nature of such behaviour, the following
examples will suffice. One of a batch of moor-hen chicks showed once,
and once only, when a week old, an incipient tendency to bathe in the
shallow tin of water which was placed in their run, but soon desisted;
nor was the action repeated, though he and the others enjoyed standing
in the water. Five weeks later one of the batch was taken to a beck.
He walked quietly through the comparatively still water near the edge;
but when he reached the part of the stream where it ran swiftly and
broke over the pebbles, he stopped, ducked, and took an elaborate bath,
dipping his head well under, flicking the water over his back, ruffling
his feathers, and behaving in a most characteristic manner. Each day
thereafter he did the same, with a vigour that increased up to the
third morning, and then remained constant. The same bird some weeks
later was swimming in a narrow part of the stream, with steep banks
on either side, when he was frightened by a rough-haired pup. Down he
dived, for the first time in his life; and after a few seconds his head
was seen to appear, just peeping above the water beneath the bank.

Ten days after receiving two nestling jays I placed in their cage a
shallow tin of water. They took no notice of it, having never seen
water before; for they were fed chiefly on sopped food. Presently one
of them hopped into it, whether attracted by the water or by accident
it is difficult to say, squatted in it bending his legs, and at once
fluttered his feathers, as such birds do when they bathe, though his
breast scarcely touched the water. The other seized the tin in his
bill, and then pecked at the water, thus wetting his beak. He, too,
fluttered his feathers in a similar fashion, though he was outside the
tin and not in the water at all. A little later the first again entered
the tin, and dipped his breast well into the water; this was followed
by much fluttering and splashing. The bird took a good bath, as did the
other shortly afterwards, and then spent half an hour in a thorough
grooming, with much fluttering of the wings, the crest feathers being
constantly raised and lowered, expressive of an emotional state.

Now, in these cases it would be impossible to say whether the behaviour
was carried out in the manner characteristic of the species, prior to
experience and independent of imitation, on the basis of mere casual
and chance observation. But in these cases the whole life-history
of the individuals concerned was known; and it can be asserted with
confidence that the behaviour was hereditary, and not acquired by any
gradual process of learning. Moreover, in each case there seemed to
be such evidence as observation can afford, that internal emotional
factors co-operated with the direct external stimuli in determining
the nature of the behaviour. Whether such actions so far contribute
to the well-being of the individual as to be of decisive advantage it
is difficult to say. Some would contend that bathing is practised by
birds merely for the pleasure it seemingly affords; others would urge
that it is a means of getting rid of troublesome and presumably hurtful
parasites, to the attacks of which birds are peculiarly subject.

[Illustration: FIG. 17.--Young Cuckoo ejecting nestling Meadow Pipit.
(From Mrs. Hugh Blackburn’s sketch in “Birds from Moidart.”)]

One of the most remarkable instincts of young birds is that of
the cuckoo, which ejects eggs and nestlings from the home of its
foster-parent. Mrs. Hugh Blackburn found a nest which contained two
meadow-pipits’ eggs, besides that of a cuckoo. On a later visit “the
pipits were found to be hatched, but not the cuckoo. At the next visit,
which was after an interval of forty-eight hours, we found the young
cuckoo alone in the nest, and both the young pipits lying down the
bank, about ten inches from the margin of the nest, but quite lively
after being warmed in the hand. They were replaced in the nest beside
the cuckoo, which struggled about until it got its back under one of
them, when it climbed backwards directly up the open side of the nest,
and hitched the pipit from its back on to the edge. It then stood quite
upright on its legs, which were straddled wide apart, with the claws
firmly fixed halfway down the inside of the nest, among the interlacing
fibres of which the nest was woven, and, stretching its wings apart and
backwards, it elbowed the pipit fairly over the margin, so far that
its struggles took it down the bank instead of back into the nest. As
it was getting late, and the cuckoo did not immediately set to work
on the other nestling, I replaced the ejected one and went home. On
returning next day, both nestlings were found dead and cold, out of
the nest.”[36] Here we have a definite account by an eye-witness, who
sketched the young cuckoo, which was naked, blind, and could scarcely
hold up its head. And her account, itself confirmatory of that given
by Jenner in 1778, is confirmed by that of Dr. John Hancock,[37] who
witnessed the ejection of a fledgling hedge-sparrow, which “was put
over the edge of the nest exactly as illustrated by Mrs. Blackburn.”
The procedure is unquestionably instinctive.

The sounds uttered by young birds are sufficiently definite to be
readily recognized and are susceptible of classification. In domestic
chicks at least six notes may be distinguished. First the gentle
“peeping” note, expressive of contentment. A further low note, a double
sound, seems to indicate extreme satisfaction and pleasure. Very
characteristic and distinct is the danger-note--a sound difficult to
describe, but readily recognized. If a humble-bee, a black-beetle, a
big worm, a lump of sugar--anything strange and largish--be thrown to
the chicks, this danger-note is at once heard; and it serves to place
others on the alert, though this is perhaps the outcome of experience.
Then there is the cheeping sound, expressive apparently of a state of
mild dissatisfaction with the present state of affairs. It generally
ceases when one throws some grain, or even stands near them. Extreme
dissatisfaction is marked by a sharper, shriller squeak, when one
seizes them against their inclination. Lastly, there is the shrill
cry of greater distress, when, for example, their swimming powers are
subjected to critical examination. With pheasants a gentle, “peeping”
note of contentment, a shriller cry of distress, and a danger-note,
generically like, but specifically distinct from, that of the chick,
are early differentiated. The complaining note of the partridge is
uttered six or seven times in quick succession, followed by a pause.
The note of the plover is high-pitched, and much like the familiar
cry of the adult bird, to which it owes its popular name of “peewit.”
So, too, the guinea-fowl in down utters from the first notes quite
characteristic of its kind, while its danger-note is not unlike that
of the chick or pheasant. The piping of ducklings is comparatively
monotonous, and there does not seem to be a definite danger-note. With
moor-hen chicks, even on the first day, two notes are well-marked--a
call-note, lower in pitch than that of the chick, and rather harsh and
raucous, and a “tweet, tweet” of pleasure, something like the contented
note of a canary. Later, five or six notes are differentiated, the most
characteristic of which is the harsh “crek, crek,” when the little bird
is from any cause excited. It is uttered in a crouching attitude, with
head thrown back and wings held outwards and forwards, waving to and
fro in a very characteristic manner. That this has suggestive value for
other moor-hen chicks is shown by its distinctly infectious effect; if
one bird has cause to utter the note and strike the attitude others
follow suit. While clearly instinctive in their mode of occurrence,
while they seem to show well the co-operation of an internal emotional
factor, their biological value seems to lie in their suggestive effect
on other members of the brood. They form an elementary but sufficient
social bond.

If these notes afford evidence of an incipient social factor, the
instinct of pecking is distinctively individualistic. Chicks peck
with considerable but not complete accuracy of aim at practically
anything of suitable size at suitable distance; but it is through
experience that they learn what to select for food and what to reject
or leave untouched. Moving objects, however, are more readily pecked
at than those which are still; and the instinctive response seems to
be stimulated if one tap on the ground near the object, or move it
with a pencil, thus simulating the action of the hen. And this is even
more marked with pheasants and partridges. Plovers seize small worms
with an avidity which looks like an inherited response to the sight
of natural food. Pheasants and partridges also appear to be specially
affected by worms, and when one of them seizes a worm for the first
time, he shakes it and dashes it against the ground. Chicks, a week or
ten days old, also seize a largish fly or bee with a dash, and maul it
on the ground, throwing it on one side before again approaching it.
And such birds seem to show an instinctive tendency to bolt with such
treasures as caterpillars or small worms. Moor-hens cannot at first be
induced to take food from the ground. It has to be held above them,
whereupon they crouch down, with head and neck held back, opening
their beaks more like the callow young of nursling birds; but they
also strike upwards at the object--these modes of behaviour being, no
doubt, correlated with the manner in which the mother moor-hen normally
feeds her young from her beak during the early days of life. Callow
fledglings, such as young jays, simply open their mouths, gaping widely
to be fed. And many will respond in this way to such a note as a low
whistle, as may readily be seen with swallows. But at a later age such
birds show instinctive modes of reaction of a more complex type. A jay,
for example, was offered a summer chafer or June bug, seized it at once
in his bill, and tried to place his foot on it. Then he hopped down on
to the floor of his cage, dropped the beetle, seized it again as it
crawled off, and after two or three attempts swallowed it, tossing it
back from the point of his bill into the throat. This was the first
time he took food from the ground or swallowed it in this manner.

On the whole, there seems to be much inherited definiteness of
co-ordination, and some tendency to respond in a definite manner to
specific stimuli. That there should not be more differentiation in
this respect than observation discloses is probably due to the fact
that the parent birds afford, under natural conditions, much guidance
in the selection of food. Since the solitary wasp unerringly seizes
its appropriate food, since it responds instinctively to specific
stimuli, there would seem no reason why birds should not show similar
instinctive differentiation. But one must remember that in the
case of the wasp there is no parental guidance; the insect is more
completely dependent on instinct than is the bird to whose needs the
hen assiduously ministers.

It is at first sight surprising that such birds as chicks and pheasants
do not peck instinctively at still water. When a shallow vessel
containing water was placed among some little chicks, several of them
ran repeatedly through the water, but took no heed of it. Then, after
about an hour, one of them standing in the vessel pecked at his toes,
and at once lifted his head and drank freely with characteristic
action. Another subsequently pecked at a bubble near the edge, and
then he too drank. In fact, the best way of inducing them to drink is
to scatter some grains of food in the tin; they peck at the grains,
which catch their eye, and incidentally find the water, and the touch
of water in the bill at once leads to the characteristic response and
congenitally definite behaviour. That the sight of a still surface does
not itself suffice to evoke this behaviour is probably again due to the
fact that under nature the hen guides them and pecks at the water, when
they follow her lead.

One fact which must be constantly borne in mind is that what is
inherited is instinctive co-ordination, often related to a definite
stimulus, not instinctive knowledge. A chick pecks at a grain when it
is at a suitable distance, not because instinct provides him with the
knowledge that this is something to be seized and tested, but because
he cannot help doing so. He is so organized that this stimulus produces
that result through an organic co-ordination that is independent of
conscious knowledge or experience. How definite is the inherited
co-ordination is shown by many observations. A young pheasant, only a
few hours old, was taken from the incubator drawer, and held snugly
while a piece of egg-yolk was moved before his eyes with the aid of
fine forceps. He did not peck at it, but followed with movements of
his head every motion of the object in a narrow circle. Simple as
this action seems, it presents a striking example of co-ordinated
movements accurately related to movements in the visual field, the
whole performed without any opportunity for learning or practice, and
less than half an hour after the bird was taken from the drawer of the
incubator and first saw daylight. Psychologists sometimes puzzle their
heads over the question how and by what steps the field of vision and
the field of movement are brought into relation with each other; but in
such a case as this, the problem ceases to be primarily psychological.
The relation is purely organic; the conscious data are grouped from the
outset. With young jays there was no such co-ordination at first; and
when they began after a few days (about twelve or fourteen) to follow
an object with the head and eye, the movements were at first jerky. But
a week later, when I swept the food through a circle a foot in diameter
in front of their cage, it was followed smoothly and evenly. Here a
certain amount of learning and practice, absent in the case of the
pheasant, was required. And it is difficult to say what proportion of
the final result was acquired, what proportion hereditary; but probably
the behaviour is in the main instinctive, though somewhat deferred.

One more example, perhaps even more trivial in the eyes of some
people, may be given. A duckling a few hours old will scratch the side
of his head. It is true he may topple over in the process, through
insufficient powers of balance, for the simultaneous performance of
poising on one leg and having a good scratch with the other is no easy
matter. But let not either our familiarity with such behaviour, nor
some observed and laughable failure on the part of the duckling, blind
us to the fact that this is a congenital activity, and one of no little
complexity, indicating a definite organic nexus. A local irritation
sets agoing movements of the hind limb of that side through which
just that particular spot is scratched in the absence of any previous
practice, any learning to localize the spot. There can be no question
that such inherited co-ordinations, whether perfect from the first,
or with deferred perfection and some aid from acquisition, afford
ready-made data to consciousness, which are of the utmost service in
the guidance of subsequent behaviour. The two-days-old chick, with
the aid of this instinctive co-ordination, performs well a number of
actions, which, had she to consciously learn them all, would probably
be still but half mastered when she was a skinny old hen.

Our whole treatment of instinctive behaviour has been based on the
assumption, already to some extent justified, that experience is
not inherited. If it be hereditary, how comes it that chicks show
no recognition of still water, which must have been familiar to the
experience of generation after generation of birds? How comes it that
they do not even seem to recognize their natural parent and protector,
the hen? Two chicks ten days old were taken to the yard whence were
derived the eggs from which they were hatched, and were placed about
two yards from a hen which was clucking to her brood. They were not in
a frightened condition, for they stood on my hand and ate grain from
it, scratching at the palm. But of the clucking of the hen they took
no notice whatever. The same results were obtained with other chicks
thirteen days old. Was this due, as Spalding suggested, to loss of
the instinctive response which was perhaps present at an earlier age?
Seemingly not. For a chick was taken at the age of two and a half days
to its own mother, which had three chicks. These followed her about,
and ran at once to her when she clucked and pecked on the ground. The
little stranger, however, took no notice, nor did he show any tendency
either to go to the hen or to follow the three chicks, having been
purposely brought up alone. When the hen took her little brood under
her wing, the stranger was placed close to her. She clucked, and seemed
anxious to entice and welcome the little fellow, seizing an oat-husk
and dropping it before him; but he remained indifferent, walking away
and standing in the sunshine. After about forty minutes he seemed more
inclined to go with the other chicks, but still ignored the existence
of the hen. The natural instinctive tendency seems to be from the first
to nestle under anything; and there is the hen provided by nature for
the purpose. By experience the chicks grow accustomed to her fussy
ways, as they grow accustomed to the ways of such a foster-parent
as the writer of these pages. Still, though there is, apparently,
no instinctive knowledge of the hen as their natural protector, and
though I have seen no observable response to the clucking sound, this
must not be taken as necessarily implying that there is no instinctive
response to any of her modes of behaviour. There is such a response
to her pecking on the ground; there is probably such a response to
her danger-note; and there may be many other such instinctive modes
of behaviour related to her actions. How far they extend can only be
ascertained by patient observation; and such responsive behaviour need
not imply any instinctive knowledge begotten of inherited experience.

We may now summarize some of the general conclusions which may be drawn
from observations of instinctive behaviour in young birds.

1. That which is inherited is essentially a motor response or train
of such responses. Mr. Herbert Spencer’s description of instinct as
compound reflex action is thus justified.

2. These often show very accurate and nicely-adjusted hereditary
co-ordinations.

3. They are evoked by stimuli, the general type of which is fairly
definite, and may in some cases be in response to particular objects.

4. They are also generally shown under conditions which lead us to
infer the presence of an internal factor, emotional or other.

5. There does not seem to be any evidence of inherited knowledge or
experience.

IV.--THE CONSCIOUS ASPECT OF INSTINCTIVE BEHAVIOUR

In our definition of instinctive behaviour all positive reference to
the presence of conscious states was omitted. By some writers, however,
the fact that it is accompanied by consciousness is regarded as a
distinguishing feature of instinct. Romanes introduced his definition
with the words:[38] “Instinct is reflex action into which there is
imported the element of consciousness.” And he emphasized the conscious
aspect when he said: “The term comprises all those _faculties of mind_
which are concerned with conscious and adaptive action, antecedent to
individual experience.” Professor Wundt also lays some stress on the
conscious accompaniments of instinctive activities which, he says,[39]
“differ from the reflexes proper in this, that they are accompanied
by emotions in the mind, and that their performance is regulated by
these emotions.” The definitions of other writers express or imply the
presence of consciousness in differing modes and degrees, culminating
in the hypothesis of inherited knowledge. Douglas Spalding, for
example, said[40] that “animals can forget the instinctive knowledge
which they never learned!”

Now, the exclusion from our definition of direct reference to the
conscious aspect must not be taken to imply that instinctive behaviour
is a mere matter of unconscious automatism; nor even that it is
unprofitable to discuss how much consciousness there may be, of what
sort, and how distributed. All that it does imply is, that the amount,
nature, and distribution of consciousness cannot well be introduced
into a definition the object of which is to help us to distinguish
certain observable types of behaviour from others. In a word, the
definition given is biological and objective, and is to be accepted
or rejected without prejudice to such psychological considerations as
those upon which we have now briefly to enter.

The first thing we have to decide is how much we are to include,
from the psychological standpoint, under instinct. For we may take
either a broader or a narrower view of the matter; and which of these
we adopt will make much difference in our conclusions. Let us first
deal with the narrower. We have said above that what is hereditary in
instinctive behaviour is the co-ordination. Now, such co-ordination of
movements into a finished and appropriate act is due to a nicely graded
distribution of efferent nerve-waves to the several muscles concerned,
so that these muscles may be caused to contract in due order, and each
to just the right extent. But efferent nerve-waves as such, and their
mode of distribution by the nerve-centres, are in all probability
unconscious, while the contraction of the muscles is a purely organic
matter. If, therefore, we narrow our conception of instinct so as to
include only the co-ordinated act by itself, excluding all reference
both to the stimuli which are its antecedents, and to the effects in
consciousness which its performance may produce; and if the data for
consciousness are in all cases supplied through afferent channels;
then there seems to be no escape from the conclusion that instinctive
behaviour as such may be, and probably is, altogether outside the
individual consciousness. It should be noted, however, that on this
view only the instinctive co-ordination in itself can be fairly
regarded as independent of the stream of experience.

Now, in the first place it is convenient so far to broaden our
conception as to include under the head of instinctive behaviour,
in its conscious aspect, not only the co-ordinated act but the data
which its performance affords to consciousness. It may indeed seem
that we are here trying to draw a distinction where no real difference
exists. The physiological distinction is, however, not only clear and
undeniable, but quite easily understood. For the sake of illustration
let us take the case of an intentional action, such as glancing up from
the words we are reading to the clock. Efferent waves course along
several motor nerves to the six muscles by which each eye is moved,
and to the muscles of accommodation within the eye. These muscles
are called into duly co-ordinated activity, by which our vision is
focussed upon the clock-face. This is one part of the physiological
procedure--that by which the intended result is attained. But there
is a second part readily distinguishable from the former. As the
eyes move, afferent messages course inwards from the muscles or the
eye-sockets and their neighbourhood; and it is these incoming waves
which afford data to consciousness, telling us that the movements are
in progress or have been effected. The nerves involved in the latter
part are quite different from those concerned in the former part, and
they proceed to areas of the brain differently situated from those
whence the efferent waves issued. Thus it is in all cases of movement;
the efferent nerves call the muscles into play; the afferent nerves
bring information that the movements are carried out. It is through the
latter that data are unquestionably afforded to consciousness.

But in the case of any complex action--and, as we have seen,
instinctive behaviour is often remarkably complex--the information
that the action has begun comes in before the behaviour is completed.
Practically we may say that any given stage of performance and the
consciousness it evokes are simultaneous; for though in strictness
the one lags just a little behind the other, yet they are so nearly
coincident in time that we may disregard the interval between them.
Such being the case, therefore, we may fairly regard the felt
performance of the instinctive act as capable of introducing important
elements into the conscious situation.

But not only does instinctive behaviour thus introduce important
elements into the conscious situation, it is also called forth by
stimuli which themselves afford not less important elements. To exclude
these from any consideration of instinct, in its conscious aspect,
would render the treatment of the problem so incomplete as to be wholly
unsatisfactory from a psychological point of view. Can we believe that
when the moor-hen dived, as it never had dived before, at the sight
of the rough-haired pup, the vivid experience of that strange and
disquieting intruder did not enter into, and form a prominent feature
in, the conscious situation? If we are to consider the conscious aspect
at all, we must try and grasp the situation as a whole. And on these
grounds we may yet further broaden our conception so as to include,
from the psychological point of view, not only the behaviour itself,
and its effects in consciousness, but also the stimulating conditions
under which it is called into play. If, then, we accept this position,
and agree to use the term “instinct” for our present purpose in a
comprehensive sense, we may now proceed to consider very briefly the
nature of the elements which enter into the instinctive situation.

First, there are the external stimuli affecting one or more of the
sense organs, and thus evoking consciousness; and secondly, there are
internal factors, having their source in the condition of the body, or
its parts and organs. It is convenient to take these two together, so
that we may see what relationship they bear to each other. Both seem to
be present, and to co-operate in a great number of instinctive acts. In
the behaviour connected with feeding, for example, an internal element
of hunger co-operates with the external presentation of the appropriate
food or prey. So, too, with the instincts concerned in the propagation
of the race. Looking at the matter generally, we may regard the
internal factors of the kind with which we are now dealing, as giving
rise to a want or need, passing in some cases into a state of craving.
In themselves such conscious states are in their inception exceedingly
indefinite; for a want can only be rendered definite in experience by
its appropriate satisfaction. In many cases of instinctive behaviour
the indefinite want and the particular and duly related stimulus seem
to lead, without prevision and by a blind impulse, to the performance
of those acts which will afford the unforeseen satisfaction. And when
once this satisfaction has been attained, subsequent wants or needs of
like character will no longer be indefinite; nor will future behaviour
of the same kind be thereafter wholly instinctive, for it can never
again be prior to, or independent of, experience.

Granted, however, that a felt need of some kind, indefinite at
first but none the less real, is present in many cases as a spur to
instinctive behaviour; is it in all cases a necessary factor? May we
say that this distinguishes instinctive from merely reflex action? The
question is, from the nature of the case, exceedingly difficult to
answer. But without going so far as to say that reflex action may be
unerringly distinguished from instinctive behaviour by the absence of
any such internal factors, we may perhaps, at any rate, go so far as
to give provisional acceptance to the view that in instinct these wants
and felt needs enter into the conscious situation in a manner and to
a degree that are so far distinctive--which seems to be the position
adopted by Professor Wundt.

There is, however, a further relation between the external stimulus and
these internal factors which is presumably of no little importance.
The stimulus intensifies the want, or may in some cases call it into
existence. Just as a whiff from the kitchen may lead us to realize
that we need the satisfaction that will erelong be presented at table,
so may the sight of his mate in the spring evoke in the breast of
the yearling sparrow a need, having its source in morphological and
physiological changes, that spurs him on to the courtship that shall
lead to its due satisfaction. Popular attention has, indeed, been so
naturally drawn to the internal needs or wants with which we are now
dealing, as to give them an almost exclusive monopoly of the term
“instinct,” which thus often comes to be regarded as a connecting link
between the stimulus and the act. The sight of a mouse, for example, is
said to call forth the instinct of the cat, which is satisfied by her
pouncing upon it. And so it comes about that, while the biologist fixes
upon the instinctive act as the essential feature, the psychologist
is apt to regard the impulse[41] which prompts to action as the more
central and characteristic element. We are here endeavouring to combine
both these points of view.

To come to closer quarters with the relationship which holds good
between the external and internal elements, it appears that, when the
stimulus evokes or intensifies the want or need, this is probably
effected by efferent waves which call the organs or parts into tonic
action, of which the animal becomes conscious through the afferent
messages which come in from them to the sensory centres; in much the
same way as the whiff from the kitchen takes effect on the salivary
and other glands, and throws the organs of digestion into a felt
preparedness for the fulfilment of their functions. But it may have
other and more indirect consequences. When the moor-hen dived to escape
from the obtrusive puppy, his heart-beat was probably affected; he
had, perhaps, an uncomfortable sinking in his gizzard; his breathing
was short and laboured; and he experienced creepy sensations in the
skin and around the feather-roots. Such we may suppose were the
accompaniments or sources of the emotional state of fear or alarm. And
they presumably entered with no little vividness into the conscious
situation at the moment of instinctive action. In all those cases in
which the behaviour is associated with such an emotional state as anger
or fear, the external stimulus seems to produce widely-spread effects
on the glands, respiratory organs, heart and blood-vessels, skin and
other parts, as well as the more direct response in productive action.
And all this must enter into the conscious situation, contributing
largely, as we shall hereafter see, to the emotions in their
instinctive origin.

Enough has now been said to indicate with sufficient clearness the
kind of co-operation and mutual relationship which subsists between
the external and the internal factors in the conscious situation which
leads to instinctive behaviour. We have seen that, not improbably, some
organic prompting is always present in greater or less degree. But the
question still remains whether anything like a definite and particular
external stimulus is in all cases a necessary factor.

When the predaceous larva of the water-beetle, _Dytiscus_, ceases to
feed, and, creeping into the moist earth near the pond’s edge, makes
a hollow cell in which to enter upon its pupal sleep, there does not
seem to be any well-defined stimulus from the outer world which can be
said to initiate the behaviour of whose purport the larva can have no
idea. Some inner need seems to impel the creature to this necessary
but as yet unknown course of action; and this appears to constitute,
if not the sole, at least the preponderant element in the conscious
situation. In healthy young birds and other animals there is after the
rest of sleep a certain exhilaration and exuberance of spirits which
seemingly leads to characteristic action; dancing, flapping of the
wings, running hither and thither in short quick spurts, and so forth.
No doubt in such cases external stimuli are present, and contribute
in some degree to the effects produced; but they do not seem to be
particularized so that one can say that just this or that well-defined
stimulus is necessary to give rise to the observed behaviour. In the
case of migration, too, an internal factor--the nature of which we do
not know--is probably as strong as if not stronger than any influence
from without. While, therefore, we may say that some external factors
are frequently, not improbably always, contributory, we must add that
observation does not enable us in all cases to define them with any
approach to accuracy; and, further, that promptings from within seem
in some instinctive acts to be the most important elements in the
conscious situation.

It now only remains to draw attention to the fact that the effects of
the behaviour, as the animal becomes conscious of the performance of
the acts concerned, serve to complete and render definite the conscious
situation. Consciousness, however, probably receives information of the
net results of the progress of behaviour, and not of the minute and
separate details of muscular contraction. These net results, having
thus entered presentatively into the situation, are subsequently
susceptible of re-presentative recall, when the recurrence of certain
salient elements serve to reproduce the essential features of the
situation of which experience has been gained on a former occasion.
Hence, as has already been noted, it is only the _first_ performance of
an instinctive action which can be described as prior to experience.
The second time the deed is done it is done by an animal which has
had opportunity of gaining experience on the foregoing occasion. And
then it may be done with a difference, with some acquired modification
of performance. By the repetition of the slightly modified behaviour
the effects of habit are introduced, and thus acquired peculiarities
of action are established as individual traits. We must not forget
that, in a large number of cases, so-called instinctive behaviour, as
presented to observation, has lost through modified repetition its
original purity of type. The acts we see are often the joint products
of heredity and individual acquisition, the inherited co-ordination
having been supplemented or otherwise altered through experience.

Even in the case of the very first exhibition of such a deferred
instinct as the moor-hen’s dive, although that organized sequence
of acts which constituted the behaviour as a whole had never before
occurred, although there was no gradual learning how to dip beneath
the surface, and to swim under water, still many of the constituent
acts had been often repeated; experience had already been gained of
much of the detail then for the first time combined in an instinctive
sequence. So that if we distinguish between instinct as congenital and
habit as acquired, we must not lose sight of the fact that there is
continual interaction, in a great number of cases, between instinct
and habit, and that the first performance of a deferred instinct may
be carried out in close and inextricable association with the habits
which, at the period of life in question, have already been acquired.
Instinct supplies an outline sketch of behaviour, to which experience
adds colour and shading. Which predominates in the finished picture
depends on the status of the animal. In the lower and less intelligent
types the outline stands out clearly, there being but little shading to
divert our attention from the clear firm lines inscribed by heredity;
but in the higher and more intelligent animals, the deft pencil of
experience has added so much detail and has interwoven with the fainter
outline so many new and skilfully introduced touches, that the original
sketch is scarcely distinguishable unless we have carefully watched
from the beginning the gradual development of the picture.

V.--THE EVOLUTION OF INSTINCTIVE BEHAVIOUR

It may be assumed that the fact of evolution is generally admitted.
The question of its method is, however, still open to discussion. It
is possible that, as some biologists contend, there is an inherent
tendency in organic beings to evolve in certain definite directions
independently of their relation to the environment. But it is scarcely
probable that instinctive behaviour is mainly due to any such inherent
tendency--of the nature of which in any case we know but little.
Setting this on one side, therefore, we have two hypotheses: first,
that instincts are the result of natural selection; secondly, that they
are due to the inheritance of acquired habits. These two views we will
now proceed to consider.

We have seen that Professor Wundt distinguishes two classes of
instinctive acts: first, those which are _acquired_ or have become
wholly or partly mechanized in the course of individual life; secondly,
those which are _connate_ or have been mechanized in the course of
generic evolution. “The laws of practice,” he says,[42] “suffice for
the explanation of the acquired instincts. The occurrence of connate
instincts renders a subsidiary hypothesis necessary. We must suppose
that the physical changes which the nervous elements undergo can be
transmitted from father to son.... The assumption of the inheritance of
acquired dispositions or tendencies is inevitable if there is to be any
continuity of evolution at all. We may be in doubt as to the extent of
this inheritance; we cannot question the fact itself.”

Now, the application of the term “instinct,” both to acquired and to
connate behaviour, seems to prejudge the question of their genetic
connection. And since we have the well-recognized term _habits_ for
actions the performance of which becomes automatic through frequency
of repetition, we may substitute this term, or the phrase _habitual
acts_, for the “acquired instincts” of Professor Wundt. Modifying,
therefore, his statement in accordance with this usage, the fact which,
he says, we cannot question is that acquired habits are inherited as
congenital instincts. This opinion has long been held: G. H. Lewes
regarded instinctive actions as transmitted habits from which the
intelligence, through which they were originally acquired, had lapsed.
Darwin believed that such inheritance was a factor in the evolution
of instinctive behaviour. Romanes distinguished instincts due to
this mode of origin as “secondary;” reserving the term “primary” for
those attributable to natural selection, and describing those in which
both factors co-operate as “instincts of blended origin.” The late
Professor Eimer, of Tübingen, going further than either Darwin or
Romanes, reverted almost entirely to what we may term the Lamarckian
interpretation. “I describe as automatic actions,” he says,[43]
“those which, originally performed consciously and voluntarily, in
consequence of frequent practice come to be performed unconsciously and
involuntarily.... Such acquired automatic actions can be inherited.
Instinct is inherited faculty, especially is inherited habit.” In his
discussion of the subject Eimer makes no express allusion to primary
instincts; but he attributes to lapsed intelligence some of those
which were classed by Romanes as primary, and his tendency is to
refer all instincts to the same source. “Every bird,” he says, “must,
from the first time it hatches its eggs, draw the conclusion that
young will also be produced from the eggs which it lays afterwards,
and this experience must have been inherited as instinct.” Why, in
the first instance, it must draw the conclusion from observation if
it inherit instinctive knowledge, is not made clear. But our present
purpose is to indicate, not to criticize, Eimer’s position. He claims
that “the original progenitors of the cuckoo, when they began to
lay their eggs in other nests, acted by reflection and design.” Of
the behaviour of mason wasps and their allies, which provide their
young with paralyzed but living prey, he exclaims, “What a wonderful
contrivance! What calculation on the part of the animal must have been
necessary to discover it!” Of the instincts of neuter bees he remarks,
“Selection cannot here have had much influence, since the workers do
not reproduce. In order to make these favourable conditions constant,
insight and reflection on the part of the animals, and the inheritance
of these faculties were necessary.” And he concludes, “Thus, according
to the preceding considerations, automatic action may be described as
habitual voluntary action; instinct, as inherited habitual voluntary
action, or the capacity for such action.”

Turning now to the opposite end of the scale of opinion, we find
that Professor Weismann, commenting on the supposed inheritance
of acquired habit, says,[44] “I believe that this is an entirely
erroneous view, and I hold that all instinct is entirely due to the
operation of natural selection, and has its foundation, not upon
inherited experiences, but upon variation of the germ.” Ziegler and
Groos in Germany, Whitman and Baldwin in America, Poulton and Wallace
in England, either deny the existence of secondary instincts, due
to the inheritance of acquired habits, or question the sufficiency
of the evidence adduced in support of such transmission. In their
explanation of the manner in which that inherited co-ordination,
which is biologically the central fact in instinctive behaviour, has
been evolved they rely mainly or entirely on the principle of natural
selection.

What, then, were the facts which appeared to Romanes sufficient to
justify a belief in the existence of a class of instincts dependent
on inherited habit for their origin? He tells us that he only gives a
few examples “amongst almost any number” that he could quote. It is
certainly unfortunate that, out of more than one hundred and fifty
pages devoted to instinct in his work on “Mental Evolution in Animals,”
only three[45] are assigned to secondary instincts; or six, if we
include one dealing with inherited peculiarities of hand-writing in
man, and two showing the force of heredity in the domain of instinct,
“whether of the primary or secondary class.” It is true that many pages
are devoted to instincts of blended origin, but the co-operation of
the Lamarckian factor is here rather assumed than proved. We must,
however, be content to take the few examples that are actually given.
They are four in number. First, that ponies in Norway are used without
bridles, and are trained to obey the voice; and that, as a consequence,
a race-peculiarity has been established, for Andrew Knight says that
it is impossible to give them what is called “a mouth.” No details are
given, and Romanes does not further discuss the evidence. Secondly,
Mr. Lawson Tait had a cat which was taught to beg for food like a
terrier. All her kittens adopted the same habit under circumstances
which precluded the possibility of imitation. Supposing the facts to
be correctly reported, and granting that the owners of the kittens,
presumably aware of the maternal propensity, did not take some pains to
teach the offspring of such a parent to beg (and this does not present
much difficulty), one can hardly found a scientific conclusion on so
slight an anecdotal basis. Thirdly, instinctive fear is said to be an
inherited acquisition; which, fourthly, is lost by disuse. But, as
we have already seen, modern investigation has placed this matter of
so-called hereditary fear of natural enemies on a different footing.
Pheasants, partridges, moor-hens, and wild duck show no fear of a quiet
dog. If approached gently, in the absence of their parents, callow
wild birds in their nest exhibit little alarm at the slow and gentle
approach of man. Mr. Hudson’s opinion has already been quoted, but
will bear repetition; it is, “that fear of particular enemies is in
nearly all cases the result of experience.” And there is no evidence to
show that, in those cases in which it is truly instinctive and not the
result of experience, the instinctive behaviour is necessarily due to
inherited habit and not to natural selection.

It cannot be said that the evidence for the supposed mode of origin
of secondary instincts is sufficiently varied and cogent to carry
conviction. On the other hand, there does seem some evidence which
points to a different conclusion. When instinctive behaviour follows
on a sensory impression, not only is the co-ordination hereditary,
but there is an inherited linkage of stimulus and response. Thus in
the solitary wasps the sight of the natural prey is followed by the
appropriate modes of attack. The _Meloë_ larva springs upon anything
hairy. In chicks the sight of a small object at a certain distance
initiates the act of pecking. In moor-hens and ducklings the stimulus
of water produces the movements concerned in swimming. And so, too,
in many other examples of instinctive behaviour, we infer from the
observed facts that stimulus and response have an organic connection
founded on hereditary links in the nervous system. Now, if such
connection were due to inherited habit, we should expect them to be
established wherever the experience to which they are related has
been constant through many generations. How comes it, then, that the
chick does not instinctively respond by appropriate behaviour to the
sight of water? How comes it that young birds do not instinctively
avoid bees, and wasps, and nauseous caterpillars? If the effects of
ancestral experience be hereditary, one would surely expect that in
these cases the connection between stimulus and response--a connection
which passes into acquired habit--would have become congenital; that
the habitual behaviour would have long ago become instinctive. But this
does not appear to be the case. And with regard to disuse causing the
loss of instinct, how comes it that young chicks swim with well-ordered
leg-movements, though swimming is not an act that is habitually
performed by the members of their race?

What, then, has the alternative hypothesis of natural selection to
advance in explanation of these facts? On this hypothesis instinctive
acts have biological value in such degree that they have become
congenital through the preservation of adaptive variations. But if this
be so, why does not the chick respond instinctively to the sight of
that which is so essential to its existence as water to drink? In reply
to this question it may be suggested that, under natural conditions,
the hen teaches all her chickens to peck at the water, and thus shields
them from the eliminating influence which gives rise to natural
selection, in the absence of which the habit of drinking in response
to the sight of water, though acquired by each succeeding generation
of birds, has not become instinctive and congenital. Or, to put the
matter from a slightly different point of view, the maternal instincts
of the hen protect her chicks from any elimination in this respect; and
in the absence of such elimination the habit has not been inherited as
instinct. But though the hen can lead her young to peck at the water,
she cannot teach them how to perform the complex movements of the
mouth, throat, and head in actual drinking. In this matter, therefore,
her own instinctive procedure does not shield them from the incidence
of that elimination which leads to survival under natural selection.
Those chicks would be eliminated which, on pecking the water, failed to
respond to the stimulus by the complex behaviour involved in drinking,
leaving those to survive in which the response had been congenitally
established. Thus it would seem that, when natural selection is
excluded, the habit has not become congenitally linked with a visual
stimulus; but when natural selection is in operation, the response has
been thus linked with the stimulus of water in the bill. Whence we may
infer that the co-operation of natural selection is an essential factor
in the evolution of instinctive behaviour.

There are, however, cases of instinctive behaviour which may seem too
trivial and unimportant to be subject to the sway of natural selection.
There are numberless little idiosyncracies of behaviour which seem to
be truly instinctive, which are readily recognizable as distinctive
traits, but which can hardly be regarded as of sufficient biological
value to determine whether the creatures in which they are developed
should survive or be eliminated in the struggle for existence. In many
cases, however, these serve rather to distinguish the detailed manner
of behaviour than its biological end or purpose. In different species
natural selection may determine the survival of those whose instinctive
behaviour meets a biological need. The relatively unimportant details,
differing slightly in each species, are mere adjuncts; and since
natural selection deals with each species or inter-generating group
separately, the essential behaviour may in each case carry with it
the associated differences of manner. We must remember, too, that, as
in the matter of structure so in that of behaviour, it is the animal
as a whole that is selected for survival; and so long as the whole
is adapted to the circumstances of life, the associated differences
of form or manner may share in, without doing much to determine,
survival. In any case these little instinctive traits, if they are so
trivial as to seem of small value from the biological point of view,
appear to be too unimportant to have been intelligently acquired as
habits.

Let us now consider one or two cases of instinctive behaviour which
would fall under Romanes’s category of instincts of blended origin
partly due to natural selection, partly to the inheritance of acquired
habit. It is the custom of the house martin to build beneath the eaves.
Forsaking the ancestral rocky haunts, it has been led to utilize
the houses that man has built. This has all the appearance of being
due to an intelligent modification of the ancestral instinct; but
how far the modification has become through heredity a congenital
variation, we do not know. The intelligence which is said to have
enabled the martin of the past to adopt this method of nidification is
still operative. The nestlings brought up under the eaves would have
opportunities for acquiring experience which might lead them to build
under similar circumstances. Nest and eaves would be associated in
the conscious situation. Nor would the effects of natural selection
be necessarily excluded. One may suppose that in the open country,
far from rock-shelters, those martins in which there was a congenital
tendency to build in house-shelters would bring up their broods and
transmit this tendency; while those in which it was absent would either
go elsewhere or fail to bring up broods at all. In the absence of
fuller knowledge as to the truly instinctive nature of the behaviour,
and as to its mode of genesis, we are in large degree at the mercy
of conjecture. But in any case the incidence of elimination is not
necessarily excluded, and there are, therefore, no grounds for denying
that natural selection has been a co-operating factor in the evolution
of the instinctive behaviour, if such it be.

It is well known that the lapwing will apparently simulate the
actions of a wounded bird, with the object, as it seems, of drawing
intruders away from her nest. And such tactics are not restricted
to this bird, nor even to one or two species. They are common,
no doubt with diversities of detail, to such different birds as
grouse, pigeons, plovers, rails, avocets, ducks, pipits, buntings,
and warblers. Granting that the behaviour is truly instinctive, it
forms a very pretty subject for transmissionists and their critics to
quarrel over. “If we seek, as an example,” the transmissionist may
exclaim, “an instinct which bears the marks of its intelligent, and
therefore acquired origin, this of feigning wounded provides all that
we can possibly demand.” “What mode of instinctive behaviour,” the
selectionist may ask, “can be adduced which is more obviously useful
to the species? Is not this just the kind of procedure which natural
selection, if it be a factor at all, must fix upon and perpetuate
through the elimination of failures? Those birds which, through
congenital variation of behaviour, acted in this way would certainly
enable their offspring to escape destruction by enemies, and these
would survive to perpetuate the instinct.”

Let us expand the transmissionist position a little further. An
extremist, of the type presented by Eimer, would perhaps urge that the
lapwing reasons thus: “If I pretend to be wounded, trail my wing, and
flutter along the ground, instead of flying off, I shall draw upon
myself the intruder’s attention, and lead him to suppose that I shall
be easily caught; and if I thus entice him away, my little ones will be
saved, and my end gained.” Thus, it may be said, might the bird argue,
and then give practical effect to its reasoning. But are we not here
attributing to the lapwing powers of ratiocination beyond the capacity
of the most intelligent of birds? Are we not assuming a histrionic
power, and a realization of the effects on others of its display, which
many a human actor might well covet?

“But may not the bird,” it may be urged in reply, “have found by
experience, without any elaborate process of abstract reasoning, that
the trick is effectual?” In any case it would be experience perilously
acquired. Granting that the bird has the wit to try the trick, a
little over-acting, a little too much lameness of wing, and she is
herself seized and killed; a little under-acting, and the trick
fails--her brood is found and destroyed. Does it not seem probable
that such experience would be dearly bought, that failure would mean
either death to the parent or death to the offspring? And is it not
clear that natural selection is thus introduced in any case? And may
not the selectionist pertinently ask: “If natural selection is thus
introduced as a factor, why halt midway between two hypotheses? Why
not take the further step--one by which all the difficulties attending
the intelligent acquisition and the biological transmission are alike
avoided--of allowing that natural selection exercises, throughout, its
influence on congenital variations, and not on acquired modifications
of behaviour?”

There is, however, a way in which, when natural selection is operative,
intelligence may serve to foster congenital variations of the required
nature and direction. We must remember that acquired habits on the one
hand, and congenital variations of instinctive behaviour on the other
hand, are both working, in their different spheres, towards the same
end, that of adjustment to the conditions of life. If, then, acquired
accommodation and congenital adaptation reach this end by different
methods, survival may be best secured by their co-operation. And the
more thorough-going the co-operation the better the chance of survival.
There would be a distinct advantage in the struggle for existence when
inherited tendencies of independent origin coincided in direction with
acquired modifications of behaviour; a distinct disadvantage when such
inherited tendencies were of such a character as to thwart or divert
the action of intelligence. Thus any hereditary variations which
coincide in direction with modifications of behaviour due to acquired
habit would be favoured and fostered; while such variations as occurred
on other and divergent lines would tend to be weeded out. Professor
Mark Baldwin,[46] who has independently suggested such relation
between modification and variation, has applied to the process the
term “Organic Selection;” but it may also be described as the natural
selection of coincident variations.

It may be urged, therefore, that if natural selection be accepted as
a potent factor in organic evolution, and unless good cases can be
adduced in which natural selection can play no part and yet habit has
become instinctive, we may adopt some such view as the foregoing.
While still believing that there is some connection between habit and
instinct, we may regard the connection as indirect and permissive
rather than direct and transmissive. We may look upon some habits as
the acquired modifications which foster those variations which are
coincident in direction, and which go to the making of instinct.

The net result of a study of instinctive behaviour is to lead us to
the conclusion that its evolution runs parallel with the evolution
of animal structure. This is perhaps best seen in the case of those
insects in which typical instinctive acts are performed by larvæ of
wholly different form and structure, though they are stages in the
development of the same species. This is exemplified in the cases
of _Sitaris_, _Argyromœba_, and _Leucopsis_ which have been briefly
described. It is probable that in all cases of instinctive action
natural selection has been a co-operating factor. Without going so far
as to assert with Professor Weismann the “all-sufficiency of natural
selection,” we may echo the words of Professor Groos,[47] and say:
“Nevertheless, we know no principle except that of selection, and
we must go as far as that will take us. Absolute knowledge of such
phenomena is unattainable.” And in this conclusion we have the support
of Dr. Peckham, who says,[48] “We have found them [the instinctive
acts of solitary wasps] in all stages of their development, and are
convinced that they have passed through many degrees from the simple
to the complex, by the action of natural selection. Indeed, we find in
them beautiful examples of the survival of the fittest.”

CHAPTER IV

_INTELLIGENT BEHAVIOUR_

I.--THE NATURE OF INTELLIGENT BEHAVIOUR

Such an animal as a newly hatched bird or an insect just set free
from the chrysalis is a going concern, a living creature. It is the
bearer of wonderfully complex automatic machinery, capable, under the
initiating influence of stimuli, of performing instinctive acts. But
if this were all we should have no more than a cunningly wrought and
self-developing automatic machine. What the creature does instinctively
at first it would do always, perhaps a little more smoothly as the
organic mechanism settled down to its work--just as a steam-engine goes
more smoothly when it has been running for a while; but otherwise the
action would continue unchanged. Instinctive behaviour would remain
unmodified throughout life. The chick, however, or the imago insect is
something more than this. It affords evidence of the accommodation of
behaviour to varying circumstances. It so acts as to lead us to infer
that there are centres of intelligent control through the action of
which the automatic behaviour can be modified in accordance with the
results of experience. When, for example, a young chick walks towards
and pecks at a ladybird, the like of which he has never before seen,
the behaviour may be purely instinctive; and so, too, when he similarly
seizes a wasp-larva. Even when he rejects the ladybird or swallows the
larva, this may be directly due to unpleasant stimulation in the one
case, and pleasant in the other. But when, after a few trials, the
chick leaves ladybirds unmolested while he seizes wasp-larvæ with
increased energy, he affords evidence of selection based on individual
experience. And such selection implies intelligence in almost its
simplest expression. We may say, therefore, that, whereas instinctive
behaviour is prior to individual experience, intelligent behaviour
is the outcome and product of such experience. This distinction is
presumably clear enough; and it is one that is based on the facts
of observation. But we must not fail to notice that, though the
logical distinction is quite clear, the acquired modifications of
behaviour, which we speak of as intelligent, presuppose congenital
modes of response which are guided to finer issues. We may say,
then, that where these congenital modes of response take the form of
instinctive behaviour, there is supplied a general plan of action
which intelligence particularizes in such a manner as to produce
accommodation to the conditions of existence.

We have already frankly admitted that, in the present state of our
knowledge, we do not know with any definiteness how intelligent
modification of behaviour is effected. But it seems probable that from
all parts of the automatically working organic machine messages come
in to the centres of conscious control, and that in accordance with
the net result of all these messages, and the past experience which
they recall, other messages go out to the automatic centres, and, by
checking their action here and enforcing it there, give new direction
to the resulting behaviour. If this be so, the consciousness associated
with the control-centres is like the person who sits in a central
office and guides the working of some organized system in accordance
with the information he is constantly receiving; who sends messages to
check activity in certain directions and to render it more efficient
and vigorous in others.

It may be said, however, that intelligent guidance is, at any rate
in such simple cases as the selection of a palatable grub and the
rejection of a nauseous ladybird, itself determined by instinctive
likes and dislikes. All young chicks apparently find wasp-larvæ
palatable and ladybirds the reverse; and this is just as much
the outcome of heredity as the instinctive act of pecking. Since,
therefore, heredity determines what shall be selected and what
rejected--since the likes and dislikes are themselves instinctive--any
essential difference between congenital and acquired behaviour seems to
be evanescent.

Now, if we apply to the affective qualities of mental states--the
pleasurable tone or its opposite which characterize such states--the
term “instinctive,” we do so in reference to the broader psychological
conception of instinct, rather than in accordance with the narrower
biological acceptation of the term. For the likes and dislikes
constitute part of the conditions under which the behaviour occurs,
and not elements in the co-ordinated response as such. Hence it is
preferable to apply to these hereditary qualities the term _innate_,
rather than the term _instinctive_. But, waiving this distinction,
it is true that such pleasant or unpleasant qualities of the sensory
results of stimuli are part of the animal’s hereditary outfit, and
are not acquired in the course of individual experience. What, then,
is acquired? What part does experience play in the development of
intelligent behaviour? Let us consider the case of the chick and the
ladybird, and see whether it helps us to answer these questions. The
chick is stimulated to the instinctive pecking response by a small
moving object. That is the first scene of the little drama. In the
second scene the ladybird is seized, sensory centres are unpleasantly
stimulated, and the insect is dropped or thrown on one side with signs
of disgust. Let us grant that this aversion with its characteristic
response is also instinctive. _There is no hereditary connection
between scene 1 and scene 2._ After an interval the curtain rises
on act ii. The characters are the same as in the first scene of the
previous act. But the action of the drama is different. The chick does
not seize the ladybird. Why? Because _there is an acquired connection
between scenes 1 and 2 of the previous act_. The chick has gained
experience of the nauseous character of the insect, and this experience
influences and modifies his behaviour. The essentially new feature,
therefore, is the establishment of a connection which is not provided
through inheritance. To put the distinction in a brief form, we may
say that instinct depends on how the nervous system is built through
heredity; while intelligence depends upon how the nervous system is
developed through use.

Assuming that an animal is capable of gaining experience and of
acquiring new nervous connections in the course of individual
experience, it follows that, as has already been indicated,
instinctive behaviour in its logical purity is only presented in
the first performance of any given co-ordinated act. For after this
the animal has gained experience of its performance; and this can
no longer conform to a definition of instinct, according to which
it is characterized as “prior to experience.” On the other hand,
intelligent behaviour cannot be presented on the first occurrence of
any action, since there is no prior experience thereof in the light
of which it may be guided. This logical distinction may be expressed
by saying that instinctive behaviour is always prior to experience,
while intelligent behaviour is always subsequent to experience. When,
however, instinctive procedure continues throughout life practically
unmodified or but little modified, we may still class it under
instinct, since the hereditary connections are still the predominant
factors. And where the latter part of an instinctive sequence is
modified by the experience gained in the former part, we may still term
the modification intelligent, however small may be the time-interval
implied in the word “subsequent.” Sharp as the logical distinction is,
the behaviour of animals is in the main a joint-product, and whether we
term it instinctive or intelligent depends upon whether the hereditary
or the acquired factor predominates.

Passing on now to consider some further characteristics of intelligent
behaviour, we may first notice what Dr. Charles Mercier, in his
work on “The Nervous System and the Mind,” terms the four criteria
of intelligence. Intelligence is manifested, he says, first in the
novelty of the adjustments to external circumstances; secondly, in the
complexity; thirdly in the precision; and fourthly, in dealing with
the circumstances in such a way as to extract from them the maximum of
benefit.

[Illustration: FIG. 18.--Leaf-case of Birch-weevil.]

If, however, we are to regard these severally as criteria of
intelligence, each should serve to differentiate intelligent from
instinctive behaviour. But this is not the case. The precision of the
adjustment cannot be regarded as a criterion of intelligence, for many
instinctive acts are remarkably precise. No grocer’s assistant rolls a
paper funnel with more precision than is displayed by the birch-weevil
(_Rhynchites betulæ_) in constructing the leaf-case in which her eggs
are laid. Curved incisions of constant form are made on either side of
the midrib, and are “of just the right shape to make the overlaps in
the rolling, and to retain them rolled up with the least tendency to
spring back,”[49] while the tip of the leaf is rolled into a second
smaller funnel, which is tucked in to close the opening of the first,
after the eggs have been deposited. “The eggs hatch in their dark
place, each giving rise to an eyeless maggot, which ultimately leaves
the funnel for the earth.... Hence the beetle cannot be considered
to have ever seen a funnel, and certainly has never witnessed the
construction of one, though, when disclosed, it almost immediately
sets to work to make funnels on the complex and perfect system”
characteristic of the species. This is but one example of instinctive
precision out of the many which could be cited. We may say, then,
that though, when an act is otherwise shown to be intelligent, the
precision is a criterion of the level attained by the intelligence,
still it cannot be said to be a criterion which serves to distinguish
intelligent from instinctive behaviour.

Nor can we regard apparent prevision (which is sometimes advanced as
a criterion of intelligence) as specially distinctive of intelligent
acts regarded objectively in the study of animal behaviour. For, as we
have had occasion to show, there are many instincts which display an
astonishing amount of what may be termed “blind prevision”--instance
the instinctive regard for the welfare of unborn offspring which the
mother will never see, and the instinctive preparation for an unknown
future existence in the case of insect larvæ.

Nor, again, is the complexity of the adjustment distinctive of
intelligence as contrasted with instinct. We have cited examples
which afford evidence of much complexity in instinctive behaviour.
The construction and storage of the nest among solitary wasps, and
their methods of capturing and conveying the insects or spiders on
which they prey, are sufficiently complex. So, too, is the behaviour
of the Sitaris larva which attaches itself to the male bee, passes to
the female, and then slips on to the eggs she lays; and so, again,
is that of the Yucca moth, which collects pollen from the anthers,
conveys it to the stigma, and then lays her eggs among the ovules.
These cases show, too, that the circumstances may be dealt with in
such a way as to extract from them the maximum of benefit. It would be
difficult intelligently to improve upon the manner of dealing with the
circumstances displayed in many familiar modes of instinctive procedure.

There remain the novelty of the adjustment and the individuality
displayed. And here we seem to have valid criteria of intelligent
behaviour. The ability to perform acts in special adaptation to
new circumstances, and the individuality manifested in dealing with
the complex conditions of a variable environment,--these seem to be
distinctive features of intelligence. On the other hand, in instinctive
behaviour there seems to be no choice; the animal is impelled to their
stereotyped performance through impulse, as by a stern necessity; they
are so far from novel that they are performed by every like individual
of the species, and have been so performed by their ancestors for
generations; and in performing the instinctive act, the animal seems to
have no more individuality or originality than a piece of adequately
wound clockwork.

Granting, then, that behaviour is shown to be intelligent by the fact
that there is evidence of profiting by experience, we may say that
the level attained by the intelligence is indicated by the complexity
of the adjustment, its precision, the individuality shown, the amount
of prevision disclosed, and in its being such as to extract from the
circumstances the maximum of benefit. Many of these points, however,
serve equally well to mark the level of instinctive procedure.

II.--INTELLIGENT BEHAVIOUR IN INSECTS

It is, as we have seen, among the higher invertebrates, especially in
insects, that some of the most remarkable and complex instincts may be
found. There is,[50] however, a tendency to ascribe the behaviour of
insects entirely to instinct, without sufficient evidence that neither
imitation, instruction, nor intelligent learning play any part. This
is, perhaps, a survival of the old-fashioned view that all the acts
of the lower animals are performed from instinct, whereas those of
human beings are to be regarded as rational or intelligent. In popular
writings and lectures, for example, we frequently find some or all of
the following activities of ant-life ascribed to instinct: recognition
of members of the same nest; powers of communication; keeping aphides
for the sake of their sweet secretion; collection of aphid eggs in
October, hatching them out in the nest, and taking them in the spring
to the daisies, on which they feed, for pasture; slave-making and
slave-keeping, which, in some cases, is so ancient a habit that the
enslavers are unable even to feed themselves; keeping insects as beasts
of burden, _e.g._ a kind of plant-bug to carry leaves; keeping beetles,
etc., as domestic pets; habits of personal cleanliness, one ant giving
another a brush-up, and being brushed-up in return; habits of play
and recreation; habits of burying the dead; the storage of grain and
nipping the budding rootlet to prevent further germination; the habits
described by Dr. Lincecum, and to a large extent confirmed by Dr.
McCook, that Texan ants prepare a clearing around their nest, and six
months later harvest the ant-rice, a kind of grass of which they are
particularly fond, even, according to Lincecum, seeking and sowing the
grain which shall yield this harvest; the collection by other ants of
grass to manure the soil on which there subsequently grows a species of
fungus upon which they feed; the military organization of the ecitons
of Central America; and so forth. Now, the description of the habits
of ants forms one of the most interesting chapters in natural history.
But to class them all as illustrations of instinct is a survival of an
old-fashioned method of treatment.

To put the matter in another way. Suppose that an intelligent ant
were to make observations on human behaviour as displayed in one of
our great cities or in an agricultural district. Seeing so great an
amount of routine work going on around him, might he not be in danger
of regarding all this as evidence of hereditary instinct? Might he not
find it difficult to obtain satisfactory evidence of the establishment
of our habits, of the fact that this routine work has to some extent
to be learnt? Might he not say (perhaps not wholly without truth), “I
can see nothing whatever in the training of the children of these men
to fit them for their life-work. The training of their children has no
more apparent bearing upon the activities of their after-life than
the feeding of our grubs has on the duties of ant-life. And although
we must remember,” he might continue, “that these large animals do not
have the advantage which we possess of awaking suddenly, as by a new
birth, to their full faculties, still, as they grow older, now one and
now another of their deferred instincts is unfolded and manifested.
They fall into the routine of life with little or no training as
the period proper to the various instincts arrives. If learning
thereof there be, it has at present escaped our observation. And such
intelligence as their activities evince (and many of them do show
remarkable adaptation to uniform conditions of life) would seem to be
rather ancestral than of the present time; as is shown by the fact that
many of the adaptations are directed rather to past conditions of life
than to those which now hold good. In the presence of new emergencies
to which their instincts have not fitted them, these poor men are often
completely at a loss. We cannot but conclude, therefore, that, although
shown under somewhat different and less favourable conditions, instinct
occupies fully as large a space in the psychology of man as it does in
that of the ant, while their intelligence is far less unerring and,
therefore, markedly inferior to our own.”

Of course, the views here attributed to the ant are very absurd. But
are they much more absurd than the views of those who, on the evidence
which we at present possess, attribute all the varied activities of
ant-life to instinct? Take the case of the ecitons, or military ants,
or the harvesting ants, or the ants that are said to keep draught-bugs
as beasts of burden: have we sufficient evidence to enable us to
affirm that these modes of behaviour are purely instinctive and not
intelligent; that all the varied manœuvres of the military ants, for
example, are displayed to the full without any learning or imitation,
without teaching and without intelligence on the part of every
individual in the army.

That in some cases there is something very like a training or education
of the ant when it emerges from the pupa condition is rendered probable
by the observations of M. Forel. As Romanes says,[51] “The young
ant does not appear to come into the world with a full instinctive
knowledge of all its duties as a member of a social community. It is
led about the nest and ‘trained to a knowledge of domestic duties,
especially in the case of larvæ.’ Later on, the young ants are taught
to distinguish between friends and foes.”

We have only to weigh the evidence brought forward by such observers
as Fabre and Dr. Peckham to see that among the solitary wasps and
mason bees the behaviour, though founded on instinct, is in large
degree modified by intelligence. The care with which a site for the
tunnelled nest in the ground is selected, betokens something more
than instinct. The following is a slightly condensed statement of Dr.
and Mrs. Peckham’s observations on one of the solitary wasps (_Aporus
fasciatus_).[52] “We were working one day in the melon-field when we
saw one of these little wasps going backwards and dragging a spider.
She twice left it on the ground while she circled about for a moment,
but soon carried it up on to one of the large melon leaves, and left
it there while she made a long and careful study of the locality,
skimming close to the ground in and out among the vines; at length she
went under a leaf close to the ground, and began to dig. After her head
was well down in the ground we broke off the leaf that we might see
her method of work. She went on for ten minutes without noticing the
change, and then, without any circling, flew off to visit her spider.
When she tried to return to her hole it was evident that some landmark
was missing. Again and again she zig-zagged from the spider to the
nesting-place, going by a sort of path among the vines from leaf to
leaf, and from blossom to blossom, but when she reached the spot she
did not recognize it. At last we laid the leaf back in its place over
the opening, when she at once went in and resumed her work, keeping
at it steadily for ten minutes longer. At this point she suddenly
reversed her operations, and began to fill in the hole that she had
made. She then glanced at the spider, selected a new place, and began
to dig again. This hole was also filled in; she looked once more at
the spider, and started a nest in a new place. This, in turn, was soon
abandoned, as was a fourth. The fifth beginning was made under a leaf
that lay close to the ground, but after twenty minutes’ work this place
also was abandoned and a sixth started. This, however, was the final
choice, and after forty-five minutes spent in digging it was completed.”

[Illustration: FIG. 19.--Solitary Wasp using a stone to beat down the
earth over its nest (after Peckham).]

This description shows an amount of apparent fastidiousness which
is quite irreconcilable with the hypothesis that the behaviour
is merely instinctive. Not less fastidious are some wasps in the
temporary closure of the hole with a stone or pellet of earth,
the operation being repeated several times with different covers
before the insect seems to be satisfied; while in other cases the
hole is hidden by bringing earth in such quantity as to render the
place indistinguishable from the rest of the field. But in one case
observed by Dr. Peckham, intelligent procedure was carried so far as
apparently to involve the use of a tool, the same behaviour having been
independently observed in the same genus (_Ammophila_) by Dr. S. W.
Williston of Kansas University. “Just here,” writes Dr. Peckham,[53]
“must be told the story of one little wasp whose individuality stands
out in our minds more distinctly than that of any of the others. In
filling up her nest she put her head down into it and bit away the
loose earth from the sides, letting it fall to the bottom of the
burrow, and then, after a quantity had accumulated, jammed it down with
her head. Earth was then brought from the outside and pressed in, and
then more was bitten from the sides. When, at last, the filling was
level with the ground, she brought a quantity of fine grains of dirt
to the spot, and, picking up a small pebble in her mandibles, used
it as a hammer in pounding them down with rapid strokes, thus making
this spot as hard and firm as the surrounding surface. Before we could
recover from our astonishment at this performance she had dropped her
stone and was bringing more earth, and in a moment we saw her pick up
the pebble and again pound the earth into place with it. Once more the
whole process was repeated, and then the little creature flew away.”

Here we have intelligent behaviour rising to a level to which some
would apply the term rational. For the act may be held to afford
evidence of the perception of the relation of the means employed to
an end to be attained, and some general conception of purpose. In
this section, which deals with description of behaviour based on
observation, the psychological explanation cannot be discussed. Similar
indications of deliberate action may be held to be afforded by the
sometimes elaborate “locality studies” which these insects seem to
make,--by the “care that is taken by wasps to acquaint themselves with
the surroundings of their nests.” A _Sphex_, for example, which had
partially made and then abandoned several nests, left them without any
locality study; but when she had completed a nest in a suitable spot
she made “a most thorough and systematic study of the surroundings.
She flew in and out among the plants, first in narrow circles near
the surface of the ground, and then in wider and wider ones as she
rose higher in the air, until at last she took a straight line and
disappeared in the distance.” Another species (_Cerceris deserta_) “has
the habit of making a number of half circles in front of the nest, and
then, after rising a little higher, of flying several times completely
round it.” The method of procedure is, it seems, so normal to the
species that it is probably founded on an instinctive basis. Dr. and
Mrs. Peckham, in commenting on their observations, say:[54] “If the
examination of the objects about the nest makes no impression upon the
wasp, or if it is not remembered, she ought not to be inconvenienced
nor thrown off her track when weeds and stones are removed and
the surface of the ground is smoothed over; but this is just what
happens.” For convenience of observation they “sometimes gently moved
intercepting objects to one side, but even such a slight change threw
the wasp out of her bearings, and made it difficult for her to recover
her treasure.” Where wasps form a number of nests in a small plot of
ground, as in the case of _Bembex_, each knows and returns to its own
hole, as was proved by Dr. Peckham, who marked the insects and their
nests with paint.

So, too, with regard to prey. In the course of his observations on
_Pompilus_, Fabre removed the spider which the wasp had deposited on
a tuft of vegetation before she made her nest. As she was at work
beneath the surface she could not see what went on above ground or
where the spider had been redeposited some twenty inches from its
former position. On emerging from the nest the wasp went straight to
the original spot, searched round it for some time, then made further
excursions, and discovered the spider. After slightly altering its
position, and placing it on another tuft of vegetation, she returned to
her subterranean labours, giving the observer an opportunity of again
moving the spider. Five times did Fabre repeat the operation, and every
time the wasp returned to the spot where she had last deposited her
prey.

The same observer records some interesting experiments with the mason
bee, _Chalicodoma_. The mud nests of the species investigated were
affixed to stones on the banks of the Rhone. When a nest was partially
constructed, the bee having flown off for more material, Fabre moved
the stone to a new position, near at hand and easily visible from the
original site. The bee went straight to the place where the nest had
been, searched the immediate neighbourhood, flew off, and returned
to the same spot to continue the search. If she came across her own
nest in its new position she did not recognize it as hers, but left it
after examination. But if a stone with the nest of another bee in about
the same stage of construction was placed in the position occupied
by her own, she adopted it. And when two nests near together, both
half built, were transposed, each bee unhesitatingly adopted the nest
which occupied the position where its own nest had been. It may well
seem strange that, the general locality-memory being so well marked,
the recognition of the particular stone and nest should be deficient.
This may be due to the fact that the so-called compound eyes are
the organs concerned in locality vision, while the ocelli deal with
details at very close range, and that the former alone afford the
requisite data for recognition; by their instrumentality alone arises
the conscious situation which affords guidance in behaviour. And in
that situation slight changes which for us make it “still the same but
with a difference” render it no longer the same for a being of more
limited intelligence--one probably incapable of analyzing the situation
and seeing that the sameness preponderates over the difference. Be
this as it may, the failure of a bee to recognize its own nest under
circumstances so foreign to its experience as removal to a new spot may
be paralleled with what I have observed in the case of sticklebacks.
A nest had been built in a round glass bell jar which stood near a
window. Some aquatic vegetation grew in the tank, and the nest was
built on the window side. An experiment was made by turning the large
bell jar through a right angle. The male stickleback searched for its
nest in the old direction on the window side--that is to say, the
same position in reference to the incidence of the light. The search
was, of course, fruitless, and a new nest was begun in this position.
Presently the old nest was discovered, and was then vigorously
destroyed in just the same way as the nest of a rival is pulled to
pieces and scattered. Here a new incidence of light and new direction
of shadows seemed to have completely transformed the visual situation.

To return to insects, it is probable that the homing faculty is not
the result of an inborn mysterious instinct dependent on some sense of
direction of which we have no knowledge, but is based upon experience
gained during their flight hither and thither--that, in a word, it is
intelligent and not instinctive. Experiments of Fabre at first seemed
to suggest some magnetic influence to which bees were sensitive; for
when a minute magnet was fixed to a bee as it started on its return
journey, the insect was at fault; but as a check experiment he affixed
a piece of straw instead of a magnet, with similar results. Some of
Fabre’s observations and those of Dr. Bethe[55] are difficult to
reconcile with the hypothesis that, in the homing, guidance is due to
acquired acquaintance with the locality. But, on the other hand, the
experiments of Lord Avebury and of Romanes seem to favour this view.
Romanes found that when bees were taken inland from their hive near
the seaboard, and then liberated, they returned from considerable
distances, the whole locality being familiar; but taken to the
seashore, where the objects around them were unfamiliar (since the
seashore is not the place where flowers and nectar are to be found),
the bees, though not far distant from the hive, were nonplussed and
lost their way. Dr. and Mrs. Peckham, as the result of their extremely
careful observations, seem to have no doubt that the homing of solitary
wasps is due to locality-experience; and of the social wasp, _Polistes
fusca_, they say:[56] “We have seen the young workers make repeated
locality studies when they first began to venture away from home, but
as they occupy the same nest all summer they, of course, grow more and
more familiar with their surroundings, until they become so thoroughly
acquainted with them that they can find their way without the least
difficulty. We have no doubt that with them, as with the solitary
wasps, the faculty is not instinctive, but is the direct outcome of
individual experience.”

In the interesting pages of the works in which Dr. and Mrs. Peckham
describe their investigations, there are many observations which show
that wasps are capable of intelligently profiting by the experience
which their instinctive behaviour places them in a position to acquire.
The inherited tendencies and aptitudes pave the way for acquired
modification and accommodation of behaviour. To catch and paralyze
spiders, to dig and prepare a tunnelled nest, and to carry the prey
to the nest, all this affords the instinctive basis; but when the
observers tell us that they “have several times seen wasps enlarge
their holes when a trial had demonstrated that a spider would not go
in,” and even on one occasion without trial when an unusually bulky
spider was brought, there is something beyond instinct; there is
intelligent adjustment to special circumstances given in experience.
Presumably intelligent is the habit frequently observed in one species
of _Pompilus_, and occasionally in another, of hanging the paralyzed
spider in a crotch of a branching stem, usually of bean or sorrel,
where it will be safe from the depredation of ants. On one occasion
Dr. Peckham, desirous of seeing the exact manner in which the victim
was stung, substituted an unhurt spider for that which the wasp had
paralyzed.[57] “According to the habit of its species when danger
threatens, it kept perfectly quiet, and when the wasp returned it was
hanging there as motionless as a piece of dead matter; but she would
not touch it; she hunted all over that plant and then over several
others near to it, returning continually to look again at the right
spot. After five minutes she flew off in the direction of the woods
to catch another spider. Why did she go to the woods? Why did she
not take the one that hung there in plain view? It could not have
been due to the fact that we had handled the spider, since when, on
other occasions, we took one that had been paralyzed, examined it, and
then returned it to the wasp, she accepted it without hesitation....
In forty minutes she came back with another spider, but, instead of
taking it into the nest, she hung it upon a bean plant near by, and
then proceeded to dig a new hole a few inches distant from the first.
Foolish little wasp, what a waste of labour! Truly, if you are endowed
with energy beyond your fellows, you are but meagrely furnished with
reason.”

[Illustration: FIG. 20.--Spiders placed by Solitary Wasps in the
crotches of branching stems (after Peckham).]

Here we have the routine of instinct--the normal mode of hunting and
capturing prey, the normal procedure of bringing the spider, and
then making the nest, predominating over any tendency to initiate
intelligent improvements. This, however, should not surprise us, in
whom the force of habit is often so strong. Nor should we feel surprise
at the apparently stupid tolerance some of these wasps display in
presence of parasites. _Bembex_, which does not store and close its
cell, but brings continual supplies of food to its larvæ, is not
disturbed by the presence in the cell of the grubs of the parasitic
fly _Miltogramma_. She could, we think, easily free her nest of these
intruders, but she continues to bring supplies, though the parasites
may absorb it all and leave her own larvæ to perish. She adapts her
procedure to the new conditions, being incapable of knowing that she is
feeding the enemies of her race.

Enough has now been said to show the extent and the limitations of the
intelligence of such insects as the solitary wasps. It will be noticed
that the acquired modifications of behaviour occur in close connection
with the inherited ground-plan of instinctive procedure. We shall
have occasion to note the same connection in our discussion of social
behaviour in the next chapter. And we shall consider the influence of
intelligence on instinct before we bring this chapter to a close.

III.--SOME RESULTS OF EXPERIMENT

It is unnecessary to give a _resumé_ of entertaining anecdotes
illustrative of intelligent behaviour in the higher animals. Such
anecdotes are too often the outcome of casual observations by untrained
observers; and the interpretation put upon the facts frequently shows
a want of psychological discrimination. Such is not the material of
which science is constituted. What is needed is systematic observation
conducted, so far as possible, under controlled conditions. Two
things are necessary: first, to distinguish instinctive behaviour,
inherited as such, from the acquired modifications or new departures
due to intelligence; and secondly, to determine the method and range
of intelligent procedure. These problems can only be solved in their
entirety by a complete knowledge of the life-history of the animal
concerned. But they may be attacked in detail by a systematic study
of particular modes of behaviour, and by an investigation into
their manner of origin. That this may be done with some approach
to accuracy, resort must be had to experiment, which permits of
observation under controlled conditions.

To ascertain, for example, how far nest-building is instinctive in
birds, Mr. John S. Budgett hatched a hen greenfinch under a canary. In
the following autumn he bought a caged bird, a cock, probably of the
same year, and in the succeeding spring turned the pair into a large
aviary, supplying such material as twigs, rootlets, dried grass, moss,
feathers, sheep’s wool and horsehair. The hen soon began to build, the
cock bird taking no share in the work, and finished her nest in a few
days. On careful comparison it was found to resemble that of a wild
greenfinch in every particular, being made of wool, roots, and moss,
lined with horsehair. A second nest the aviary greenfinch built was
also quite normal.

In the case of a bullfinch which Mr. Budgett reared, having obtained it
when a few weeks’ old, the first nest was composed of dried grass with
a little wool and hair, but without either rootlets or twigs. A second
which she built was, however, quite typical, made of fine twigs and
roots, and lined with horsehair; as was also a third nest.

It is just possible, though most improbable, that the bullfinch
utilized its three weeks’ experience gained in the nest from which it
was taken. But Mr. Jenner Weir describes[58] observations on canaries
in which this source of experience is excluded. “It is usual,” he
says, “with canary fanciers to take out the nest constructed by the
parent birds, and to place a felt nest in its place, and when her young
are hatched, and old enough to be handled, to place a second clean
nest, also of felt, in the box, removing the other. But I never knew
that canaries so reared failed to make a nest when the breeding time
arrived. I have, on the other hand, marvelled to see how like a wild
bird’s the nests are constructed. It is customary to supply them with
a small set of materials, such as moss and hair. They use the moss for
the foundation, and line with the finer materials, just as a wild
goldfinch would do.”

Experiment seems, therefore, to show in a way, and with a clearness
impossible of attainment by observation under natural uncontrolled
conditions, that nest-building in birds is instinctive. That the manner
and method of procedure is often modified in accordance with special
conditions--that the instinctive outline of nidification receives
its final touches through individual experience--is sometimes seen
under nature, and more often under the semi-experimental conditions
of domestication. Thus three pairs of pigeons in the Wilson Tower
of Clifton College made their nests in 1898, as I am informed by
Mr. H. C. Playne, of galvanized iron wire, pieces of which were
left in a corner at the top of the tower, thus affording a parallel
to the behaviour of the unconventional crow of Calcutta, mentioned
by Mr. F. W. Headley,[59] which made its nest of soda-water bottle
wires, which it picked up in a back yard. But even in this matter
experiment serves to bring out clearly the selective influence which
is exercised by intelligence. Bolton,[60] in 1792, observed a pair of
goldfinches beginning to build their nest in his garden. They formed
the ground-work of moss, grass, etc., as usual; but on his scattering
small parcels of wool in different parts of the garden they, in great
measure, left off the use of their own stuff and used the wool.
Afterwards he gave them cotton, and they then used this instead of the
wool; then he supplied fine down, and they finished their work with
this, leaving the wool and cotton.

In studying the behaviour of wild animals under natural conditions, it
must always be difficult to distinguish the congenital basis from the
acquired elements; for both tend to bring about a working adjustment
to the conditions of life, and we can seldom have opportunities of
tracing the interplay of the factors which produce the instinct-habits
of adult life. But under domestication we seek to bring about a new
working adjustment to conditions imposed by man. The skilful trainer
utilizes the natural instinctive tendencies as a basis; and, by a
system of rewards and punishments, leads the intelligent modifications
of behaviour along lines directed by his deliberate purpose. The
conditions are largely those of experiment, and they bring out the
play and range of intelligence in a way which would otherwise elude
our observation. The training of falcons for the chase affords a good
illustration, since they cannot be bred in confinement, and the effects
of training cannot therefore be hereditary. The falconer’s object is
to modify the congenital instinctive behaviour of a bird of prey for
the purposes of sport. She is trained to the lure at first at short
distances, and step by step through longer flights; she is taught by
snatching away the lure to stoop at it repeatedly as often as it is
jerked aside; and then she is trained on living quarry, at first under
easy conditions, till eventually she can be flown at a wild bird. And
as a result a well-trained falcon will follow her master from field
to field, regulating her flight by his movements, always ready for a
stoop when the quarry is sprung. The fact that she can be thus educated
for her work shows that her behaviour is plastic, and can be moulded
by intelligence. Experimental conditions reveal the fact; but under
nature the moulding influence of intelligence is presumably not less
important, though it is more directly in line with the congenital
instinctive tendencies.

That much of the behaviour of the higher animals is guided by
experience similar to that which plays so large a part in their
training under the experimental conditions of domestication is
generally admitted. But what are the range and limits of animal
intelligence, and whether it attains the level of rational conduct,
in the restricted sense of the term “rational,” are questions open to
discussion, to which answers are more likely to be obtained through
experiment than by chance observations.

Before giving some of the results of such experiment it will be well
to revert to the distinction, which was drawn in the second chapter,
between the lower or intelligent stage of mental development and the
higher or rational stage. It will be remembered that rational processes
were characterized by the fact that the situations contain the products
of reflective thought, presumably absent in the earlier stages of
development; that they were further characterized by a new purpose or
end of consciousness, namely, to explain the situations which at an
earlier stage are merely accepted as they are given in presentation or
re-presentation; they require deliberate attention to the relationships
which hold good among the several elements of successive situations;
and they involve, so far as behaviour is concerned, the intentional
application of an ideal scheme with the object of rational guidance.

On the other hand, the animal at the stage of intelligent behaviour
deals with the circumstances of his comparatively simple life by
making use of the particular situations which have been presented to
consciousness in the course of his practical experience. If such an
animal be placed in the midst of new circumstances he has to find out
by a process of trial and error how they are to be met. After a longer
or shorter period of trial, guided only by particular experiences,
he chances to hit upon a mode of procedure which is successful. The
successful act is then incorporated in a new situation; at first,
perhaps, only incompletely. The association is eventually established
by repetition, through which is acquired the habit of doing the right
thing in the appropriate manner. Why he does this and not something
else, in so far as he is intelligent and not rational, he probably
neither knows nor has the wit to consider. The satisfaction of success
suffices for intelligence as such. If the circumstances be so modified
as to render the particular mode of meeting them ineffectual, after
trying again and again in the old way, he will sometimes stumble upon
the proper mode of overcoming the difficulty, and after doing so two
or three times a new conscious situation involving the requisite
associations will be established, and the appropriate behaviour will
become habitual. But why this new mode of procedure rather than any
other is adopted, intelligence as such does not know, because it does
not analyze the situation and disentangle the essential relationships.
The satisfaction of success again suffices. In a word, such an animal
in the perceptual stage of mental development seems wanting in the
power of reflection. He does not appear to show evidence of framing
anything like a general scheme of knowledge which he can apply to the
solution of particular problems, of a practical nature, involving
difficulties and obstacles.

The method of intelligence--in the sense in which we are using this
term--the method of varied trial and error with the utilization of
chance success, is a lengthy and somewhat clumsy process; but it
suffices. Now contrast it with the procedure of a rational animal, such
as man is or may be. When he is confronted by a difficulty he is not
content to meet it by trying this way, and that way, and another way,
anyhow, and trusting to chance to bring success, but he considers the
problem in all its relations with a view to ascertaining the essential
nature of the difficulty. For each attempted mode of meeting the case
he has a definite reason. He knows why he does this and not that. He
has a plan or scheme which he puts into execution. And if it fail,
he is not content till he finds out wherein the failure lay. This
enables him to plan a better scheme. He sees why it is better; and if
at last he be successful by a happy hit, as in the chance procedure
of intelligence, he looks for the reason of it. And seeing why this
fortunate attempt, unlike his previous efforts, just meets the case,
he repeats it because he perceives that herein lies the essential
solution of the difficulty. Both in the case of intelligence and in
that of reason, as here distinguished, present procedure is based upon
past experience; but reason has built upon the foundations thus laid an
orderly scheme, and knows its whys and wherefores, while intelligence
is at the mercy of chance associations. The reason for success it has
not the wit to assign.

The essential difference between the two cases may be put in another
way by saying that the intelligent being forms sensory impressions and
sensory images linked together by bonds of association, combining and
coalescing to constitute a conscious situation effective in behaviour
under the guiding influence of pleasure and pain; while the rational
being not only does all this, but goes further. He fixes his attention
on the way in which the elements in the situation are connected and
related; he builds an ideal framework on which the sensory impressions
are set or move in an orderly manner. And it is this scheme, fashioned
by reason and transforming the situation, which he utilizes in dealing
with difficulties.

Yet another way of putting the same essential distinction is to say
that intelligence deals with pictures, either directly presented to
the senses or called up in re-presentation. If we state the matter
thus, however, we must remember that the “pictures” may be painted in
colours supplied by any of the senses; and that smells, tastes, sounds,
touches, pressures, limb-movements, and so forth, are elements in the
pictured product. Bearing this in mind, we may say that intelligence
deals with sensory impressions and their revived images in concrete
and particular situations; while reason analyzes the pictures, and
extracts from them general notions in terms of which the pictures may
be explained. For example, we picture a stone falling to the earth;
but we explain it by the general notion of gravitative attraction. The
conception forms part of our ideal scheme of knowledge, which is not
itself picturable, though this or that example of its action may be
presented or re-presented in sensory imagery.

Once more we may say--and this way of looking at the question arises
naturally out of what has gone before--that intelligence deals with
concrete examples, and does not rise to the abstract and general
rule. The ideal scheme of reason is the result of abstraction and
generalization. It is a framework of conceptions which can be applied
to the particular facts which fall under observation to see whether
it fits and meets the case. Intelligence has to deal with the facts
as they present themselves, without the aid of an organized system of
knowledge built up into an ideal scheme.

Enough has now been said to indicate the distinction between the
method of intelligence and that of reason. It may, no doubt, be said
that the terminology used is open to criticism; for, on the one hand,
the words “intelligence” and “intelligent” are frequently used as
synonymous with “reason” and “rational;” and, on the other hand, acts
requiring neither abstraction, generalization, nor the application
of any scheme of knowledge are frequently spoken of as “rational.”
Hence there is, it may be urged, some danger of misunderstanding. This
may be granted. And unless some such restriction of meaning under
suitable terms be accepted by psychologists, misunderstanding will
continue. More essential, however, than the distinctive terms we are
to use is the distinction of method which underlies them. That, I
trust, is sound. Dr. Lindley, in an interesting paper on “A Study of
Puzzles,”[61] has utilized the distinction in his investigation of the
mental development of children, and has found that the procedure of
young children is predominantly of the “sense-trial and error” order
which has above been termed intelligent; and he expresses the opinion
that “most of the adaptations of animals are on this sense-trial and
error level.”

Such certainly seems to be the conclusion to be drawn from my own
experimental observations on dogs. It has frequently been asserted
that the behaviour of a dog with a stick in his mouth, when he comes
to a narrow gap, shows that he at once perceives the nature of
the difficulty, and meets it in a rational manner by adopting the
appropriate plan of action. He pulls the stick through by one end. But
experiments, which I have elsewhere described,[62] showed that a fox
terrier, fourteen months old, seemed to be incapable of perceiving
the nature of the difficulty which vertical iron railings presented
to his passage with a stick in his mouth, and only imperfectly learnt
to overcome it after many ineffectual trials and many failures. The
results obtained on the first afternoon may be quoted to indicate the
nature of the evidence. The dog was sent after a short stick into a
field, and had to pass through vertical rails about six inches apart.
On his return the stick caught at the ends. I whistled and turned as
if to leave; and the dog pushed and struggled vigorously. He then
retired into the field, lay down, and began gnawing the stick, but,
when called, came slowly up to the railings and stuck again. After some
efforts he put his head on one side, and brought the stick, a short
one, through. After patting and encouraging him, I sent him after it
again. On his return he came up to the railings with more confidence,
but, holding the stick by the middle, found his passage barred. After
some struggles he dropped it and came through without it. Sent after it
again, he put his head through the railings, seized the stick by the
middle, and then pulled with all his might, dancing up and down in his
endeavours to effect a passage. Turning his head in his efforts, he
at last brought the stick through. A third time he was again foiled;
again dropped the stick; and again seizing it by the middle tried to
pull it through. I then placed the stick so that he could easily seize
it by one end and draw it through the opening between the rails. But
when I sent him after it, he went through into the field, picked up the
stick by the middle, and tried to push his way between the railings,
succeeding, after many abortive attempts, by holding his head on one
side.

Subsequent trials on many occasions yielded similar results. But the
following summer, when I resumed the experiments, I was able with some
guidance to teach him to bring a long stick to the railings, drop
it, and then draw the stick through by one end; though even then,
if he had dropped it so that one end just caught a rail, he often
failed, shaking his head vigorously, dropping the stick and seizing
it again, and repeating this behaviour until it chanced to fall in
a more favourable position. He did not apparently perceive that by
gently moving the stick a little one way or other the difficulty
could be simply overcome with little effort. Nor when given a crooked
stick, which caught in a rail, did he show any sign of perceiving that
by pushing the stick and freeing the crook he could pull the stick
through. Each time the crook caught he pulled with all his strength,
seizing the stick now at the end, now in the middle, and now near the
crook. At length he seized the crook itself, and with a wrench broke
it off. A man who was passing, and who had paused for a couple of
minutes to watch the proceedings, said, “Clever dog that, sir; he knows
where the hitch do lie.” The remark was the characteristic outcome of
two minutes’ chance observation. During the half hour or more during
which I had watched the dog he had tried nearly every possible way of
holding and tugging at the stick. Such is the mode of behaviour based
on intelligence--continued trial and failure, until a happy effect is
reached, not by methodically planning, but by chance.

Two of my friends criticized these results, and said that they only
showed how stupid _my_ dog was. _Their_ dogs would have acted very
differently. I suggested that the question could easily be put to the
test of experiment. The behaviour of the dog was in each case--the
one a very intelligent Yorkshire terrier, the other an English
terrier--similar to that above described. The owner of the latter was
somewhat annoyed, used forcible language, and told the dog that he
could do it perfectly well if he tried.

In experimenting with my fox terrier on the method adopted in seizing
and carrying differently balanced objects, I used (1) a straight
stick, the centre of gravity of which was at the middle; (2) a Kaffir
knob-kerrie, the centre of gravity of which was about six inches from
the knob; (3) a light geological hammer; and (4) a heavier hammer. In
the last, the centre of balance was close to the hammer head. The net
result of the observations was that the best place for seizing and
holding the object was hit upon in each case after indefinite trials;
that after three or four days’ continuous experience with one (say the
knob-kerrie), another (say the stick) was at first seized nearer one
end, showing the influence of the more recent association; and that
there was little indication of the dog’s seizing any one of the four
at once in the right place, that is to say, the point of seizure was
not clearly differentiated in accordance with the look of the object. I
tied a piece of string, in later trials, round the centre of balance,
but this, at the time of the dog’s death, had not served as a sure
guide to his experience.

The way in which my dog learnt to lift the latch of the garden gate,
and thus let himself out, affords a good example of intelligent
behaviour. The iron gate outside my house is held to by a latch, but
swings open by its own weight if the latch be lifted. Whenever he
wanted to go out the fox terrier raised the latch with the back of his
head, and thus released the gate, which swung open. Now the question in
any such case is: How did he learn the trick? In this particular case
the question can be answered, because he was carefully watched. When
he was put outside the door, he naturally wanted to get out into the
road, where there was much to tempt him--the chance of a run, other
dogs to sniff at, possibly cats to be worried. He gazed eagerly out
through the railings on the low parapet wall shown in the illustration;
and in due time chanced to gaze out under the latch, lifting it
with his head. He withdrew his head and looked out elsewhere; but
the gate had swung open. Here was the fortunate occurrence arising
out of natural tendencies in a dog. But the association between
looking out just there and the open gate with a free passage into the
road is somewhat indirect. The coalescence of the presentative and
re-presentative elements into a conscious situation effective for the
guidance of behaviour was not effected at once. After some ten or
twelve experiences, in each of which the exit was more rapidly effected
with less gazing out at wrong places, the fox terrier had learnt to
go straight and without hesitation to the right spot. In this case
the lifting of the latch was unquestionably hit on by accident, and
the trick was only rendered habitual by repeated association in the
same situation of the chance act and the happy escape. Once firmly
established, however, the behaviour remained constant throughout the
remainder of the dog’s life, some five or six years.

[Illustration: FIG. 21.--Fox-terrier lifting the latch of a gate.]

Mr. E. J. Shellard observed[63] an act of similar import in a Scotch
staghound, which “appeared at first to be the result of thought,”
but which, on closer observation, was clearly seen to be the result
of intelligence in the restricted sense of the term. The dog released
the lever-latch of a yard door. “At first he raised his paws to the
door and scratched violently, manifesting various signs of impatience.
His scratches, which extended from the top of the door downwards, and
over the whole area, would thus inevitably at some time or other reach
the handle of the latch, which was thus struck forcibly downwards, the
latch itself rising upwards. The door would then open from the weight
of the dog pushing against it. The dog always opened the door in this
manner from the time when the incident was first noticed until he left,
a period of about three years. The door was opened with no greater
ease at the expiration of that period than at the commencement. His
paws would strike various parts of the door, and he never appeared to
exercise any degree of judgment in the localization of his strokes, the
fact of his paws striking the handle of the latch being a necessary
result, providing the dog had sufficient patience and strength to
continue.”

One or two more experiments with my fox terrier may be briefly
described. I watched his behaviour when a solid indiarubber ball was
thrown towards a wall standing at right angles to its course. At first
he followed it right up to the wall and then back as it rebounded. So
long as it travelled with such velocity as to be only just ahead of
him he pursued the same course. But when it was thrown more violently,
so as to meet him on the rebound as he ran towards the wall, he
learnt that he was thus able to seize it as it came towards him. And,
profiting by the incidental experience thus gained, he acquired the
habit--though for long with some uncertainty of reaction--of slowing
off when the object of his pursuit reached the wall so as to await its
rebound. Again, when the ball was thrown so as to glance at a wide
angle from a surface, at first--when the velocity was such as to keep
it just ahead of him--he followed its course. But when the velocity
was increased he learnt to take a short cut along the third side of a
triangle, so as to catch the object at some distance from the wall. A
third series of experiments were made where a right angle was formed
by the meeting of two surfaces. One side of the angle, the left, was
dealt with for a day or two. At first the ball was directly followed.
Then a short cut was taken to meet its deflected course. On the fourth
day this method was well established. On the fifth, the ball was thrown
so as to strike the other or right side of the angle, and thus be
deflected in the opposite direction. The dog followed the old course
(the short cut to the left) and was completely non-plussed, searching
that side, then more widely, and not finding the ball for eleven
minutes. On repeating the experiment thrice, similar results were that
day obtained. On the following day the ball was thrown just ahead of
him, so as to strike to the right of the angle, and was followed and
caught. This course was pursued for three days, and he then learnt
to take a short cut to the right. On the next day the ball was sent,
as at first, to the left, and the dog was again non-plussed. I did
not succeed in getting him to associate a given difference of initial
direction with a resultant difference of deflection.

I may here mention that, whenever searching for a ball of which he had
lost sight in the road, he would run along the gutter first on one
side and then on the other. A friend who was walking with me one day
regarded this as a clear case of rational inference. “The dog knows,”
he said, “the effects of the convex curvature of the road as well as we
do.” I am convinced, however (having watched his ways from a puppy),
that this method of search was gradually established on a basis of
practical experience. No logical inference on his part is necessary for
the interpretation of the facts; and we should not assume its presence
unless the evidence compels us to do so.

Dr. E. L. Thorndike, in a monograph on “Animal Intelligence” published
as a supplement to the _Psychological Review_ (June, 1898), has fully
described and carefully discussed a number of interesting experiments.
The subjects (one might, alas! almost say victims) of some of these
were thirteen kittens or cats from three to eighteen months old. His
method of investigation shall be stated in his own words.

“After considerable preliminary observation of animals’ behaviour
under various conditions, I chose for my general method one which,
simple as it is, possesses several other marked advantages besides
those which accompany experiment of any sort. It was merely to put
animals when hungry in enclosures from which they could escape by
some simple act, such as pulling at a loop of cord, pressing a lever,
or stepping on a platform. The animal was put in the enclosure,
food was left outside in sight, and his actions observed. Besides
recording his general behaviour, special notice was taken of how he
succeeded in doing the necessary act (in case he did succeed), and a
record was kept of the time that he was in the box before performing
the successful pull, or clawing, or bite. This was repeated until the
animal had formed a perfect association between the sense-impression
of the interior of that box and the impulse leading to the successful
movement. When the association was thus perfect, the time taken to
escape was, of course, practically constant and very short.

“If, on the other hand, after a certain time the animal did not
succeed, he was taken out, but _not fed_. If, after a sufficient
number of trials, he failed to get out, the case was recorded as one
of complete failure. Enough different sorts of methods of escape
were tried to make it fairly sure that association in general, not
association of a particular sort of impulse, was being studied.
Enough animals were taken with each box or pen to make it sure that
the results were not due to individual peculiarities. None of the
animals used had any previous acquaintance with any of the mechanical
contrivances by which the doors were opened. So far as possible the
animals were kept in a uniform state of hunger, which was practically
utter hunger.”

[Illustration: FIG 22.--Cage used in Professor Thorndike’s
experiments.]

To Dr. Thorndike’s monograph we must refer those who desire detailed
information as to apparatus and procedure. It must here suffice to
state that the box-cages employed were rudely constructed of wooden
laths, and formed cramped prisons about twenty inches long by fifteen
broad and twelve high. Nine contained such simple mechanisms as Dr.
Thorndike describes in the passage above quoted. When a loop or cord
was pulled, a button turned, or a lever depressed, the door fell open.
In another, pressure on the door as well as depression of a thumb-latch
was required. In one cage two simple acts on the part of the kitten
were necessary, pulling a cord and pushing aside a piece of board; and
in yet others three acts were requisite. In those boxes from which
escape was more difficult a few of the cats failed to get out. The
times occupied in thoroughly learning the trick of the box by those
who were successful are plotted in a series of curves, the essential
feature of which is the graphic expression of a gradual diminution
in the time interval between imprisonment and escape in successive
trials. This is shown in Fig. 23, which is constructed from some of Dr.
Thorndike’s data. In some cases the cats were set free from a box when
they (1) licked themselves or (2) scratched themselves.

[Illustration: FIG. 23.--Diagram showing times taken by a kitten to
escape from the cage in twenty-four successive experiments.]

Dr. Thorndike comments on the results of his experiments as follows:--

“When put into the box the cat would show evident signs of discomfort
and of an impulse to escape from confinement. It tries to squeeze
through any opening; it claws and bites at the bars or wire; it
thrusts its paws out through any opening, and claws at everything
it reaches; it continues its efforts when it strikes anything loose
and shaky: it may claw at things within the box. It does not pay
very much attention to the food outside, but seems simply to strive
instinctively to escape from confinement. The vigour with which it
struggles is extraordinary. For eight or ten minutes it will claw,
and bite, and squeeze incessantly.... The cat that is clawing all
over the box in her impulsive struggle will probably claw the string,
or loop, or button so as to open the door. And gradually all the
other non-successful impulses will be stamped out, and the particular
impulse leading to the successful act will be stamped in by the
resulting pleasure, until, after many trials, the cat will, when put
in the box, immediately claw the button or loop in a definite way....
Starting, then, with its store of instinctive impulses, the cat hits
upon the successful movement, and gradually associates it with the
sense-impression of the interior of the box until the connection is
perfect, so that it performs the act as soon as confronted with
the sense-impression.... Previous experience makes a difference
in the quickness with which the cat forms the associations. After
getting out of six or eight boxes by different sorts of acts, the
cat’s general tendency to claw at loose objects within the box is
strengthened and its tendency to squeeze through holes and bite
bars is weakened; accordingly it will learn associations along the
general line of the old more quickly. Associations between licking
or scratching and escape are similarly established, and there was
a noticeable tendency to diminish the act until it becomes a mere
vestige of a lick or scratch. After the cat gets so that it performs
the act soon after being put in, it begins to do it less and less
vigorously. The licking degenerates into a mere quick turn of the
head with one or two motions up and down with tongue extended.
Instead of a hearty scratch, the cat waves its paw up and down
rapidly for an instant.”

Such experiments carried out on a different method give results in line
with my own. The conditions are, however, somewhat unnatural, which
I regard as in some respects a disadvantage. But we need experiments
on different methods--the more the better,--and if the results they
furnish are in accord, their correctness will be rendered the more
probable. It is to be hoped that Dr. Thorndike will devise further
experiments in which (1) the conditions shall be somewhat less strained
and straitened, while the subjects are in a more normal state of
equanimity (cannot “utter hunger” be avoided?), and (2) there shall
be more opportunity for the exercise of rational judgment, supposing
the faculty to exist. To establish the absence of foresight in the
procedure of the cats, it is surely necessary so to arrange matters
that the connections are clearly open--nay, even obvious--to the eye of
reason. It appears that this consideration has not weighed sufficiently
with Dr. Thorndike.

A series of experiments were made to ascertain whether instruction
(in the form of putting the animal through the procedure requisite
for a given act) was in any degree helpful. The conclusion is that
such instruction has no influence. Those who have had experience in
teaching animals to perform tricks will probably agree here--though
some trainers give expression to a different opinion. It is, however,
essential to distinguish carefully between showing an animal how a
trick is done, and either stimulating its attention or furnishing
accessory guidance (such as the occasional taps of the trainer’s whip
when he wants a performing horse to kneel), or affording suitable
conditions the results of which temporarily enter into the association
complex. If the latter be eliminated the practice of trainers, I
believe, bears out the general result of the experiments. Dr. Thorndike
never succeeded in getting an animal to change its way of doing a thing
for his. Nor was I, after repeated trials, able to modify the way in
which my dog lifted the latch of the gate. He did it with the back
of his head. I could not get him to do it (more gracefully) with his
muzzle.

It may be said that the remarkable feats of performing animals imply
the existence of faculties of a higher order than Dr. Thorndike and
I are prepared to admit on the basis of our experiments. Mr. P. G.
Hamerton many years ago described[64] how, in his own house, a cleverly
trained dog would fetch in their right order the letters which spelt
the English or German equivalents of common French words, and do other
wonderful things. But the owner of the dog (M. du Rouil) admitted that
there was a means of rapport between them which he was not prepared to
divulge. It is just because the trainer has to lead up to and utilize
chance experiences that such prolonged patience and care are required.
The animal is but the instrument on which his clever trainer plays;
an instrument of wonderful intelligence, but lacking in the higher
rational faculty. The organized scheme is the master’s, not that of his
willing slave. A rational being might not do more wonderful things; but
he would learn them more rapidly and by a less wearisome method. As it
is, the clever performing dog originates little or nothing, and repeats
again and again the same stereotyped behaviour, which--if one witnesses
the performance often--touches one with a profound sense of its lack of
rational spontaneity.

As at present advised, therefore, I see no reason for withdrawing
from the position provisionally taken up. The utilization of chance
experience, without the framing and application of an organized
scheme of knowledge, appears to be the predominant method of animal
intelligence.

On this view, then, we may see in instinctive behaviour, and the
multifarious automatic acts of animals, a means of providing
experience of the right kind and on profitable lines. We may see in
the play-instincts of the young a training ground for the more serious
business of animal life--a theme developed by Professor Groos. We
may see in the imitative tendency--the innate proclivity to follow
a lead blindly and at first unintelligently--a further means of
providing those useful items of experience which intelligence finds so
serviceable. And we may see in the intelligence which can profit by
chance occurrences that arise in these several ways all that suffices
for the simple needs of animal existence.

With some differences of opinion Dr. Thorndike and I have much in
common in the conclusions to which we have been independently led
as to the method and limits of animal intelligence. We seem to be
in essential agreement in the belief that the method of animal
intelligence is to profit by chance experience without rational
foresight, and that unless such experience be individually acquired,
the data essential for intelligent progress are absent. While in our
attempts to realize the general nature of animal consciousness there
is a close similarity of treatment. In my “Introduction to Comparative
Psychology” a good deal of space is devoted to an analysis of the
psychology of skill “in order that we may infer what takes place in
the minds of animals;” and I said:--“When I am playing a hard game of
tennis, or when I am sailing a yacht close to the wind in a choppy
sea, self does not at all tend to become focal. Hence, though I am a
self-conscious being I am not always self-conscious. And presumably
when I am least self-conscious, I am nearest the condition of the
animal at the stage of mere sense experience. I am exhilarated with the
sense of pleasurable existence, my whole being tingles with sentient
life. I sense, or am aware of, my own life and consciousness, in an
unusually subtle manner. Experience is vivid and continuous. Such I
take it to be the condition of the conscious but not yet self-conscious
animal.”

I can therefore cordially endorse Dr. Thorndike’s conclusions as
expressed in the following passages:--

“One who has watched the life of a cat or dog for a month or more under
test conditions, gets, or fancies he gets, a fairly definite idea of
what the intellectual [intelligent] life of a cat or dog feels like. It
is most like what we feel when consciousness contains little thought
about anything, when we feel the sense-impressions in their first
intention, so to speak, when we feel our own body, and the impulses
we give to it. Sometimes one gets this animal consciousness while in
swimming, for example. One feels the water, the sky, the birds above,
but with no thoughts about them or memories of how they looked at other
times, or æsthetic judgments about their beauty; one feels no ideas
about what movements he will make, but feels himself make them, feels
his body throughout. Self-consciousness dies away. Social consciousness
dies away. The meanings, and values, and connections of things die
away. One feels sense-impressions, has impulses, feels the movements he
makes; that is all.”

And after an illustration from such a game as tennis, Dr. Thorndike
adds: “Finally the elements of the associations are not isolated.
No tennis-player’s stream of thought is filled with free-floating
representations of any of the tens of thousands of sense-impressions
or movements he has seen and made on the tennis-court. Yet there
is consciousness enough at the time, keen consciousness of the
sense-impressions, impulses, feelings of one’s bodily acts. So with the
animals. There is consciousness enough, but of this kind.”

It may be said that between the method of intelligence and that of
fully developed rational procedure there is a wide gap which must
have been bridged in the course of mental evolution. Unquestionably.
And in contending that the methods of the animal are predominantly
intelligent, I am far from wishing to assert dogmatically that in no
animals are there even the beginnings of a rational scheme. Indications
thereof do not indeed at present appear to have been clearly disclosed
by experiment. But the experimental development of the subject is still
in its infancy. We shall probably have to await the further results
which must be the outcome of patient and well-directed child-study.
The human child does pass in the course of his individual development
from intelligent to rational procedure. Here there is a bridge which
is crossed by every child. When we know more about the stadia of this
development we shall be in a position to apply the results obtained in
child-study in the analogous field of animal-study. Till then we must
possess our souls in patience, and base our provisional conclusions on
the results of systematic investigation, rather than on those of casual
observation and anecdote.

IV.--THE EVOLUTION OF INTELLIGENT BEHAVIOUR

No attempt can be made in this section to trace the successive stages
of the evolutionary progress of intelligence from its lower to its
higher developments. It is indeed questionable whether comparative
psychology has, as yet, accumulated a sufficient body of data to render
such a task profitable or even possible. And the lower the level of
intelligence with which we have to deal, the less reliable are the
scanty psychological data which we can obtain. To interpret the mental
processes which accompany the acts of even the higher animals is a
hard task, requiring careful psychological analysis. Still harder is
the task to infer the psychological basis of the actions of the lower
animals.

It is difficult to say where, in the hierarchy of animal progress, the
beginnings of intelligence can first be traced. In the articulated
animals, such as the insects, spiders, and crustacea, there is abundant
evidence of intelligence of a relatively high grade. But even in their
case, how hard it is to realize the nature of their experience--to
get any adequate notion of their mental processes! We are inevitably
forced to describe their psychology in the most general terms. So, too,
with forms still lower in the scale of intelligence. Many molluscs
unquestionably profit by experience. But can we clearly picture to
ourselves the nature and manner of acquisition of this experience? The
way in which limpets return to the scars on the rock which form their
homes seems to show that they have acquired a practically adequate
experience of their near surroundings. Romanes cites[65] some of the
earlier observations which have been extended by Professor Ainsworth
Davis.[66] I looked into the matter myself some years ago, at Mewps Bay
near Lulworth in Dorsetshire. The method adopted[67] was to remove the
limpets from the rock, and affix them at various distances from their
scars. This can be done without difficulty or injury to the mollusc if
one catches them as they are moving. But one must make sure that they
are just leaving or returning to their proper homes, and are not taken
in the midst of a more extended peregrination, as in that case their
special scars cannot be noted. Failure to be careful in this matter
vitiated my earlier observations, which are therefore excluded in the
following table:--

---------+------------+------------------------------------+
Number | Distance | Number returned. |
removed. | in inches. +-------------+-------------+--------+
| | In 2 tides. | In 4 tides. | Later. |
---------+------------+-------------+-------------+--------+
25 | 6 | 21 | -- | -- |
21 | 12 | 13 | 5 | -- |
21 | 18 | 10 | 6 | 2 |
36 | 24 | 1 | 1 | 3 |
---------+------------+-------------+-------------+--------+

From the nature of the rock surfaces the removal of a limpet to a
distance of two feet almost invariably involved placing them on the
further side of an angle. And though some returned over such an angle,
the majority did not.

In most cases the individuals which failed to return to their
respective scars took up new positions; and in several instances, when
they were subsequently removed to a distance of a few inches from this
new position, they returned to it. Their return to the scar was watched
in many cases, and the course was fairly, but not quite direct. One
limpet covered a distance of ten inches, over a somewhat curved course,
in a little under twenty minutes. In another case the limpet on its
return journey had to pass between two others, which necessitated the
lifting of the shell to some height so as to clear one of them. On
reaching the scar they twist and turn about so as to fit down in the
normal position which is constant. When they come up the wrong way
round they rotate pretty rapidly through the 180 degrees to get into
position. One was observed to make a short excursion from and return to
its scar under stillish water. But as a rule they seem to remain fixed
when they are submerged, moving for the most part when the tide has
just receded.

The greatest distance I have watched a limpet reach from its home was
twenty-two inches. But I have found them at a distance of three feet
from their scars--that is to say, from those to which they fitted
perfectly. This was on a large flat surface.

When they move, the tentacles are projected out beyond the shell, and
keep on touching and slightly adhering to the rock. On reaching the
scar they carefully feel round it with the tentacles. By excision
of these feelers Professor Davis was led to conclude that it is not
through their instrumentality that the limpet finds its way back to its
particular scar. But I am inclined to question these results. At any
rate, further observations and experiments are needed to settle the
point.

Snails will also return to special dark hollows or crannies in the
wall after their foraging excursions. Such behaviour in molluscs
affords evidence of something more than instinct. In popular speech,
we should say that there is memory of the locality. And in any case
it is difficult to interpret the facts without the assumption that
the animals are conscious, and that re-presentative states are
evoked through the mediation of presentative sense-impressions. But
how difficult, if not impossible, it is to form anything like a
satisfactory conception of the rudimentary mental processes of a limpet!

The most highly developed molluscs are the cephalopods. They have
long sensitive mobile arms with which they feel for and capture their
prey. “Now Schneider observed,” writes Dr. Stout,[68] “a very young
octopus seize a hermit-crab. The hermit-crab covers the shell in which
it takes up its abode with stinging zoophytes. Stung by these, the
octopus immediately recoiled and let its prey escape. Subsequently it
was observed to avoid hermit-crabs. Older animals of the same species
managed cleverly to pull the crab out of its house without being
stung.” Such cases afford evidence of profiting by experience through
the exercise of intelligence.

Darwin’s careful observations on the manner in which earthworms
drag leaves into their burrows seem to show that these annelids act
intelligently, and deal with leaves of different shapes in different
ways. The leaves of Pine trees, consisting of two needles arising
from a common base, were almost invariably drawn down by seizing this
basal point of junction; while the leaves of the Lime were, in 79
per cent. of the cases examined, drawn down by the apex; in only 4
per cent. by the base; and in the remaining 17 per cent. by seizing
some intermediate portion. On the other hand, the leaves of the
Rhododendron, in which the basal part of the blade is often narrower
than the apical part, were in 66 per cent. of the observations drawn
down by the narrower base. Triangles of paper were in the majority of
cases seized by the apex. Commenting upon his observations, carried
out with great care under experimental conditions, Darwin says,[69]
“As worms are not guided by special instincts in each particular case,
though possessing a general instinct to plug up their burrows, and as
chance is excluded, the next most probable conclusion seems to be that
they try in different ways to draw in objects, and at last succeed
in some one way;” that is to say, they profit by experience based on
the method of trial and failure. But Darwin adds that the evidence he
obtained shows “that worms do not habitually try to draw objects into
their burrows in many different ways.” And he seems to attribute to
them an almost rational power of dealing with the circumstances in the
light of general conceptions. “If worms,” he says, “are able to judge,
either before drawing or after having drawn an object close to the
mouths of their burrows, how best to drag it in, they must acquire some
notion of its general shape. This they probably acquire by touching it
in many places with the anterior extremity of their bodies, which acts
as a tactual organ. It may be well to remember how perfect the sense of
touch becomes in a man when born blind and deaf, as are worms. If worms
have the power of acquiring some notion, however rude, of the shape of
an object and of their burrows, as seems to be the case, they deserve
to be called intelligent; for they then act in nearly the same manner
as would a man under similar circumstances.”

Such power of perceiving the relation of the shape of a leaf or other
object to the form of the burrow is presumably beyond the reach of
an earthworm. It may be regarded as more probable that the earthworm
inherits an instinctive tendency to draw down objects in special
ways, and that this is subject to some modification under the play
of experience, without the formation of anything so psychologically
complex as a general notion, however rude. In any case the behaviour
of earthworms in closing their burrows seems to afford indications
of something more than instinct--of that profiting by the results of
experience which characterizes intelligent procedure. More than this we
cannot say.

Professor Whitman[70] has made some interesting observations on
the leech _Clepsine_. “Place the animal,” he says, “in a shallow,
flat-bottomed dish, and leave it for a few hours or a day, in order
to give it time to get accustomed to the place, and come to rest
on the bottom. Then, taking the utmost care not to jar the dish or
breathe upon the surface of the water, look at the _Clepsine_ through
a low magnifying lens, and see what happens when the surface of the
water is touched with the point of a needle held vertically above the
animal’s back. If the experiment is properly carried out, it will be
seen that the respiratory undulations (if such movements happen to be
going on) suddenly cease, and that the animal slightly expands its body
and hugs the glass. Wait a few moments until the animal, recovering
its normal composure, again resumes its respiratory movements. Then
let the needle descend through the water until the point rests on the
bottom of the dish at a little distance from the edge of the body.
Again the movements will cease, and the animal will hug the glass with
its body somewhat expanded. Now push the needle slowly along towards
the leech, and notice as the needle comes almost in contact with the
thin margin of the body, that the part nearest the needle begins to
retreat slowly before it. This behaviour shows a surprising keenness of
tactile sensibility, the least touch of the water with a needle-point
being felt at once.... If its back were rubbed with a brush or the
handle of a dissecting needle, in order to test its sensitiveness to
touch, the appearance would probably be that of insensibility and
indifference to the treatment. Closer examination, however, would
show that the flesh of the animal was more rigid than usual, and that
the surface was covered with numerous stiff, conical elevations, the
dermal papillæ or warts, which are so low and blunt in the normal
state of rest as to be scarcely visible. It would be seen that the
animal, although motionless, was in a state of active resistance to
attack.... _Clepsine_ has another and entirely different method of
keeping quiet. The animal rolls itself up (head first and ventral side
innermost) into a hard ball, outwardly passive, free to roll or fall
whithersoever gravity or currents of water may direct it.... If by
chance the animal has eggs, it will not desert them to escape in this
way.... This species, then, has two quite distinct and peculiar ways
of keeping quiet, and thus avoiding its enemies. If the animal has no
eggs, or if it has young, it may adopt either mode of escape, while
if it has eggs it has no choice but to remain quiet over them.... The
act of rolling up into a passive ball may be performed (_a_) _under
compulsion_, as when it is her last resort in self-defence; (_b_)
_under a milder provocation_, as _one_ of three courses of behaviour,
as when the resting-place is turned up to light, and the choice is
offered between remaining quiet in place, creeping away at leisure,
or rolling into a ball and dropping to the bottom; (_c_) or finally,
_under no special external stimulus_, but rather _from internal_
motive, the normal demand for rest and shady seclusion, presumably very
strong in _Clepsine_ after gorging itself with the blood of its turtle
host.”

Professor Whitman rightly regards the act of rolling into a ball as
instinctive, and due to natural selection. But he does not undertake
to discuss the question as to how much intelligence, if any,
_Clepsine_ may have. Nor, indeed, is it an easy matter to determine.
The differential reaction according as the animal has eggs or not
suggests intelligence; but it may be instinct varying according to
the conditions of stimulation external and internal. The different
behaviour which may be seen in different cases when a stone is turned
to the light again suggests intelligence, but again may be determined
directly by the conditions of stimulation. Prompted by Dr. Whitman’s
observations, I endeavoured to determine whether a leech would grow
accustomed to frequent gentle stimulation with a camel’s-hair brush,
and cease to react under circumstances which were followed by no ill
effects. But though I incline to think that this is the case, the
observations were not such as to be satisfying and convincing. If
intelligence be present we seem to find it in an early and rudimentary
state.

Observation, we must confess, seems to afford little indication of the
conditions under which intelligence first makes its appearance in the
animal kingdom. And if we turn to general considerations, which at the
best afford uncertain guidance, little light is thrown on the subject.
If we accept the view already indicated,[71] that the nerve-centres
which are concerned in the conscious control begotten of experience
are independent of those primarily concerned in normal reflex action,
we may perhaps believe that the simplest nervous system, worthy of
the name, contains both these elements, and that in the course of the
evolution of nervous systems in higher and higher grades, there go on
_pari passu_ the further differentiation of these elements, and the
progressive integration of reflex and control centres into a closely
connected and effective whole. Not that any expression of the facts, if
such they be, in terms of an evolution formula, adds anything to our
knowledge of the organic _modus operandi_. We know but little of the
intimate nerve physiology of even the highest invertebrates. We see
ample evidence of the control of behaviour in the light of individual
experience. Of any detailed knowledge concerning the manner in which
this control is effected we do not seem to possess more than the rude
initial phases.

When we compare, however, the several grades of intelligence which
observation suggests, and when we watch the conscious development of
the more intelligent animals, we seem to find evidence of the growth
of a system of experience, at first in very close touch with inherited
modes of procedure, but gradually acquiring more of independence and
freedom. Increase of the range and complexity of behaviour brings
with it, not only increase in the range and complexity of experience,
but also--what is, perhaps, even more essential to effective
progress--greater unity and closer connection into a well-knit whole.
And with this greater unity and closer connection there goes what one
may term a condensation of experience by an elimination of detail and
the survival of essential features repeatedly emphasized. This is
analogous in the development of intelligence to the generalization
and abstraction which play so important a part in the development of
reason. It affords, in fact, the data which reflection utilizes in the
purposive and intentional condensation and concentration of knowledge
at a higher stage of mental development.

The omission of detail and the survival of the salient features is well
known to us in the familiar facts of memory. We have seen thousands
of sheep and oxen, no two of which are probably alike in all their
external details as presented to vision. But we remember what a sheep
or an ox looks like, and many of us can form a visualized image of
either of these animals. This, however, is not the re-presentative
image of any particular sheep or ox. It is what psychologists term a
generic image. It is like a composite photograph made by superimposing
on the same plate a number of individual images so that the salient
features which all possess in common stand out clearly by their
coincidence on the plate, while the distinctive details are but
dimly presented. Thus does memory preserve the essentials common
to many impressions while the distinguishing details are lost and
fade, eliminated by forgetfulness. And thus in the experience which
intelligence practically utilizes are the net results of a thousand
particular impressions condensed in one effective image.

Condensation of experience is also effected by the elimination, under
the guidance of consciousness, of those modes of behaviour which are
not efficacious--a process to which Professor Mark Baldwin applies
the phrase Functional Selection. There is a tendency at first to the
overproduction of relatively useless actions. The multifarious random
movements of the human infant, though their inexactness renders the
child terribly helpless, afford a wide store of plastic material which
intelligence can guide to its appropriate use. And the prolonged period
of pupilage in the child is correlated with an unsurpassed range of
combination and recombination of the abundant plastic material. The
hereditary legacy, though it contains fewer drafts for definite and
specific purposes than are placed to the credit of an animal rich in
instinctive endowment, affords a far larger general fund on which
intelligence may draw for the varied purposes of the freer financial
existence of a rational being.

The relatively helpless young of many of the higher mammalia exhibit
also much overproduction of seemingly aimless movements. But from
these intelligence selects those which are of value for the purposes
of life--those which experience proves to be effective. These--the
relatively few--afford the motor impressions which by repetition stand
out in experience, while the rest lapse from memory and are eliminated
from experience as they are eliminated from practical performance. This
is a great gain. Motor experience is rendered generic; the composite
image that is retained is the net result of effective behaviour; and
all that is valuable in the acquisitions of early life is condensed
within manageable limits.

This process of rendering generic the particular items of a widening
experience has a marked effect in the development of the conscious
situations in the light of which behaviour is intelligently guided.
It is not the master holding this whip or that ball which suggests
to the dog a hiding or a scamper; it is a generic situation with
interchangeable details. It is not this, that, or the other previously
unseen cat that at once determines the situation for the fox terrier;
the particular animal has never entered into his past experience: it is
the fulfilment of the essential conditions of the generic image that
is operative in behaviour. The experience of animals must inevitably
become in large degree generic by the elimination of the unessential
and survival in re-presentative consciousness of the salient elements
in many slightly diverse situations.

Stated in terms of this conception, the familiar phenomena of mimicry
are due to the fact that the mimicking form accords sufficiently well
with the generic image to carry the same suggested meaning. As is
well known, the model has been proved in many cases to be unpalatable
or hurtful, while the mimic is in itself neither the one nor the
other. The drone-fly, _Eristalis_, mimics the drone. And it has been
urged that this cannot be a true case of mimicry, since the drone
is harmless, though the female and “neuter” bees are possessed of
stings. But I have satisfied myself by experiments with young birds,
that (1) after experience with bees drones are avoided, and (2) that
after similar experience drone-flies are also left untouched. Hence it
seems that all three fall within the same generic image, the points of
resemblance outweighing the differences in detail--as they do, indeed,
with many men and women.

Such examples of mimicry belong to what is known as the “Batesian
type”--so called after H. W. Bates, who, in 1861, discussed its
occurrence among Amazonian insects in the light of the theory of
natural selection. There are, however, certain groups of insects
which, although themselves “protected,” possess common warning
colours, causing them to resemble each other. These are sometimes
classed under the head of “Müllerian mimicry”--so called after Fritz
Müller, who, in 1879, first offered an explanation of the facts
based on the theory of natural selection. He suggested that such
mutual resemblance is advantageous to both protected forms, since it
lessens the number of those which are killed by young birds and other
animals while they are learning by experience what to eat and what
to leave. For, as the result of careful observation, Mr. Frank Finn
concludes “that each bird has to separately acquire its experience,
and well remembers what it has learnt,”--a conclusion with which, as
already stated, my own observations are entirely in accord. There is
therefore a certain amount of destruction of even well-protected forms
by young and inexperienced birds. If, then, two such forms resemble
each other, the acquisition of experience is thereby facilitated and
the amount of destruction reduced, on the assumption that the two
fall within the same generic image. Upholders of natural selection
are not, indeed, at one in accepting this explanation, and further
observation is unquestionably needed. It is not improbable, however,
that common protective coloration, such as the banding of yellow and
black, seen in such different forms as the caterpillar of the cinnabar
moth and the imago of the wasp, is of mutual utility. The following
experiment was made with young chicks. Strips of orange and black paper
were pasted beneath glass slips, and on them meal moistened with
quinine was placed. On other plain slips meal moistened with water
was provided. The young birds soon learnt to avoid the bitter meal,
and then would not touch plain meal if it were offered on the banded
slip. And these birds, save in two instances, refused to touch cinnabar
caterpillars, which were new to their experience. They did not, like
other birds, have to learn by particular trials that these caterpillars
are unpleasant. Their experience had already been gained through the
banded glass slips; or so it seemed. I have also found that young birds
who had learnt to avoid cinnabar caterpillars left wasps untouched.
Such observations must be repeated and extended. But they seem to show
that one aspect of the Müllerian theory is not without some facts in
support of it; and, so far as they go, they afford evidence that black
and orange banding, irrespective of particular form, may constitute a
guiding generic feature in the conscious situation.

It may be said that the generic condensation of experience here
indicated implies the formation of general and abstract ideas, and
that we cannot in face of the evidence accept Locke’s dictum that
abstraction is “an excellency which the faculties of brutes do by no
means attain to.” Romanes contended[72] that “all the higher animals
have general ideas of ‘good-for-eating’ and ‘not-good-for-eating’ quite
apart from any particular objects of which either of these qualities
happens to be characteristic,” and he quoted with approval Leroy’s
statement,[73] that a fox “will see snares when there are none; his
imagination, distorted by fear, will produce deceptive shapes, to
which he will attach an abstract notion of danger.” According to such
views animals form concepts; and concepts belong to the sphere of
rational thought. It is not my intention to enter at length into the
refinements of psychological distinction. Many psychologists, however,
seek to distinguish between, on the one hand, the predominance by
natural emphasis, of certain qualities, such as that of being suitable
for food, and, on the other hand, the intentional isolation of these
qualities for the purposes of thought and rational explanation.
Abstraction they regard as a deliberate process applied with rational
intent to the material afforded by experience and reflection.
Generalization, too, they regard as deliberate, and carried out with
like intent. The result is not merely a composite or generic product,
but something more subtle and less dependent on sense. “All trees
hitherto seen by me,” said Noiré, “leave in my imagination a mixed
image, a kind of ideal presentation of a tree. Quite different is my
concept, which is never an image.” The concept “tree” is a deliberate
synthesis of abstract qualities intentionally isolated, and recombined
in accordance with the general relationships which subsist between them.

If we accept this distinction, if we regard abstraction and
generalization as intentional mental processes carried out with the
rational intent of discovering the relationships of phenomena with the
object of explaining them and recombining their essential features in
an ideal scheme of thought, we shall probably admit, with John Locke,
that these are excellencies which the faculties of brutes do by no
means attain to. But we shall none the less see that the predominance
of certain salient features in experience by reiterated emphasis in
association with natural needs, and the development of generic in place
of merely particular re-presentations will afford the appropriate
material for abstraction on the one hand, and generalization on the
other. Intelligence supplies the embryonic mental structures from
which, under the quickening influence of a rational purpose, abstract
and general ideas may be evolved.

The essential features of the evolution of intelligence seem, then,
to be, first, the development of controlling nerve-centres, by which
the responsive action of reflex automatic or instinctive centres
may be checked, augmented, or modified; secondly, the increased
differentiation and integration of these control centres with extension
of the range and complexity of experience in close touch with practical
needs; thirdly, the condensation and concentration of experience by
the formation of generic products through the reiterated emphasis
begotten of recurrent situations having certain salient features
in common, though differing in details; and fourthly, an increased
plasticity of behaviour, especially in early life, enabling an animal
to deal effectually with an environment far less simple than that
to which the more stereotyped instinctive behaviour is fitted by
inheritance to respond. And this evolution of intelligent behaviour is
working its way up to, though as such it cannot reach, the succeeding
phase of mental evolution in which the data, supplied by intelligence,
are treated with a new purpose for higher ends in the rational thought
which seeks to explain the phenomena, and frame an ideal scheme of
their relations and interconnections.

Two further points may be noticed. First, that it is during the early
and plastic days or months of life that intelligence is setting
its seal on animal behaviour, and stamping it with its distinctive
character. Adult life is very much what youth has made it; and old
age is stereotyped through habit. In times of progress, the character
of the race is determined by plastic possibilities of the young.
Among them it is that the incidence of elimination makes itself felt,
resulting in the survival of those whose intelligence can mould
behaviour in accordance with the new circumstances of a wider life.

Secondly, this selection of the intelligent involves the survival
of those in whose higher brain-centres there is room for a greater
range and variety of interconnection by means of associating fibres.
It involves a selective survival of the larger and more finely
organized brains. It is probable, as Professor Ray Lankester has
recently indicated, that the ridiculously small-brained mammals and
reptiles of the past were creatures of instinct with little capacity
for intelligent control. Their lives were simple, and their enemies
and competitors no better provided with higher brain-centres than
themselves. Stereotyped instinctive behaviour sufficed to enable them
to hold their own, and meet the requirements of a life of dull and
unprogressive monotony. Strength without cunning made these big-framed
animals for a while masters of the situation. But among those existing
animals whose skeletons indicate an analogous zoological position,
there is none which exhibits a cerebral development so poor. And we
may fairly conclude that the fact that these huge creatures have left
no lineal descendants may be taken as evidence of the importance and
value, in evolution, of that cerebral tissue which is the organic basis
of intelligence. The higher brain contains the potentiality of that
experience without which the evolution of intelligent behaviour in any
race of vertebrate animals is impossible.

V.--THE INFLUENCE OF INTELLIGENCE ON INSTINCT

We have seen that the relation of instinct to intelligence is
essentially that of congenital to acquired behaviour. We have seen,
too, that in the Lamarckian interpretation what is acquired in the
course of life may be transmitted through inheritance, and thus the
intelligent behaviour of one generation may become instinctive and
congenital in the next. But serious biological difficulties stand in
the way of the acceptance of this interpretation; there is, moreover,
little or no evidence of the assumed transmission to offspring of any
acquired modifications of structure or behaviour. We have, therefore,
been led to infer that instinctive behaviour has been evolved through
the selection of adaptive variations of germinal origin, the influence
of intelligence being restricted to the fosterage of co-incident
variations, that is to say, of those congenital variations which
coincide in direction with the acquired modifications of behaviour due
to intelligence. It is clear that on this interpretation the influence
of intelligence on instinct is more indirect and less simple than that
implied by the Lamarckian hypothesis. Intelligence and instinct are
in large degree independent, though there is continual interaction
between them. We have now to consider the nature of this interaction,
and to this end we must indicate the relation of acquired modifications
to the hereditary groundwork of the animal constitution.

The basal fact is, that the bodily tissues are subject to a certain
amount of structural change during the course of individual life in
accordance with the amount of functional strain put upon them. The
labourer’s thickened skin, the enlarged and strengthened muscles of
the athlete, the juggler’s acquired suppleness are familiar cases.
Less familiar instances are afforded under abnormal conditions.
Should one kidney from any cause be slowly destroyed, the other will
slowly enlarge to carry on the increased work of elimination of waste
products; when the larger shin bone of a dog has been removed after
injury, the smaller bone becomes thickened to bear the added strain;
new joint surfaces are sometimes formed where bones have been broken
and the natural joints injured.

One may say that the normal development of any structure depends upon
a due amount of use. But, since in the course of strenuous life any
organ is from time to time subject to an abnormal amount of strain, it
must be fitted to respond to a super-normal call on its strength and
functional activity. Were the heart and the lungs, for example, unable
to meet the greatly added drain on their energies, due to unwonted
and severe exertion, collapse, perhaps death, would ensue if such
exertion were imperatively demanded under special circumstances. And
it is clear that many wild animals must be not infrequently placed in
such circumstances as will subject their muscular structures and the
functional activity of their organs of circulation and respiration to a
strain nearly up to their extreme limits of endurance. The carnivorous
hunter would often fail to secure his prey if his organization were
unequal to a hard and prolonged chase; the hunted prey would not
survive to procreate his kind if he fell a victim to the first pursuer
through inability to stand the exertion necessary to enable him to
make good his escape. It is thus, we may believe, through natural
selection that a sufficiently high standard of strength and functional
endurance is maintained. The failures in these respects are steadily
eliminated. It is difficult to realize the great strain put upon a
bird’s organization by the migration flight. Some ten times as many
birds leave our shores in the autumn as return to them in the following
spring. What proportion of these is weeded out in the act of migration
we do not know; but we may be sure that only those fitted to stand a
severe test of physical endurance return to rear broods which shall
inherit in large degree similar vigour of constitution.

Two factors, then, determine the limits of efficiency in the bodily
organs--heredity and use. And these two co-operate in such a way
that we may say, either that due use is the essential condition of
the effective development of the hereditary powers, or that heredity
serves to condition their effective development through use. But though
closely related, so that each may be regarded as conditional on the
other, they are, if we accept the view that acquired characters are not
transmitted as such, so far independent in that use adds nothing to,
disuse subtracts nothing from, the hereditary store. It is, indeed,
difficult to conceive how, on any view, the absence of the conditioning
factor of normal use can be the efficient cause of a positive
diminution of the balance at the bank of heredity. And Lamarckian
thinkers have not succeeded in placing their conception of the matter
in the clear light of a working hypothesis.

The amount of what we may term “modifiability” by use differs a good
deal in the several organs and tissues. The teeth of carnivora and the
antlers of deer may be cited as structures in which the conditioning
effects of use form a relatively unimportant factor. On the other
hand, the nervous system, with which we are here primarily concerned,
is of all animal structures that in which what is acquired may attain
the greatest importance in the successful conduct of life; the nature
and the range of behaviour affording an index of the amount of
modifiability in this respect.

We have already seen that instinctive behaviour is primarily a matter
of the first occasion on which any given action is performed, and that
many instinctive acts are subject to subsequent modification in the
light of the experience gained during the early performances. The range
of such modification varies both in different animals and also with
respect to different modes of behaviour in the same animal. The more
fixed and deeply rooted an instinct the less readily does intelligence
obtain a hold on it, so as to direct the behaviour into new channels
of better accommodation to the circumstances. M. Fabre describes how
a _Sphex_, one of the solitary wasps, instinctively draws its prey, a
grasshopper, into the burrow by its antennæ. When these were cut off
the wasp pulled the grasshopper in by the jaw appendages; but when
these were removed she seemed incapable of further accommodation to the
unusual circumstances. It would seem an easy and obvious application
of intelligence to seize the prey by one of the forelegs. But this
was not done; and the grasshopper was then left. Intelligence did
not seem equal to meeting the altered conditions presented by the
maimed grasshopper. Still, there was some modification of the normal
instinctive behaviour; and, as Dr. Peckham has shown, there may be more
than Fabre noted. Let us assume the existence of an animal whose every
act is instinctive, whose whole behaviour is marked out in strictly
hereditary lines, no new departures being acquired in the course of
individual life. This extreme case would afford an example of what we
may term completely stereotyped behaviour. On the other hand, let us
assume the existence of an animal with no hereditary definiteness of
reaction, whose every act is intelligent, whose whole behaviour is the
result of individual acquisition. This antithetical extreme case would
afford an example of what we may term completely plastic behaviour.
It is questionable, however, whether either of these extreme types
occur in nature. What we find in our study of animal behaviour is
some intermediate condition in which both factors co-operate, with a
predominance either of stereotyped instinctive response on the one
hand, or of plastic intelligent acquisition on the other hand. And in
the latter case, as such behaviour approaches its ideal limits, we have
modifiability under the circumstances of individual life at its maximum.

The evolution of intelligence as such runs parallel with the evolution
of plastic behaviour; and this plasticity is necessitated by the
variety and the complexity of the conditions of life--a variety and a
complexity requiring many subtle modifications of response to enable
the behaviour to reach accommodation to the changeful exigencies of
diverse circumstances. To meet constant and relatively fixed conditions
stereotyped instinctive responses suffice; and the elimination under
natural selection of those individuals which fail to respond in fixed
ways by specially adaptive behaviour tends to render definite the
hereditary channels of nervous intercommunication. An inherited system
of no little complexity may thus be evolved; of which we have seen
examples in our study of instinctive behaviour. But the essential
condition of the successful working of such a system is constancy
in the environment to which the instinctive behaviour is adapted.
Completely stereotyped behaviour, in its theoretical perfection, is
in exact adaptation to the circumstances. Where instincts are only
relatively perfect, further adaptation is secured through congenital
variation and the survival of the individuals in which the behaviour
is better adapted to the comparatively invariable circumstances.
This is one line of evolution. But the evolution of intelligence is
along independent lines of progress. Both, however, result from the
functional activity of the same nervous system, they jointly determine
the behaviour, they interact not only in the course of individual life
but in the process of evolution, and they are both subject to the
incidence of natural selection, which can determine whether the one
line or the other shall preponderate--whether instinct or intelligence
shall dominate behaviour.

If an answer must be given to the question whether instinct or
intelligence has priority in the course of the evolution of behaviour,
it may be urged that, on theoretical grounds, the claims of instinct
are the stronger. Taking animals as we actually find them, however,
they afford numberless examples of behaviour at first instinctive but
subsequently modified, in greater or less degree, in accordance with
the teachings of experience. Let us, first, assume that the environment
is slowly changing, or has changed, in some definite manner. Such
change would, of course, be relative, and might be due, either to new
conditions brought to bear on the animal, or to the animal being itself
brought, in the expansion of its life, within their influence. The
old instinct is no longer quite adapted to the changed circumstances.
If the change were sufficient in amount, and occurred somewhat
suddenly, variations of instinct might not occur soon enough to enable
the animal to reach adaptation by the gradual process of natural
selection. If dependent on instinct alone the animal would, under
these circumstances, be eliminated. But if intelligence were able to
modify the behaviour to meet the new conditions this elimination would
be prevented. In successive generations intelligence would constantly
modify behaviour in the same manner and in a definite direction.
Meanwhile congenital variations in different directions would occur.
Those which were in directions antagonistic to that dictated by
intelligence would tend to thwart accommodation and render it less
effectual; but those which were coincident in direction would conspire
with accommodation and render it more effectual. The individuals in
which variations of instinct tended to thwart intelligence would be
eliminated; while those in which coincident variations assisted and
aided intelligent modification would survive. Thus intelligence would
lead the way along lines which congenital variations would follow. And
in the course of a number of generations the new instinct would reach
the fully adaptive level, and further modification by intelligence
would become unnecessary unless the environment continued to change yet
more. Individual accommodation of behaviour would in this way determine
the direction of instinctive variation; and yet throughout the process
there would be, strictly speaking, no transmission of the intelligently
acquired characters of the behaviour.

But though under constant and uniform changes in the environment the
net result would be only a guided variation of the original instinct,
under more variable and indefinitely changing circumstances the
result would be different. The higher animals exhibit an intelligent
plasticity which enables them to meet the requirements of the
more complex environment into which their wider life has risen;
for evolution lifts the animal from narrower into progressively
wider spheres of activity and behaviour, so that its environment
becomes relatively more complex. Here stereotyped behaviour would be
rather a hindrance than an advantage. The winning animal in life’s
struggle would be the one in which behaviour was most rapidly and
most surely modified to meet particular needs--the one in which the
teachings of experience were most promptly utilized in effective
action. The inevitable tendency of the evolution of intelligence
must be disintegration of the stereotyped modes of behaviour and the
dissolution of instinct. Natural selection, which under a uniform and
constant environment leads to the survival of relatively fixed and
definite modes of response, under an environment presenting a wide
range of possibilities leads to the survival of plastic accommodation
through intelligence. It is not that intelligence has any direct
influence tending to undermine the hereditary foundations of instinct,
for acquired plasticity is not inherited as such; it is rather that
when the stereotyped and the plastic are pitted against each other in
the struggle for existence in the wider, freer, and more varied life of
the higher animals the plastic survives and the stereotyped succumbs.

Imperfect as is our present knowledge of the manner in which the
nervous connections implied in psychological associations are
established, there can be no question that they are acquired in the
course of individual life; they are modifications of nervous structure
due to a special mode of use under the conditions of experience.
Here, then, in the case of the nervous system, as in that of the
bodily organs before mentioned, two co-operating factors determine
the limits of efficiency--heredity and use. Just as the heart and
lungs must inherit the power of standing abnormal strain if the animal
is to avoid elimination in times of unwonted exertion, so must the
nervous system inherit some reserve power of dealing effectively with
unwonted circumstances by intelligent accommodation, if the animal
is not to fall a victim to such circumstances. In other words, at
times of heightened competition those animals which can draw on a
reserve fund of intelligent accommodation will survive, while the
stupid blunderers will be eliminated. We may term this reserve fund of
intelligent accommodation, this inherited ability to meet specially
difficult circumstances as they arise, _innate capacity_. From the
nature of the case it must be indefinite, for it must carry with it the
ability to meet unforeseen combinations of the environing forces by new
combinations of the results of experience. Its distinguishing mark is
plasticity, in contradistinction to the stereotyped fixity of typical
instinct. And accompanying its evolution there is probably, as we have
seen, a dissolution of its antithesis, instinct. Thus may we account
for the fact that man, with his great store of innate capacity, has so
small a number of stereotyped instincts.

But the dissolution of instincts is not complete. Residua are left
in the inherited mental constitution. And these we term _congenital
tendencies_ and _propensities_. They differ from the typical instincts
in the fact that the definiteness of response has been lost. They
dictate a general trend of action, but the particular application in
behaviour is due to intelligent accommodation. They are commonly spoken
of as instinctive; and their mode of origin justifies the use of the
adjective in association with the term “propensities.” But it must
be remembered that the behaviour to which they lead is not, as such,
wholly instinctive; it is a joint product of instinct and intelligence,
the general trend being due to the instinctive propensity, while the
mode of application is guided by intelligence.

There is, however, another way in which analogous propensities may
be ingrained in the mental constitution, not as residual vestiges of
old instincts, but as congenital rudiments fostered by new habits.
It is a well-known and familiar fact that the frequent repetition of
intelligent accommodation in certain definite lines begets habits,
which so far simulate instincts as to be commonly described in
popular speech as instinctive. Professor Wundt indeed places them
in the category of “acquired instincts”--a usage which we regard as
unsatisfactory, seeing that it tends to mask the distinction between
the congenital and acquired factors in behaviour, and seeing that
we have the well-defined term “habits” for acts rendered to a large
extent automatic through repetition. Lamarckian thinkers regard habit
as the mother of instinct, assuming that the acquired automatism
of one generation may be transmitted to become congenital in the
succeeding generation. This conclusion we provisionally reject,
regarding the basal assumption as at present unproven. But though
we cannot accept the view that habit is the mother of instinct, we
regard it as not improbable that habit may be the nurse of congenital
propensities. Remembering that similar habits are acquired by animals
of the same species throughout a series of succeeding generations, and
assuming that congenital variations are constantly occurring in many
directions, it seems probable that some of these variations will be
coincident in direction with the acquired habits. Thus would arise a
congenital propensity to perform the habitual acts; and should they
be of sufficient importance in the conduct of life to be subject
to the action of natural selection, those animals in which such
propensities were congenital would survive, whereas those in which
no such propensities existed would be eliminated. It is unnecessary,
however, to elaborate this conception further, since it is in line with
that already discussed in considering the influence of intelligence in
fostering a diversion of instinct under changing circumstances. Then we
were considering how habit may lead to a congenital change in an old
instinct; here we are dealing with the development of a new propensity.

Sufficient has now been said to illustrate some of the ways in which
instinct and intelligence interact in the evolution of behaviour. Such
interaction is further exemplified in the social life of animals, which
will be dealt with in the next chapter.

CHAPTER V

_SOCIAL BEHAVIOUR_

I.--IMITATION

The characteristic feature of social behaviour is that it is in large
degree determined by the behaviour of other members of the social
community. In all animals which mate there is a temporary or more
lasting influence on each other of the individuals which unite to
procreate their kind; and in those which foster their young there
is a social relation of parents and offspring. Some of these mutual
relationships will be discussed, in their emotional aspects, in the
next chapter. Here we will consider the more general factors which
serve to determine the course of social evolution.

Among these is commonly reckoned imitation. M. Tarde says, “La
société c’est l’imitation.” But this word, like so many others which
are employed alike in popular speech and in more or less technical
discussions, carries a somewhat wide range of meaning, and is by
some writers used in a broader, by others in a narrower sense. Thus
Professor Mark Baldwin[74] says, “that all organic adaptation in a
changing environment is a phenomenon of _biological_ or _organic
imitation_,” under which category will fall, therefore, the organic
behaviour of the protozoa and of plants. On the other hand, Professor
E. L. Thorndike, though he admits in the lower animals “certain
pseudo-imitative or semi-imitative phenomena,” has been led by
experiments, to be presently noticed, to the conclusion that animals
as high in the scale of life as cats and dogs cannot form new
associations under the influence of imitation. “It seems sure,” he
says,[75] “from these experiments, that the animals were unable to
form an association leading to an act from having seen another animal,
or animals, perform the act in a certain situation.” In face of such
apparently diverse usage it is necessary to show within what limits
and with what qualifications the word may profitably here be used to
indicate a factor in social evolution.

Professor Mark Baldwin’s use of the term “imitation” can only be
understood in its relation to an hypothesis of organic and mental
evolution, which he develops with no little skill and brilliancy.[76]
He regards the processes of life as issuing in a great twofold
adaptation, due to expansions and contractions,--the former
representing waxing, the latter waning vitality; and he holds that
all special adaptations are secured by the new hold upon beneficial
stimulations reached by the expansive out-reaching movements. “Among
the variations in organic forms,” he says, “it is easy to see that
some of them might react in such a way as to keep in contact with the
stimulus, to lay hold of it, and so keep on reacting to it again and
again--just as our rhythmic action in breathing keeps the organism in
vital contact with the oxygen of the air. These organisms will get all
the benefit or damage of the repetition or persistence of the stimulus,
or of their own reactions, again and again; and it is self-evident that
the beneficial stimulations are the ones which should be maintained
in this way, and that the organisms which did this would live. The
organisms which reacted in such a way as to retain the damaging
stimulations, on the other hand, by this same process, would aid nature
in killing themselves. If this be true, only those organisms would
survive which had the variation of retaining useful stimulations in
what I have called, in speaking of imitation elsewhere, a ‘circular
way’ of reacting.... So, when we come to consider phylogeny and
ontogeny together, we find that if by an organism we mean a thing of
contractility or irritability, whose round of movements is kept up by
some kind of nutritive process supplied by the environment--absorption,
chemical action of atmospheric oxygen, etc.--and whose existence is
threatened by dangers of contact and what not, the first thing to do
is to secure a regular supply to the nutritive processes, and to avoid
these contacts. But the organism can do nothing but move, as a whole
or in some of its parts. So, then, if one of such creatures is to be
fitter than another to survive, it must be the creature which, by its
movements, secures more nutritive processes and avoids more dangerous
contacts. But movements toward the source of stimulation keep hold
on the stimulation, and movements away from the contacts break the
contacts; that is all. Nature selects these organisms; how could she do
otherwise?”

“Thus a ‘circular’ activity is found in operation; life-processes
issuing in increased movements, by which in turn the stimulations to
the life-processes are kept in action.” But when a child imitates,
himself reproducing the “copy” set for imitation, the reaction at which
imitative suggestion aims is one which will _reproduce the stimulating
impression_, and so tend to perpetuate itself. The stimulus starts a
motor process, which tends to reproduce the stimulus, and, through it,
the motor process again. It is a “circular activity.” Thus “we are able
to reconstruct the theory of adaptation in such a way as to show that
this kind of organic selection by movement, and this kind of imitative
selection by consciousness, are the same thing. Organic imitation
and conscious imitation--each a circular process tending to maintain
certain stimulations and to avoid others--here is one thing;” and to
this one thing the common term “imitation” is applied by Mr. Baldwin.

This extended usage is admitted by the author to be somewhat of an
innovation. But if his hypothesis be sound this need be no bar to its
acceptance. Two salient questions must, however, receive satisfactory
answers. First, is all organic adaptation in a changing environment a
circular process--a phenomenon of organic imitation? Secondly, does
all conscious imitation tend to reproduce the imitating stimulus?

Professor Baldwin speaks of organic imitation and conscious imitation
as “each a circular process tending to maintain certain stimulations
and to avoid others.” Now, it may be granted that the tendency to
maintain or repeat certain stimulations may be regarded as a “circular
process.” But can the avoidance or non-repetition of others be so
regarded? A large proportion alike of the hereditary adaptations and
the acquired accommodations of behaviour are directed to this avoidance
or non-repetition of hurtful stimulations. The instinctive shrinking
of a chick from an aggressive animal is just as much adaptive as the
repeated cuddling beneath the warm wing of the mother. The avoidance of
nauseous cinnabar caterpillars is just as much an accommodation to the
constitution of the environment as the reiterated seizing of palatable
grubs. Even low down in the scale of animal life, Dr. Jennings’s
observations on Paramecia seem to show that the retention of favourable
stimulation is not due to its direct influence, but is the indirect
result of a reaction to the relatively unfavourable stimulation
which occurs when the Paramecium passes away from more satisfactory
surroundings. A favourable environment is secured through the avoidance
of the unfavourable. Unless, therefore, we exclude adaptive avoidance
from the category of adaptations, we cannot regard all organic
adaptation in a changing environment as a phenomenon of organic
imitation due to a circular process tending to the reinstatement of
stimulation.

Passing to the second question--Does all conscious imitation tend
to reproduce the initiating stimulus?--we cannot unreservedly give
an affirmative answer. It is true that when a child more or less
successfully reproduces a sound which falls upon its ear, a like
sound stimulus is afforded which may by a circular process incite to
renewed effort, and lead to yet more successful reproduction. But
when Professor Baldwin’s child, between nine and ten months old,
imitated certain movements of the lips, there was no reproduction of
the initiating visual stimulus. A chick seeing its companions run away
or crouch will follow suit; and this would commonly be termed an
imitative action; but there is here no reproduction of the initiating
stimulus. Very much of the behaviour which is usually ascribed to
imitation produces effects in consciousness quite different from that
of the original stimulation. It is only by selecting one’s examples
that one finds in them evidence in favour of Professor Baldwin’s
“circular process.”

Since, therefore, this circular mode of activity is neither a
characteristic of all conscious imitation, nor a distinguishing mark
of all adaptive organic action, the grounds on which Professor Baldwin
bases his extended usage of the term appear to be fallacious. And in
this usage we cannot follow him.

Turning now to Professor Thorndike’s very different contention--that
animals even so high as the cat and dog do not imitate in the sense
of forming an association leading to an act from having seen another
animal perform the act in a certain way--we may first describe some of
his ingenious experiments designed to submit the matter to the test of
observation under controlled conditions.[77]

Experiments were made with chicks in several ways. They were, for
example, placed in pens, from which, in each case, “there was only one
possible way of escape, to see if they would learn it more quickly
when another chick did the thing several times before their eyes. The
method was to give some chicks their first trial with an imitation
possibility, and their second without, while others were given their
first trial without and their second with. If the ratio of the average
time of the first trial to the average time of the second is smaller in
the first class than it is in the second class, we may find evidence of
this sort of influence by imitation. Though imitation may not be able
to make an animal do what he would otherwise not do, it may make him
do _quicker_ a thing he would have done sooner or later anyway. As a
fact, the ratio is _much longer_. This is due to the fact that a chick,
when in a pen with another chick, is not afflicted by the discomfort
of loneliness, and so does not try to get out. So the other chick,
who is continually being put in with him to teach him the way out,
really prolongs his stay in. This factor destroys the value of these
quantitative experiments, and I do not,” says Mr. Thorndike, “insist
upon them as evidence against imitation, though they certainly offer
none for it.”

Chicks, from sixteen to thirty days old, were also placed in boxes from
which escape was open to them by such acts as pecking at the door,
stepping on a platform, or pecking at a tack. The method of experiment
was to put a chick in, leave him from sixty to eighty seconds, then
put in another who knew the act, and on his performing it to let both
escape. No cases were counted unless the imitator apparently saw the
other do the thing. After about every ten such chances to learn the
act, the imitator was left in alone for ten minutes. Out of thirteen
cases tabulated only once was the act performed, in spite of the ample
chance for imitation. “I have no hesitation,” adds Mr. Thorndike, “in
declaring this one’s act in stepping on the platform the result of mere
accident, and am sure that any one who had watched the experiments
would agree.”

To test the influence, if any, of imitation in cats, the following
method was adopted. A box was arranged with two compartments separated
by a wire screen. “The larger of these had a front of wooden bars
with a door which fell open when a string stretched across the top
was bitten or clawed down. The smaller was closed by boards on three
sides and by the wire screen on the fourth. Through the screen a
cat within could see the one to be imitated pull the string, go out
through the door thus opened, and eat the fish outside. When put in
this compartment, the top being covered by a large box, a cat soon
gave up efforts to claw through the screen, quieted down, and watched
more or less the proceedings going on in the other compartment. Thus
this apparatus could be used to test the power of imitation. A cat who
had no experience with the means of escape from the large compartment
was put in the closed one; another cat, who would do it readily, was
allowed to go through the performance of pulling the string, going
out, and eating the fish. Record was made of the number of times he did
so, and of the number of times the imitator had his eyes clearly fixed
on him.... After the imitatee had done the thing a number of times, the
other was put in the big compartment alone, and the time it took him
before pulling the string was noted and his general behaviour closely
observed. If he failed in five or ten or fifteen minutes to do so, he
was released and not fed. This entire experiment was repeated a number
of times. From the times taken by the imitator to escape and from
observation of the way that he did it, we can decide whether imitation
played any part.... No one, I am sure, who had seen the behaviour of
the cats would have claimed that their conduct was at all influenced by
what they had seen. When they did hit the string the act looked just
like the accidental success of the ordinary association experiment.
But, besides these personal observations, we have in the impersonal
time-records sufficient proofs of the absence of imitation.” Some
observations on dogs are also described. From these it appears that
the three individuals on which experiments were made failed to learn
the way of getting out of a cage from seeing another dog escape. One
of them was also allowed to see another dog beg for meat 110 times.
But he never tried to imitate him and thus secure a piece of meat as a
reward. It therefore “seems sure,” says Mr. Thorndike, “that we should
give up imitation as an _a priori_ explanation of any novel intelligent
performance. To say that a dog who opens a gate, for instance, need
not have reasoned it out if he had seen another dog do the same thing,
is to offer instead of one false explanation another equally false.
Imitation in any form is too doubtful a factor to be presupposed
without evidence.”

Professor Thorndike is of opinion that monkeys are probably imitative
in ways beyond the capacity of dogs and cats; but, at the time
of writing, he had not substantiated his opinion, by analogous
experiments. If so, it will perhaps prove that they are rational
beings in the narrower sense defined in a previous chapter of this
work. For it appears that the kind of imitation which Mr. Thorndike’s
experiments go far to disprove, is what we may term reflective
imitation. A cat with no experience of the means of escape, one that
has tried to get out of the box by chance efforts in many directions
and has failed, sees another cat perform an act acquired in this way,
and learns nothing from the sight. This, no doubt, proves that the cat
had not in any sense grasped the nature of the problem before it, had
no notion of just where the difficulty lay, had not the wit to see that
the performance of the other cat supplied the missing links in its own
previous behaviour. It is questionable whether such missing links could
be supplied in this way in the absence of some powers of reflection.
The cat is unable to form an association, leading to an appropriate
act, from having seen another animal perform the act in a certain way,
partly because it cannot perceive the reason of its previous failure,
and see that the other’s performance affords the requisite clue. The
whole gist of the chance experience interpretation of animal behaviour
is that there must be chance experience to build on. The cat cannot
gain this by looking on never so intently, unless it be provided with
a rational as well as a sensory eye. The act of pulling the string has
been reached by the successful cat through the gradual elimination
of many failures; it is a differentiated act, having no place in the
previous experience of the kitten. It has never entered into the
conscious situation, and cannot be supplied at will by a non-rational
being.

As Mr. Thorndike himself says, “no cat can form an association leading
to an act unless there is included in the association an _impulse_
of its own which leads to the act.”[78] By “impulse,” Mr. Thorndike
“means the consciousness accompanying a muscular innervation apart
from that feeling of the act which comes from seeing one’s self move,
from feeling one’s body in a different position, etc. It is the direct
feeling of doing as distinguished from the idea of the act done gained
through eye, etc.... The act in this respect of being felt as to be
done or as doing is in animals the important thing, is the thing which
gets associated, while the act as done, as viewed from outside, is a
secondary affair.” I take it that by “impulse” is here meant what Dr.
Stout would term the direct experience involved in conation.[79] If it
have a place in experience distinguishable from that of stimulation
and response it is included in what I have on a former page spoken
of as the consciousness of behaviour as such, which was said to be
essential. And I am surprised that Mr. Thorndike should have supposed
that I believe that this could by any animal be “supplied at will.” In
any case it seems probable, as the result of observation, that unless
the consciousness of behaving in a specific manner has entered into the
situation as developed in experience it cannot in animals enter into
any subsequent representative complex. And it is the absence of such
consciousness of behaving in a specific manner which the sight of the
escaping cat fails to supply in Mr. Thorndike’s experiments.

Interesting and valuable as these experiments are, they are open
to the criticism to which, as we have seen, his other experiments
are also open--that the conditions are abnormal and cramped. Apart
from reflective imitation, which they tend to disprove, they do not
conduce to the kind of conscious situation which appears to be most
favourable for the development of intelligent imitation founded on
hereditary tendencies and propensities. It is through such imitation
that, as Herr Groos says,[80] “animals learn perfectly those things
for which they have imperfect hereditary dispositions.” The kind of
situation which conduces to such intelligent imitation is that which
involves the attitude of attention and interest rising, when these
are sufficiently varied in their direction, into what is spoken of as
curiosity. These, in their natural occurrence in animals, are parts
of, or in any case accompaniments of the conative attitude--they are
connected with activities and impulsive tendencies to behaviour. If
attention and interest are directed to the behaviour of another animal,
the conative attitude is that of imitation. Miss Romanes has described
how skilfully a capuchin imitated the actions necessary to unlock a
trunk. It does not seem necessary to assume that reflective imitation
is here exemplified. The monkey need not regard the key and lock as
the related parts of a puzzle to be practically solved, need not have
any free idea of the difficulty it presents, need not in unlocking the
trunk grasp the true nature of the difficulty or have any conception of
its solution. Every several act of the capuchin, the seizing the key,
the directing it here or there, and so on, is already supplied with
the impulse of which Dr. Thorndike speaks. Attention, itself charged
with impulse, directs and combines these pre-existing impulses to a new
end. And since that which directs the attention is the act of another,
we call the procedure imitative. But the varied and persistent effort
differs in no essential respect from that of a two days’ chick, which
pecks again and again at some speck which catches its eye, or that
of a nestling jay, which will peck for long at some nail or piece of
wire in its cage, twisting and turning its bill in many and varied
ways. And success in opening the trunk is reached by the capuchin,
not, it would seem, through any real appreciation of the essential
kernel of the practical problem, but through the chance results of
many varied efforts. Although in no other animals is it developed to
so high a degree as in the monkeys, interest in the doings of others
is an attitude by no means rare, and affords the basis of intelligent
imitation. Perhaps the conditions in Dr. Thorndike’s experiments were
not the best for the development of such interest in the procedure
of another. And in any case the imitation of a particular mode of
procedure, reached by the gradual defining of the impulse, could hardly
be expected in the absence of the series of experiences by which that
definition had been reached, unless the cat were capable of what has
been above spoken of as reflective imitation.

If, then, we agree to exclude from the category of imitative behaviour
in animals, on the one hand, any “circular process” which may occur in
the same individual, and on the other hand any reflective imitation,
such as is so important a factor in human education, it remains to be
seen what may be fairly included in this category.

It is probable that in animals imitation has its foundations
in instinctive behaviour, of which it may be regarded as the
characteristically social type. If one of a group of chicks learn by
casual experience to drink from a tin of water, others will run up and
peck at the water, and thus learn to drink. A hen teaches her little
ones to pick up grain or other food by pecking on the ground and
dropping suitable materials before them, while they seemingly imitate
her action in seizing the grain. One may make chicks and pheasants
peck by simulating the action of a hen with a pencil point or pair
of fine forceps. According to Mr. Peal, the Assamese find that young
jungle pheasants will perish if their pecking responses are not thus
stimulated; and Professor Claypole tells me that this is also the case
with young ostriches hatched in an incubator. A little pheasant and
guinea-fowl followed two older ducklings, one wild, the other tame, and
seemed to wait upon their bills, to peck when they pecked, and to be
guided by their actions. It is certainly much easier to bring up young
birds if older birds are setting an example of eating and drinking; and
instinctive acts, such as scratching the ground, are performed earlier
if imitation be not excluded. If a group of chicks have learnt to avoid
cinnabar caterpillars, and if then two or three from another group
are introduced and begin to pick up the caterpillars, the others will
sometimes again seize them, though they would otherwise have left them
untouched. One of my chicks, coming upon a dead bee, gave the danger
or alarm note; another at some little distance at once made the same
sound. A number of similar cases might be given; but what impresses
the observer as he watches the early development of a brood of young
birds, is the presence of an imitative tendency which is exemplified
in many little ways not easy to describe in detail. It is probable,
however, that these imitative tendencies or propensities are not wholly
indefinite. The young birds do not imitate any actions, but behaviour
of certain specific types, the imitation of which has been engrained
through the action of natural selection.

What generalization, then, can be drawn from this somewhat indefinite
group of facts, to which many others of like import could be added
from observations on the young of mammals? What is their relation
to instinctive procedure in general? It would seem that they are
characterized by a special relation of the external stimulus to the
response. When this stimulus is afforded by the behaviour of another
animal, and the responsive behaviour it initiates is similar to that
which affords the stimulus, such behaviour may be termed imitative. A
chick sounds the danger note; this is the stimulus under which another
chick sounds a similar note, and we say that the one imitates the
other. Such an action may be described as imitative in its effects,
but not imitative in its purpose. Only from the observer’s standpoint
does such instinctive behaviour differ from other modes of congenital
procedure. It may be termed biological, but not psychological,
imitation. And if it be held that the essence of imitation lies in the
purpose so to imitate, we must find some other term under which to
describe the facts. This does not seem necessary, however, if we are
careful to qualify the term “imitation” by the adjective “instinctive”
or “biological.” And the retention of the term serves to indicate that
this is the stock on which deliberate imitation is eventually grafted.

The fact that instinctive imitation leads, under natural conditions,
to behaviour which is already familiar to us in the species concerned,
prevents us from recognizing the influence of this social factor
so easily as might otherwise be the case. The abnormal arrests our
attention more readily than the normal, and hence the cases commonly
cited are generally those which strike us as unusual, such as the
imitation of human sounds by the parrot. But if the young inherit a
tendency to imitate certain actions of their parents, and if there is
among the members of a gregarious species such instinctive imitation
as shall tend to keep them gregarious, we have here a social factor
in animal life of no slight importance. Just as the higher type of
reflective imitation is of great value in bringing the human child to
the level of the adults who form the family and social environment,
so, too, does the sub-conscious instinctive imitation of the lower
animals bring the young bird or other creature into line with the
members of its own species. In broods of chicks brought up under
experimental conditions, there are often one or two more active,
vigorous, intelligent, and mischievous birds. These are the leaders
of the brood; the others are their imitators. Their presence raises
the general level of intelligent activity. Remove them, and the others
show a less active, less inquisitive, less adventurous life. They seem
to lack initiative. From which one may infer that imitation affords
to some extent a means of levelling up the less intelligent to the
standard of the more intelligent; and of supplying a stimulus to the
development of habits which would otherwise be lacking. When a mongrel
pup, whose development Dr. Wesley Mills watched and has described, was
introduced to the society of other dogs, its progress was, he tells us,
“extraordinarily rapid.”

Instinctive imitation thus introduces into the conscious situation
certain modes of behaviour, and if the development of the situation as
a whole is pleasurable, there will be a tendency to its redevelopment,
under the guidance of intelligence, on subsequent occasions. As in
the case of other instincts and propensities, there is given through
inheritance a more or less definite outline sketch of social procedure,
which intelligence further defines, and refines, and shapes to more
delicate issues. As a rule, however, intelligence does not tend to
make the imitation as such more perfect. It may perfect the behaviour,
but not necessarily on imitative lines. In the case, however, of
the song and call-notes of birds, and not improbably the sounds
of other animals, there does seem a predisposition to render the
imitation as such more perfect. The facts, as afforded by such birds
as the magpie, jay, starling, marsh-warbler, and mocking-bird, are
familiar; and I have elsewhere[81] given some account of them. It
may be specially noted that we have in this case that circular mode
of activity on which, as we have seen, Professor Mark Baldwin lays
so much stress. Professor Thorndike seems to regard the phenomena
presented by imitative birds as somewhat of a mystery, and as the
result of a specialization removed from the general course of mental
development. And he says that, until we know whether there is in birds
which repeat sounds any tendency to imitate in other lines, we cannot
connect these phenomena with anything found in the mammals, or use them
to advantage in a discussion of animal imitation as the forerunner
of human. Upon the view, however, that such imitation is primarily
instinctive and only secondarily intelligent, there seems no reason
why we should expect to find imitation in birds running along any
other lines than those which the hereditary instinct has marked out.
And so far from being unable to use the phenomena to advantage in a
discussion of animal imitation as a forerunner of human, we may perhaps
see in them the best examples, other than those afforded by apes, of
that intelligent imitation which is the precursor of the rational and
reflective imitation of the boy or girl.

In the case of the human child we may see the three stages in the
development of vocal imitation. First, the instinctive stage, where the
sound which falls upon the ear is a stimulus to the motor-mechanism of
sound production. Secondly, the intelligent stage of the profiting by
experience. Intelligence, as we have seen, aims at the reinstatement
of pleasurable situations, and the suppression of those which are
the reverse. The sound-stimulus, the motor effects in behaviour, and
the resulting sound-production coalesce into a conscious situation,
which appears to be pleasurable or the reverse, according as the sound
produced resembles or not the initiating sound-stimulus. If we assume
that the resemblance of the sounds he utters to the sounds he hears is
itself a source of pleasurable satisfaction (and this certainly seems
to be the case), intelligence, without the aid of any higher faculty,
will secure accommodation and render imitation more and more perfect.
And this appears to be the stage reached by the mocking-bird or the
parrot. But the child soon goes further. He reflects upon the results
he has reached; he at first dimly, and then more clearly realizes that
they are imitative; and his later efforts at imitation are no longer
subject to the chance occurrence of happy results, but are based on a
scheme of behaviour which is taking form in his mind, are deliberate
and intentional, and are directed to a special end more or less clearly
perceived as such. He no longer imitates like a parrot; he begins
to imitate like a man, and may, by the study of good models and the
maintenance of a high ideal, acquire the moving cadences of an orator.

According to our interpretation, instinctive imitation is a factor of
wide importance in animal behaviour, intelligent imitation, arising
in close connection with interest in the doings of others, is a
co-operating factor, but of intentional and reflective imitation there
is at present no satisfactory evidence in any animal below man.

II.--INTERCOMMUNICATION

The foundations of intercommunication, like those of imitation, are
laid in certain instinctive modes of response, which are stimulated by
the acts of other animals of the same social group. These have been
fostered by natural selection as a means of social linkage furthering
the preservation, both of the individual and of the group.

Some account has already been given of the sounds made by young birds,
which seem to be instinctive and to afford an index of the emotional
state at the time of utterance. That in many cases they serve to evoke
a like emotional state and correlated expressive behaviour in other
birds of the same brood cannot be questioned. The alarm note of a chick
will place its companions on the alert; and the harsh “krek” of a
young moor-hen, uttered in a peculiar crouching attitude, will often
throw others into this attitude, though the maker of the warning sound
may be invisible. That the cries of her brood influence the conduct
of the hen is a matter of familiar observation; and that her danger
signal causes them at once to crouch or run to her for protection is
not less familiar. No one who has watched a cat with her kittens,
or a sheep with her lambs, can doubt that such “dumb animals” are
influenced in their behaviour by suggestive sounds. The important
questions are, how they originate, what is their value, and how far
such intercommunication--if such we may call it--extends.

There can be but little question that in all cases of animals under
natural conditions such behaviour has an instinctive basis. Though
the effect may be to establish a means of communication, such is not
their conscious purpose at the outset. They are presumably congenital
and hereditary modes of emotional expression which serve to evoke
responsive behaviour in another animal--the reciprocal action being
generally in its primary origin between mate and mate, between parent
and offspring, or between members of the same family group. And it
is this reciprocal action which constitutes it a factor in social
evolution. Its chief interest in connection with the subject of
behaviour lies in the fact that it shows the instinctive foundations on
which intelligent and eventually rational modes of intercommunication
are built up. For instinctive as the sounds are at the outset, by
entering into the conscious situation and taking their part in the
association-complex of experience, they become factors in the social
life as modified and directed by intelligence. To their original
instinctive value as the outcome of stimuli, and as themselves
affording stimuli to responsive behaviour, is added a value for
consciousness in so far as they enter into those guiding situations by
which intelligent behaviour is determined. And if they also serve to
evoke, in the reciprocating members of the social group, similar or
allied emotional states, there is thus added a further social bond,
inasmuch as there are thus laid the foundations of sympathy.

“What makes the old sow grunt and the piggies sing and whine?” said
a little girl to a portly substantial farmer. “I suppose they does
it for company, my dear,” was the simple and cautious reply. So far
as appearances went, that farmer looked as guiltless of theories as
man could be. And yet he gave terse expression to what may perhaps be
regarded as the most satisfactory hypothesis as to the primary purpose
of animal sounds. They are a means by which each indicates to others
the fact of his comforting presence; and they still, to a large extent,
retain their primary function. The chirping of grasshoppers, the song
of the cicada, the piping of frogs in the pool, the bleating of lambs
at the hour of dusk, the lowing of contented cattle, the call-notes of
the migrating host of birds--all these, whatever else they may be, are
the reassuring social links of sound, the grateful signs of kindred
presence. Arising thus in close relation to the primitive feelings of
social sympathy, they would naturally be called into play with special
force and suggestiveness at times of strong emotional excitement, and
the earliest differentiations would, we may well believe, be determined
along lines of emotional expression. Thus would originate mating
cries, male and female after their kind; and parental cries more or
less differentiated into those of mother and offspring, the deeper
note of the ewe differing little save in pitch and timbre from the
bleating of her lamb, while the cluck of the hen differs widely from
the peeping note of the chick in down. Thus, too, would arise the notes
of anger and combat, of fear and distress, of alarm and warning. If we
call these the instinctive language of emotional expression, we must
remember that such “language” differs markedly from the “language” of
which the sentence is the recognized unit.

It is, however, not improbable that, through association in the
conscious situation, sounds, having their origin in emotional
expression and evoking in others like emotional states, may acquire
a new value in suggesting, for example, the presence of particular
enemies. An example will best serve to indicate my meaning. “In the
early dawn of a grey morning,” says Mr. H. B. Medlicott,[82] “I was
geologizing along the base of the Muhair Hills in South Behar, when
all of a sudden there was a stampede of many pigs from the fringe of
the jungle, with porcine shrieks of _sauve-qui-peut_ significance.
After a short run in the open they took to the jungle again, and in a
few minutes there was another uproar, but different in sound and in
action; there was a rush, presumably of the fighting members, to the
spot where the row began, and after some seconds a large leopard sprang
from the midst of the scuffle. In a few bounds he was in the open, and
stood looking back, licking his chaps. The pigs did not break cover,
but continued on their way. They were returning to their lair after
a night’s feeding on the plain, several families having combined for
mutual protection; while the beasts of prey were evidently waiting for
the occasion. I was alone, and, though armed, I did not care to beat
up the ground to see if in either case a kill had been effected. The
numerous herd covered a considerable space, and the scrub was thick.
The prompt concerted action must in each case have been started by
the special cry. I imagine that the first assailant was a tiger, and
the case was at once known to be hopeless, the cry prompting instant
flight, while in the second case the cry was for defence. It can
scarcely be doubted that in the first case each adult pig had a vision
of a tiger, and in the second of a leopard or some minor foe.”

If we accept Mr. Medlicott’s interpretation as in the main correct,
we have in this case: (1) common action in social behaviour, (2)
community of emotional state, and (3) the suggestion of natural
enemies not unfamiliar in the experience of the herd. Under uniform
conditions of experience the alarm-notes of some birds may well call
up, re-presentatively, salient features in previous situations.
Unquestionably, in the parrot, the word-sounds they imitate become
associated with definite objects of sense-experience. In the following
case, a particular sound appeared to be suggestive of a particular
sense-idea in the dog. The parent blackbirds, which built near a
house in Clifton, were wont to give the alarm-note when marauding
cats appeared in sight. This sound, it would seem, became definitely
associated, in the experience of a terrier, with the animals the
presence of which called it forth; and on hearing the alarm note the
dog would rush out into the garden, apparently, as I am informed by
his mistress, in fullest expectation of a pleasant worry. It is a not
improbable hypothesis, therefore, that in the course of evolution
the initial value of uttered sounds is emotional; but that on this
may be grafted in further development the indication of particular
enemies. If, for example, the cry which prompts instant flight among
the pigs is called forth by a tiger, it is reasonable to suppose
that this cry would give rise to a representative generic image of
that animal having its influence on the conscious situation. But if
the second cry, for defence, was prompted sometimes by a leopard
and sometimes by some other minor foe, then this cry would not give
rise to a re-presentative image of the same definiteness. Whether
animals have the power of intentionally differentiating the sounds
they make to indicate different objects, is extremely doubtful. Can a
dog bark in different tones to indicate “cat” or “rat,” as the case
may be? Probably not. It may, however, be asked why, if a pig may
squeak differently, and thus, perhaps, incidently indicate on the one
hand “tiger” and on the other hand “leopard,” should not a dog bark
differently, and thus indicate appropriately “cat” or “rat”? Because it
is assumed that the two different cries in the pig are the instinctive
expression of two different emotional states, and Mr. Medlicott could
distinguish them; whereas, in the case of the dog, we can distinguish
no difference between his barking in the one case and the other, nor do
the emotional states appear to be differentiated. Of course, there may
be differences which we have failed to detect. What may be regarded,
however, as improbable, is the _intentional_ differentiation of sounds
by barking in different tones with the _purpose_ of indicating “cat”
or “rat.” Mr. R. L. Garner, in a work[83] which unfortunately contains
much hasty and immature generalization, distinguished nine sounds
made by capuchins. But none of these, so far as can be gathered from
the data given, is necessarily indicative of a particular object. All
of them may be emotional expressions of satisfaction, discontent,
alarm, apprehension, and so forth. In any case, there is no evidence
for that intentional employment of sounds, to the realized end of
intercommunication, which would involve the exercise of an incipient
rational faculty. Such powers of intercommunication as animals possess
are based on direct association, and refer to the here and the now.
A dog may be able to suggest to his companion the fact that he has
descried a worriable cat; but can a dog tell his neighbour of the
delightful worry he enjoyed the day before yesterday in the garden
where the man with the biscuit-tin lives? Probably not, bark he never
so expressively.

Although some anecdotes are commonly interpreted as affording evidence
of descriptive intercommunication among animals, we need the decisive
results of experiment before this view can be unreservedly accepted.
Sir John Lubbock, now Lord Avebury, made careful experiments with
ants, and discusses the question with his customary lucidity and
impartiality. “Much of what has been said,” he writes,[84] “as to the
powers of communication possessed by bees and ants depends on the fact
that if one of them in the course of her rambles has discovered a
supply of food, a number of others soon find their way to the store.
This, however, does not necessarily imply any power of describing
localities. If the ants merely follow a more fortunate companion, or
if they hunt her by scent, the matter is comparatively simple; if, on
the contrary, the others have the route described to them, the case
becomes very different.” Experiments were therefore made to decide the
question. For example, when an ant returned from the discovered store
of food to the nest, and then emerged with a following of other ants,
she was taken up on a slip of paper and transferred to the food. The
followers, thus deprived of their leader, in nearly all cases failed to
find the store. “I conclude, then,” says Lord Avebury, “that when large
numbers of ants come to food they follow one another, being also, to a
large extent, guided by scent. The fact, therefore, does not imply any
considerable power of intercommunication.” There are, moreover, some
circumstances which seem to strengthen this conclusion. For instance,
“if a number of slave-ants are put in a box, and if in one corner a
dark place of retreat be provided for them, with some earth, one soon
finds her way to it. She then comes out again, and going up to one
of the others, takes her by the jaws and carries her to the place of
shelter. They then both repeat the same manœuvre with other ants, and
so on until all their companions are collected together. Now, it seems
difficult to imagine that so slow a course would be adopted, if they
possessed any power of communicating description.”

Lord Avebury is, however, of opinion that such insects can transmit
simpler ideas. He found, for example, that where ants were put to
a large and a small store of larvæ under similar circumstances, a
greater number of insects followed the ant that had discovered the
larger store. This may, indeed, have been due rather to a difference in
manner than to any intentional communication; but the fact remains that
through some difference of behaviour there resulted suggestive effects
on other members of the community.

But although there can be little doubt that the behaviour of social
insects has suggestive value for others, it may still be regarded as
very doubtful whether they are able to communicate information to one
another by any system of language or signs, purposively employed as a
system to this end. The distinguished geologist, Hague, communicated
to Darwin[85] the effects on ants of crushing some of their number as
they proceeded along a definite trail. “As soon as those ants which
were approaching arrived near to where their fellows lay dead and
suffering, they turned and fled with all possible haste.” “When such
an ant, returning in fright, met another approaching, the two would
always communicate, but each would pursue its own way, the second ant
continuing its journey to the spot where the first had turned about,
and then following that example.” There seems nothing to show that the
“communication” here was effective.

From the many anecdotes of dogs calling others to their assistance, or
bringing others to those who feed them or treat them kindly, we may
indeed infer the existence of a social tendency and of the suggestive
effects of behaviour, but we cannot derive conclusive evidence of
anything like descriptive communication. And although domestic animals
may learn or be taught to associate the words we utter with certain
acts or things, or may even, in a sense, communicate their wishes to
us by special modes of behaviour--as in the case of Lord Avebury’s
poodle, Van,[86] who was taught to bring cards on which such words
as “Food” or “Out” were printed, and in that of a cat which touches
the handle of the door when she wants it opened for her,--still,
all these are founded on direct association, and are in a line with
the act of Mr. Thorndike’s cat, which licked herself or scratched
herself when imprisoned in a cage, such act having entered into the
association-complex.

Such intentional communication as is to be found in animals, if indeed
we may properly so call it, seems to arise by an association of the
performance of some act in a conscious situation involving further
behaviour for its complete development. Thus the cat which touches the
handle of the door when it wishes to leave the room has had experience
in which the performance of this act has coalesced with a specific
development of the conscious situation. The case is similar when your
dog drops a ball or stick at your feet, wishing you to throw it for
him to fetch. And on these lines may probably be interpreted such
behaviour as Romanes[87] thus described:--“Terrier A being asleep in
my house, and terrier B lying on a wall outside, a strange dog, C,
ran along below the wall on the public road, following a dog-cart.
Immediately on seeing C, B jumped off the wall, ran upstairs to where
A was asleep, woke him up by poking him with his nose in a determined
and suggestive manner, which A at once understood as a sign: he jumped
over the wall and pursued the dog C, although C was by that time far
out of sight round a bend in the road.” Romanes did not probably intend
to imply that A by poking B, conveyed specific information that there
was another dog, C, which had proceeded in a particular direction.
That would be descriptive communication. The meaning attaching to
A’s action was presumably similar to that which characterizes other
“meaning” for intelligent animals--the development of the situation on
lines marked out by previous experience. Still, it is clear that such
an act would be the perceptual precursor of the deliberate conduct of
the rational being by whom the sign is definitely realized as a sign,
the intentional meaning of which is distinctly present to thought.
This involves a judgment concerning the sign as an object of thought;
and this is probably beyond the capacity of the dog. For, as Romanes
himself says,[88] “it is because the human mind is able, so to speak,
to stand outside of itself, and thus to constitute its own ideas the
subject-matter of its own thought, that it is capable of judgment,
whether in the act of conception or in that of predication. We have no
evidence to show that any animal is capable of objectifying its own
ideas; and, therefore, we have no evidence that any animal is capable
of judgment.”

It seems, therefore, that the sounds made by animals, and certain other
modes of behaviour, may be regarded as primarily instinctive acts which
have been evolved with the biological end of affording suggestive
stimuli furthering intercommunication between the members of the social
group. Their performance, however, affords data to consciousness, which
intelligence makes use of in the guidance of behaviour in accordance
with the results of experience. And since the similar acts performed
by the socially linked members are in many cases closely connected with
emotional states, there arises the further social link of community
of feeling--that which, perhaps, more than anything else conduces to
community of action and similarity of social behaviour. Occasionally
particular sounds or special acts may, through constant and uniform
association, indicate particular objects, such as natural enemies. But
there does not appear to be convincing evidence of any intentional
differentiation of the means of communication, or of any use of sounds
for descriptive ends.

Still, just as the instinctive imitation we considered in the last
section may be regarded as the precursor, in the animal world, of
the reflective and rational imitation of which we may watch the
development in children, so may instinctive modes of intercommunication
be regarded as supplying the foundations on which deliberate and
intentional communication may be based. And here imitation will be a
co-operating factor. We see in the early stages of the development of
children’s language how large a share simple and direct association
takes in the process. For a while, indeed, there seems to be this and
nothing more. But gradually there arises a realization of a further
import and purpose in the hitherto isolated associations. It is seen
that they symbolize elements in that incipiently rational scheme of
thought and things which is beginning to take form in the child’s mind.
The relationships which hold good within the conscious situations
of daily life begin to occupy the focus of attention, and hitherto
unappreciated word-sounds are perceived to stand out as signs for
these relationships. Of course the relationships[89] are implicit in
the conscious situations of the higher animals and of infants. Only by
reflection can they become explicit, and rivet the attention. Something
is needed to bring them into prominence and focus the mental eye upon
them. And descriptive intercommunication supplies this need. If a
description, even the simplest, is to be apprehended or presented to
the apprehension of others, then the relationships must be rendered
explicit. Try to describe an ordinary visual scene, or the most
commonplace sequence of events, and see if you can do so without making
clear to the mind the relationships involved. The thing is impossible.
An infant or a dog cannot understand the simplest possible description,
because the words and suffixes which indicate the relationships have
no meaning. The words which stand for substantive impressions may
have suggestive value through direct association. The word “cat” or
“rats” may have for the dog a very definite suggestive value; and hence
some people fancy that when they say to their dog, “There is a cat in
the garden,” the animal understands what they say. But it is quite
sufficient to suppose that the word “cat” has suggestive force, all the
rest being for the dog mere surplusage of sound. When we talk to our
four-footed companions, how much can they be said to understand of what
we say? Perhaps a score of words have for a dog a definitely suggestive
value, each associated with some simple object or action. “Out,”
“down,” “up,” “walk,” “biscuit,” “cat,” “fetch,” and so forth elicit
appropriate responses. Even with these, tone is more suggestive than
articulation, and in each word the salient feature is the chief guide.
When I said “Whisky,” for example, to my fox-terrier, he would at once
sit up and beg; not because his tastes were as depraved as those of
his master, but because the _isk_ sound, common both to “Whisky” and
“biscuit,” was what had for his ears the suggestive value.

In a paper on the “Speech of Children,”[90] Mr. S. S. Buckman exhibits
the animal stage in the incipient speech of the human infant. We cannot
here discuss, still less criticize, his paper. One or two examples
will serve to illustrate how instinctive sounds may serve as the
basis for subsequent speech. He regards _ma_ as primarily a forcible
expression of an emotional state. “If the child require attention
it makes the loudest noise which it can produce; the parting of the
lips and opening of the mouth to the widest extent while the full
volume of breath is emitted produces the sound _ma_.” At first the
sound seems to have the value of a simple expression of an emotional
state. “But if the infant require attention it is its mother whom it
wants, and from whom it receives this attention; therefore _ma_ very
soon comes to be recognized as the call for mother, and, by a further
step in development, as the name for mother.” Here, if we accept the
interpretation, we have the passage from the emission of a sound as
the expression of emotion to the use of the sound from its association
with a particular object of sense-experience to indicate that object.
Similarly, according to Mr. Buckman, with _kah_. At first “a strong
sign of displeasure at anything nasty to the taste,” it passes, we are
told, into a symbol for the bad; hence κακός; and is perhaps narrowed
down to the particularly offensive κάκκη. _Da_ and _ta_ are regarded
as recognition sounds, the former being associated eventually with the
father, the latter with strangers. This appears somewhat hypothetical,
but, granting the accuracy of Mr. Buckman’s interpretation, these
sounds also illustrate again the transition from the expression of an
emotion to sounds indicative of particular objects of experience.

Interesting, however, as are such observations on the animal stage of
sound-production in the human infant, they do not touch the crucial
period in the development of language. Mr. Buckman, indeed, regards as
a remarkably dogmatic assertion Professor Max Müller’s dictum that “the
one great barrier between the brute and man is language;” and he tells
us that “there are more than twelve different words in the language of
fowls,” on which assertion, in turn, the distinguished linguist whom he
criticizes might have something piquant to say. No doubt the difference
of opinion turns on the definition of the word “language.” But if,
as is now generally accepted, the sentence and not the word is the
distinguishing unit in language, and the copula in some form, explicit
or implicit, is the pivot of the sentence, the wisest hen is probably
incapable of language. The word becomes an element in language--a word
proper--only when it assumes the office of a part of speech, that is
to say, a constituent element in an interrelated whole. The animal
“word,” if we like so to term it, is an isolated brick; a dozen, or
even a couple of hundred such bricks do not constitute a building.
Language, properly so called, is the builded structure, be it a palace
or only a cottage; hen language, or monkey language, is, at best, so
far as we at present have evidence, an unfashioned heap of bricks. It
is just because language is the expression of a portion of a scheme of
thought that it indicates in the speaker the possession of a rational
soul, capable of perceiving and symbolizing the relationships of things
as reflected in thought.

Herein lies the practical value, for human advance in mental
development, of language as a means of descriptive intercommunication.
It renders explicit relationships otherwise merely implicit, and forces
them to the front; and since these relationships are the stuff of which
knowledge is built--without the realization of which any complex ideal
scheme is impossible of attainment--the importance of descriptive
intercommunication can scarcely be overestimated. And though there is
no conclusive evidence of its occurrence among animals, yet we have in
them the instinctive and intelligent basis on which in due course of
evolution it may be securely based.

III.--SOCIAL COMMUNITIES OF BEES AND ANTS

Apart from human societies the most noteworthy social communities of
animals are found among insects, especially in ants, bees, wasps, and
termites. It is true that in the mammalia we find such communities as
the troop of apes, the herd of cattle, the pack of wolves, the school
of porpoises, the so-called “rookeries” of seals, and the colonies of
“prairie dogs” and of beavers; and that among birds there are analogous
communities. Undoubtedly the temporary or permanent association of many
individuals is in such cases an advantage to the race, and confers
mutual benefits on the associates. But in none of these cases is
division of labour carried to such a high degree as among the social
insects. And it is through such division of labour that the social
community reaches its highest expression.

It is a somewhat remarkable fact that in man, where we find the social
division of labour brought to a high pitch of perfection, and carried
out with great nicety of accommodation to those circumstances which
civilization has rendered extremely complicated, there is no organic
differentiation of structure among the co-operating individuals;
whereas, so low down in the scale of life as the colonial polype,
_Hydractinia_, which is often found growing on the shells occupied
by hermit crabs, there are at least three kinds of differentiated
individuals: nutritive polypes with mouth and tentacles; mouthless
sensitive members; and others whose sole office is reproduction.
But these differentiated individuals in the colonial zoophytes are
connected at their bases by a common flesh; and the division of labour
is a product of organic evolution, and is probably not in any degree
determined or guided by consciousness. We may say, then, that the
division of labour in the zoophyte is wholly physical, whereas in man
it is chiefly conscious or psychical; as is also the bond of union
between the several members of the colony. Intermediate between these
extremes stand the social insects. In them there is no physical bond of
union, for each individual is distinct and separate; the social linkage
is in some degree conscious under the conditions of their nurture; and
the division of labour is partly conscious, though probably in large
degree based on instinctive foundations, and partly the outcome of an
organic differentiation of structure seen in the reproductive members
and in the sterile workers, as exemplified in the common wood ant (Fig.
24). In some cases the workers themselves may be divided into different
castes.

[Illustration: FIG. 24.--Wood ant. 1, Queen; 2, male; 3, worker (from
Shipley).]

So much has been written--and well written--on the social life of
insect communities, that it will here suffice to indicate some of
the problems which arise when we endeavour to interpret the modes of
behaviour which have been carefully observed. In the honey-bee we have
the well-known differentiation of structure into drones or effective
males, queens or egg-laying females, and workers or ineffective
females, in which the development of the reproductive organs is
arrested or modified. Distinct modes of behaviour are correlated with
these structural differences. When a swarm of bees leaves a hive it
generally consists of the old queen-mother and a certain number of the
workers which are her offspring. When they have found new quarters,
or have been safely housed under domestication, the workers busy
themselves in making the cells in which the queen may lay her eggs, and
in which food may be stored. In doing this the bees act in concert,
and though the mathematical accuracy of the form and size of the cells
has been much exaggerated, the comb which results is a very beautiful
and well-adapted product of mutual co-operation in joint labour. And
though intelligence may, under special circumstances, modify the method
of procedure there can be little doubt that comb-building is primarily
due to inherited instinct. The cells are not, however, all of the same
size, those for the drones being somewhat larger than the cells in
which the workers are reared, while much larger and differently shaped
cells are prepared for the future queens. If instinctive therefore--as
it seems to be in the main--the behaviour runs into different lines,
the immediate causes of which, internal or external, we are not able
accurately to assign.

The reproductive behaviour of egg-laying in the queen-mother is also
instinctive. It is believed that the drones are developed from eggs
from which the queen bee withholds the fertilizing fluid, which she
retains for months or years after the nuptial flight, stored in a
special receptacle. And the size and shape of the drone-cell may supply
the stimulus through which her behaviour in this respect is determined.
But she lays similarly fertilized eggs in both the worker-cells and the
queen-cells; and in these two cases the stimulating conditions must be
different.

When the eggs have been laid, and the grubs hatched, the worker bees
assume new duties--the feeding and tending of the young. They eat
honey and pollen, which is partially digested, and supplied as pap to
the grubs in such quantities that they seem bathed in it; but after a
short time a mixture of honey pollen and water is substituted for this
pap. It is said that the drone larvæ are fed with pap for a longer
period than the workers; and the queen larva undoubtedly receives far
more of this pap--or, perhaps, of a still richer nutritive product,
sometimes spoken of as royal jelly--and, indeed, is supplied therewith
throughout larval life. It is generally believed that this high feeding
is the cause of queen-development, and that should the queen larvæ die
ordinary worker larvæ are fed up, and produce queens nowise dissimilar
to those developed in the royal cells. It is clear, if this be so, that
the behaviour of the nurses decides the difference between the future
queens and working bees--that is to say, the fertile and the sterile
females. In any case, the feeding of the young by members of the same
community is a fact to be specially noted. It is commonly said that the
family is the germ from which the social community springs; and it may
be added that food-collection or food-administration in some form makes
the difference between the family that coheres and the family that
scatters.

When the larvæ have been fed, each after its kind, the workers seal up
the cells with lids of pollen and wax; the larvæ spin cocoons, pass
into the pupa stage, and then change to perfect bees, which bite a way
through the lid and take their place in the hive. These young bees
now become the nurses, while the older bees go abroad to fetch honey
and pollen to be stored away in some of the cells. But when a queen
emerges, her first act is to go round to the other royal cells, tear
them open, and sting to death the helpless occupants. Meanwhile the
old queen may have led off the surplus population in a swarm, and the
new queen reigns in her stead. Idle drones have also been emerging
from their cells; and when the young queen starts forth on her nuptial
flight she is followed by the drones, mates with one of them, and
returns a potential mother of thousands. So long as there is abundance
of food the useless drones are tolerated; but when there is scarcity
they are ejected, and drone eggs, larvæ, and pupæ are said to be
destroyed.

In the works of Huber and others, further marvels of hive-life, some
well-authenticated, others more or less doubtful, are duly set forth.
But enough has here been said to show that a social community of bees
presents problems of animal behaviour which are sufficiently difficult
of explanation. How far is the behaviour instinctive? How far is it
due to experience individually acquired? Are we constrained to admit
a rational factor? If so, is it, like human reason, the result of
generalization from experience of the relationships of phenomena? Or
are there features of insect psychology which differ from any of which
we have firsthand knowledge? These questions are more easily put than
answered. As in the case of bird-migration, so too in that of the
social life of bees, there is much that honesty forces us to confess
our inability satisfactorily to explain.

So, too, is it in the social life of ants. Among these insects the
males and perfect females bear wings, though these appendages may be
subsequently shed. In some kinds, however, there are also wingless
males or females capable of exercising the reproductive function. The
workers are wingless, and are often of two or three kinds, differing
in form and appearance, and in some cases playing different parts in
the social economy. There is also, in some cases, a separate class
of large-headed soldier ants; so that differentiation of structure
among the sterile females is carried further in ants than in bees.
Their nests generally consist of an elaborate system of chambers and
passages, either built with pine-needles, as in our common wood ant,
or hollowed out in the earth or in wood, or sometimes built with a
paper-like material, or formed of rolled leaves. It is said that a
common ant in Eastern Asia (_Œcophylla smaragdina_) “forms shelters
on the leaves of trees, by curling the edges of leaves and joining
them together.... The perfect ant has no material with which to fasten
together the edges it curls; its larva, however, possesses glands that
secrete a supply of material for it to form a cocoon with, and the
ants utilize the larvæ to effect their purpose.”[91] This has recently
been confirmed by Mr. E. G. Green, Government entomologist, at the
Botanic Gardens at Peradeniya, Ceylon. “He has seen ants actually
holding larvæ in their mouths and utilizing them as spinning machines.
To find out what would be done, some leaves were purposely separated
by Mr. Green. The edges of the leaves were quickly drawn together by
the ants, and, about an hour later, small white grubs were seen being
passed backwards and forwards across the gaps made in the walls of the
shelter. A continuous thread of silk proceeded from the mouth of the
larva, and was used to repair the damage.”[92] This is a remarkable
act of apparently intelligent behaviour. But when we remember how much
of the time of ants is occupied in carrying about their larvæ, it is
hardly an act of which it can be affirmed that it could not arise as
the result of chance experience.

In some cases two different genera are found in the same nest, with
separate chambers and passages, as in the case of the robber-ant
(_Solenopsis_) and the slave-ant (_Formica fusca_). The orifices by
which the former enter are too small to allow of the entrance of the
latter, “hence the robber obtains an easy living at the expense of the
larger species,” for “they make incursions into the nurseries, and
carry off the larvæ as food.”

In a few cases the foundation of a new colony has been carefully
watched. Blockmann was successful in observing the formation of new
nests by _Componotus ligniperdus_ at Heidelberg. “He found under
stones, in the spring, many examples of females, either solitary
or accompanied only by a few eggs, larvæ, or pupæ. Further, he
was successful in getting isolated females to commence nesting in
confinement, and observed that the ant that afterwards becomes the
queen, at first carries out by herself all the duties of the nest.
Beginning by making a small burrow, she lays some eggs, and when these
hatch, feeds and tends the larvæ and pupæ: the first specimens of these
latter that become perfect insects are workers of all sizes, and at
once undertake the duties of tending the young and feeding the mother,
who, being thus freed from the duties of nursing and of providing food
while she is herself tended and fed, becomes a true queen-ant. Thus
it seems established that, in the case of this species, the division
of labour found in the complex community does not at first exist,
but is correlative with increasing numbers of the society. Further
observations as to the growth of one of these nascent communities, and
the times and conditions under which the various forms of individuals
composing a complete society first appear, would be of considerable
interest.”[93]

The queen does not, as in the case of the bee, deposit her eggs in
separate cells where they are tended by nurses. The eggs, which are
laid in the chambers of the nest, are subjected to much licking by
the nurses; the larvæ are, moreover, moved about from place to place,
so as to be subjected to the requisite conditions of moisture and
temperature. They are carefully cleaned, and after they have passed
into the pupa stage the emerging insects are stripped of a delicate
investing skin. And not only do the ants assiduously feed their
young; those who have gone forth and drunk their fill of sweet juices
feed those who have remained behind. Forel took some specimens of
_Componotus ligniperdus_, “and shut them up without food for several
days, and thereafter supplied some of them with honey, stained with
Prussian blue; being very hungry, they fed so greedily on this that
in a few hours their hind bodies were distended to three times their
previous size. He then took one of these gorged individuals, and
placed it among those that had not been fed. The replete ant was at
once explored by touches of the other ants and surrounded, and food
was begged from it. It responded to the demands by feeding a small
specimen from its mouth, and when this little one had received a good
supply, it in turn communicated some thereof to other specimens; while
the original well-fed one also supplied others, and thus the food was
speedily distributed. This habit of receiving and giving food is of
the greatest importance in the life-history of ants.”[94] It affords
the basis or starting-point of the keeping of aphides, the making of
slaves, the curious development of honey-pot ants, and in some cases
the association with ants of other insects.

[Illustration: FIG. 25.--Beetle soliciting food from Ant (after
Wasmann).]

Some of these insects, of which there are many species belonging to
several orders, are parasitic; others appear to be hostile, and yet are
able to maintain themselves in the nest; others simply live side by
side with the ants, which seem to be neither hostile nor friendly to
them. In some of these cases the biological purpose of the association
is unknown, while in others the ant serves as a model which the
associated insect mimics. Thus in the nest of an Indian ant (_Sima
rufa-nigra_) occur a small wasp and a spider which, to some extent in
form and more markedly in coloration, mimic their hosts. “Wherever you
find this species in any numbers,” says Mr. Rothney,[95] “if you watch
a few moments, you will see a mimicking spider, _Salticus_, running
about among the ants, which it very closely resembles in appearance,
much more so in life than in set specimens placed side by side; I have
seen numbers on the most friendly footing with the ants, though I
have never seen them enter their burrows.... They are, I should say,
the only friends the ant has, with the exception of a sand-wasp, a
new species of _Rhinopsis_ since described by Mr. Cameron, which also
very closely mimics the ant, and which, on first observing among the
workers, I took to be the male.” But there are some beetles which
are not only tolerated, but fed by the ants with which they live. In
the case of the genera _Atemeles_ and _Lomechusa_, which are always
found in or near ants’ nests, the good offices are reciprocal, for the
beetles “have patches of yellow hairs, and these secrete some substance
with a flavour agreeable to the ants, which lick the beetles from time
to time. On the other hand, the ants feed the beetles; this they do by
regurgitating food, at the request of the beetle, on to their lower
lip, from which it is then taken by the beetle. The beetles in many of
their movements exactly resemble the ants, and their mode of requesting
food, by stroking the ants in certain ways, is quite ant-like. So
reciprocal is the friendship, that if an ant is in want of food the
beetle will in its turn disgorge for the benefit of its host. The young
of the beetles are reared in the nests by the ants, who attend to them
as carefully as they do to their own young. The beetles are, however,
fond of the ants’ larvæ as food, and, indeed, eat them to a very large
extent, even when their own young are receiving food from the ants.
Wasmann (to whom we are indebted for most of our knowledge on this
subject) seems to be of opinion that the ants scarcely distinguish
between the beetle larvæ and their own young; one unfortunate result
for the beetle follows from this, viz. that in the pupal state the
treatment that is suitable for the ant larvæ does not agree with the
beetle larvæ. The ants are in the habit of digging up their own kind,
and lifting them out and cleaning them during their metamorphosis: they
do this also with the beetle larvæ, with fatal results; so that only
those that have the good fortune to be forgotten by the ants complete
their development.”[96]

Aphides, or plant-lice, yield to the solicitations of ants, which
stroke them with their antennæ, by emitting a drop of sweet and viscid
secretion, and it appears that the caress of the ant is the natural
stimulus for the emission of the drop. Not only, however, do the ants
go forth in search of aphides in their natural haunts, they bring them
to the neighbourhood of the nest, and may even impound them by building
a wall of earth round and over them. Huber stated that ants collected
the eggs of the aphides and tended them in their nests, and the
accuracy of the observation has been shown by Lord Avebury and others.
“The aphid eggs are laid early in October, on the food plant of the
insect. They are of no direct use to the ants, yet they are not left
where they are laid, where they would be exposed to the severity of the
weather and to innumerable dangers, but brought into the nests by the
ants, and tended by them with the utmost care through the long winter
months until the following March, when the young ones are brought out
and again placed on the young shoots of the daisy.”[97] Dr. McCook
noticed that ants, returning from the trees on which aphides abounded,
fed others near the nests, and he regarded this as a case of division
of labour, the foragers obtaining food for the nurses which remained in
or near the nest.

A further division of labour, carried to lengths which seem almost
absurd, is found in the honey-pot ant of the United States and Mexico.
The juice on which these ants feed is obtained from an oak-gall.
Foragers go forth at night and return distended with the sweet fluid,
and, having fed the ordinary workers in the nest, apparently discharge
the balance of their store into living honey-pots, which remain in
the nest and preserve the food till it may be required by the members
of the community. Their abdomens are enormously distended, they never
leave the nest, and they seem to form a distinct caste, whose function
it is to passively accumulate stores of reserve food for the community.
Curiously enough the same peculiar social arrangement is found in
different genera living as far apart as Mexico, Australia, and South
Africa.

[Illustration: FIG. 26.---Honey-pot Ant.]

There is no doubt that in some cases the division of labour is not
restricted to the individuals of the same species, but that other
species are introduced into the nest to perform certain functions--thus
giving rise to the so-called slavery among ants. This is carried to
an extreme in the European species _Formica rufescens_, the males and
queens of which do no work, while the sole function of the workers
is to capture slaves of the smaller species _Formica fusca_. In
association with this specialized mode of instinctive behaviour, “even
their bodily structure has undergone a change; their mandibles have
lost their teeth, and have become mere nippers, deadly weapons indeed,
but useless except in war. They have lost the greater part of their
instincts: their art--that is, the power of building; their domestic
habits--for they take no care of their own young, all this being done
by the slaves; their industry--they take no part in providing the
daily supplies; if the colony changes the situation of its nest, the
masters are all carried by the slaves to the new one; nay, they have
even lost the habit of feeding.... I have had a nest of this species
under observation for a long time, but never saw one of the masters
feeding. I have kept isolated specimens for weeks, by giving them a
slave for an hour or two a day to clean and feed them, and under these
circumstances they remained in perfect health, while, but for the
slaves, they would have perished in two or three days.”[98]

In this matter, we have in different species successive stages in the
development of the instinctive behaviour which is thus carried so far
in _Formica rufescens_. Our English ants, of the species _Formica
sanguinea_, have fewer slaves and are less dependent on them; they
can feed and forage for themselves, and during migration carry their
slaves--which are of the same species as in the other case--instead of
being carried by them. In the nests of the common wood ant or horse
ant (_Formica rufa_) there are occasionally a few slaves. Lord Avebury
thinks it likely that they are developed from larvæ or pupæ, originally
taken for food, which have by chance come to maturity in the nest of
their captors.

But one more incident in the social life of ants can here be
noticed--though many others could be given did space permit. The
leaf-cutting ants of America form paths from their nests to suitable
trees, from which to obtain the small coin-like leaf fragments, which
they carry in the mandibles, and hence have gained the name of umbrella
or parasol ants. These paths are sometimes underground; and Mr. McCook
measured one which ran at a depth of some 18 inches beneath the surface
for 448 feet, and was then continued for another 185 feet to the tree
which the ants were stripping. The whole path was in an almost perfect
straight line from nest to tree. The leaf fragments are stored in large
quantities in the nest, and it was long a matter of uncertainty for
what purpose they were collected. The problem was solved by Alfred
Möller, who found that the leaves, which are subdivided and masticated
by a special set of workers within the nest, form the appropriate
material in which the threads of a fungus ramify and flourish. This
fungus is tended by the ants with great care, and is made to produce a
specially modified form of growth, not found under other circumstances,
in the form of white aggregations, termed by Möller “Kohlrabi clumps.”
These form the principal food of the ants; and the spongy mass of earth
and leaves is called the fungus garden. “If a nest be broken into
and the fungus garden scattered, the ants collect it as quickly as
possible, especially the younger parts, taking as much trouble over it
as over the larvæ. They also cover it up again as soon as possible to
protect it from the light.”[99]

Again, it may be asked with regard to the social life of ants as
with respect to that of bees--How far is their complex behaviour
instinctive? How far is it due to imitation? What part does
intelligence play, and under what conditions of acquisition? Is reason,
in the restricted sense of the word, a factor in the development of
the behaviour? I cannot answer these questions, and am of opinion that
much detailed observation is yet needed before we can do much more
than speculate in the matter. Much indeed has been done, but yet more
remains for future investigation.

The conditions under which much of the behaviour is carried out seem to
indicate strong instinctive tendencies which give an hereditary trend
to the direction which the social behaviour takes. Dr. Bethe,[100]
indeed, goes so far as to regard the behaviour as almost entirely
instinctive, affording little evidence of that modifiability of
reactions which indicates intelligent guidance. He shows as the result
of careful experiment that the behaviour of ants to friends and enemies
are direct reactions to smell. Enemies washed with the excretions of
members of the nest are treated as friends, notwithstanding their
different colour, size, and general appearance. By scent, too, they
follow the lead of others and retrace their way to the nest; this, he
says, is not the result of a mental process, but is the reaction of a
complicated reflex mechanism. As the outcome of careful observation,
Dr. Bethe’s conclusions are of great value and interest. But he seems
to go too far in denying to ants any power of intelligent accommodation
to circumstances. If we admit intelligence, then the fact that the
insects come forth in the midst of a community in full social activity
would tend to the imitative or intelligent acquisition of like modes
of procedure. It is difficult to distinguish the share taken by these
two factors which may well co-operate. And if natural selection is
exercising its influence through the elimination of those which do not
fall into line in social behaviour, there would be ample opportunity
for the survival of coincident variations.[101] If one may be allowed
to speculate, it seems probable that the interaction of instinct
and intelligence will be found with fuller knowledge to suffice for
the explanation of the facts, without calling in the known but here
improbable factor of rationality or any factors unknown elsewhere in
psychology.

Some interesting observations of Lord Avebury’s are sometimes quoted
as evidence that ants are lacking in intelligence, but (if we accept
the distinction already drawn[102]) they seem rather to show the lack
of reason. “I placed food,” he says,[103] “in a porcelain cup, on a
slip of glass surrounded by water, but accessible to the ants by a
bridge, consisting of a strip of paper two-thirds of an inch long and
one-third wide. Having then put an ant (_Formica nigra_) from one of
my nests to this food, she began carrying it off, and by degrees a
number of friends came to help her. When about twenty-five ants were
so engaged, I moved the little paper bridge slightly, so as to leave a
chasm just so wide that the ants could not reach across. They came to
the edge and tried hard to get over, but it did not occur to them to
push the paper bridge, though the distance was only about one-third of
an inch, and they might easily have done so. After trying for about a
quarter of an hour they gave up the attempt and returned home. This I
repeated several times. Then, thinking that paper was a substance to
which they were not accustomed, I tried the same with a bit of straw
one inch long and one-eighth of an inch wide. The result was the same.
Again, I placed particles of food close to and directly over the nest,
but connected with it only by a passage several feet in length. Under
these circumstances it would be obviously a saving of time and labour
to drop the food on to the nest, or at any rate to spring down with
it, so as to save one journey. But though I have frequently tried the
experiment, my ants never adopted either of these courses. I arranged
matters so that the glass on which the food was placed was only raised
one-third of an inch above the nest. The ants tried to reach down, and
the distance was so small that occasionally, if another ant passed
underneath just as one was reaching down, the upper one could step on
to its back, and so descend; but this only happened accidentally, and
they did not think of throwing the particles down, nor, which surprised
me very much, would they jump down themselves. I then placed a heap of
mould close to the glass, but just so far that they could not reach
across. It would have been quite easy for any ant, by moving a particle
of earth for a quarter of an inch, to have made a bridge by which the
food might have been reached, but this simple expedient did not occur
to them.”

Now, when we remember that the method of intelligence is to profit
by chance experience, while the method of reason is, with foresight
and intention, to adapt means to ends, we shall see that to move a
straw even a quarter of an inch, or to make a bridge with particles
of mould, would require rational and not merely intelligent powers.
Chance experience would not supply the necessary data to be utilized
by intelligence when repetition had established an association in the
conscious situation. Granting that the ants were intelligent but not
rational, they could not be expected to overcome the difficulties,
simple as they seem to us, which Lord Avebury placed in their path. Had
they been overcome the fact would be more difficult to explain than the
use of a stone tool by the sand wasp, since this could more readily be
hit upon by chance experience. And what these valuable experiments, of
which kind more are needed, seem to show is, that the ant, probably
the most intelligent of all insects, has no claim to be regarded as a
rational being.

IV.--ANIMAL TRADITION

In that interaction between instinct and intelligence which, when
further detailed work has sifted and purified our knowledge of the
psychology of animal communities, may prove sufficient to account for
the well-established facts, animal tradition will probably have to be
recognized as of no little importance. When a newly emerging ant or
bee, or a young bird or mammal is born into a community where certain
modes of behaviour are already in full swing, an imitative tendency
of the follow-my-leader type may lead it to fall in line with the
traditional habits. It is said that young ants follow the older workers
about the nest, and are “trained to a knowledge of domestic duties,
especially in the case of larvæ.” On the other hand, we have seen that,
in certain observed cases, the queen ant is the solitary starting-point
of a new community, and that the division of labour follows with the
increasing numbers of the newly formed social group; so that, in such
cases, whatever part tradition may play in the later phases of social
life, it cannot afford a sufficient account of the division of labour
in the earlier history of the community. We need, however, fuller
information concerning the continued life-history of such communities
under natural conditions, and as to how far they remain self-contained
without any incorporation of older members from adjoining nests. In
the case of bees, where the old queen departs with a swarm, there may
be greater continuity of tradition. But how far this is a necessary
factor in social development is at present a matter of conjecture. In
the herd of mammals and the flock of birds, and in all the family and
social life in these classes of animals, the example of elders, without
any imitation of the higher reflective type, can scarcely be without
its influence on the behaviour of the young which, one would suppose,
would tend to fall in with the ways which had become traditional in
the species. Professor Wesley Mills tells us that a mongrel pup, whose
psychical development he carefully watched, showed “extraordinarily
rapid” progress when he was introduced to the society of other dogs,
and was thus subjected to the influence of canine tradition.

How far this influence extends in animal communities--how far it
is either a necessary or even an important contributory factor in
the development of certain modes of behaviour--is at present in
large degree a matter of speculation. And the only justification
for speculation in science is that it may open our eyes to modes of
influence the range and limits of whose effects may be submitted to the
touchstone of careful observation, and, if possible, experiment. In
this instance it is rather the indefiniteness of the evidence before us
than its absence that stands in the way of any profitable discussion of
the problem from the evidential point of view. And this indefiniteness
is partly due to the fact that the need of observation is not realized,
because this factor in animal behaviour has not been distinguished with
sufficient clearness. It is worth while, therefore, to devote a short
space to a consideration of the relation of this tradition to instinct
and intelligence with a view to the focussing of observation on the
facts by which it may be further elucidated.

In the first place, it is probable that, as in other modes of animal
behaviour, traditional procedure is founded on an instinctive basis.
This must be an imitative tendency of the broad follow-my-leader
type indicated in the first section of this chapter. And this would
afford wide instinctive foundations, which would owe their hereditary
character to the fact that, under natural selection, those individuals
in the community would survive which fell into line with the adaptive
behaviour of their companions, while those which failed in this respect
would be eliminated as more or less isolated outsiders, standing apart
from the social life. In illustration we may take a hypothetical
case, founded, however, upon observation. The Rev. S. J. Whitmee, a
missionary in Samoa, believes that the tooth-billed pigeon of these
islands (_Didunculus strigirostris_) “has probably been frightened when
roosting, or during incubation, by attacks of cats, and has sought
safety in the trees. Learning, from frequent repetition of the fright,
that the ground is a dangerous place, it has acquired the habit of
building, roosting, and feeding on the high trees; and this habit is
now operating for the preservation of this interesting bird, which a
few years ago was almost extinct.”[104] Now, in this case, the young
birds which followed the lead of those who, under experience, had
acquired the habit, would stand a better chance of survival than those
who, failing to do so, were caught napping on the ground. In further
illustration, we may take the case of two species of rats found by
Mr. C. M. Woodford on one of the Solomon Islands. These two species
are regarded by Mr. Oldfield Thomas as slightly altered descendants
of one parent species, with adaptations due to the fact that, of this
original species, some have adopted a terrestrial, others an arboreal
life. Thus _Mus rex_ lives in trees, has broad footpads, and a long
rasp-like, probably semi-prehensile tail; while _Mus imperator_ lives
on the ground, has smaller pads, and a short smooth tail. How far the
different modes of behaviour in the two species may have been fostered
by the influence of tradition we do not know; but it is not improbable
that such an influence would be a co-operating factor in the process of
segregation, and that in the course of time each form has been adapted
to its special environment through the elimination of those individuals
which were not in harmony with the conditions of their life.

Such a case--admittedly hypothetical in the interpretation put upon the
facts--may help us to see how the general instinctive follow-my-leader
tendency might become specialized in certain essential lines of racial
behaviour, and how, under natural selection, coincident variations in
the line of traditional acts might become more and more definitely
inherited as, at first, strong instinctive tendencies, and eventually
more stereotyped modes of instinctive behaviour. This, indeed, may have
been the mode of origin of some of the social instincts.

Reverting, however, to the stage where the general instinctive
follow-my-leader tendency is only partly or incompletely specialized
along particular lines of behaviour, we should have at this stage
certain hereditary trends of action, dependent on stimuli afforded
by the behaviour of others, but needing, for their guidance to finer
issues and more adequate and highly perfected performance, the play
of intelligence and the satisfaction of nascent social impulses. In
the economy of the hive or the nest there are, no doubt, instinctive
tendencies and predispositions; but there is also something more than
organic heredity with its transmitted modes of behaviour analogous
to the inherited form and structure of the body or its parts.
Consciousness exerts a guiding influence. The insect is not independent
of experience, but is capable of profiting by the teachings of that
fertile mother of all intelligent behaviour. It is unnecessary,
however, to insist on the fact that such insects are something more
than instinctive automata, but are guided in their behaviour by the
results of experience. Many careful observers lay stress upon this;
if, indeed, they do not go further and claim for the social insect the
higher rational faculty. “When we see,” says Lord Avebury,[105] “an
ant-hill tenanted by thousands of industrious inhabitants, excavating
chambers, forming tunnels, making roads, guarding their home, gathering
food, feeding the young, tending their domestic animals--each one
fulfilling its duties industriously, and without confusion--it is
difficult altogether to deny to them the gift of reason; and the
preceding observations tend to confirm the opinion that their mental
powers differ from those of man, not so much in kind as in degree.”

If the term “reason” be here accepted in the broad sense, and not
in the narrower sense before indicated, this passage will probably
be endorsed by the majority of those who have paid any attention to
the subject. Even those who regard “reason,” in the more restricted
acceptation of the term, as outside any scheme of evolution, since it
differs in kind and not merely in degree, would probably deny this
faculty to ants. In any case the passage expresses the conviction of
a close and singularly unprejudiced observer, that the doings of ants
involve conscious guidance in the light of experience individually
acquired.

And yet the behaviour of different species of ants, each after its
kind, is remarkably constant--so constant that, to use the words of Dr.
Peckham in another connection, it is characteristic of the species, and
would be an important part of any definition of the insect based upon
its habits. And some part of this constancy may be due to tradition,
though much of it may result from strong instinctive tendencies which
intelligence guides to similar ends, because the conditions are similar
in successive generations of social insects.

From the point of view of observation, however, it is particularly
difficult to distinguish the part played by tradition as a
psychological influence from that played by what we have above
described as instinctive imitation. In our study of other modes of
instinctive behaviour we can isolate an individual, or group of young
individuals, and observe how far certain acts are performed prior
to any experience. Thus chicks behave in certain instinctive ways
under conditions which preclude their learning from the hen or other
older birds--so that tradition cannot be operative. But where social
behaviour is concerned, such methods of observation are necessarily
excluded, since isolation involves the absence of the social factor.
And if certain instinctive acts require for their due performance
the stimulus of the like performance in others, what is this but a
form of instinctive tradition; and how are we to distinguish it from
intelligent tradition, where a psychological factor has freer play
and exercises guidance over the performance? In the present state
of our knowledge we can do no more than suggest, as not improbable,
that tradition passes through three phases: the first in which it is
instinctive; the second in which it becomes intelligent through the
satisfaction which the due performance of traditional acts arouses in
consciousness; and the third in which, at any rate in man, it takes
on a rational form, and is made to accord with an ideal scheme, the
product of conceptual thought and of reflection on data which have
been generalized and considered in their due relationships to the
scheme which takes definite form in the mind. Whether in the social
communities of insects or those of beavers, among mammals, or rooks
among birds, tradition has begun to pass into the third or rational
stage, we do not know. It may be so, but probably the development along
these lines has not been carried far. Presumably in the ant, rook, and
beaver anything like an ideal scheme of thought based on reflection, if
it exist, is as yet exceedingly indefinite.

But even supposing that no animal has yet risen beyond the second or
intelligent stage, it is none the less important to realize that we
have here, in animal life, the foundations on which may be raised what
may, perhaps, be regarded as one of the characteristic features of
human progress. This characteristic is the transference of evolution
from the organism to the environment handed on from generation to
generation. Thus man, “availing himself of tradition, is able to
seize upon the acquirements of his ancestors at the point where they
left them.”[106] Thus “he has slowly accumulated and organized the
experience which is almost wholly lost with the cessation of individual
life in other animals.”[107] But he is able to do so through the
extension, refining, and fixing of that instinctive and intelligent
tradition which begins to take form in animal communities.

V.--THE EVOLUTION OF SOCIAL BEHAVIOUR

“Animals of many kinds,” said Darwin,[108] “are social; every one
must have noticed how miserable horses, dogs, sheep, etc., are when
separated from their companions. The most common mutual service in
the higher animals is to warn one another of danger. Every sportsman
knows how difficult it is to approach animals in a herd or troop.
Wild horses and cattle do not, I believe, make any danger-signal; but
the attitude of any one of them who first discovers an enemy warns the
others. Rabbits stamp loudly on the ground with their hind feet as a
signal; sheep and chamois do the same with their fore feet, uttering
likewise a whistle. Many birds and some mammals post sentinels. The
leader of a troop of monkeys acts as such, and utters cries expressive
both of danger and of safety. Social animals perform many little
services for each other: horses nibble, and cows lick each other;
monkeys search each other for external parasites, and are said to
remove thorns and burrs. Social animals mutually defend each other.
Bull bisons in North America, when there is danger drive the cows and
calves into the middle of the herd, whilst they defend the outside.
Among baboons the old males come forward to the attack. Wolves hunt in
packs; and pelicans fish in concert.

“It has often been assumed,” continues Darwin, “that animals were in
the first place rendered social, and that they feel as a consequence
uncomfortable when separated from each other, and comfortable whilst
together; but it is a more probable view that these sensations were
first developed, in order that those animals which would profit by
living in society should be induced to live together, in the same
manner as the sense of hunger and the pleasure of eating were, no
doubt, first acquired in order to induce animals to eat. The feeling
of pleasure from society is probably an extension of the parental and
filial affections, since the social instinct seems to be developed by
the young remaining long with their parents; and this extension may be
attributed in part to habit, but chiefly to natural selection. With
those animals which were benefited by living in close association,
the individuals which took the greatest pleasure in society would
best escape various dangers; while those which cared least for their
comrades, and lived solitary, would perish in greater numbers. In
however complex a manner the feeling of sympathy may have originated,
as it is one of high importance to all those animals which aid and
defend one another, it will have been increased through natural
selection; for those communities which included the greatest number of
the most sympathetic members would flourish best, and rear the greatest
number of offspring.”

It is impossible to improve upon this pithy description of the salient
facts, and terse explanation in terms of the hypothesis of natural
selection. It may, perhaps, be urged that, on this hypothesis, the
origin of the social state, through a biological association of
individuals, probably neither preceded nor followed the development of
a psychical bond arising from the sense of satisfaction and comfort
afforded by social life, but that both originated _pari passu_. If
the linkage was primarily instinctive, its intelligent continuance
could only be effected through the pleasure social behaviour carried
with it, and the discomfort of separation from the community. No
instinctive acts would be persistently repeated, under the guidance of
individual experience, if that experience proved bitter and not sweet.
An animal with thwarted instincts is one with unsatisfied impulses;
its biological and its psychological tendencies are alike unfulfilled.
What Darwin saw and wished to enforce, however, was that the psychical
link of conscious satisfaction was a necessary prerequisite of the
continuance and further evolution of sociability; and that without the
integrating bonds of sympathy any advance of social development was
impossible.

In two able and interesting articles in the _Nineteenth Century_
review,[109] on “Mutual Aid among Animals,” Prince Kropotkine gives a
useful and sufficiently detailed summary of the chief facts concerning
the social relationships which have been observed in the animal
kingdom--including, perhaps, some rather apocryphal instances,--and
combats Huxley’s statement[110] that, “beyond the limited and temporary
relations of the family, the Hobbesian war of each against all is the
normal state of existence” among animals and primitive men. “Life in
societies,” says Prince Kropotkine, “is no exception in the animal
world. It is the rule, the law of nature, and it reaches its fullest
development with the higher vertebrates. Those species which live
solitary, or in small families only, are relatively few, and their
numbers are limited.”[111] “Life in societies enables the feeblest
insects, the feeblest birds, and the feeblest mammals to resist, or to
protect themselves from, the most terrible birds and beasts of prey; it
permits longevity; it enables the species to rear its progeny with the
least waste of energy, and to maintain its numbers, albeit with a very
slow birth-rate; it enables the gregarious animals to migrate in search
of new abodes. Therefore, while fully admitting that force, swiftness,
protective colours, cunningness, and endurance to hunger and cold,
which are mentioned by Darwin and Wallace, are so many qualities making
the individual or the species the fittest under certain circumstances,
we maintain that under _any_ circumstances sociability is the greatest
advantage in the struggle for life.... The fittest are thus the most
sociable animals, and sociability appears as the chief factor in
evolution, both directly, by securing the well-being of the species
while diminishing the waste of energy, and indirectly by favouring the
growth of intelligence.”[112] And summarizing his argument, Prince
Kropotkine says,[113] “We have seen how few are the animal species
which live an isolated life, and how numberless are those which live
in societies, either for mutual defence, or for hunting and storing
up food, or for rearing their offspring, or simply for enjoying life
in common. We have also seen that, though a good deal of warfare goes
on between different species, or even different tribes of the same
species, peace and mutual support are the rule within the tribe, or the
species; and that those species which best know how to combine, and to
avoid competition, have the best chances of survival and of further
progressive development. They prosper, while unsociable species decay.”

Prince Kropotkine seems, however, to push his argument too far.
The assertion that the fittest are the most sociable animals, that
sociability appears as the chief factor in evolution, and that
unsociable species decay, is not likely to be accepted without
qualification by zoologists. What grounds have we for saying that the
solitary wasps are less fit than the social wasps? Each has a fitness
according to its kind. Can it be maintained that the unsocial tiger
is less fit than the social jackal? And can it be said that tigers,
which are reported absolutely to swarm in Java and Sumatra, exemplify
the decay of an unsociable species? Is it seriously contended that
the hawk, which may be successfully mobbed by a number of wagtails,
is less fit than his more social assailants? And are the unsocial
raptorial birds decaying species? Such questions might be asked by the
score. And the answer in every case is that the social and unsocial
alike are fitted to their several states of life. In fact, it might
be contended, with every whit as much if not more cogency, that
sociability is nature’s device for enabling the weaker, and hence in
themselves the less fit, to resist the attacks and encroachments of the
stronger and individually fitter. Discussing the possibilities of human
ancestry, Darwin said:[114] “In regard to bodily size or strength, we
do not know whether man is descended from some comparatively small
species like the chimpanzee, or from one as powerful as the gorilla.
We should, however, bear in mind that an animal possessing great size,
strength, and ferocity, which, like the gorilla, could defend itself
from all enemies, would not perhaps have become social; and this would
most effectually have checked the acquirement of the higher mental
qualities, such as sympathy and the love of his fellows. Hence it
might have been an immense advantage to man to have sprung from some
comparatively weak creature.”

Zoologists, again, will hardly accept without question Prince
Kropotkine’s assertion that “life in societies is no exception in the
animal world, but is the rule, the law of nature.” Many will contend,
on the other hand, that life in societies with anything like division
of labour, or with mutual aid (and this seldom carried far), is, taking
the animal kingdom as a whole, of comparatively rare occurrence, though
none the less noteworthy where it exists. And, in any case, it seems
somewhat extravagant to say that sociability is the chief factor in
evolution. No doubt it might be plausibly urged that human society is,
from man’s point of view, the highest product of evolution; that in
attaining to this end sociability has been the leading factor; and that
obviously the leading factor in the evolution of the highest product
may properly be called the chief factor in evolution. But Prince
Kropotkine apparently means that sociability is the chief factor, not
only in this evolution, but in all organic, or, at least, all animal
evolution. In this he will receive the support of but few zoologists.
By some extravagance of statement he has weakened his own case,
which is otherwise not lacking in points of weakness. The legitimate
inferences from animal behaviour are, that co-operation is in some
cases a factor in the evolution of a successful species, that in human
progress it has been an important factor giving strength to a creature
weak in tooth and claw, and that this factor has co-existed, and still
coexists, with that of competition, in the absence of which the race
would be dragged down to lower levels of efficiency by the incubus of
weaklings.

To Professor Alfred Espinas[115] we owe the best and fullest discussion
of the social life of animals, and to his work the reader may be
referred for a careful and, for the most part, unstrained and unbiassed
consideration of the phenomena. In common with others who have
devoted serious attention to the subject, he sees in the family the
starting-point of the higher and more comprehensive social group, or
“peuplade.” Prince Kropotkine seems, indeed, to combat this view; but
the divergence of opinion is more apparent than real. He tells us[116]
that anthropology “has established beyond any doubt that mankind did
_not_ begin its life in the shape of small isolated families. Far
from being a primitive form of organization, the family is a very
late product of human evolution.... Societies, bands, or tribes--not
families--were thus the primitive form of organization of mankind and
its earliest ancestors.” And in support of his views he adduces the
sexual communism which is said to be found in the lowest savages,
and briefly traces the development of monogamy and the genesis of
the family ideal as we conceive it. It may at once be admitted that
in all probability mankind did not have its origin in small isolated
families. If we do not admit this we must accept the alternative
hypothesis, that man was developed from an unsocial ancestor. For
though the biological family is the starting-point of the community,
it does not of course follow that wherever there is so much coherence
between parents and offspring as to form a temporary family group, a
social community must in due course arise. In such unsocial carnivora
as the tiger, the temporary linkage of family life is strong while it
lasts. But though mankind presumably originated in a prehuman race that
had already reached some degree of social coherence, there remains
behind the question--what was the origin of this social group? And to
this question, Prince Kropotkine, in common with Darwin and Espinas,
would probably answer without hesitation, that the primeval germ of
the social community lay in the prolonged coherence of the group of
parents and offspring. In the unsocial animals the family separates and
disintegrates before the offspring mate. But if the family continue to
cohere, the mating of offspring will give rise to the continuity of
coherence found in the herd, or troop, or tribe. For new family groups
will be constantly arising before the old family groups have ceased to
be associated. Thus would be afforded more opportunity for tradition
than among the unsocial animals.

How, then, can it be said that, “far from being a primitive form of
organization, the family is a very late product of human evolution”?
By using the word “family” in a sense somewhat different--nay,
widely different--from that in which it is employed in a biological
discussion. In the latter usage sexual communism is not excluded; A.,
B., and C., D. may have offspring this season; A., D., and C., B.
next season. In each season there are family groups with interchange
of partners. This does not, however, conform with our conception of
the family as realized under civilization. Herein, in fact, lies the
essential difference between the human and the animal family. The one
is a realized ideal; the other is merely a natural occurrence. Even in
the case of monogamous animals, mating for life is probably not conduct
in conformity with an ideal, but is due to the fact that instinctive
tendencies have taken this line of direction. On the other hand, in
monogamous communities of mankind, there is, unfortunately, evidence
that in some cases the ideal is not strong enough to prevent presumably
ancestral tendencies in the direction of communism.

The basis of human social conduct is unquestionably to be traced
in the social behaviour of animals, in inherited tendencies to
co-operation and mutual help, in the bonds of sympathy arising through
the satisfaction of impulses towards such behaviour, and perhaps, to
some extent, in the influence of tradition. It is not, however, until
this tradition is rendered, through descriptive communication, more
continuous and more effective; it is not until an ideal of mutual
aid, and social conduct generally, takes form and is rendered common
to the tribe; it is not until the more or less realized conceptions
of one generation are handed on to become the environment under which
the succeeding generations are nurtured; it is not indeed until man
consciously and reflectively aims at the bettering of his environment
in accordance with standards rationally conceived and deliberately
carried into execution; that a new _régime_ of civilized progress,
elsewhere unknown in nature, takes definite form. Under this _régime_,
the elimination of failures through natural selection, though it may
not be entirely superseded, plays a subordinate part; alongside the
organic continuity which is due to physical heredity, there runs a
continuity of tradition through social inheritance.

Human civilization is an embodiment of reason, a product of reflection,
a realization of ideals conceived by the leaders of mankind. All this
forms the environment of each one of us. And it is this environment
which is undergoing progressive evolution and playing on the rational
faculties of those which are submitted to its moulding influence.
There is no sufficient evidence of anything of the kind in the social
communities of animals. This, of course, must be accepted merely as an
expression of opinion. But on the hypothesis that animals are rational
beings, capable of reflection, it is difficult to understand why they
should remain at so low a level of social achievement. The absence
of powers of descriptive intercommunication is often assigned as the
cause of their comparatively unprogressive condition; but it may be
regarded as the sign, rather than the cause, of their lack of reason in
the more restricted sense of the term. We cannot, however, enter into
the much-disputed question whether reason is the product of language,
or language the outcome of reason. Perhaps the safest position is to
assume that rationality and true speech are in large measure different
aspects of one evolutionary movement--speech arising out of such
preceding modes of communication as were considered in the second
section of this chapter; reason developing out of intelligence which
supplies its necessary data. It is sometimes said that, notwithstanding
their powers of speech, savages in their social relations show little
advance on animal communities. But surely such statements must be made
in forgetfulness of the fact that savage customs almost invariably
indicate the presence and sway of ideals which puzzle us from their
quaintness, and from the fact that they seem contrary to the dictates
of intelligence and due to motives and conceptions the nature and force
of which we find it difficult to estimate. The passage from intelligent
social behaviour to the rationality which has assumed such strange
aspects among existing savages took place somewhere at some time in the
past; and the stages of its evolution are hidden from our view. All
we can say is, that it is possible to trace in animal behaviour some
of the instinctive tendencies and intelligent modes of accommodation
to social circumstances, together with the germs of imitation,
intercommunication, and tradition, and the establishment of bonds of
sympathy, without which the subsequent stages of evolution would be
inconceivable.

CHAPTER VI

_THE FEELINGS AND EMOTIONS_

I.--IMPULSE, INTEREST, AND EMOTION

Any discussion of animal behaviour must deal largely with what is
termed the conative aspect of consciousness. “The states designated by
such words as _craving_, _longing_, _yearning_, _endeavour_, _effort_,
_desire_, _wish_, and _will_,” says Dr. Stout, in his admirable “Manual
of Psychology,”[117] “have one characteristic in common. In all of
these there is an inherent tendency to pass beyond themselves and
become something different. This tendency is not only a fact, but an
experience; and the peculiar mode of being conscious, which constitutes
the experience, is called _conation_.” Closely associated with this
conation is _impulse_, which Dr. Stout defines as “any conative
tendency, so far as it operates by its own isolated intensity, apart
from its relation to a general system of motives. Action on impulse
is thus contrasted with action which results from reflection and
deliberation.”[118] In the interpretation we have advocated, animals
are essentially creatures of impulse, and not to any large extent,
if at all, reflective agents. And their impulses may be associated
either with their inherited and congenital behaviour, or with that
which is due to acquired experience. In other words, their impulses may
be divided broadly into two classes, the one instinctive, the other
acquired.

Dr. Stout says that conation is not only a fact, but an experience.
Now, first as to the fact. It seems to be the correlative in
consciousness of the behaviour of the nervous system under stimulation.
Let us take some simple case such as that, for example, of a hungry
chick pecking at a grain of corn. This is explained from the
physiological point of view by saying that internal and external
stimulation--internal from the digestive organs and system in need
of food, external through the eye--gives rise to a state of unstable
equilibrium in the nerve-centres; and that, when the instability
reaches a certain value, the nervous system discharges into the
motor organs, the chick pecks, and stable equilibrium is restored.
The tendency to discharge in some way under stimulation is an
essential characteristic of a nervous system. It is one of the facts
of physiological science. So, too, the conative tendency is one of
the facts of psychological science; it is a change in the situation
introduced by the effects of the physiological discharge.

Let us here parenthetically notice that the physiological tendency
in the nervous system is an evolved complication and a specialized
development of one of the fundamental properties of protoplasm--that
which is often spoken of as irritability. One of the characteristics
of all living matter is its “explosive” instability. So that at the
very threshold of organic behaviour we have the analogue of that which,
in its developed form, becomes the tendency of the nervous system to
discharge as the result of stimulation. The conative tendency of the
psychologist, therefore, has its roots deep down in the elemental germs
of all organic life.

And this conative tendency is, says Dr. Stout, not only a fact but an
experience. Let us return to our hungry chick that pecks at a grain of
corn. And let us grant that as the result of stimulation there arise
states of consciousness which we describe as a feeling of hunger and
the sight of the grain of corn. The nervous system now discharges;
and there are introduced into the situation a further group of data,
the motor consciousness of the actual behaviour, sensory data from
the results of the act, the seizing of the grain and so forth. The
situation has unquestionably changed. But is there any specific
consciousness of the conative tendency as such? Is there any “peculiar
mode of being conscious which constitutes the experience which is
called conation”? It is difficult to say. Hence we find differences of
opinion among psychologists as to what, from the psychological point
of view, the impulse actually is. Is it simply the conscious situation
prior to the response? Is it a feeling of the change from the initial
to the succeeding phase? Or are new data introduced apart from those
afforded by stimulation on the one hand and response on the other? We
will not attempt to decide. Without determining its exact nature we
may rest content with the very general statement that impulse is a
concomitant of a change in the conscious situation.

There is, however, a use of the term concerning which it seems
necessarily to enter a word of protest. Impulse is by some regarded as
the underlying cause of the conative tendency. Now science, as such,
has nothing whatever to do with underlying causes. If, as a matter
of observation and inference, we have reason to believe that there
is such a tendency, science simply accepts the fact, and endeavours
to formulate the conditions under which it arises, and to trace its
observed or inferred antecedents. No doubt many of us find it difficult
or impossible to rest content with the strictly scientific position,
that of unquestioning acceptance of the facts of nature as we find
them given in experience. We say: Here is an observed tendency the
conditions and antecedents of which are described by science. But what
causes the tendency; what is the impelling force? Now to such questions
science can give no answer. Science deals with phenomena, and tries to
tell us all about their conditions and their antecedents. But whenever
Science is asked: “What is the underlying cause of the phenomena,--that
which calls them into being?” Science should always give one answer
and one only: “Frankly, I do not know; that lies outside my province;
ask my sister Metaphysics.” Science ought to have nothing whatever to
do with force as the underlying cause of anything in this universe of
phenomena. And impulse, as the impelling force which calls a conative
tendency into being, is a metaphysical, not a scientific conception.

We need not further discuss the psychological nature of impulse.
Indeed, the little that has been said would not have been necessary
to our inquiry were it not that we frequently have occasion to speak
of animals as “creatures of impulse,” and to refer to their behaviour
as due to impulse. What do we mean by such expressions? If we regard
conative tendency as a fact (whatever may be said for or against its
being also a specific experience), and if this fact is the tendency
of the conscious situation to develope in certain definite ways, then
we may define _impulse_ with sufficient clearness by saying, with
Dr. Stout, that it is characterized by being unreflective. Conative
tendency thus comprises two categories--impulse and volition; the one
unreflective, the other involving deliberation.

Before passing on to consider how impulse is partly determined by the
feeling-tone and the emotional attributes of the conscious situation,
we may first draw attention to the important way in which the results
of conative tendency afford the data through which consciousness
attains its unity in the midst of diversity of experience.

We said that the impulses might be divided broadly into two
classes--the one instinctive, the other acquired. Now, from the
point of view suggested by a study of behaviour, if not also, as I
am disposed to think, from the more general standpoint of a genetic
study of mental development, it is convenient to start with the
instinctive act and the conscious situation it implies. We have here
a piece of experience which, if we may so phrase it, hangs together;
in which experience of things in the environment is included in the
same elemental synthesis with that of bodily acts in organic relation
to these things. It is closely linked, on the one hand, with a
foregoing act of attention, itself of the instinctive type; closely
linked, on the other hand, with the results of behaviour through
which the environing things call forth a new conscious situation
and evoke a further response. Thus not only does the experience of
an instinctive act hang together, but a series of such acts do so
likewise. And coalescent association not only links and groups the
elements within the situation called forth by the single act, but
comprises also the elements of the developing situation afforded
by the whole series. We see this in the young chick, where, as the
result of experience, attention is emphasized where the material is
palatable, and lapses where it is nauseous--such nauseous substances
being soon ignored. Furthermore many environing things appeal in
different ways to the same limited number of sense organs, while the
same motor organs respond in different ways in successive modes of
instinctive behaviour. The same brain forms the physical basis of
varied situations overlapping in many ways, and receives afferent
messages from the same body. Hence, in its organic unity it affords
the conditions for an underlying stratum of mental unity, amid all
the diversities of experience; while the multiplicity of messages
on the one hand from external things, and on the other hand from
internal happenings, lays the foundations of a differentiation between
the external world and the self--a differentiation long to remain
implicit, and only to be rendered explicit on a far higher level of
mental development. For at this early stage, and perhaps throughout
animal life, “there is no single continuous self contrasted with a
single continuous world. Self, as a whole, uniting present, past, and
future phases, and the world as a single coherent system of things and
processes, are ideal constructions, built up gradually in the course
of human development. The ideal construction of self and the world
is comparatively rudimentary in the lower races of mankind, and it
never can be complete. On the purely perceptual plane [with which we
are now dealing] it has not even begun.”[119] But though the ideal
constructions of self and the world have not, as Dr. Stout says,
at this stage, even begun, yet, as the same author observes,[120]
“animals distinguish in the environment, and treat as a separate thing,
whatever portion of matter appeals to their peculiar instincts, and
affords occasion for their characteristic modes of activity.” And this
differentiation of specially interesting things from each other, and
from their relatively uninteresting surroundings, must be accompanied
by some differentiation of these things from themselves as affected
by them and reacting to them. So that here, as we have seen to be the
case in other matters, what is commonly called the perceptual life of
animals affords the rough-hewn materials from which ideal constructions
may be elaborated by rational beings.

We cannot here attempt to do more than barely indicate the manner
in which the perceptual process in animals may acquire unity and
diversity--unity through the functioning of the same brain and body,
diversity from the different modes of functioning and the differential
effects of diverse modes of stimulation. The interesting point for us
in our special inquiry is that it is through behaviour that all this is
brought about.

As we interpret the facts, the restless activity of the young is
primarily a biological fact, and is to be dealt with as an organic
problem--a complication of the fundamental irritability of protoplasm.
But it is also an essential condition to the acquisition of conscious
experience; and the more there is of it in varied modes the wider is
the range of the data afforded to consciousness. Congenital behaviour
is thus the goal of organic heredity, and the starting-point of
conscious accommodation and adjustment; it is the biological end of
variation, and affords the means to intelligent modification.

So much for some of the results of conative tendency. Not only does
it secure adaptation or adjustment to the environment, but it affords
the conditions of mental development by which further accommodation is
rendered possible. But, in addition to the attainment of biological
ends, in addition to the furtherance of survival in the struggle for
existence, mental development has another aspect. All sensory data,
whether from the special senses, from the motor processes concerned in
responsive behaviour, or from other sources, may, and perhaps always
do, carry with them some amount of what is termed _feeling-tone_,
giving rise to a net result in consciousness which we call pleasure
or the reverse. Pleasure or satisfaction--however we name that which,
though vague and indeterminate in outline, is a very real attribute
of the conscious situation--affords its sanction to certain modes of
conation, and may thus be regarded as the psychological end of their
continuance or their repetition. It is partly, no doubt, a direct
adjunct of sight, hearing, taste, and so forth, and of smooth and
easy movements of the body and limbs; but it is partly due to a great
body of stimulation coming from many parts of the organic system. The
blood-vessels are dilated or contracted, the heart’s action increased
or diminished; respiration is deepened or the reverse, and its rhythm
may be altered; glands are thrown into a state of activity; the tone of
the muscles is affected, and there may be either incipient contraction
or relaxation. These are primarily organic effects; but they influence
the conscious situation, and are themselves suffused with feeling-tone.
For, from all the parts so affected, messages are carried in to the
brain, and such afferent messages afford data to consciousness. It may
be that the experience of the conative tendency, for which Dr. Stout
and others claim a distinctive place in consciousness, is largely due
to afferent messages from the motor organs incipiently innervated in
preparation for the behaviour which follows. In any case these probably
form very important elements in the conscious situation antecedent to
the actual response. In what we may term motor attention--the state
well exemplified by a cat in the strained pause which precedes the
spring on to the prey, or in ourselves when we poise before a dive
or hold the billiard cue in preparation for a delicate stroke--this
incipient innervation, felt through afferent messages from the parts
thus braced for action, enters with much distinctness into the
conscious situation. In sensory attention, on the other hand, reflex
acts have actually taken place, having for their end and purpose the
focussing of the sense organs on the object which stimulates them,
so that in this way further and more effective stimulation may be
received. But, as the sense organ is steadily held to the focus, and
made effectually to cover the stimulating thing, the motor apparatus
concerned is kept on the strain, and is all the while contributing data
to the conscious situation.

In primary genesis attention, both motor and sensory, is unquestionably
organic and reflex in its nature. It is a product, and an invaluable
product, of biological evolution. Without this as a basis, the higher
forms of attention under conscious guidance would be impossible. For
all these higher forms are modifications and complications of what is
given in organic heritage. Here, as elsewhere throughout the whole
range of behaviour, consciousness only guides to finer issues what is
presented to it in rough outline, or in isolated fragments, as the
outcome of biological evolution. But the organic responses afford
the data which consciousness uses that it may mould and fashion the
behaviour so as to reach higher and more complex modes of adjustment.

Lest a familiar form of words should give rise to misapprehension,
it may here be stated that, when we say that consciousness moulds
and fashions behaviour, we do not intend to imply that consciousness
is an underlying cause. We are not using the term consciousness in
a metaphysical sense. We mean that consciousness is the expression
of certain conditions under which behaviour is guided. Instead of
saying, therefore, that consciousness utilizes certain sensory data,
it would be more correct to say that it _is_ the sum-total of these
data which are the psychical expression of certain brain conditions
under which behaviour, as a matter of fact, takes a given set or
direction. We use the word consciousness, then, not in its metaphysical
sense of an underlying cause or force, but in its scientific sense,
as the concomitant of certain antecedent conditions. Our common modes
of speech lend themselves with misleading facility to metaphysical
assumptions, all the more insidious since they are not consciously
acknowledged as such. And not only what we comprise under the broader
group-name “consciousness,” but what we include under narrower
group-names, such as “impulse,” “volition,” “instinct,” “intelligence,”
“reason,” and the like, often do duty as underlying causes of the
phenomena, which, from the scientific point of view, they do no more
than name.

We often say, for example, that _interest_ guides behaviour in this
direction or in that. But such interest must not be regarded as an
impelling force; it is an attribute of the conscious situation, more or
less suffused with feeling-tone. It is not easy to define; but it seems
to take on its distinctive character when re-presentative elements
contribute what Dr. Stout[121] terms “meaning” to the conscious
situation. The meaning in the early stages of mental development is,
however, merely perceptual, and not that which comes much later--that
which is implied in the phrase “rational significance.” In the chick
which has tasted a cinnabar caterpillar the situation evoked by the
sight of this larva has meaning in virtue of the actual experience.
But, in this case, the meaning is not conducive to continued interest,
since it checks, rather than stimulates, behaviour. At first, indeed,
there may be the repellent interest of aversion. But this passes by,
and the larvæ are soon ignored. Small worms also acquire meaning, and
here the interest is attractive, and is stimulated afresh each time
the meaning is reinforced by repetition of the act of seizing and
swallowing.

We have seen that it is through behaviour that things become
differentiated from their surroundings, and acquire relative
independence in experience. It is through behaviour that what we have
termed conscious situations develop. The thing is the centre or nucleus
of a developing situation--that which starts the behaviour, and towards
which the behaviour is directed; or, since the behaviour may be that
of avoidance or escape, we should, perhaps, rather say, it is that to
which the behaviour has reference. Now, if interest is the feeling-tone
attaching to the whole attentive situation, and if the nucleus of the
situation is the thing, it naturally follows that the thing becomes
the centre of interest. The mouse is a centre of absorbing interest to
the cat, her eggs to the mother-bird, his mate to the sparrow in the
spring. Companions are centres of abiding interest to social animals,
because they are also the centres of social behaviour and the conscious
situations arising thereout; because they evoke in special ways the
attentive situation.

The differentiated thing being thus a centre of interest, a relatively
fixed nucleus in a changing conscious situation, the development of
which is due to behaviour, there can be no question that, among social
animals, the companion becomes a peculiar and specialized centre.
Around him develops a particular type of behaviour. Towards him the
reactions are of a quite distinctive kind. Mother and offspring, mate
and mate, are reciprocal centres of interest. To the offspring the
parent is a common centre of interest. As they grow up together, what
is of interest to one is likewise of interest at the same time to
others. Imitation begets similarity of conscious situations. In many
ways such community of interest is fostered; and through this community
of interest the conscious situations acquire their distinctively social
character. Not only is the companion, as the nucleus of a situation,
a thing which reacts in altogether special ways, so that it becomes
differentiated from other things as something the meaning of which,
and the interest in which, are _sui generis_ and unique in type; but
it enters into other situations in ways that are also peculiar and
characteristic. A worm is thrown to a couple of chicks, and is to each
a centre of interest--the nucleus of a situation involving appropriate
modes of behaviour. But into this situation there enters for each of
them, in a quite peculiar and distinctive way, the action and behaviour
of the other chick. The situation is complicated by the introduction of
a second centre of interest, and the behaviour has reference to both
centres. Instead of quietly and leisurely dealing with the worm in
accordance with its special meaning, as it does when there is no rival
in the field, the chick darts at it, and bolts with it in accordance
with the special meaning which its neighbour’s presence, under such
circumstances, has acquired. And this different behaviour carries with
it a felt difference in the conscious situation--the interest of which
is centred in the companion. Or take the case of a herd of cattle,
which attacks a common enemy. The enemy is the primary nucleus of the
situation, but it is profoundly modified by the presence of companions
by which the behaviour of attack is determined. The situation is
social, and not merely individual, and a social interest suffuses it,
and gives it a distinctive character.

In this social interest probably arise the germs--but only the
germs--of the sense of personality. Some, indeed, go so far as to
urge that we learn to know ourselves only through knowing others. The
genetic order, so far as there is an order, is, they say, not first
the ego and then the alter, but first the mother and companions and
then through them the self. Or, to put this point of view in a less
questionable form, it is only through the reaction of one on the other
that the two are differentiated. Be this as it may, it is only through
the action of environment on the organism, and the reaction of the
organism on the environment in behaviour, that experience becomes
polarized into subject and object. Let it be clearly understood that
for the animal, in all probability, subject and object are not clearly
distinguished, and set over against each other in the antithesis of
thought. Only late in mental development are the self and the world
distinguished in subtle analysis as different aspects of the common
experience in which both have their inseparable being. Animals, and
perhaps the majority of mankind, never trouble themselves about object
and subject as clearly realized products of conception and reflective
thought. For these concepts are exceedingly subtle. And here, too, the
external aspect of experience has the precedence, so far as there is
precedence. A healthy lad from the moment he gets up in the morning
till the moment he goes to bed, lives chiefly in the objective aspect
of experience, an aspect which is in us chiefly associated with the
products in consciousness of the leading senses of sight and hearing.
But the subjective aspect creeps in when he is hurt, when he is hungry,
when he is fatigued. He does not argue about the matter, or formulate
it in definite terms. He just dimly feels that the interest has
somehow shifted. Still more dimly does the animal feel that, apart from
external interests which prompt nine-tenths of its behaviour, chiefly
through the senses of sight, hearing, and smell, there are also matters
in which the interest has somehow shifted to his own body. For the germ
of self is essentially an embodied self. And perhaps the emotions,
which ring through the system for some time after the external cause
has been removed, serve in some degree to aid in this dimly felt
shifting of interest.

Whatever may be the exact psychological nature of the emotions--and
there has been much discussion of the question--it may be regarded
as certain that they introduce into the conscious situation elements
which contribute not a little to the energy of behaviour. They are
important conditions to vigorous and sustained conation. And so
closely interwoven are these elements with the whole situation in
its impulsive aspect, that their disentanglement, in psychological
analysis, is a matter of extreme difficulty. I have elsewhere[122]
devoted some space to the consideration of the matter. I there follow
Professor William James in regarding organic effects, other than motor
sensations, as specially characteristic of the emotions in their
primary genesis. The cold sweat, the dry mouth, the catch of the
breath, the grip of the heart, the abdominal sinking, the blood-tingle
or blood-stagnation--these and their like, in varied modes and degrees,
characterize the emotions of fear, dread, anger, and so forth, when
they rise to any pitch of intensity, and contribute largely to their
sharpness and piquancy. These organic effects may be regarded as part
of the private and individual business of the body; but in experience
they closely coalesce with the motor effects through which the animal
has to deal in practical behaviour with that which evokes the emotion.

On this view these organic states which contribute characteristic
elements in the emotional consciousness are due to afferent data from
the vascular system and visceral organs, just as motor consciousness
is due to afferent data from the parts concerned in overt behaviour.
But, associated with emotional states, there are also certain motor
reactions, which we speak of as their “expression”--so carefully
discussed and elucidated by Darwin,--and these unquestionably
contribute data to consciousness which coalesce with those afforded
by the visceral and vascular elements. The whole is commonly suffused
with feeling-tone, and the object which excites the emotion is a
centre of pleasurable or painful interest. Representative elements, as
experience develops, crowd into the conscious situation and render it
more complex. And in addition to all this, there is, apart from the
motor expression, the strenuous behaviour of flight or attack, or other
mode of vigorous procedure which we commonly speak of as the outcome
of the emotional state. The conscious situation, in the case of an
enraged or scared animal actually behaving as such, is thus exceedingly
complex. And it should be understood that in urging the importance of
vascular and visceral elements, this complexity is nowise denied. What
is suggested is that these elements are essential, and that they serve
to characterize the distinctively emotional factor in the situation,
that in any case they heighten the conative tendency.

Sufficient has now been said to indicate--but scarcely more than
indicate--the importance of feeling-tone, interest, and emotion
in determining the nature, character, and effective energy of the
conscious situations which arise in the course of animal behaviour.
They largely influence, and in part direct, the course of the conative
tendency. But they also occur as its sequel. In animal, as in human
life, the successful attainment of the end towards which conation
sets is highly pleasurable. The equilibrium that is reached after
instability, though it marks the close of present endeavour, leaves
after-effects in consciousness in a sense of satisfaction which enters
re-presentatively into later situations and helps to further more
strenuous endeavour.

II.--PLAY

“There are two quite different popular ideas of play,” says Professor
Groos, in his admirable work on “The Play of Animals.” “The first is
that the animal (or man) begins to play when he feels particularly
cheerful, healthy, and strong; the second that the play of young
animals serves to fit them for the tasks of later life.” The former
view, in which the latter may be included incidentally as a result, is
closely associated with the names of Schiller,[123] who suggested it,
and of Mr. Herbert Spencer,[124] who developed it. Mr. Wallaschek[125]
expresses the conception briefly and clearly when he says, “It is the
surplus vigour in more highly developed organisms, exceeding what is
required for immediate needs, in which play of all kinds takes its
rise, manifesting itself by way of imitation or repetition of all those
efforts and exertions which are essential to the maintenance of life.”
That surplus vigour is often a condition favouring the manifestation
of play is probable enough, and seems to be supported by observation
and experience; but that it is likewise a condition favouring the
chase, combat, mating, and much of the serious business of animal life
seems equally unquestionable. Success in all these matters is largely
determined by overflowing energy. In play, however, this surplus vigour
finds vent when there is no serious occasion for its exercise. But, as
Professor Groos says,[126] “while simple overflow of energy explains
quite well that the individual who finds himself in a condition of
overflowing energy is ready to do something, it does not explain how
it happens that all the individuals of a species manifest exactly the
specific kind of play expression which prevails with their own species,
but differs from every other.” And if to this it be replied, that the
specific kind is determined by repetition or imitation of what we have
called the serious business of animal life, Professor Groos’s rejoinder
is,[127] that “the conception of imitation here set forth--namely,
as the repetition of serious activities to which the individual has
himself become accustomed--cannot be applied directly to the primary
phenomena of play--that is, to its first elementary manifestations”
prior to any experience of these serious activities. The repetition
(with a difference!) is in such cases not the re-enactment of what has
been previously performed in full earnest by the individual, but rather
the reappearance in the young of ancestral modes of procedure--in
other words, its specific character is such because it is a piece of
instinctive behaviour or arises from instinctive proclivities. And this
is the central point of the interpretation elaborated with great skill
and candour by Professor Groos. Play is instinctive; and its biological
value lies in the training it affords for the subsequent earnest of
life.

Before leaving the surplus energy theory of play one more point
made by Professor Groos may be mentioned. He contends that, though
superabundant energy is a favouring condition of animal play (as it
is, indeed, of all animal behaviour), still it is not a necessary
condition. Animals often play when they are tired out. “Notice a kitten
when a piece of paper blows past. Will not any observer confirm the
statement that, just as an old cat must be tired to death or else
already filled to satiety if it does not try to seize a mouse running
near it, so will the kitten, too, spring after the moving object,
even if it has been exercising for hours and its superfluous energies
are entirely disposed of? Or observe the play of young dogs when two
of them have raced about the garden until they are forced to stop
from sheer fatigue, and they lie on the ground panting, with tongues
hanging out. Now one of them gets up, glances at his companion, and
the irresistible power of his innate longing for the fray seizes him
again. He approaches the other, sniffs lazily about him, and, though he
is evidently only half inclined to obey the powerful impulse, attempts
to seize his leg. The one provoked yawns, and in a slow, tired kind
of way puts himself on the defensive; but gradually instinct conquers
fatigue on him too, and in a few minutes both are tearing madly about
in furious rivalry until want of breath puts an end to the game. And so
it goes on with endless repetition, until we get the impression that
the dog waits only long enough to collect the needed strength, not till
superfluous energy urges him to activity.”[128]

Coming now to Professor Groos’s interpretation of play, we find in it,
perhaps for the first time in the literature of the subject, adequate
stress laid on its biological value. “The play of young animals,” he
says,[129] “has its origin in the fact that certain very important
instincts appear at a time when the animal does not seriously need
them.... Its utility consists in the practice and exercise it affords
for some of the more important duties of life, inasmuch as selection
[in the higher animals] tends to weaken the blind force of instinct,
and aids more and more the development of independent intelligence as
a substitute for it. At the moment when intelligence is sufficiently
evolved to be more useful in the struggle for existence than the most
perfect instinct, then will selection favour those individuals in
whom the instincts in question appear earlier and in less elaborated
forms--in forms that are merely for practice and exercise,--that is
to say, it will favour those animals which play.... Animals cannot be
said to play because they are young and frolicsome, but rather they
have a period of youth in order to play; for only by so doing can
they supplement the insufficient hereditary endowment with individual
experience, in view of the coming tasks of life.”

Some stress is here laid on the fact that important instincts appear
at a time when the animal does not seriously need them. It seems to
imply the doctrine of what biologists term “acceleration”--which means
the development of an organ or mode of behaviour at an earlier period
in the descendants than that at which it appeared in the ancestors.
Thus the adult fighting or hunting instinct of past generations appears
in the young to-day as a fighting-play or a hunting-play. It is open
to question, however, whether either the instinctive behaviour or
the conscious situation in the one case and the other is so nearly
identical that the playful fight or hunt can fairly be called the
same instinctive procedure as the serious combat or chase. We may
hold, with Professor Groos, that the one is an invaluable preparation
for the other without identifying them as the same behaviour under
different conditions. Indeed the conditions are so different that the
identification seems strained. The question may be left open, however,
without impairing the value of Professor Groos’s suggestion. And we
may divide the preparatory behaviour in what is commonly called play
under two heads: first, general preparation for varied modes of serious
effort in after-life; and secondly, special preparation for particular
forms of this after-effort. Under the first will fall what Professor
Groos terms experimentation and movement play, including what Dr.
Stout, who fully realizes its importance, calls “manipulation”;[130]
under the second, such forms as hunting-play and fighting-play.

Nothing is more characteristic of the young of intelligent animals than
the variety and persistency of their behaviour, their sensitiveness
to stimuli of many different kinds, their restlessness of swiftly
changing attention and response, with occasional pauses of continued
effort in some special direction. Constantly on the alert, they exhibit
in all its shifting phases behaviour which we interpret as indicating
curiosity, inquisitiveness, love of mischief, destructiveness, and so
forth. The facts are so familiar to every observer of young animals
that it is unnecessary to give any detailed illustration. Watch
a kitten in this stage of its development and carefully note its
behaviour during half an hour; the variety of effort, the _rôles_
played by trial, failure, and success, the gain of skill and control
over behaviour, will at once be evident. Or devote an equal space of
time to observing young jays, magpies, or jackdaws. Every projecting
piece of wire or bit of wood in their cage is pulled at this way and
that way, from above, from below, from the side. Now one, then another,
loose object is picked up and dropped, turned over, carried about,
pulled at, hammered at, stuffed into this corner and into that, and
experimented with in all possible ways. Then the wise bird goes to
sleep, and wakes up again only to resume with new zest its persistent
and varied efforts, by which it becomes acquainted with all the details
of its environment. Watch young birds on the wing gaining their
mastery of the air in flight, young seals tumbling in the water, young
foals scampering and kicking up their heels in the meadows. A little
observation, as occasion serves, a little attention to the progress
towards an adequate experience of the meaning of things, towards
more complete control, and increased nicety of behaviour, whether in
reference to their surroundings, or in powers of finished locomotion,
will serve to bring home what Professor Groos includes under
experimentation and movement plays. He regards it all as play, since it
seems to have no serious end, and is just a preparation for the sterner
realities of adult life. And for human beings, whose work is so largely
enforced, the freedom and evident joy of it all suggests the play which
has acquired for us the meaning of relaxation from irksome effort, and
glad abandonment to less constrained modes of behaviour. But in young
animals such play is, after all, the serious business of their time of
life. Its import for their future welfare can scarcely be overestimated.

And its import is in large degree psychological. If we watch a young
puppy or kitten learning gradually to deal effectively with some
difficulty in its extending environment, we see that it puts forth its
efforts at first in a somewhat random and indefinite fashion. It is one
of those animals in which intelligence has been evolved to supersede
and become the more plastic substitute for instinct. The random and
indefinite movements, are in detail reflex responses to stimuli.
But whereas, in a piece of highly elaborated instinctive behaviour,
such reflexes are grouped into a whole which is co-ordinated through
inherited nervous mechanism; in the case of the acts of the puppy
or kitten they have to be further co-ordinated, or more elaborately
grouped, through experience. To act in one way some of the reflexes
have to be checked as redundant and not to the point: to act in another
way other reflexes have to be similarly checked; and in a third way,
yet others. But in all three some of the reflexes are utilized to
different ends. Many conscious situations contain common elements; and
this tends to give unity to the developing experience. But they contain
also elements and groupings which afford that diversity without which
conscious behaviour could not be accommodated to them. So that we
have here the conditions under which what is technically termed “the
concomitant differentiation and integration of experience” can proceed.

And if we speak of the instinct of experimentation we must remember
that what we are dealing with is rather an innate tendency or
instinctive propensity than a definite and relatively clean-cut piece
of instinctive behaviour. It comprises a great number of inherited
reflex acts, and may perhaps be fairly called instinctive in detail.
But experimentation must be regarded rather as the proximate end of
a conative tendency, or group of conative tendencies, whose ultimate
biological end is success in dealing with the environment in the
sterner struggle for existence during adult life. The tendency
is inherited, and therefore falls under the head of instinctive
propensity. But “experimentation” is a group-term under which we
comprise the general drift of varied modes of behaviour, founded indeed
on a congenital basis, but receiving its stamp and character from
what is acquired in the course of the experience it provides. It is
essentially a process whereby the conscious situations acquire what
Dr. Stout terms meaning; and is specially interesting as affording an
example of the way in which intelligence moulds and refashions a number
of disconnected reflex responses. And if, following Professor Groos,
we call it play, it is a little difficult to see how it can be brought
in line with his statement[131] that “the play of youth depends on
the fact that certain instincts, especially useful in preserving
the species, appear before the animal seriously needs them.” Does
experimentation occur before it is needed in the economy of animal
behaviour? And might we not with equal truth say that the play of youth
depends on the fact that certain acquired habits, especially useful in
preserving the species, are gained before the animal seriously needs
them?

Passing now to those forms of play which afford more special
preparation for particular forms of after-effort, under which fall
such types as hunting-play and fighting-play, we may refer the reader
to the copious examples so carefully collected by Professor Groos.
The way in which a kitten pats a cork or a ball, making it roll and
then pouncing upon it, is a characteristic example of animal play.
Valuable as a preparation for dealing successfully with a mouse when
occasion shall arise, this is a specialized form of experimentation;
and it is more obviously in line with the hunting-behaviour of later
life than is general experimentation with any particular modes of
future behaviour. Still it is essentially experimentation, with the
instinctive propensity setting in more definite channels. Its value
lies in the acquisition of skill under circumstances easier than those
presented in the serious chase. So, too, in the case of the playful
tussles of puppies or in that of the kitten, which not only shows
playful fight to its brothers and sisters, but also to its mother,
who responds by holding down the struggling and scratching little
creature. Unquestionably, there is an instinctive propensity; much of
the detail, and some of the grouping, exhibit inherited reflexes due to
special modes of stimulation. No doubt many of these responses occur
in a similar but more emphatic way in a serious fight, and yet we may
hesitate before committing ourselves to the theory of acceleration.
It is at least equally probable that play as preparatory behaviour
differs in biological detail (as it almost certainly does in emotional
attributes) from the earnest of after-life, and that it was evolved
directly as a preparation, as a means of experimentation through which
certain essential modes of skill were acquired,--those animals in
which the preparatory play propensity was not inherited in due force
and requisite amount being worsted in the combats of later life, and
eliminated in the struggle for existence. For, in the preparatory
tussles and squabbles and playful fights of young animals, experience
is gained without serious risk to life and limb.

The modifications of Professor Groos’s biological interpretation of
play which we would suggest are so slight that we may be said to accept
it almost unreservedly. The play of youth, we may urge, depends on
instinctive propensities to experimentation in varied ways, some of
more general and others of more special import; and the value of such
experimentation lies in the fact that it is a means of acquiring,
under circumstances more easy and less dangerous than those of sterner
life, experience and skill for future use. In a word, play depends on
instinctive propensities of value in education.

Passing now to a brief consideration of the feelings and emotions
which we may suppose to accompany play, we may place first those which
characterize, from this point of view, general experimentation. We have
here rapidly varying situations charged with conative impulse, the
satisfaction of which must bring pleasure--the occasional thwarting
of which is probably toned with the opposite--the latter serving,
through contrast, to enhance the satisfaction of ultimate success. Both
pleasure and its antithetical state of feeling are primarily matters of
the conscious situation as a whole, and even in ourselves are difficult
to distribute in analysis. But assuredly no small share of the total
product must be assigned to the successful behaviour which consummates
the conative tendency. Indeed, it is the thwarting of free action which
is the source of much of the discomfort of the young. Unimpeded and
vigorous behaviour also brings with it secondary effects in organic
processes--fuller heart-beat, freer circulation, deeper respiration,
better digestion, firmer muscular tone, and so forth--which have a
marked effect on the conscious situation, and aid in producing that
emotional tone which cannot, perhaps, be named in better terms than
“good spirits” and the joy of existence, so forcibly suggested during
the free play of youth. On the other hand, there is no more piteous
sight than that afforded by the young animal, “cabined, cribbed,
confined,” suffering from _ennui_ and depression--all its organic
processes sluggish and craving to be quickened into the natural vigour
of life, not creeping slowly through the veins, but coursing at full
flood.

In the psychological aspect of play Dr. Groos assigns perhaps the first
place to pleasure in the possession of power, or, as Preyer phrases
it, pleasure in being a cause. We must be careful, however, lest in
using such expressions we seem to imply that animals--even quite young
animals--are capable of entertaining ideas which belong to a much
later stage of mental development. Speaking of “joy in ability or
power,” Professor Groos says,[132] “This feeling is first a conscious
presentation to ourselves of our personality as it is emphasized by
play.... But it is more than this; it is also delight in the control
we have over our bodies and over external objects. Experimentation
in its simple as well as its more complicated forms is, apart from
its effect on physical development, educative in that it helps in the
formation of causal associations.... The young bear that plays in the
water, the dog that tears a paper into scraps, the ape that delights
in producing new and uncouth sounds, the sparrow that exercises its
voice, the parrot that smashes his feeding trough--all experience
the pleasure in energetic activity, which is, at the same time, joy
in being able to accomplish something.” But those who agree with Dr.
Stout, as I do without hesitation, in denying personality (save in a
very embryonic condition) and the conception of causation to animals
in the perceptual stage of mental evolution, though they may find in
Dr. Groos’s contention a central core of truth, will be unable fully
to accept his manner of presenting it. “Any single train of perceptual
activity,”[133] says Dr. Stout, “has internal unity and continuity.
But where conscious life is mainly perceptual, the several trains of
activity are relatively isolated and disconnected with each other. They
do not unite to form a continuous system, such as is implied in the
conception of a person. We must deny personality to animals.” To this
I would merely add that, even where perceptual continuity in animals
reaches its maximum, it is not reflectively grasped as a whole, and the
ideal construction of the personal ego is not conceived as antithetical
to the impersonal world of objects. With what Dr. Stout says about
causality I am in complete agreement. “We must notice,”[134] he urges,
“the essential difference which separates the merely perceptual
category from that of ideational and conceptual thought. The perceptual
category is always purely and immediately practical in its operation.
It is a constitutive form of thought only because it is a constitutive
form of action. The question ‘Why?’ has no existence for the merely
perceptual consciousness. It does not and cannot inquire how it is
that a certain cause produces a certain effect. It does not and cannot
endeavour to _explain_, to analyze conditions so as to present a cause
as a _reason_. It does not compare different modes of procedure or
different groups of circumstances, so as to contradistinguish the
precise points in which they agree from those in which they disagree,
and in this way to explain why a certain result should follow in one
case and a different result in another case. Causality in this sense
can only exist for the ideational consciousness, and the development
of the ideational consciousness in this direction is a development of
conceptual thinking--of generalization.”

Wherein, then, lies the central core of truth in Professor Groos’s
contention? In the satisfaction that arises from the success of any
conative activity. We see that the animal striving and doing falls
within our conception of a cause, in the scientific sense of the
word,--a relatively constant and continuous antecedent of diverse
sequent effects. We infer that pleasure accompanies the satisfaction of
the multifarious conative impulses. The pleasure is the animal’s; the
conception of causality and of self as a continuous person, still the
same amid diversity of conscious situations, is ours. If we bear this
in mind there can be no objection to our attributing to animals joy
in ability or power. It is the pleasure derived from that successful
conation whereby animals fall into the category of causes within the
scheme of our rational thought.

In fighting-play and hunting-play, too, there arise in more specific
forms the pleasures of successful conation with the antithetical
feelings accompanying thwarted conation. And these are distinguished
from earnest, partly because the companion or the inanimate substitute
for prey is the centre of a different situation from that afforded by
an enemy or the natural object of the chase; partly by the absence of
certain insistent emotional states which characterize earnest and the
serious business of life. In fighting, this is anger. And we often see
the tendency of this to arise in the midst of fighting-plays, and at
once say that it becomes serious and passes into fighting in earnest.
Indeed, some tinge of earnest, with its fuller emotional tone, forms
part of the preparation for future life, and so far falls within the
definition Professor Groos gives of play. From which we may see that
play is not easily marked off from other forms of conation.

Brief reference to the element of “make-believe,” which Dr. Groos
assigns to the higher forms of play, may be reserved for our fourth
section; and some further discussion of its psychological aspect to the
concluding chapter.

III.--COURTSHIP

We have seen that Professor Groos regards play as the practice and
preparation for the serious business of animal life. Founded on
instinctive tendencies, it has its biological value in the acquisition
of practical acquaintance with the environment, and of skill in
dealing with it effectually. It is an education in behaviour of the
utmost service in view of the struggle for existence. It is full of
the pleasure derived from the satisfaction of innate impulse, the
success of conative effort, and the diffused sense of well-being which
accompanies a life of action, free and unrestrained. This freedom and
gladness lead us to call it play; but we must not draw the inference
that the playful animal knows that it is playing, or forms any
conception of the antithesis between work and play, which is a product
of late development.

In laying stress on the biological value of certain modes of behaviour
which we thus call play, a value which lies in the practice and
preparation they afford for life’s more earnest work, Professor Groos
deserves our hearty thanks. Nor need our thanks be less hearty if we
find that he has in some degree been anticipated by Darwin; for he has
elaborated with systematic care what Darwin suggested incidentally.
“Nothing is more common,” said Darwin,[135] “than for animals to take
pleasure in practising whatever instinct they follow at other times for
some real good. How often do we see birds which fly easily, gliding and
sailing through the air, obviously for pleasure! The cat plays with the
captured mouse, and the cormorant with the captured fish. The weaver
bird, when confined in a cage, amuses itself by neatly weaving blades
of grass between the wires of its cage. Birds which habitually fight
during the breeding season are generally ready to fight at all times;
and the males of the capercailzie sometimes hold their _Balzen_, or
_leks_, at the usual place of assemblage during the autumn. Hence it is
not at all surprising that male birds should continue singing for their
own amusement after the season of courtship is over.”

In the behaviour of courtship we have what is essentially part of the
serious business of animal life. And in including it under the heading
of “Love Plays,” Professor Groos may seem to be forgetful of his own
definition of play. He is, however, too clear a thinker not to see, and
too honest an exponent not to say, that much of the emotional behaviour
commonly regarded as courtship falls outside his main thesis “in being,
strictly speaking, not mere practice preparatory to the exercise of
an instinct, but rather its actual working.”[136] But behaviour of
a somewhat similar kind is seen in young animals before the time of
mating has arrived, and is exemplified both in young and adults under
circumstances different from those which distinguish what we may term
the pairing situation. This, at any rate, may be regarded as a form of
experimentation and practice in the arts of courtship. On different
grounds does Professor Groos attempt to justify the inclusion of actual
courtship under the head of play. For it may also, he thinks, even at
the time of its serious exercise, be to some extent artful, involving
“make believe,” and therefore playful in a somewhat different and more
subtle sense; but a brief reference to “make believe” we may reserve
for our next section.

There can be no question that special modes of behaviour often
characterize the pairing situation, and that these not only exemplify
an instinctive tendency, but from their constancy and relative
definiteness constitute types of instinctive behaviour. They would
form parts of any definition of a species founded not on structure but
on behaviour. And if animals have feelings and emotions at all--if
they are not Cartesian automata, which merely _seem_ to be guided in
their actions by consciousness--there can be but little question that
the behaviour which characterizes the sexual situation is unusually
charged with feeling-tone, and accompanied by all those adjuncts
which distinguish an emotional state, broadly considered. This matter
is of no little importance in our interpretation of the phenomena
described as courtship. Do the accompanying feeling-tone and the state
of emotional exaltation influence the behaviour, or would it run a
similar course in the absence of any such accompaniments? If, as we
can scarcely doubt, the consciousness attending the situation does
profoundly influence the behaviour, the further question arises--Is
this influence mainly the result of the presence and behaviour of an
individual of the opposite sex? To this, again, we must answer that,
so far as we can learn by observation, behaviour unquestionably is
determined by such influence in the serious business of courtship. And
then the further question arises--Is it a matter of indifference what
the appearance and behaviour of the individual of the opposite sex may
be? Are A., B., C., and the rest of the male alphabet, precisely alike
in stimulating in a similar manner, and to a similar degree, the sexual
impulse of the female? If we admit any differential influence, and if
this influence takes effect in the sexual union to which courtship is
preparatory, we so far admit the efficacy of that which Darwin termed
sexual selection.

Let us, however, before proceeding with general considerations, present
one or two examples of the facts which observation has furnished with
regard to specialized modes of behaviour at the time of pairing.
Speaking of American night-hawks, Audubon says, “Their manner of flying
is a good deal modified at the love season. The male employs the most
wonderful evolutions to give expression to his feelings, conducting
them with the greatest rapidity and agility in sight of his chosen
mate, or to put to rout a rival. He often rises to a height of a
hundred metres and more, and his cries become louder and louder as he
mounts; then he plunges downward with a slanting direction, with wings
half open, and so rapidly that it seems inevitable that he should be
dashed to pieces on the ground. But at the right moment, sometimes when
only a few inches from it, he spreads his wings and tail, and, turning,
soars upward once more.”[137] Mr. Strange, quoted by Darwin[138] says
of the satin bower-bird, “at times the male will chase the female all
over the aviary, then go to the bower, pick up a gay feather or a large
leaf, utter a curious kind of note, set all his feathers erect, run
round the bower and become so excited that his eyes appear ready to
start from his head; he continues opening first one wing, and then the
other, uttering a low, whistling note, and, like the domestic cock,
seems to be picking up something from the ground, until at last the
female goes quietly towards him.”

Darwin describes how, in the Argus pheasant,[139] “the immensely
developed secondary wing-feathers are confined to the male, and each
is ornamented with a row of from twenty to twenty-three ocelli, each
above an inch in diameter. These beautiful ornaments are hidden until
the male shows himself before the female. He then erects his tail, and
expands his wing-feathers into a great, almost upright, circular fan or
shield, which is carried in front of the body. The ocelli are so shaded
that, as the Duke of Argyll remarks, they stand out like balls lying
loosely within sockets. But when I looked at a specimen in the British
Museum, which is mounted with the wings expanded and trailing downward,
I was,” adds Darwin, “greatly disappointed, for the ocelli appeared
flat or even concave. Mr. Gould, however, soon made the case clear to
me, for he held the feathers erect, in the position in which they would
naturally be displayed, and now, from the light shining on them from
above, each ocellus at once resembled the ornament called a ball and
socket.” The primary wing-feathers are scarcely, if at all, inferior in
beauty to the secondaries, though the markings are quite different, the
chief ornament being a space parallel to the dark-blue shaft, which in
outline forms a perfect second feather lying within the true feather.
“Now the secondary and primary wing-feathers are not at all displayed,
and the ball and socket ornaments are not exhibited in full perfection,
until the male assumes the attitude of courtship.”

It is unnecessary to describe the song of birds which is generally, but
not always, at its best during the period of pairing. Bechstein, who
kept birds during his whole life, and studied them with care, asserts
that “the female canary always chooses the best singer, and that in a
state of nature the female finch selects that male out of a hundred
whose notes please her most.”[140]

Thus we are led back to sexual selection. If we are satisfied that the
males of certain species do as a matter of fact behave in specific
and distinguishable ways at the breeding season, and in presence of
their would-be mates, the question is, What, if any, is the biological
value of such behaviour? What has fostered and guided it in the course
of its evolution? From the case of the Argus pheasant, which is only
a sample of the large class of cases in which the male has special
adornments, we see that the behaviour has often direct relation to the
display of such plumage, or, in some apes, of coloured surfaces, so
that behaviour and ornamentation must be taken together. The essence
of Darwin’s contention is, that the adornments and behaviour give rise
to a situation through which the female is stimulated or excited to
accept the male; that the male in which they are best developed gives
rise to the most effective situation, produces most excitement, and
therefore has the best chance of acceptance, being “unconsciously
preferred;”[141] and that he thus begets offspring which inherit his
adornments and modes of behaviour, such inheritance being, however,
confined to the males. Thus sexual selection takes effect through
preferential mating, whereby certain hereditary traits are transmitted
and become racial characteristics. And this is brought about through an
appeal to consciousness, and seems to involve choice--generally that of
the female.

Now, as I have elsewhere urged,[142] the hypothesis of sexual selection
has often been placed in a false light by the introduction of the
unnecessary supposition that the hen bird, for example, must possess a
standard or ideal of æsthetic value, and that she selects that singer
which comes nearest to her conception of what a songster should be.
Darwin occasionally expressed himself unguardedly in the matter; he
says, for example, that the female appreciates the display of the
male, and places to her credit a taste for the beautiful.[143] But he
also distinctly states that “it is not probable that she consciously
deliberates; she is most excited or attracted by the most beautiful, or
melodious, or gallant males.”[144] This is all that is really necessary
for the theory of sexual selection. The hen accepts that mate which by
his song or otherwise excites in sufficient degree the pairing impulse;
if others fail to excite this impulse, they are not accepted. Even
Mr. A. R. Wallace, who rejects the theory save in a very subordinate
form, says[145] that “it may be admitted, as highly probable, that the
female is pleased or excited by the display,” and speaks[146] of a
possible choice of “the most vigorous, defiant, and mettlesome male,”
giving, moreover,[147] several telling examples of preferential mating.
Stripped of all its unnecessary æsthetic surplusage, at any rate so far
as this implies an æsthetic ideal, or æsthetic motive, the hypothesis
of sexual selection suggests that the accepted mate is the one which
adequately evokes the pairing impulse.

Here Dr. Groos makes an interesting and important contribution to the
subject. He lays stress on the coyness and reluctance of the female,
and illustrates it by examples derived from observation. “Thus the
female cuckoo answers the call of her mate with an alluring laugh that
excites him to the utmost, but it is long before she gives herself
up to him. A mad chase through tree-tops ensues, during which she
constantly incites him with that mocking call, till the poor fellow
is fairly driven crazy. The female kingfisher often torments her
devoted lover for half a day, coming and calling him, and then taking
to flight. But she never lets him out of her sight the while, looking
back as she flies and measuring her speed, and wheeling back when he
suddenly gives up the pursuit. The bower-bird leads her mate a chase
up and down their skilfully built pleasure-house, and many other birds
behave in a similar way. The male must exercise all his arts before her
reluctance is overcome. She leads him on from limb to limb, from tree
to tree, until it seems that the tantalizing change from allurement to
resistance must include an element of mischievous playfulness.”[148]

Professor Groos regards the instinctive coyness of the female as the
most efficient means of preventing the too early and too frequent
yielding to sexual impulse.[149] He thinks it probable that “in order
to preserve the species the discharge of the sexual function must
be rendered difficult, since the impulse to it is so powerful that,
without some such arrest, it might easily become prejudicial to that
end. This same strength of impulse is,” he adds,[150] “itself necessary
to the preservation of the species; but, on the other hand, dams must
be opposed to the impetuous stream, lest the impulse expend itself
before it is made effectual, or the mothers of the race be robbed
of their strength, to the detriment of their offspring.” It has its
origin in the general fact that, before any important motor discharge
takes place, there is apt to be a preparatory and gradually increasing
excitement. But this is specially emphasized in association with the
sexual impulse. As Professor Zeigler wrote, in a private communication
to Dr. Groos,[151] “Among all animals a highly excited condition of the
nervous system is necessary for the act of pairing, and consequently we
find an exciting playful prelude very generally indulged in.”

Courtship may thus be regarded from the physiological point of view
as a means of producing the requisite amount of pairing-hunger; of
stimulating the whole system and facilitating general and special
vascular changes; of creating that state of profound and explosive
instability which has for its psychological concomitant or antecedent
an imperious and irresistible craving. This not only overcomes the
coyness of the female, but generates and strengthens the ardour of
the male--a point on which, perhaps, Professor Groos does not lay
sufficient stress. For the process is reciprocal; and though the male
leads in the ardour of courtship, yet this ardour constantly grows till
at last it overcomes the barriers of reluctance. Courtship is thus
the strong and steady bending of the bow that the arrow may find its
mark in a biological end of the utmost importance in the survival of a
healthy and vigorous race.

The coyness and reluctance of the female afford the conditions under
which the bow is bent to the full. But they also afford the conditions
of the apparent act of choice. This takes the place, on the perceptual
plane of mental development, of that deliberation which precedes the
higher act of choice on the ideational plane. For psychology, as well
as for biology, then, Dr. Groos’s suggestion is a welcome and helpful
one. Both upholders of sexual selection and critics of that hypothesis,
have been apt to regard the choice of a mate in animals from too
anthropomorphic a point of view--to look upon it as the outcome of
rational deliberation, of weighing in the æsthetic balance the relative
attractiveness of this suitor and of that, and of reaching a definite
conclusion that the one is to be accepted because he behaves or is
adorned in such and such a way, while the other is to be rejected
because he falls below all reasonable standards of requirement. The
choice exercised by the female, if so we term it, is far simpler and
more naïve. Indeed, Professor Groos goes so far as to say that on his
hypothesis the element of choice is altogether abolished. “It is the
instinctive coyness of the female,” he says,[152] “that necessitates
all the arts of courtship, and the probability is that seldom or never
does the female exert any choice. She is not awarder of the prize, but
rather a hunted creature. So, just as the beast of prey has special
instincts for finding his prey, the ardent male must have special
instincts for subduing female reluctance. According to this theory,
there is choice only in the sense that the hare finally succumbs to the
best hound, which is as much as to say that the phenomena of courtship
are referred at once to natural selection.” He reaches this conclusion,
however, by gradual stages. He first urges[153] that “it would be
absurd to affirm that all bird songs originate in a conscious æsthetic
and critical act of judgment on the part of the female. A conscious
choice either of the most beautiful or the loudest singer is certainly
not the rule, and probably never occurs at all. But,” he adds, “is it
not still a choice, though unconscious, when the female turns to the
singer whose voice, whether from strength or modulation, proves most
attractive? Even if the song is primarily a means of recognition or an
invitation from the male, still the psychological effect must be that
the female follows the songster that excites her most, and so exerts a
kind of unconscious selection.”

The phrase “unconscious choice” is, however, somewhat unsatisfactory,
especially when we remember that it is used to indicate the result
of a direct appeal to the conscious situation. If, however, we say
that it is perceptual choice arising from impulse as distinguished
from ideational choice due to motive and volition, we see that the
distinction is in line with that which we have drawn again and again,
and which Dr. Stout so well emphasizes in his “Manual of Psychology.”
But we have also drawn the distinction between instinctive behaviour
prior to individual experience, and intelligent behaviour the result
of such experience. Under which of these classes does the behaviour
of the female during courtship fall? Professor Groos, in the further
development of his hypothesis, seems to place it in the instinctive
category. “Instead of a conscious or unconscious choice, of which we
know nothing certain,” he says,[154] “we have the need of overcoming
instinctive coyness in the female, a fact familiar enough, but hitherto
not sufficiently accounted for. Then the question no longer is, which
among many males will be chosen by the female, but which one has the
qualities that can overcome the reluctance of the female whom he woos.
Sexual selection would then become a special case of natural selection.”

I am unable to follow Professor Groos in this view, which I find it
rather difficult to reconcile with such statements as that already
quoted, in which he says that the female’s “tantalizing change from
allurement to resistance seems to include an element of a mischievous
playfulness.” It is more probable that instinctive coyness and
reluctance afford the conditions under which experience of the
pleasures of courtship may be gained. It is said that a flirt, when
taken to task for her conduct at ball and picnic, justified it by
asking demurely how else she was to gain that wide experience of men
which was absolutely necessary to guide her in exercising a wise and
becoming choice. Let us hope that when the fateful time arrived she
acted with due deliberation. Now the coquetry of birds affords the
opportunity of gaining just such experience in the light of which a
perceptual choice may be made.

Let us remember that courtship is, as Darwin said, “a prolonged
affair,” and that coyness is a means to its prolongation. And let us
remember that in simple cases, as also in more complex matters, the
intelligent exercise of choice depends upon what Dr. Stout terms the
acquisition of meaning. “The chicken does not, at first,” he says,[155]
“distinguish between what is edible and what is not. This it has to
learn by experience. It will at the outset peck at and seize all worms
and caterpillars indiscriminately. There is a particular caterpillar
called the cinnabar caterpillar. When this is first presented to the
chicken it is pecked at and seized, like other similar objects. But
as soon as it is fairly seized it is dropped in disgust. When next
the chicken sees the caterpillar, it looks at it suspiciously, and
refrains from pecking. Now, what has happened in this case? The sight
of the cinnabar caterpillar re-excites the total disposition left
behind by the previous experience of pecking at it, seizing it, and
ejecting it in disgust. Thus the effect of these experiences [what
I have termed the conscious situation] is revived. The sight of the
cinnabar caterpillar has acquired a _meaning_.” Take now the case of a
coy hen bird, to whom several males pay court. The sight of this one,
behaving after his kind, excites in small degree the sexual impulse and
emotions. Her heart beats but little the faster for all his antics,
her respiratory rhythm is scarcely affected, her feathers, like her
feelings, remain comparatively unruffled. He has acquired meaning from
the reaction to his presence; it is not, however, a very attractive
meaning. But that other, perhaps from mere persistency, perhaps because
he is more “vigorous, defiant, and mettlesome” (she, at any rate,
certainly knows not why), deeply stirs her organic being, sets her all
aglow, and breaks down the barriers of her coyness. And this he does
because he is the centre of a conscious situation which has acquired,
through her experience of his presence, a meaning and an interest that
are at last irresistibly attractive. It is a choice from impulse, not
the result of deliberation; but it is a choice which is determined
by the emotional meaning of the conscious situation. And it is the
reiterated revival of the associated emotional elements which generates
an impulse sufficiently strong to overcome her instinctive coyness and
reluctance.

And this coyness is the natural correlative of the ardour of the male,
an ardour increased by his courtship antics. If the female yielded
readily and at once, the behaviour of courtship would never have been
evolved. Superabundant vigour in the male is, no doubt, a favourable
condition of courtship, as it is of play; but neither is it a _sine
quâ non_, nor in any case does it, or can it, afford any guidance of
behaviour into just those specific channels in which we find it setting
during the breeding season. If sexual selection be not a _vera causa_
of the specific direction, we have at present no other hypothesis which
in any degree fits the facts. And to the criticism of those who, like
Mr. W. H. Hudson, urge that dance and song, and aërial evolutions in
birds, are seen at times when the immediate business of courtship forms
no part of the situation, Professor Groos’s theory of play affords
a sufficient answer. If courtship, whose biological end is of such
supreme importance, forms a central feature in the serious business of
animal life; and if play is the preparation and practice for behaviour
of biological importance; we should expect to find manifestations (with
an emotional difference, and no doubt many differences in detail) of
all those actions, the due performance of which, in the supreme hour of
courtship, will alone enable the adequately prepared and well-practised
male to overcome the reluctance of the female, and beget offspring to
transmit his instinctive and emotional tendencies.

IV.--ANIMAL “ÆSTHETICS” AND “ETHICS”

In this section we shall consider some types of behaviour which suggest
situations that contain the germs of æsthetics and ethics, with a
view to determining, so far as possible, the principles on which they
should be interpreted. This is a peculiarly difficult subject; for
we are endeavouring to get behind the behaviour, and to infer the
mental conditions which accompany it, and through which it assumes its
distinctive character. The difficulty is twofold: first, because, as
Dr. Stout puts it,[156] “human language is especially constructed to
describe the mental states of human beings, and this means that it is
especially constructed so as to mislead us when we attempt to describe
the workings of minds that differ in any great degree from the human;”
and secondly, because, to quote the same careful thinker,[157] “the
besetting snare of the psychologist is the tendency to assume that an
act or attitude which in himself would be the natural manifestation
of a certain mental process must, therefore, have the same meaning in
the case of another. The fallacy lies in taking this or that isolated
action apart from the totality of conditions under which it appears.
It is particularly seductive when the animal mind is the subject of
inquiry.”

We must, therefore, base our method of procedure on some definite
principle. The canon of interpretation which I have elsewhere
suggested[158] is, that we should not interpret animal behaviour as the
outcome of higher mental processes, if it can be fairly explained as
due to the operation of those which stand lower in the psychological
scale of development. To this it may be added--lest the range of
the principle be misunderstood--that the canon by no means excludes
the interpretation of a particular act as the outcome of the higher
mental processes, if we already have independent evidence of their
occurrence in the agent. Now, the conclusion to which we are led by
direct experiment and a critical study of the actions of animals whose
life-history is known to us is, that most of their behaviour--perhaps
all--is due to what Dr. Stout terms the perceptual, as opposed to the
ideational, exercise of cognition. Their behaviour can be explained
without having recourse to the hypothesis that they reflect, and attain
to ideal schemes as the result of abstraction and generalization
consciously directed to this end. Rather than repeat what I have
already said, I will quote Dr. Stout’s summary of the position to
which he, too, has been led. “The vast interval,” he says,[159]
“which separates human achievements, so far as they depend on human
intelligence, from animal achievements, so far as they depend on animal
intelligence, is connected with the distinction between perceptual and
ideational process. Animal activities are either purely perceptual,
or, in so far as they involve ideas, these ideas serve only to prompt
and guide an action in its actual execution. On the other hand, man
constructs ‘in his head,’ by means of trains of ideas, schemes of
action before he begins to carry them out. He is thus capable of
overcoming difficulties in advance. He can cross a bridge before he
comes to it.”

It has already been stated that in the intelligent behaviour of animals
under man’s teaching he is the rational agent, they his willing slaves.
This may be here again illustrated to enforce the distinction drawn
by Dr. Stout in the above passage. Those who have seen a shepherd’s
dog working sheep on a moorland fell, and have taken the trouble to
ascertain how the results he sees have been attained, will appreciate,
on the one hand, how well the dog knows and responds to the signals of
his master, and, on the other hand, how completely all initiation is
in the master’s mind, not that of the keenly intelligent dog. Those
who merely witness such a performance without inquiry or investigation
will probably misunderstand the whole matter. In the north of England
competitions are not uncommon where, say, three sheep have to be driven
over a definite course, between certain posts and round others,
through narrow passages and into a fold--all within a certain time
limit. At such a competition success depends on two things: first,
the training of the dog to respond at once to some six or eight
whistle-signals, often accompanied by gestures and movements of a
stick; and secondly, the judgment of the shepherd. The signals, given
in different whistle-tones and inflections, have for the dog meaning,
such as drive straight on, from this side, from that, stop, lie down,
creep, and so forth. The dog’s whole business is to obey these signals.
And the instant response of a well-trained dog is admirable. But in the
whole proceeding he is merely the executant of his master’s orders.
He originates no important step. And if you listen to the criticisms
by other shepherds during a competition you will find that they are
mainly passed on the judgment shown by the master, and only in palpable
failures in obedience on the behaviour of the dog. The intelligent
animal is what he is trained to be--one whose natural powers are under
the complete control of his master with whom the whole plan of action
lies.

Since, then, in the cognitional field we find no independent evidence
of the higher processes, we are bound, in accordance with our canon, to
interpret emotional situations on similar principles, unless we find in
them outstanding facts which cannot be explained in this way.

In considering the pairing situation we urged that the framing of an
ideal of beauty to which a given suitor approaches, or from which
he falls short, is unnecessary for the interpretation of the facts.
We should not in strictness, therefore, speak of “an appreciation
of beauty” or “a taste for the beautiful” in birds, since such
expressions almost inevitably imply that these creatures have reached
some conception of beauty as distinguished from and contrasted with
ugliness. At the same time the hen certainly appears to enjoy the
situation of which the plumed cock, attitudinizing thus, forms the
centre of interest--through which he acquires meaning. Although,
therefore, there is probably no ideal or standard of beauty, there are
afforded the data in experience from which, were the bird capable of
reflection, such an ideal might, in ideational sublimation, be derived.
Before comparison, abstraction, and generalization can be applied,
in the reflective laboratory of thought, there must be suitable
experiences to form the raw material on which these rational processes
can be exercised. Long ere, in the course of mental evolution, the
correlative conceptions implied in the phrase “beautiful or ugly” had
taken definite form, perceptual situations must have arisen, where, by
direct appeal to the senses, by the diffused effects of stimulation
and their accompanying feeling-tone, and by the natural satisfaction
of mere impulse, the foundations were laid of that appreciation of the
beautiful which forms the reflective superstructure we build upon them.
Indeed, the pleasure and satisfaction attending particular situations,
as they severally arise, appear to contain the perceptual germs of what
in later development becomes æsthetic appreciation.

The bird which, having completed its nest, eyes it with apparent
satisfaction, may well have the germs of that which, when rendered
schematic in our thought, we call taste. Dr. Gould, indeed, states that
certain humming-birds decorate their nests “with the utmost taste,”
weaving into their structure beautiful pieces of lichen. And the
gardener bower-bird collects in front of its bower flowers and fruits
of bright and varied colours. What meaning these carry in the conscious
situation we do not know; we can only suppose that they incidentally
contribute to the heightening of the sexual impulse, and have been
evolved as a means of stimulation to the biological end towards which
sexual selection is unconsciously directed. For it is probable that all
the situations with which pleasure and satisfaction are in high degree
associated are, in primary origin, closely connected with behaviour
directed, through natural or sexual selection, to some definite
biological end, or, in brief, with behaviour of biological value. And
it is, perhaps, not improbable that the states of consciousness most
highly toned with strong emotion have their origin in those situations
which arise amid the pairing, parental, and companiable relations of
animal life.

We have already said that the companion, as the nucleus of a situation,
is a thing which reacts in altogether special ways, so that it becomes
differentiated from other things as something the meaning of which, and
the interest in which, are _sui generis_ and unique in type. It becomes
the centre of emotional situations, which we ascribe to rivalry,
emulation, jealousy, and so forth. And we have also drawn attention to
the view that the genetic order, so far as there is an order, is not
first the ego and then the alter, but first the mother and companions
and then through them the self. We learn to know ourselves only through
knowing others. We must now ask the question--a question which must be
answered before we can touch on the possible ethics of animals--how
far, and in what sense, the social animal regards others as of like
nature to itself, and capable also of like feelings and emotions.
Stated in this form we must, I think, answer the question in the
negative. The expression, “of like nature to itself,” implies that the
self has already taken more or less definite form, and that the animal
infers that, since the alter behaves and reacts in like manner to the
ego, it also is an ego. This is distinctly an act of reasoning. As
Clifford phrased it, the companion becomes an _eject_. We can never by
direct experience become acquainted with the feelings of others, but we
can endow them ejectively with personality analogous to our own.

But, though it is exceedingly doubtful whether any animal can regard
its companion as an “eject,” may there not be a perceptual anticipation
of the ideational process that comes with later-developed reflection? A
decade ago I gave the following answer to this question: “For myself,
I cannot doubt that animals project into each other the shadows of
the feelings of which they are themselves conscious.”[160] Professor
Mark Baldwin speaks of the stage at which this takes place, as the
“projective stage” of development. “Now, in the fact,” he says,[161]
“of herding, common life and arrangements for the protection of the
herd, animal societies of various kinds, animal division of labour,
etc.,--whatever be the origin of it,--we have what seems to be such
an epoch in animal life. These creatures show a real recognition
of one individual by another, and a real community of life and
reaction, which is quite different from the individualism of purely
sensational and unsocial consciousness. And yet it is just as different
from the reflective organization of human society, in which the
self-consciousness and personal volition of the individual play the
most important _rôle_. I see no way of accounting for the gregarious
instinct anywhere, except on the assumption of such a projective epoch
of animal consciousness.”

Now, in endeavouring to realize how the situation feels to an animal
in this projective stage, the first difficulty we encounter is
that of divesting ourselves of those products of reflection which
characterize our own mental situation; and to avoid what Dr. Stout,
in the passage above quoted,[162] terms the psychologist’s besetting
snare. The second difficulty is to grasp that, in experience, subject
and object are inseparable, however clearly we may learn to perceive
that they are distinguishable aspects of that experience. If the
subject is eventually regarded as that which experiences, and the
object as that which is experienced, it is surely obvious that each is
necessary to the other. But, before these different aspects are clearly
distinguished, there is, in the perceptual stage of mental development,
what we may term a distribution of the items of experience among the
centres of interest.

In illustration of the kind of distribution which we may suppose to
come naturally to an animal, in what Professor Baldwin terms the
projective epoch, let us take three animal situations: first, a chick
pecks at a soldier-beetle, and finds it nauseous; secondly, a hen-bird
hears the joyous song of her mate; thirdly, a puppy in play bites
its companion, and receives a painful nip in return. Each of these
constitutes an experience-situation; assuming that the results of the
experience are distributed, how may we suppose them to be allocated?

In the first case, the soldier-beetle is the centre of interest in the
situation. As the situation develops, the element of nauseousness is
introduced. As Dr. Stout puts it, this is what gives the soldier-beetle
meaning. Can it be doubted that, if there be any distribution, the
nauseousness, though it is altogether what we have learnt to call
a subjective affection, attaches itself to the soldier-beetle? The
plain man, unsophisticated by Berkeleyan discussion, says simply, in
such cases, “The thing is nauseous.” And this probably indicates the
naïve and primitive distribution. Turning now to our second example,
when the hen hears the courtship song the mate is the centre of a
situation suffused with pleasurable feeling. How is the joyousness,
again essentially subjective for our later thought, distributed?
Surely, if at all, on the mate who forms the centre of interest. This
it is which gives him meaning. The joy of the bearer is projected on
to the singer. Not entirely, perhaps; the hen literally, on Professor
James’s theory of the emotions, feels her heart-beat quickened by his
presence, and the delightful ruffling of her feathers. But our aim is
not to deny that the germs of the subjective arise in the midst of such
situations, but to contend that some at least of the joyous character
of the situation attaches to the song of the singer, that some of the
feeling is projected, and that this is what gives the mate meaning. In
our third case, the playful puppy bites his companion, and is sharply
bitten in return. Pain enters into the coalescent situation as a whole.
How is it distributed? In the phraseology of association, the nip he
gives is closely linked with the pain he receives. By coalescence
the pain and the nip form parts of the developed situation. But the
companion is the centre of interest. And part of the pain is probably
projected on this centre. That such projection actually occurs is
rendered probable by such cases as the following, which was told me
some years ago. A child, whose exact age I have forgotten if I then
ascertained, was pricked by a pin, and he said, “Pin ’urted; poor pin.”
It is, indeed, not unlikely that with animals the outward projection
of feeling is widely distributed over inanimate, as well as animate,
objects, and that its due restriction comes far later in development,
of which the so-called personification of lifeless things by savages
may be a relic. In any case, the give-and-take of play in young
animals, and the after-earnest of courtship and fighting, would seem to
afford ample opportunity for the external and internal distribution of
feeling which sows the seed in perceptual life of that which blossoms
into self and alter in the reflective life of ideational thought.

Although, therefore, an animal cannot conceive its companion as another
self of similar nature, and with like passions to his own, yet a
considerable share of the feeling-element of the conscious situation
is projected on to that companion as the chief centre of interest. And
if it be said that this is his feeling and not his neighbour’s, the
objection will be seen to lose its force, so soon as it is realized
that even man has no experience of any feelings save his own. The only
way we can reach fellow-feeling is through sympathy; and sympathy has
its roots in the projective process we have endeavoured to describe.
We endow our neighbours with natures as sensitive to pain and pleasure
as our own. This is a pre-requisite to the social relationships termed
ethical. But when we hear people say, and find even Mr. Romanes
putting on deliberate record,[163] that “the feelings which prompt a
cat to torture a captured mouse can only be assigned to the category
to which, by common consent, they are ascribed--delight in torturing
for torture’s sake,” I venture to think that common consent, if such
it be, is wrong. As I said a dozen years ago,[164] before Professor
Groos had so carefully elaborated his theory of play, “the cat or
kitten plays with the mouse not from innate cruelty, but for the sake
of getting some little practice in the most important business of cat
life. Only man, who has the capacity for nobler things, can be cruel
for cruelty’s sake;” and this is the direction in which Dr. Groos’s
opinion[165] tends to set. Mr. Romanes might have learnt a lesson in
caution from his sister, who at first attributed a sense of shame to
the capuchin she so carefully studied, but subsequently was led to
adopt a simpler interpretation. “He bit me in several places to-day,”
she says, in her admirable diary,[166] “but he seemed ashamed of
himself afterwards, hiding his face in his arms, and sitting quiet for
a time.” She adds, however, in a footnote: “On subsequent observation,
I find this quietness was not due to shame at having bit me; for
whether he succeeds in biting any person or not, he always sits quiet
and dull-looking after a fit of passion, being, I think, fatigued.”

Shame is an ethical feeling. And as we have briefly discussed the
germs of æsthetics in animals, so we may now as briefly consider the
germs of ethics. In its developed form ethics is one of the “normative
sciences” involving standards of right and wrong. It is, as Professor
Mackenzie says,[167] “the science of the ideal in conduct.” It involves
a standard of “ought,” the product of reflection and generalization.
Conduct is compared with the ideal, and perceived to be either below,
up to, or perhaps beyond, the normal standard accepted by civilized
mankind. This involves a judgment; and so far as conduct is shaped in
accordance with the ideal we attribute the guidance to ethical motives.
Such ideals, such judgments, and the control of conduct through the
play of such motives, are probably beyond the mental capacities of
animals. They belong to the ideational stage of mental development,
when the conative tendency becomes volitional; not to the perceptual
stage, when it is impulsive. They do not enter into the conscious
situation as it takes form in the animal mind. Behaviour has not in
them acquired ethical meaning, since in developed ethics, as normative,
such meaning always has reference to the norm, or standard. A real
sense of shame implies that our acts have fallen below our ideal.

It may be said that we cannot prove that animals do not frame such
ideals. But, if we accept the canon of interpretation above laid
down, what has to be proved is that they do frame them. Is there any
case among the hundreds that are popularly adduced to show that dogs
are ashamed of themselves, that they possess a sense of justice,
that they feel the prick of conscience, that on the one hand they
know when they have done wrong, or on the other hand enjoy a sense
of conscious rectitude--is there any particular case so described in
the popular phraseology of anecdote, which could not be more simply
described as the direct outcome of the coalescent situation, without
the introduction of any implied reference to a standard of behaviour
reached by reflective thought? The pug that has taken a nap on the
drawing-room sofa, leaps down and slinks off with a “guilty” look on
his master’s approach. One can surely picture the previous situations,
and be tolerably certain that they contained an element of reproof or
something more energetic. The poodle that has successfully performed
his tricks bounds to his mistress with an air of duty well performed.
Has he never been petted and patted under such circumstance? Routine in
many animals--so often creatures of habit--begets a customary sequence,
the breach of which is at once felt. To this I ventured[168] to
ascribe the conduct of the turnspit dog reported by Arago. He refused
with bared teeth to enter out of his turn the drum by which the spit
was rotated. The companion dog was put in for a few moments and then
released; whereupon the dog which before had been so refractory seemed
satisfied that his turn for drudgery had come, and, entering the wheel
of his own accord, began turning the spit as usual. The bared teeth may
be here perhaps ascribed to an outraged sense of justice. But is it not
a more simple, and just as probable, supposition that the behaviour
was due to breach of customary routine. A trainer with whom I had some
conversation on this matter pointed out a collie bitch, and said, “If
I put her through her tricks in the usual order she does them like an
angel; but if I try and make her alter the order she snaps and sulks
like the devil.”

I have elsewhere[169] expressed my opinion that, though animals may
behave in ways which may tend to mislead us, they do not act with
intent to deceive. A dog is described[170] as “showing a deliberate
design of deceiving” because he hobbled about the room as if lame and
suffering from pain in his foot. But may not this be simply due to the
fact that chance experience had led to a situation through which a
hobbling gait had acquired the meaning of more petting and attention
than usual? To behave with deceit as a deliberate motive implies the
idea that the action will be interpreted as having a significance
different from that which it really has. It is only possible on the
ideational plane of mental development. It implies, too, from the
ethical standpoint, a conscious departure from the standard of truth.
The black that is acted has conscious reference and relation to the
white that is not black. Few, however, will credit animals with deceit
of this fully conscious and deliberate kind. Like the fibs of little
children, the apparent deceit of animals is probably merely behaviour
which has been associated in experience with pleasant results.

The case of shamming sickness, quoted from K. Russ, is thus interpreted
by Professor Groos.[171] And yet he adds, “When we see deception used
so effectively to serve practical ends, examples of which are very
common, it can hardly be doubted that there is in all probability
more consciousness of shamming in play than we have any means of
demonstrating.” And elsewhere in the same work he observes,[172]
“Many a grown animal still takes pleasure in the mock combats that he
learned in youth. From a psychological point of view this phenomenon
is especially noteworthy, from the fact that the adult animal, though
already well acquainted with real fighting, still knows how to keep
within the bounds of play, and must therefore be consciously playing
a _rôle_, making believe.” I fail, however, to see the justification
for the “therefore.” Surely the difference of behaviour in this
example, and in other such examples, is sufficiently explained
as the outcome of diverse situations, without having recourse to
anything so psychologically complex as the conscious self-illusion of
make-believe--interesting and important as this is in the psychology
of children. To suppose that a monkey who nurses a bit of blanket has
any ideas about its being a make-believe baby is _not_ to interpret the
behaviour of animals in accordance with the canon we have adopted for
our guidance.

To return to the “ethics” of animals. I have urged that ethical ideas,
properly so called, have no place in their psychology. But just as the
pleasure and satisfaction attending particular situations, as they
severally arise, appear to contain the perceptual germs of what in
later development becomes æsthetic appreciation; so, too, do they also
contain the perceptual germs of what becomes, through reflection in
man, ethical approbation. And the situations in which these ethical
germs must be sought are those which entail behaviour for the good
of the social community. Indeed, we may go so far as to say that the
perceptual foundations of ethics are laid in the social instincts.
The satisfaction or dissatisfaction arising from the performance or
non-performance of instinctive behaviour, evolved for the biological
end of the preservation of the social community, is the perceptual
embryo from which conscience is developed. Professor Mackenzie has
indicated the ambiguities in the use of the term “conscience.” “It is,”
he says,[173] “sometimes used to express the fundamental principles
on which the moral judgment rests; at other times it expresses the
principles adopted by a particular individual; at other times it
means ‘a particular kind of pleasure or pain felt in perceiving our
own conformity or nonconformity to principle.’[174] This last seems
to me,” adds Mr. Mackenzie, “the most convenient acceptation of the
term, except that I should prefer to say simply that it is a feeling of
pain accompanying and resulting from our nonconformity to principle.”
According to this definition the existence of a principle or ideal is
presupposed; and the fact that Professor Mackenzie lays stress upon the
pain of nonconformity, shows that the ideal is a high one. In the case
of the animal, however, such an ideal of right conduct has probably not
taken form. But Mr. Mackenzie also speaks of the “quasi-conscience”
begotten of custom. This comes nearer to the feeling which animals may
be supposed to have when their behaviour does not accord with that
which through instinct or habit is the usage of the community. And
if, as seems to be shown by observation, animals sometimes punish the
breaches of such usage--when, for example, cats punish their kittens
for uncleanliness--the quasi-conscience will assume a more developed
form.

We may say, then, that the perceptual data are given in animal
experience from which, in ideational sublimation, ethical ideals may be
derived by a process of reflection and generalization. As in the case
of æsthetics, so in that of ethics; long ere, in the course of mental
evolution, the correlative conceptions implied in the phrase “right or
wrong” had taken definite form, perceptual situations must have arisen
in which behaviour carried with it the feelings of satisfaction or the
reverse which laid the foundations of that approbation of the right
which forms the superstructure we build upon them by the exercise of
reflective thought.

V.--THE EVOLUTION OF FEELING AND EMOTION

“Whatever conditions,” says Dr. Stout,[175] “further and favour
conation in the attainment of its end, yield pleasure. Whatever
conditions obstruct conation in the attainment of its end, are sources
of displeasure. This is the widest generalization which we can frame,
from a purely psychological point of view, as regards the conditions of
pleasure and displeasure respectively.” Here Dr. Stout seems carefully
to avoid the commonly accepted and much advertised conclusion, that
pleasure and pain (to use this more familiar word as the antithesis
of pleasure) are themselves the end of conative endeavour. And he is
so far right that they by no means constitute the sole or indeed the
primary end of all conative process. Attention is a conative act; but
its primary end is not pleasure, but rather, as Dr. Stout says,[176]
the fuller presentation of the object. No doubt this brings pleasure;
but the fuller presentation comes first, and carries the pleasure with
it. Instinctive response to felt stimulus falls within the conative
attitude. In it there is that “inherent tendency to pass beyond itself
and become something different,” which Dr. Stout assigns to conation as
its chief characteristic. But the end is not pleasure, but simply the
instinctive behaviour. And if we say that the attainment of this end
does bring satisfaction, which is a form of pleasure, Dr. Stout would
probably reply that this is rather a result of the process than its
true end.

Now, in such cases, what we are really dealing with is a class of
_organic_ processes having conscious accompaniments. No doubt the
conscious accompaniments are of importance; they certainly cannot
be neglected by the psychologist: but their feeling-tone does not
constitute that which makes instinct run its course. And I have
introduced the subject for present discussion in this way to reinforce
what has already been repeatedly urged in the foregoing pages, that
individual behaviour, in its first intent, is a biological legacy
with ends predetermined through heredity. The inherent tendency to
pass beyond itself and become something different, which for the
old psychology was a heaven-sent impulse, or, as Addison said, “an
immediate impression from the first Mover and the Divine energy acting
in the creatures,” becomes for the new psychology an organic bequest.
But the attainment of ends thus already predetermined has feeling-tone,
both as process and in its resulting consciousness, and this
feeling-tone serves to modify, through the situation it introduces,
future behaviour, and thus, in a sense, affords a new end to subsequent
conation.

“Life,” wrote James Martineau,[177] “is a cluster of wants physical,
intellectual, affectional, moral, each of which may have, and all
of which may miss, the fitting object. Is the object withheld or
lost? there is pain: is it restored or gained? there is pleasure:
does it abide or remain constant? there is content. The two first
are cases of disturbed equilibrium, and are so far dynamic that they
will not rest till they reach the third, which is their posture of
stability and their true end.” This is an adequate description of the
essential features in conative process. But in genetic precedence,
as in individual development, the physical wants come first, and,
at the outset of behaviour, the satisfaction or content is not and
cannot be foreseen, since it has never yet entered into experience.
To adopt a distinction suggested by Professor Mackenzie,[178] the
conation is _purposive_, since we see that an end is involved, but not
_purposeful_, since there is no definite consciousness of the end aimed
at. But when experience has introduced feeling-tone into the situation,
we may say that this, in a sense, introduces a new end to subsequent
behaviour.

Mr. Herbert Spencer has said[179] that pleasure is that which we seek
to bring into consciousness and retain there; pain, that which we seek
to get out of consciousness and keep out. May we assert, then, that,
in the modification of behaviour due to experience, the pleasure to be
gained or the pain to be avoided is the psychological end? Certainly
not without qualification, unless we be among those who are content
to accept any form of words which gives a general sort of notion of
the kind of thing which we suppose is meant, and which is probably
more or less correct. We want here and now to get clear ideas, and to
express them with some approach to accuracy. To say that pleasure is
the psychological end of intelligent behaviour is to put the matter
too subjectively and in too abstract a form. Professor Mackenzie has
clearly indicated the ambiguity in the word “pleasure.” “Pleasure,” he
says,[180] “is sometimes understood to mean agreeable _feeling_, or
the feeling of satisfaction, and sometimes it is understood to mean an
_object_ which gives satisfaction. The hearing of music is sometimes
said to be a pleasure, but of course the hearing of music is not a
feeling of satisfaction; it is an object that gives satisfaction.
Generally, it may be observed that when we speak of ‘pleasures’ in
the plural, or rather in the concrete, we mean objects that give
satisfaction; whereas when we speak of ‘pleasure’ in the abstract, we
more often mean the feeling of satisfaction which such objects bring
with them.” May we not go a step further, but entirely in the same
direction, and say that pleasure is a constituent part of the concept
self as an object of thought or desire; that its proper sphere is in
the ideational consciousness; and that, as we interpret the animal
mind, it has no place as such therein? The hedonist regards pleasure as
the most excellent and distinctive characteristic of his ideal self and
his ideal community. But animals have not risen or fallen to the level
of hedonism. Pleasure is not for them a motive of conduct, though nice
objects, as such, are attractive, and through them impulse acquires
direction and force.

If, in animal psychology, we are to use the words pleasure and pain
(as the antithesis of pleasure)--and they seem more properly to belong
to a plane of mental development to which animals probably have not
attained--we may say that the pleasure or the pain which attaches
to any centre of interest in the situation is that which gives it
attractive or repellent meaning; it furthers conation either towards
or, as Hobbes would say, fromwards. But if we put the matter in this
somewhat abstract form, let us keep in view, if it be only in the
background of our thought, the kind of concrete example which may
be adduced in its illustration--the dog with his attractive bone,
the kitten that has raced off at sight of him, the cock-sparrow with
trailing wings hopping after his mate, the falcon stooping on her
quarry, the rabbit diving into his burrow at sight of the fox, and so
forth. If we have such cases in view, where the centre of the situation
has acquired or is acquiring meaning, a meaning which in large degree
attaches to the external nucleus of the situation with only the germs
of subjective reference, we may, perhaps, summarize the position by
saying that in each case some pleasure to be gained or some pain to be
avoided is the psychological end of conation.

But in each case the conation has also a biological end--the
preservation and conservation of the race. “An animal,” said
Darwin,[181] “may be led to pursue that course which is most beneficial
to the species by suffering, such as pain, hunger, thirst, or fear; or
by pleasure, as in eating and drinking, and in the propagation of the
species; or by both combined, as in the search for food.” The important
point here to notice is that the two ends agree--the psychological
end of the attainment of pleasure and the avoidance of pain, and the
biological end of race preservation. Under the joint influence of
pleasure and pain, the needle of animal life sets towards the pole of
beneficial action.

This consonance of end was in old days ascribed to the beneficent
foresight of the Creator. The modern view, that it is a product of
evolution, does not necessarily ascribe it to any other ultimate cause.
For many still piously hold that evolution is only a name which we give
to the method of creation. And there is not a fact or generalization in
science by which such a conclusion can be disproved, for the premises
lie outside the field of scientific inquiry. But the consonance of
end is, for science, a remarkable fact, and one worthy of attentive
consideration.

We have already seen that, if the claim for the inheritance of acquired
characters be, on the evidence, judged unproven, and if instinct cannot
be ascribed to transmitted habit, or regarded as a legacy of that which
has been ancestrally acquired, the only scientific explanation of
instinctive behaviour is one which involves the principle of natural
selection. But no one doubts that, in the course of experience, animals
acquire modes of procedure which are beneficial to the race. This is
well seen in the play of animals as interpreted by Professor Groos.
Now, why do animals play? From the psychological point of view, because
they like it; from the biological point of view, because they thus gain
practice and preparation for the serious business of their after-life.
But why do they like it? because, under natural selection, those who
did not like it, and therefore did not play, proved unfit for life’s
struggle, and were eliminated. Suppose that an animal were born with a
rooted hereditary aversion to everything nutritious and an inherited
hunger for anything harmful and unfit for food. What chance would it
stand of survival? Hereditary likes and dislikes determine the general
course of acquired behaviour, just as hereditary nerve-connections
determine the course of instinctive behaviour. Wherein, then, lies
the difference between the two? In the fact that in the one case the
nerve-connections are transmitted ready-made, while in the other they
result from association or coalescence in the course of individual
life. But in both cases the pursuit and attainment of the beneficial
brings satisfaction.

Now, the consonance of end has long been regarded as an inevitable
deduction from the hypothesis of evolution. “That pains are
correlatives of actions injurious to the organism,” wrote Mr. Herbert
Spencer in his “Principles of Psychology,”[182] “while pleasures are
the correlatives of actions conducive to its welfare, is an induction
not based on the vital functions only. It is an inevitable deduction
from the hypothesis of evolution, that races of sentient creatures
could have come into existence under no other conditions. Those
races of beings only can have survived in which, on the average,
agreeable or desired feelings went along with activities conducive to
the maintenance of life, while disagreeable and habitually avoided
feelings went along with activities directly or indirectly destructive
of life, and there must ever have been, other things being equal, the
most numerous and long-continued survivals among races in which these
adjustments of feelings to actions were the best, tending ever to
perfect adjustment.” And he safeguards the position by adding: “It is
frequently taken for granted that the beneficial actions secured must
be actions beneficial to the individual; whereas the only necessity is
that they shall be beneficial to the race.”

This aspect of the consonance is now quite familiar; but let us
carefully note how completely dependent it is on natural selection. Mr.
Herbert Spencer’s testimony is especially valuable, since he has always
laid much stress on the hereditary transmission of acquired characters
and still holds[183] “that the inheritance of functionally-caused
alterations has played a larger part than Darwin admitted even at the
close of his life; and that, coming more to the front as evolution has
advanced, it has played the chief part in producing the highest types.”
Now, in these types we certainly find a wide range of consonance
between the psychological and the biological ends of behaviour; of
which the phenomena of play may again be adduced as an example. Hence
the special value of Mr. Herbert Spencer’s testimony to the part played
by natural selection in establishing the consonance. “Only those races
of beings,” he says, “_can have survived_ in which, on the average,
agreeable feelings went along with activities conducive to life;” and
again, “The most numerous _survivals_ must ever have been among races
in which these adjustments of feelings to actions were the best.” The
stress is here laid on the survival of those in which the consonance
has obtained; the elimination of those in which it was absent: that
is to say, on natural selection. And where else can it be laid? It is
not the sort of thing which could be acquired. Suppose that, as we
suggested above, an animal were born with a rooted hereditary aversion
to everything nutritious and an inherited hunger for anything harmful
and unfit for food. Under what conceivable conditions could such an
animal acquire a complete change of its affective nature? Animals like
things or they do not like them; only to a very limited extent, if at
all, under natural conditions, can they learn to like them. We, indeed,
can in some degree learn to take pleasure in that which at first, and
by nature, is distasteful; but we do so by some external constraint, or
from some motive of ideational origin. We put pressure upon ourselves,
or have pressure put upon us, repeatedly to perform some irksome task;
we fall into routine and custom; and the performance becomes so far
second nature that its discontinuance produces an uncomfortable sense
of something lacking in the daily round. Perhaps domestic animals learn
to like the good offices we force them to perform for us. But here we
have the element of external constraint, which is wholly, or almost
wholly, absent under natural conditions. And there is no evidence
that such acquired likings are inherited. That, however, is another
question. Our present point is that, under nature, the conditions of
such acquisition are lacking; so that, there being no acquisition,
there is, in this case, nothing acquired to be transmitted.

But, so far as behaviour is concerned, “functionally caused
alterations” are those due to the exercise of intelligence, by which
the behaviour acquires direction and character in reference to the
meaning introduced into the situations. See, then, the position
to which we are logically driven. The acquisition of that which
has beneficial value in behaviour depends on a consonance between
psychological and biological end. But this consonance is dependent
on survival, and, apart from special creation, or some kindred
hypothesis such as Leibnitzian harmony, can be due to nothing else.
Even if we grant, therefore, that the effects of acquisition are
inherited, the conditions of beneficial acquisition are dependent on
natural selection. And thus the inheritance of acquired characters,
which is so often urged as a principle of evolution independent of
natural selection, is, so far as intelligent behaviour is concerned,
indirectly, if not directly, due to this very natural selection of
which it is said to be independent. Surely, under these circumstances,
the hypothesis in question may be said to be not only unproven, but
altogether unnecessary.

And what is true of those diverse feelings which we group under
the concepts pleasure and pain respectively, is true also of those
more complex dispositions which we call emotional--using this term
in a broad and comprehensive sense. We say that in their primary
manifestations they are instinctive; and they certainly seem to
accompany organic behaviour due to co-ordinated reflex actions. But
the emotion, as instinctive, is a matter only of its first occurrence.
In the course of experience it enters into conscious situations, the
centres of interest in which have acquired meaning.

Take a particular case.[184] Your dog is dozing on the lawn in the
sunshine. Suddenly he raises his head, pricks his ears, scents the air,
looks fixedly at a gap in the hedge, and utters a low growl. Place
your hand on his shoulder, and you will find that his muscles are all
a-tremble; on his ribs, and you will feel how strongly his heart is
beating. Soon the growing excitement leads to vigorous action, and he
darts through the gap. You follow him across the lawn, look over the
hedge, and see him facing his old enemy, the butcher’s cur. They are
moving slowly past each other, head down, teeth bared, back roughened.
You whistle softly. Such a call would generally bring him bounding to
your feet; but now it is apparently unheard, at any rate unheeded. The
two dogs have a short scuffle, and the cur slinks off. Your dog races
after him; and he flees, yelping. The situation is over. Spot returns,
wagging his short tail, jumps up at you playfully, and then lies down
again on the grass. But now and then, for ten minutes or so, he raises
his head and growls softly.

Let us briefly analyze the dog’s condition and actions, reading into
them, conjecturally, the accompaniments in consciousness. As he lies
on the lawn, he receives a sense-stimulus, auditory or olfactory. It
has already acquired meaning, from many a tussle with the butcher’s
cur. It has organic effects, and it generates a conscious situation
which has acquired complexity through coalescence. As the result of
this situation the head is raised, the ears pricked, and so on. The
dog is on the alert. His attention is aroused. The muscles of neck,
eyes, ears, are brought into play in such a way as to bring the senses
to bear on the exciting object. He probably sees the cur through the
gap in the hedge. The muscles of the frame are innervated so as to be
in a state of preparation to act rapidly and forcibly. At the same
time the vaso-motor system is disturbed, the heart-beat is quickened,
respiration is altered; there is probably hardly an organ in the body
which remains unaffected. Then the dog rushes through the hedge,
and stands with bared teeth before his antagonist. A whole set of
appropriate muscles are now strongly innervated. There is, perhaps,
a double innervation, stimulating to activity and yet restraining
from action. He bares his teeth and growls deeply. Attention is so
concentrated that he heeds not, perhaps does not hear, his master’s
whistle. He is keenly on the alert. The blood-system, respiratory
organs, and all his inner machinery are still pulsating with nervous
thrills; his back is up. Then he sees his chance, and flies at his
opponent. Much that he has learnt in play, and all that he has learnt
in earnest, comes to his aid in the short angry scuffle. And what we
call his emotion of anger spurs him on to the fight; the cowardly dog
in which this is lacking or is replaced by fear is spurred to flight.
Each may contribute to self-preservation, but in different ways.

Now, we shall not attempt to determine how the distinctively emotional
elements arise. Some think they arise by a sort of irradiating nervous
diffusion in the nerve-centres as a direct result of the originating
stimulus. Mr. Rutgers Marshall regards them as due to the motor
activities in fight or flight; Professor William James contends that
they have their source in the visceral affections of heart, lungs,
glands, and so forth; Professor Lange attributes them to vaso-motor
effects. The problem is a difficult one, and hard to determine by
experiment; for we have to deal with a matter of primary genesis, of
how they are at the outset introduced into the conscious situation.
Experiments on animals which have already gained emotional experience
cannot decide the question of genesis. Professor Sherrington, for
example, has shown[185] that, after severance of the spinal cord in
the lower region of the neck, and of the vagus nerves, by which “a
huge field of vascular, visceral, cutaneous, and motor reaction”
were “deprived of all connection with the nervous centre necessary
to conscious response,” “the emotional states of anger, delight at
being caressed, fear and disgust were developed with, as far as could
be seen, unlessened strength.” But the avenues of connection were
closed _after_ the motor and visceral effects had played their parts
in the _genesis_ of the emotion on the hypothesis that the emotion is
thus generated. Although new presentative data of this type were thus
excluded, their re-presentative after-effects in the situation were
not excluded. It is, moreover, an essential part of Professor James’s
doctrine, as I provisionally accept it, that the “expression” and the
visceral and vascular efforts are independent results of stimulation in
certain ways, and that these independent results are conjoined through
natural selection. Suppose we sever the connection through which the
one takes effect, there is no reason to expect that the manifestation
of the other would cease. Professor Sherrington cut off the channels of
communication with the visceral and vascular apparatus: if the channels
of expression remained open there is no reason why such expression
should cease.

We need not, however, for our present purpose, attempt to ascertain how
the distinctively emotional characteristics arise. It is sufficient
that they are presumably present in the situation. Now, as Dr. Stout
well points out,[186] the emotions generally presuppose the existence
of certain specific tendencies. “The anger produced in a dog by
taking away its bone presupposes the specific appetite for food. The
anger produced in it by interfering with its young presupposes the
specific tendency to guard and tend its offspring. So the presence of
a rival who interferes with its wooing causes anger because of the
pre-existence of the sexual impulse.” In general, we may say that
emotional states are, under natural conditions, closely associated with
behaviour of biological value--with tendencies which are beneficial
in self-preservation or race-preservation--with actions that promote
survival, and especially with the behaviour which clusters round the
pairing and parental instincts. The value of the emotions in animals
is that they are an indirect means of furthering survival. But how has
the close association between emotional condition and the biological
end it furthers been established? Again, we must say that under natural
conditions it is not the sort of thing which could be acquired. And
again we must urge that natural selection through survival is, apart
from some theory of pre-established harmony, the only hypothesis in the
field on which the close association can be explained.

There is one more point to which attention may be drawn. If there be
one thing, and there certainly are not many, on which all writers on
the emotions are agreed, it is as to their vagueness. They do not
readily submit to definition, and cannot be described in a sentence.
This is not due to any indefiniteness of biological end, nor to much
indefiniteness in the mode of “expression;” it is due, rather, to
an inherent dimness and haziness of psychological outline. We seem
unable to focus them and get a clear-cut result. This is, no doubt,
in part due to the complexity of emotional states. But, may it not be
largely due to the fact that there is no necessity for definiteness?
They fulfil their purpose just as well if they are vague. It is quite
necessary for the dog to have a clear-cut impression of his antagonist;
and, on the cognitive side of consciousness, meaning must be in some
degree definite to be of real value. But, so long as the emotion raises
the temperature, so to speak, to the boiling-point of vigorous action,
it matters little what the psychological source of heat may be. If this
be so, we should expect an emotional vagueness, since natural selection
puts no premium upon emotional definiteness. And from this it follows,
as a corollary, that, whereas we may infer that an animal’s perceptual
products are probably closely similar to our own, since sight, touch,
hearing, smell, and taste are of value in so far as they convey
definite meaning, in interpreting their feelings and emotions we have
less secure grounds of inference, since all that is requisite is that
there should be a sufficiently high emotional temperature to afford the
conditions for definite and vigorous action.

In conclusion, then, we may say that the primary purpose of the
evolution of feeling and emotion is to promote beneficial behaviour,
and that the observed consonance of the psychological end of attaining
satisfaction, and the biological end of securing survival, seems to be
due to natural selection--is, indeed, scarcely explicable on any other
naturalistic hypothesis.

A word of warning may be added. We have repeatedly spoken of biological
and psychological ends. By this we mean what seems to the observer, as
an interpreter of natural processes, the purpose and object of their
existence. But the word “end” is often used in such a way as to imply
foresight and contrivance on the part of a rational being. We have not
used it in this sense. Whether the whole of nature, including animal
behaviour, is driven onwards to definite ends by an underlying Cause,
is a metaphysical question. It is not one on which science has any
right to express an opinion one way or the other. Science deals with
the phenomena; the causes of their being lie outside her province.

CHAPTER VII

_THE EVOLUTION OF ANIMAL BEHAVIOUR_

I.--THE PHYSIOLOGICAL ASPECT

At the outset of our inquiry, we used the word “behaviour” in a wide
and comprehensive sense. Thus broadly used, I said, the term in all
cases indicates and draws attention to the reaction of that which
we speak of as behaving in response to certain surrounding forces
or circumstances which evoke the behaviour. The behaviour of living
cells is dependent on changes in their environment; that of deciduous
trees, as they put forth their leaves in the spring or shed them in
the autumn, is related to the change of the season; instinctive,
intelligent, and emotional behaviour are called forth in response
to those circumstances which exercise a constraining influence at
the moment of action. Used in this comprehensive sense, the term
“behaviour” neither implies nor excludes the presence of consciousness.
We know from our own experience, however, that consciousness does in
some cases accompany behaviour, and we infer that in many other cases
it may be present. But we need a criterion of its presence to guide
our inferences, and this criterion we found in the ability of living
beings to profit by experience. In Dr. Stout’s phraseology, if a thing
seems to acquire meaning for such a being, and the behaviour is guided
in accordance with such acquired meaning, we infer the presence of
consciousness as supplying conditions effective in determining its
course. Still this does not exclude, nay, rather it presupposes the
presence of sentience at a lower stage of evolution, a sentience which
is as yet ineffective since the process of conscious coalescence has
not begun, or has not been carried far enough.

In foregoing chapters we have constantly held the problems of evolution
in view, and in special sections directed attention to them. But the
subject is so central to modern thought and discussion, that some
further consideration of certain aspects of the evolutionary process
and products will fitly serve to bring our inquiry to a conclusion.

We must accept, as a datum from the physiological point of view, the
fact that protoplasm does respond to stimuli,--that it possesses the
fundamental property of irritability. It is a substance that is in a
state of unstable equilibrium. Its tendency to pass to a condition of
more stable equilibrium is that in and through which organic behaviour
in its very simplest expression is possible. And this, with progressive
complication, runs through the whole gamut of animal behaviour, and
eventually passes over into the sphere of consciousness. “The tendency
to equilibrium,” writes Dr. Stout,[187] “is the physiological correlate
of what on the psychical side we call conation,--the striving aspect of
consciousness.” But, protoplasm at the outset--or as near the outset
as we can get--is, in technical phrase, differentially responsive. The
nature of the stimulus and the nature of the conditions decide what
the nature of the response shall be. And even in that jelly-like speck
of living matter, the _Amœba_, the responses conspire to a biological
end. If they did not so conspire, we should not have the phenomena of
life. The mere act of living, building up from food-stuff and oxygen an
unstable substance which “explodes” and contracts under stimulation,
implies that the processes which thus conspire are related in such
a manner as to fulfil and secure their end. In higher unicellular
animals, such as the _Paramecium_, the relations are less simple; but
in them the continuance of that sum of organic behaviour which we
call life, is secured only on the condition that these less simple
relations are duly preserved, and that the vital processes conspire
with sufficient unity of biological purpose. And when we pass to the
higher creatures in which many cells unite to form one animal, the very
word “unite” indicates that the vital processes of all must conspire
with sufficient _unity_ of biological purpose to insure the continued
life of the whole.

Now, in all the higher and more active animals a nervous system is
developed, which has for its purpose and end the preservation and
furtherance of unity amid circumstances of progressively increasing
diversity. And in the course of its evolution an added means of
preserving and furthering the essential unity is provided in
consciousness, which, through the coalescence of scattered units of
sentience, leads behaviour to acquire a new and higher unanimity of
purpose. Thus a mental evolution is engrafted on the organic evolution
which precedes it. But every step in this mental evolution presupposes
a step in organic evolution. And such is the complexity of structure
and process in all the higher animals that much of the business of
behaviour is relegated to quasi-independent nervous centres, which
perform this business automatically, and will continue to perform it,
with much subsidiary unity of end, when they are left to themselves and
all connection with the supremely unifying sensorium has been severed.

Before proceeding to give some examples of this fact, and to indicate
its bearing on our interpretation of behaviour, it may be well to
state distinctly that no attempt is or will be here made to trace in
detail the course of the evolution of animal behaviour through the
ascending grades of life, nor, indeed, to prove that there has been any
such evolution. Evolution by natural genesis is here assumed as the
only hypothesis with which science has any concern. If it be false,
then have the labours of workers and thinkers, since Darwin and Mr.
Herbert Spencer worked and thought, been vain. Special creation is
not a scientific hypothesis, but a reference of biological and mental
phenomena to an ultimate cause, which lies beyond and altogether apart
from the scope of scientific inquiry. The fundamental assumption of
the man of science is, that any natural event he may select for
detailed study has natural conditions and antecedents. And it is only
in such detailed study--taking this or that particular occurrence and
endeavouring to ascertain what were its related antecedents--that
advance in the evolutionary interpretation of nature can be secured.

Such advance has been secured by the labours of those physiologists
who have established by careful experiment the quasi-independent
action of subsidiary nerve-centres as constituents of the nervous
system as a whole. In such animals as the crayfish and the lobster
the central nervous system consists of a chain of “ganglia,” or
nerve-knots, which are connected together by nerve-strands. If these
strands be cut between the thorax, which carries the walking limbs,
and the abdomen or hinder portion of the body, the nerve-connection
between these parts is severed. If the forepart be irritated through
its sense-organs, the limbs of that part will respond; but, whereas
an unmutilated crayfish, subjected to such irritation, would give a
vigorous flap of the tail, this does not take place in the crippled
animal.[188] Still, if the abdomen be irritated, it will respond by a
strong and swift contraction. The two portions of the body are each
capable of acting independently with well co-ordinated movements, but
no longer of working together with unity of purpose. In the hinder
portion the abdominal limbs, or swimmerets, all swing backwards and
forwards simultaneously with rhythmic strokes; they act in concert.
Sever now the connections between their ganglia, and each pair of
limbs will continue to swing rhythmically but not with concerted
rhythm. We have isolated a number of quasi-independent centres, and
rendered them really independent. Each is concerned with its own
proper co-ordination, but can no longer combine with others in a
wider co-ordination. Mr. Hyde[189] has shown that in the king-crab,
_Limulus_, when the nerve-chain is severed just in front of the
abdominal region, the rhythmic respiratory movements of the abdominal
segments still proceed regularly and co-ordinately. Even when only
a fraction of the nerve-cord, separated by severances in front and
behind, is left, corresponding with a single abdominal segment,
the rhythmic action of that segment continues; but it is no longer
synchronous with that of adjacent segments similarly isolated.

It will probably not be contended that the co-ordinated rhythm of
the isolated segment in crayfish or king-crab is anything but a bit
of organic and physiological behaviour. Whether it be accompanied by
consciousness--a bit of consciousness isolated from other bits--we
do not know; but we have no grounds for supposing that the rhythmic
behaviour is guided by consciousness. And when, as Dr. Carpenter
pointed out half a century ago, a water-beetle, from which the “brain”
has been removed, swims forwards if placed in water, we must surely
regard the co-ordinated progression as organic behaviour, whatever view
we may hold with regard to a consciousness which in such a case is in
a very literal sense a divided consciousness.

In these invertebrates the central nervous system is obviously
segmented--one can distinguish the ganglia and their connecting
nerve-strands. In the vertebrate the brain and spinal cord form a
continuous mass of nerve-tissue without obvious segmentation. But the
pairs of spinal nerves, each nerve with its afferent and efferent
“root,” indicate a really segmented condition, though in the cord
itself the segments so run together and overlap that they cease to be
externally obvious. And there is a certain, though limited, amount of
overlap in the distribution of these segmental nerves. Still, well
co-ordinated responses occur when comparatively short portions of the
spinal cord are isolated by severance from the rest. In the male frog,
especially during the breeding season, a clasping reflex is produced by
stimulating the dark swollen pads on the inner side of the hand, and
this, as Goltz has shown, is exhibited when all the central nervous
system has been destroyed save the segments to which the nerves for
the arms proceed. “Similarly,” writes Dr. Sherrington,[190] “in the
cat and monkey, the reflex wagging of the tail persists when behind
the spinal transection only the sacral region of the cord is left
intact.” When the spinal cord of the dog is severed, so as to isolate
that portion which is concerned with movements of the hinder part of
the body, pressure on the pad of one hind-foot usually produces, not
only a lifting of that leg, but also an extension of its fellow--that
is to say, a co-ordinated response of the two limbs. But in the case
of the vertebrates, more than in that of the invertebrates, the
co-ordinated response of an isolated part of the central nervous system
seems to lack the furtherance of its action, which normally comes
from the higher centres from which it has been severed. “The spinal
reflexes significant of progression seem,” says Dr. Sherrington,[191]
“to contribute chiefly towards preparatory posture in readiness for
the onset of action executed by the musculature under the driving of
higher centres. Thus the well-known reflex spinal posture of the frog
is flexion of the hind limbs, the extensors of the joints being taut
and ready for the jump. The spinal reflexes, which in their results
approximate most closely to the normal reactions of the unmutilated
individual, are those connected with the pelvic and abdominal
viscera,” many of which “are executed as spinal reflexes in a manner
presenting little or no physiological defect from the normal. And if
the bulb”--the continuation of the spinal cord within the skull to form
the basal portion of the brain--“be included with the spinal cord, and
these together, including their nerves, be isolated from the rest of
the nervous system, the animal as regards its visceral life, including
that of the heart and lungs, is practically intact.”

Huxley graphically describes the actions of a frog from which the
cerebral hemispheres have been removed. “If that operation,” he
says,[192] “is performed quickly and skilfully, the frog may be kept
in a state of full bodily vigour for months, or it may be for years;
but it will sit unmoved. It sees nothing; it hears nothing. It will
starve sooner than feed itself, although food put into its mouth is
swallowed. On irritation, it jumps or walks; if thrown into water it
swims. If it be put on the hand it sits there, crouched, perfectly
quiet, and would sit there for ever. If the hand be inclined very
gently and slowly, so that the frog would naturally tend to slip off,
the creature’s fore paws are shifted on to the edge of the hand, until
he can just prevent himself from falling. If the turning of the hand
be slowly continued, he mounts up with great care and deliberation,
putting first one leg forward and then another, until he balances
himself with perfect precision on the edge; and if the turning of
the hand is continued, he goes through the needful set of muscular
operations, until he comes to be seated in security on the back of the
hand. The doing of all this requires a delicacy of co-ordination and a
precision of adjustment of the muscular apparatus of the body which are
only comparable to those of a rope-dancer.”

Now, why have we entered into these details? To reinforce, from a
somewhat different point of view, that which has again and again been
urged in the preceding sections of this inquiry, that much of animal
behaviour is an organic legacy. A going mechanism of great delicacy,
with ready-made co-ordinations, the products of biological evolution,
affords to consciousness a vast body of its primary data. As Dr.
Sherrington himself says,[193] “co-ordination is abundantly shown
to result from the independent power of the spinal arcs, altogether
apart from the influence of the great cranial sense-organs, and of
the cerebral arcs superposed upon them. These senses and the brain
find the elementary co-ordination of the skeletal musculature an
achievement already provided and to hand in the spinal cord. And no
doubt the product of the instrument is, with the instrument itself,
given over to their use in the reactions they elicit from the spinal
musculature.” We have seen how instinctive behaviour, in those animals
in which it is best studied, affords in hereditary biological outline,
a sketch which subsequent acquisition, under experience, serves only
to elaborate by the filling in of details and of the more delicate
shading in behaviour. But in the higher animals, in which a period of
youth is a time for the acquisition of experience--for experimentation
and practice,--it might seem that the inherited biological legacy was
of less importance. The “spinal animal,” as Dr. Sherrington calls
it,--that is, the animal in which the spinal centres are isolated
from the cerebral centres--goes far to disprove any such view. In
them the cerebral senses and the brain find elementary co-ordination
of the bodily movements an achievement already provided and to hand
in the spinal cord. But when different animals are compared--frog,
bird, rabbit, dog, and monkey--the permanent effects of severance of
brain connection, the effects which remain when the temporary period
of disturbing “shock” is over, are more marked in the higher than
the lower types. And concerning this, Dr. Sherrington says,[194]
“The deeper depression of reaction into which the higher animal, as
contrasted with the lower, sinks when made spinal, appears to me
significant of this, that in the higher types, more than in the lower,
the great cerebral senses actuate the motor organs, and impel the
motions of the individual.”

Whether in the animal in which all direct connection between the
anterior and posterior portions of the central nervous system has been
severed there is a double consciousness--a cerebral consciousness and a
spinal consciousness--we are not in a position accurately to determine.
If the generally accepted opinion, that the higher brain-centres
constitute the sensorium or seat of consciousness, be correct, we must
suppose that a maimed consciousness, with many avenues of experience
closed, is retained in the anterior moiety, while the posterior is
relegated to a condition of mere sentience at best. In any case all
relation between the two is prevented. The two--if two there be--are
rendered quite independent through severance of the cord in the region
of the neck. But there is a point of view indicated by Dr. Sherrington
which is full of suggestion and interest.

“It is significant in the evolution of animal form,” he says,[195]
“that the organ that exhibits most uninterrupted and harmonious
increase in development, as studied successively in passing from lowest
to highest, is the brain. And it is significant that in the nervous
system--segmental system as it is--the brain is developed, not in those
segments whose sense organs are ordinary cutaneous (tactual, etc.),
muscular and visceral, but in the segments connected with the visual,
olfactory, and auditory sense-organs; in other words, the brain is
developed in the head. The head is, so to say, the individual; it has
the mouth, it takes the food, including air and water, and it has the
main sense organs providing data for both space and time. To this the
body, an elongated motor organ with a share of the viscera and the
skin, is appended primarily as a machine for locomotion. This latter
must of necessity lie at the behest of the great sense organs of the
head.”

Now let us try and picture to ourselves a spinal animal, or one which
retains only the lowest portion of the brain, the part known as the
bulb or _medulla oblongata_; let us assume that it is conscious and
capable of acquiring experience through the association and coalescence
of the data afforded by the senses that remain to it; and let us try
to imagine the conscious situations which would arise, and their
value in the guidance of behaviour. The senses that remain are touch
and the temperature sense, the motor sense affording data from the
muscles, joints, and tendons, and those which supply certain visceral
sensations. There is not one of much, if any, guiding value left. There
is not one of what we may term anticipatory use. There is not one
which could serve to infuse anything like definite meaning into the
situation. For, after all, meaning is expectation. There is an element
of anticipation in all those senses which are of any real guiding value
in the conscious situation. Sight, hearing, and, especially for some
animals, smell,--these are the senses which forewarn of something
which may follow; of other sensations with which in the course of
experience they have coalesced. And they are all cut off from the
supposed spinal animal. A light touch might in some cases forewarn
of the shock or severe pressure, which would perhaps follow. But the
shocks would so often come suddenly that it is questionable whether the
warning would be of much avail. Still, touch is a warning and cognitive
sense, and through it the environment would acquire a limited amount of
meaning.

Now, the biological value of coalescent association lies in this
very element of warning. The anticipatory senses, sight, hearing,
smell, are in their several degrees the “projective” senses, the
senses which carry with them the quantity of “outness.” And their
“projective” character is the necessary psychological expression of
their distinctive biological end. They must be projective, must carry
with them “outness,” if they are to convey what we, following Dr.
Stout, have so often spoken of as meaning. But if the biological value
of coalescent association lies in the expectation it renders possible;
and if, in the spinal animal, there are no senses left save touch,
which could receive from the environment preparatory warning of what
is coming; it would seem exceedingly improbable that it should develop
quasi-independent conscious situations of its own. In the unmutilated
animal, at any rate, tactual experience would most probably coalesce
with that derived from the senses which more distinctively take the
lead in the acquisition of meaning. And we may therefore, on these
grounds, as well as on others, acquiesce in the current view that the
quasi-independent functioning of the spinal cord and its constituent
segments is, at best, lit up with those flashes of mere sentience of
which Sir Michael Foster speaks in the passage we quoted in an earlier
section.[196]

If from the consideration of the isolated spinal animal we turn for a
moment to that of the isolated cerebral animal, we find it in a very
different position. It is possessed of the warning senses--those which
from several points of view are the leading senses--but they are
leaders without a following; they have only a very limited company to
conduct into action. The company is there, on the further side of the
severance, but they have lost touch with it. They know not what it is
doing, and have therefore neither the data nor the executive power to
guide its manœuvres in the field of behaviour. They can form maimed
coalescent situations, but they are as impotent as a mere theorist
devoid of all power of practical application. We need not, however,
follow the theme further. We need only add that, could we isolate
tracts of nervous tissue in the lower brain-centres of such a cerebral
animal, we should find that subsidiary co-ordinations would belong, as
a physiological heritage, to these isolated fragments.

The conclusions we may draw, then, with regard to the evolution of
behaviour, as viewed in its physiological aspect, are that it is,
in its simplest expression and in its most complex, conditioned by
sufficient unity of purpose to meet the biological end of survival;
that the complex unity of purpose may be analyzed into a multiplicity
of subsidiary processes each with its subsidiary unity of purpose; and
that the psychological coalescence which gives unity to experience
under the guidance of the leading senses, is paralleled in a
physiological coalescence within the nexus of the nervous system.

II.--THE BIOLOGICAL ASPECT

The biological aspect of behaviour--its relation to biological
ends--has so often come under our consideration in the foregoing
chapters that little need be added in this section: and that little
may be most appropriately devoted, first to the question whether
consciousness does influence behaviour; and secondly, this being
accepted, to the importance of the _rôle_ that is played by the
development of conscious situations in securing, in the higher animals,
the biological end of racial preservation.

That this end is secured without the aid of consciousness in the
case of many organic species, in all those, for example, which we
classify as plants, must not be taken as presumptive evidence that in
other species, for instance in the multitudinous host of insects, the
development of conscious situations is of no biological value. The fact
that chlorophyll is not developed in any mammal does not show that the
possession of this substance is of no service to the higher plants.
It would not be worth while to give expression to this very obvious
truth, were it not that critics of natural selection persistently
argue that because one species gets on perfectly well without this
or that particular character it can have played no part in securing
the survival of another species. When I described, at a meeting of
naturalists, how well young chicks could swim, such a critic drew me
aside after the meeting, and expressed his surprise that this did
not convince me that the webbed foot of the duck could not logically
be attributed to natural selection. This is an extreme case, and one
obviously taken on peculiarly weak grounds. But even Huxley urged
that, because a frog, from which the cerebral hemispheres have been
removed, performs many co-ordinated actions without conscious guidance,
consciousness is, throughout nature, merely an accompaniment of certain
molecular changes in the brain. “Such a frog,” he says,[197] “walks,
hops, swims, and goes through his gymnastic performances quite as well
without consciousness, and consequently without volition, as with it;
and if a frog, in his natural state, possesses anything corresponding
with what we call volition, there is no reason to think that it is
anything but a concomitant of the molecular changes in the brain which
form part of the series involved in the production of motion.

“The consciousness of brutes,” he continues, “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 which 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. It does not enter into the chain
of causation of their actions at all.”

If the literal truth of this contention--the logical soundness of this
conclusion--be admitted, it seems absurd to speak of the biological
value of consciousness in behaviour or to discuss the importance of the
_rôle_ that is played by the development of conscious situations in
securing the biological end of racial preservation.

Now, consciousness is regarded by an influential school of thinkers as
a sort of _deus ex machina_, which, sitting enthroned, and crowned with
a capital letter as Will, directs, like a being from another sphere,
the doings of the body. It was against the doctrines of this school
that Huxley took up arms. They do not concern us here. The will, or
volition, as an underlying cause, stands outside the pale of scientific
inquiry. It belongs to the wide realm of metaphysics; its plea must be
heard in another court. In this part of his contention Huxley was, we
believe, unquestionably right from the scientific standpoint. Neither
will, nor impulse, nor instinct, nor consciousness itself, should be
introduced into any scientific description or explanation of phenomena
as a cause of their existence or being, for as such it does not enter
into the sequence of events; it is that which metaphysics claims as
their _raison d’être_--that which gives them being. Science in this
matter should be frankly agnostic--neither affirming nor denying
aught. This, of course, is not equivalent to saying that the agnostic
position is the true end of human reason. That would only be so on the
assumption that the problems of science are the only problems with
which that reason can deal. To exclude metaphysics from science is not
to exclude it from human thought. As a matter of fact such exclusion
is neither possible nor reasonable. But to clearly distinguish the
problems of science from those of metaphysics is absolutely necessary,
if we are to prevent hopeless confusion of issues.

In contending, however, against the introduction of metaphysical
doctrines into the region of scientific explanation, Huxley seems
to have been carried too far by the force of his own attack. So long
as he held to the position that every conscious state has, as its
concomitant, a molecular change in the brain, he had all the forces
of evolution on his side. But when he said that consciousness is
merely the steam-whistle of life’s locomotive, or merely answers to
the sound which the animal-bell gives out when it is struck, he takes
up another position of far less strategical strength. For whereas
the frog from which the physical centres of consciousness have been
removed sits crouched and motionless, and “will starve sooner than
feed itself, although food put into its mouth is swallowed;” the frog
in which conscious situations can take form in unmutilated cerebral
hemispheres behaves in a very different manner. It is nothing less
than pure assumption to say that the consciousness, which is admitted
to be present, has practically no effect whatever upon the behaviour.
And we must ask any evolutionist who accepts this conclusion, how he
accounts on evolutionary grounds for the existence of a useless adjunct
to neural processes.

“It is,” says Huxley,[198] “experimentally demonstrable--any one who
cares to run a pin into himself may perform a sufficient demonstration
of the fact--that a mode of motion of the nervous system is the
immediate antecedent of a state of consciousness. We have as much
reason for regarding the mode of motion as the cause of the state of
consciousness, as we have for regarding any event as the cause of
another. How the one phenomenon causes the other we know as much, or as
little, as in any other case of causation; but we have as much right
to believe that the sensation is an effect of the molecular change, as
we have to believe that motion is an effect of impact; and there is as
much propriety in saying that the brain evolves sensation, as there is
in saying that an iron rod, when hammered, evolves heat.” But if we
speak of the related antecedent as the cause, it is not obvious why we
should not describe the desire to demonstrate the supposed fact as the
cause of running in the pin. We seem to have just as much reason for
calling this antecedent state of consciousness the cause of certain
movements and behaviour, as of calling a mode of motion in the brain
the cause of a further state of consciousness. It is true that we
have not the least idea how the desire can cause the act; but Huxley
practically admits that we have no idea how molecular change can be the
cause of consciousness. In the one case we are no worse off than we
are in the other. Neither position is logically defensible; since each
assumes that physical events and states of consciousness can constitute
links in the same causal chain.

The philosophical hypothesis known as monism regards the molecular
change, not as the antecedent of a conscious state, but as its
concomitant. That which from a physical and physiological point of
view is a complex molecular disturbance is, at the same time, from a
psychological point of view, a state of consciousness. The two are
different aspects of one natural occurrence. Why such an occurrence
should have two so different aspects we have not the faintest idea; but
here we are not one whit worse off than we were before. The hypothesis
does, however, help us to get over our difficulty. An essential
feature of Huxley’s contention is that the physical and physiological
chain of causation is complete in itself, which may be granted; and
further, that if consciousness does arise it is merely an adjunct
without influence on the sequence of events--what is influential is
the molecular disturbance, not the consciousness which accompanies it.
But according to monism the state of consciousness actually is that
very same something which the physiologist calls, in the language of
physics, a molecular disturbance. And in saying that consciousness
influences behaviour one who accepts this hypothesis is merely avoiding
a cumbrous form of circumlocution. He puts it in this way instead
of saying that the nerve-changes in the cerebral hemispheres, or
elsewhere, which from a psychological point of view _are_ a conscious
situation, influence and determine the course of behaviour. But from
this point of view it is absurd to say that the consciousness is merely
an adjunct--absurd to say that were there no conscious situation the
neural situation would remain unchanged. They are the very same thing
from different points of view; and to say there is no influential
conscious situation is simply equivalent to saying that there is not
this determining neural situation.

However we explain the fact, there are few who hesitate to accept it
for the purposes of scientific explanation. The conscious situation,
having no doubt for the physiologist a neural aspect if he could only
get at it as a whole, does practically determine the behaviour of the
animal which has gained the requisite experience. If we accept the
fact, we may pass on to its importance in securing the biological end
of race preservation.

It is a commonplace of evolutionary doctrine that, other things being
equal, those races will survive, in the constituent members of which
intelligent behaviour enables them to deal most effectually with an
environment of increasing complexity. And it is a matter of familiar
observation that such behaviour is closely connected with delicacy
and refinement of development in those senses which take the lead in
cognitional process, and with rapidity and precision in the motor
co-ordination through which prompt and skilful advantage is taken of
the situation which has, through experience, acquired meaning.

But though the importance of intelligent adjustment to the
circumstances of life is widely admitted as a general principle, it
is perhaps through a study of animal behaviour that we are best able
to realize its full range and extent. Biologists are so largely, and
quite wisely, occupied in the study of morphological and physiological
problems, which admit of a treatment more exact than the most ardent
advocate of the investigation of behaviour, under natural or even
under experimental conditions, can claim; they devote, again quite
rightly, so large a share of attention to the variation and natural
selection of adaptive structure in its adult condition and embryonic
stages; the pendulum of opinion has, under the teaching of Professor
Weismann, swung so far in the direction of the non-acceptance of
the hereditary transmission of characters individually acquired
through intelligent adjustment or otherwise; that the part played by
consciousness in the evolution of the higher and more active animals is
apt to pass unnoticed or unrecorded. It is well, therefore, to put in
a reminder that a great number of animals would never reach the adult
state in which they pass into the hands of the comparative anatomist
save for the acquisition of experience, and the effective use of the
consciousness to which they are heirs; that their survival is due,
not only to their possession of certain structures and organs, but,
every whit as much, to the practical use to which these possessions
are put in the give and take of active life; and that many interesting
problems which are keenly discussed by evolutionists in the light of
natural selection presuppose conscious situations which are more or
less tacitly taken for granted.

Let us cast a rapid glance over some of these topics of biological
discussion. The fascinating subject of mimicry, involving as it
necessarily does the discussion of the value of warning colours and
behaviour, a subject opening up an extensive group of problems so
brilliantly studied by Professor Poulton, is meaningless save in so
far as there is implied a conscious reaction to colour and form on the
part of animals which can learn from experience. The warning colours
reinstate a conscious situation, so that, misled by appearances, a bird
mistakes the mimicking insect for its nauseous “model.”

The whole range of behaviour, included under play, experimentation, and
practice, on the importance of which, following the lead so ably given
by Professor Groos, we have insisted, is equally meaningless, save as a
means to the acquisition of serviceable experience for use in the more
serious business of after-life; and experience is the establishment,
through association and coalescence, of conscious situations which
possess guiding value. And if, as we shall hereafter see, they may
also be regarded as a means of securing pleasure, as a psychological
end of behaviour, it is not less obvious that it is only through the
development of consciousness that such a psychological end can have any
existence.

It matters not if the particular form assumed by play and
experimentation be largely dependent on instinctive tendencies. For
all the phenomena of instinct, profoundly organic as are the modes of
behaviour comprised under this head, definite as are the inherited
co-ordinations in the most typical examples of its occurrence, have
also, except in some doubtful cases, a conscious aspect. At any rate
this is the case in so far as instinctive response forms the hereditary
basis on which is reared a more nicely adjusted intelligent edifice,
in so far as instinctive procedure is subsequently modified and guided
by acquired experience, in so far as there creeps in that “little dose
of judgment” which Huber found in bees, Lord Avebury attributes to
ants, Dr. Peckham sees in spiders and solitary wasps, and all observers
find in birds and mammals. For if in these cases instinctive behaviour
were unconscious, it would, as such, remain outside experience; and if
outside experience, there could be no data on which consciousness could
base any modification of inherited behaviour, no opportunity of taking
up the ready-formed responses into the mental synthesis and utilizing
them for the wider ends of intelligent purpose.

In social behaviour there is a reciprocity of suggestion between the
members of the community. And such suggestion is operative through an
appeal to consciousness. However instinctive the forms of procedure
may be in social insects, there remains much beyond which is hard to
explain on the hypothesis that there is, in them, nothing analogous to
a conscious situation; while in such vertebrates as birds and mammals
we cannot but believe that consciousness is the main determinant of
much behaviour which seems to imply the germs, or more than the germs,
of sympathy. The little monkey I saw in Hamburg cuddling up caressingly
to a wounded companion, must surely have experienced a conscious
situation analogous to that which prompts a child to nestle alongside
her companion in distress. And he who has seen no signs of sympathy in
dogs, has either watched their behaviour in vain, or is himself lacking
in sympathy.

In sexual selection by preferential mating, even if we follow Professor
Groos in believing that it is a special mode of natural selection,
the conscious situation is essential. If we accept the theory in any
form, we must regard the adornments, antics, and display of the male
as an appeal in some way to the consciousness of the female, whatever
particular form the effects in that consciousness may take, whether the
appeal evoke a sense of beauty, or simply be a means of exciting to the
consummation of the natural end of courtship. Even if we follow Mr.
Wallace in regarding plume and song as “recognition marks,” it is only
by their appeal to consciousness in this way, if in no other, that they
are of any biological value. And this, of course, applies equally to
the whole range of his theory of recognition marks--their sole utility
lies in their being a stimulus to consciousness through which the end
of recognition is secured. So, too, not only the specialized behaviour
which we dignify by the name of “courtship,” but every case in which
mate is drawn to mate through sight, smell, hearing--any of the leading
senses--testifies to the importance of consciousness in furthering an
end of supreme biological importance.

And if, as Darwin urged, the “law of battle” among the males
co-operates with preferential mating, as we can hardly deny, in
securing strong, vigorous, and healthy fathers of the generation they
beget, here, too, consciousness is an important factor. Can we conceive
a “law of battle” among unconscious beings? If success in the combat
were a mere matter of brute strength, it would imply some consciousness
in its dull exercise. But it is more. It is also a trial of skill.
Were it not so our forefathers would not have spent hours in watching
a cock-fight, or laid heavy odds on their particular “fancy.”

We need not labour the theme. In the search for food or a nesting
site, in the capture of prey and escape from enemies, in all that
demands attention, and in all that necessitates practice, in what
M. Houssay calls “the industries of animals,” and in that which Mr.
Hudson calls “tradition,” consciousness has a part to play. Even
plants unconsciously appeal to the consciousness of insects, birds,
and mammals. Their bright, scented, nectar-bearing flowers, and their
sweet, coloured fruits are means of effecting the biological ends of
fertilization and the dissemination of seeds, but only on condition
that their colours stimulate the sense of sight, and their scent and
sweetness the senses of smell and taste. It is, perhaps, going too far
to claim that, wherever sense-organs exist they imply at least some
dim and rudimentary form of conscious situation of guiding value so
far as it goes; for it is possible that in some cases the coalescence
of elementary items of sentience has not been carried far enough to
justify us in speaking of experience by which the animal can profit.
But it is surely not going too far to claim that, wherever two or three
such sense-organs are gathered together in any living being, there is
consciousness in the midst of them, beginning to exercise that guidance
which serves so markedly to differentiate the typical animal from the
typical plant.

But throughout the animal kingdom, until we reach its highest
development in man, the guidance of consciousness, important as it
is, seems to be almost wholly subservient to a biological end, that
of the preservation of the race, and for the race of the individual.
Practical utility is the touchstone of animal intelligence, and of the
whole range of feeling and emotion in beings still under examination in
the stern school of natural selection. By this we mean that practical
utility has determined what degree and complexity of intelligence,
feeling, and emotion shall be attained. If the requisite level be not
attained--elimination. Higher levels no doubt bring advantage--so long
as they are practically useful. But in the school of natural selection
useless accomplishments are not much taught. Although its examinations
are in a sense competitive, all are allowed to pass who qualify for
survival. But the competitors become more numerous and the standard
for a pass rises. As the school increases in size higher classes with
harder problems to solve are established. Progress is an incident of
the constant survival of the fittest when there are variations in
fitness.

III.--THE PSYCHOLOGICAL ASPECT

On the hypothesis of monism, the nature of which, so far as it bears
on our inquiry, was briefly indicated in the foregoing section, the
conscious situation is the psychical or mental expression of that
which for the physiologist is what we may term a neural situation. As
such it does not enter into the chain of physical causation; nor do
physical events as such--that is to say, save as experienced--enter
into the chain of mental causation. For mental development they have
no independent existence, and are negligible except in so far as they
enter as items of experience into the conscious situation.

But altogether apart from the way or ways in which we may attempt to
explain the fact, most of us believe, with unquestioning confidence,
that the growth of practical experience, somehow associated with
nervous changes in the brain or sensorium, is of real value in the
guidance of behaviour in such manner as to secure biological ends.
Conscious experience must therefore, in the animal world, serve its
biological purpose, or it will be of no avail. If there be not a
pre-established harmony, there must be an evolved harmony; and how such
a harmony could be evolved if consciousness be not by some means in
vital touch with behaviour, influenced by and in turn influencing it,
we cannot conceive. The steam-whistle theory of consciousness leaves
the matter, for the evolutionist, in this inconceivable position.

We need not, however, flog a dead horse. We need not ask how, on the
steam-whistle theory, those states of feeling which we broadly classify
as pleasurable could become associated with behaviour conducing to
welfare, and those which we group as hurtful with behaviour which
is biologically harmful. It is more important, again, to notice
that, associated and consonant with the biological end, there
arises a psychological end of behaviour--what we may term, with the
qualifications before considered,[199] the getting of pleasure and the
avoidance of pain. This is the purpose of behaviour as viewed from the
psychological aspect. The biological end of animal conation is racial
survival; its psychological end is individual satisfaction. And the two
ends are, in the main and broadly speaking, consonant--a result which
would unquestionably be secured by natural selection, but is on any
other naturalistic hypothesis difficult of explanation.

But the two ends are not only consonant; they are supplementary one
to the other. During much of the life of the higher animals there is
no need, immediately present and pressing, for the output of action
to meet biological ends. There are periods of life and intervals of
time when the sharp incidence of the struggle for existence does not
call for the serious business of behaviour. But at these periods and
in these intervals the animal is not inactive; indeed, it is restless
in its activity. Unless it be weary with unwonted exertion, or basking
in the psychical sunshine of content, due to the unsought advent of
pleasant stimulation or the after-effects of previous behaviour (for
example, when hunger has been relieved), the healthy animal must be up
and doing. This familiar fact no doubt affords the basis in observation
of the surplus-energy theory of play. But is it necessarily surplus
energy? Is it not rather normal energy which expends itself in this way
when there is no immediate and serious biological business on hand?
And, as Professor Groos has pointed out, play is seen when we have
every reason to suppose there is no surplus energy, nay, even when the
normal energy is at a low ebb. There is no more pathetic sight than a
sick kitten, with energy obviously much below par, utilizing its little
remaining strength in feeble attempts to play.

It is unnecessary to do more than remind the reader of the theory
elaborated with so much skill and care by Professor Groos, that the
forms assumed by play--in which, it will be remembered, he includes a
very wide range of behaviour--have a very important indirect biological
end in practice and experimentation. Our present point is, that its
direct psychological end is the satisfaction it affords. Without
this the individual would not be impelled to the continuance of
performances which occupy a wide space in the field of animal behaviour
in which the biological end has reference, not to present requirements,
but to future needs.

No one has given better expression to the sway of this psychological
end than Mr. W. H. Hudson. “We see,” he says,[200] “that the inferior
animals, when the conditions of life are favourable, are subject to
periodical fits of gladness, affecting them powerfully and standing
out in vivid contrast to their ordinary temper. And we know what
this feeling is--this periodic intense elation which even civilized
man occasionally experiences when in perfect health, more especially
when young. There are moments when he is mad with joy, when he cannot
keep still, when his impulse is to sing and shout aloud and laugh at
nothing, to run and leap and exert himself in some extravagant way.
Among the heavier mammalians the feeling is manifested in loud noises,
bellowings, and screamings, and in lumbering, uncouth motions--throwing
up the heels, pretended panics, and ponderous mock battles.

“In smaller and livelier animals, with greater celerity and certitude
in their motions, the feeling shows itself in more regular and often in
more complex ways. Thus Felidæ, when young, and in very agile sprightly
species, like the puma, throughout life, simulate all the actions of
an animal hunting its prey--sudden, intense excitement of discovery,
concealment, gradual advance, masked by intervening objects, with
intervals of watching, when they crouch motionless, the eyes flashing
and tail waved from side to side; finally, the rush and spring, when
the playfellow is captured, rolled over on his back, and worried to
imaginary death. Other species of the most diverse kinds, in which
voice is greatly developed, join in noisy concerts and choruses; many
of the cats may be mentioned, also dogs and foxes, capybaras and other
loquacious rodents; and in the howling monkeys this kind of performance
rises to the sublime uproar of the tropical forest at eventide.

“Birds are more subject to this universal joyous instinct than mammals,
and there are times when some species are constantly overflowing with
it; and as they are so much freer than mammals, more buoyant and
graceful in action, more loquacious, and have voices so much finer,
their gladness shows itself in a greater variety of ways, with more
regular and beautiful motions, and with melody. But every species or
group of species has its own inherited form or style of performance;
and however rude and irregular this may be, as in the case of the
pretended stampedes and fights of wild cattle, that is the form in
which the feeling will always be expressed.”

That all this, which Mr. Hudson so graphically describes, belongs to
the psychological aspect of animal behaviour and is directly prompted
by conative tendencies whose immediate end is conscious satisfaction,
the mere joy of unrestrained and healthy activity, may be freely
admitted, without denying that all this exuberant psychical life
owes its evolution to the fact that it is in consonance with and
supplemental to biological ends which secure survival. It is with
animals as it is with man; play is the preparation for earnest. As I
have elsewhere said,[201] what our national games have done for the
English race it is difficult to overestimate. They train us to use our
bodies and expend our energies to the best advantage. An old soldier,
watching a football match, said, “That’s the training for our future
soldiers and sailors.” The playing fields are the finest school of
organized co-operation in the world. But, apart from compulsion, a
boy will not enter into the game with that zest through which alone
it acquires real value for training, unless there be an immediate
psychological end in the satisfaction he derives. And with animals
practice and preparation for the business of life could not occur if
the ultimate biological purpose of it all were not supplemented by the
enjoyment it brings for its own sake.

But in animal play, as indeed in that of human youth, we are perhaps
a little apt, in laying stress on the bodily skill and readiness
of response to which it so effectually ministers, to forget that it
is also a psychological training. In technical phraseology, we are
disposed to fix our attention on the acquired co-ordination of act
and movement rather than on the correlation of conscious data, which
renders possible the skilful performance. And yet, rightly considered,
the behaviour itself is simply the outcome of a conscious situation,
duly elaborated, and knit together through the association and
coalescence of its constituent data. It is a means to the unification
of consciousness by bringing into relation scattered and, at first,
quasi-independent sensory and emotional elements. Success is only
attained through the concentration of attention and effort on that
which is the centre of interest and also the focus of endeavour. And
this close attention and well-directed effort, which are trained in
the playful output of energy, are just the mental qualities which
will stand the animal in good stead when the real incidence of life’s
struggle comes upon it, when the reward of success is survival and
the penalty of failure elimination. For they are not merely physical
qualities, though their effects are bodily movements of attack and
defence, of active escape, or merely “lying low.” They are essential
psychological features of a unified and well-directed conative process.

In the fairly abundant play-time of animal life, this unification and
direction of conative process can take form under conditions wherein
the preliminary failures which accompany all forms of learning do
not entail the severe penalty of elimination. If we may so put it,
and so apply a deeply instructive parable, Natural Selection says
to her more favoured children, in which conscious situations can be
developed, “Here are the talents with which I have endowed you; make
use of them till I come, as come I shall in due time.” This animal
puts them out to usury in play; that animal keeps them laid up in the
napkin of inactivity. Then Natural Selection, the austere one, comes;
gives the commendation of survival to the animal that had learnt to
put its talents to use in the period of preparation, and condemns to
elimination that which had not traded with his talents at the bank of
play. In animal life, on the perceptual plane, we have the same need
for training in little things and seemingly unimportant matters in
preparation for the stress and storm which may, nay must, come upon
them, that we find in men and women on the higher ethical plane. To
those who think that the play of animals is too trifling a thing to
affect the question of survival, we would suggest the application, with
a necessary difference, of the thought which Miss Edith Simcox puts
into the following words: “Does it,” she says, “seem a trifling thing
to say that in the hours of passionate trial and temptation a man can
have no better help than his own past? Every generous feeling that has
not been crushed, every wholesome impulse that has been followed, every
just perception, every habit of unselfish action, will be present in
the background to guide or to sustain. It is too late, when the storm
has burst, to provide our craft with rigging fit to weather it; but we
may find a purpose for the years that oppress us by their dull calm, if
we elect to spend them in laying up stores of strength and wisdom and
emotional prejudices of a goodly human kind, whereby, if need arises,
we may be able to resist hereafter the gusts of passion that might else
bear us out of the straightforward course.” To apply the thought, the
trifles of play supply the psychological rigging which alone can save
the animal craft in the coming storm of the struggle for existence. And
the point on which we have to lay special stress in this section is,
that it is psychological rigging--or, if this seems to lay too much
emphasis on the genesis of conscious situations, we may at least urge
that the psychological ropes are of co-ordinate importance with the
biological spars.

So far, then, we reach the following conclusion: that if we classify
the behaviour of the higher and more intelligent animals under two
heads, the one comprising all those acts which are of direct biological
value in enabling the animal to escape elimination under the immediate
stress of the struggle for existence, and the other including all those
acts which are of indirect preparatory or educative value, the latter,
which are under their biological aspect not less important than the
former, are under their psychological aspect of perhaps even greater
importance. For the conditions of actual struggle are not those under
which mental development could most easily be furthered, though they
are those in which it is most effectually tested. Hence, the more
intelligent animals pass through a period during which they are more
or less shielded from the incidence of natural selection by their
parents, and this is the period of play and of psychological education.
And the tendency to play is so far organic, in that it is dependent on
inherited instinctive propensities, and so far psychological in that
it is accompanied by a felt want, which constitutes a conative impulse
finding its appropriate end in the consciousness of satisfaction. But
play--if we accept the term as the group-name for all these modes
of behaviour which fall under our second class, those of indirect
biological value--does not cease with the period of youth; it occupies
all the intervals in the more serious business of animal life. And no
discussion of animal behaviour can be adequate which does not assign
to this class its due place, alike in biological and in psychological
evolution.

The whole value of experience lies in the linkage and coalescence
of the data afforded to consciousness. It is true that an inherited
nervous system supplies the organic conditions of that physiological
linkage and functional coalescence of which experience is the
psychological expression. It is true that this physical integration
secures a ready-made grouping of the conscious data which are the
concomitants of orderly molecular changes in the brain or analogous
sensorium. Still, it also remains true that the value of experience
lies in the further linkage and coalescence that is acquired by the
individual in the course of what we may fitly call its education. Every
step in this education gets its psychological sanction through the
satisfaction it affords in consciousness; and the time of acquisition
is not during the stress of examination in the actual struggle for
existence, but rather in the youthful period and in the subsequent
intervals of preparation and practice during the play-time of animal
life.

The examination analogy--if, indeed, it may not be rightly regarded
as something more than an analogy--may be pressed a little further
as a means of fixing our attention on two points which are worthy
of consideration. The first is that, in the preparation for the
examination, specific practice as much of it is, cramming is not
the system exemplified by the higher animals. A good all-round
education in the acquisition of conscious situations more or less
coalescent into a unified system of experience, and in their effective
utilization without unnecessary delay and bungling along more or
less converging lines of practical behaviour; this is what secures a
“pass” in survival, especially where the circumstances of life have
reached a considerable degree of complexity. The instinctive act,
with its relatively definite response to a question which is almost
certain to be set to every candidate for survival, is that, which is
the analogue in behaviour to the result of a system of cram. Organic
nature does employ this system in the lower classes of her school;
definite responses are ground into merely instinctive types generation
after generation, and the right answers are given, automatically and
unintelligently, whenever the oft-recurrent questions are set. But this
will not do when the questions require the exercise of intelligence,
when they are of the nature of problems, with just those delicate but
not unimportant shades of difference which baffle the candidate who
has been drilled in a merely mechanical fashion. Hence the cramming
of instinct does not suffice for animals whose environment presents
problems of greater variety and greater complexity. Intelligence
is required to meet the particular combinations as they arise. The
greyhound, which is loosed on a hare, has never seen that hare run in
exactly that way over that special tract of country. But he has been
trained in such situations, and is thus prepared to meet the special
problem in its details as they present themselves in the light of the
experience he has gained of other like problems. And his skill in
pursuit has not only been gained through education in coursing. In a
thousand ways, as puppy and dog, he has learnt how to use well those
sinewy limbs. The training of his whole life is brought to bear on the
question immediately before him.

The general bearing of these facts is obvious. Play, as a means of
animal education, is varied, and has for its end all-round training
of the animal mind in its sphere of operation. Although there are
some specific propensities, certain observable trends of behaviour,
as in hunting-play, courtship-play, and the like, we must not expect,
nor do we find, anything like stereotyped definiteness of conative
activity. We find that freedom and elasticity in animal education which
is, perhaps, more often advocated than carried into practice in human
education.

The second point arising out of the examination analogy is, that its
range determines the level of preparation therefor. It is, for animals,
a practical examination, not a theoretical. Not a single question is
set demanding an explanation. The problems are such as can be solved by
intelligence, not such as require the exercise of reason, as we have
used the term in foregoing pages. These higher problems are only set
when the sixth form is reached, and there is no conclusive evidence
that any animals get into the sixth. This, however, is entirely a
question of evidence, and many of us will be glad to welcome them
there, if proved ability to deal reflectively with ideational questions
justifies their promotion.

If any of them do belong to this form, they have probably got there
through play. For in the stress of the actual examination there is not
much time for reflection. Or perhaps we may rather say that, not in
actual struggle, and not in active preparation for it in play-time,
but in intervals of leisure between both, when the animal lies quietly
turning over in his mind we know not what, will experience be reviewed,
and generalizations drawn as to the why of events in this strange
world. Probably the animal accepts things as they are, and does not
trouble about their explanation. But it may not be so. At any rate,
if animals lack the means of descriptive inter-communication, and
have no words as concrete pegs on which to hang abstract ideas, their
explanations cannot be carried far. Theories without the power of
disputation would be a poor solace in leisure moments.

One more point may be noticed with regard to the psychological aspect
of the evolution of behaviour--the reciprocal action of intelligence.
It is the intelligence of others that introduces so much variety and
complexity into the environment. Hunters and hunted, combatants,
rivals, mate and mate, enemies or companions in their varied aspects,
introduce through their intelligence complications which only
intelligence can meet. And, as intelligence begets intelligence, so do
emotional attitudes beget answering emotional states. Psychological
evolution translated into practical behaviour gives rise to situations
of reciprocal complexity. This point of view is, however, so familiar,
that nothing need be said in its further elucidation. The behaviour
of any given animal does not stand alone, but is closely related with
the behaviour of others. Among social animals the relationships are
peculiarly close, and it is among them that the psychological aspect of
behaviour reaches its highest expression.

IV.--CONTINUITY IN EVOLUTION

Under the head of organic behaviour, in the widest acceptation of
the term, fall the whole of physiology, the whole of embryological
development, nay, more, the whole of organic evolution; while mental
evolution, in all its stages, may be regarded as the psychological
aspect of that which, from the physiological aspect, is the evolution
of nervous systems. Life itself is the behaviour of a particular kind
of substance which is found more or less abundantly under natural
conditions. No other known substance behaves in this way, and so
ignorant are we as to the conditions of its natural origin, that it is
useless to guess at a scientific explanation. And even if we knew all
the antecedents and conditions of its origin we should be no nearer a
comprehension of why protoplasm has the peculiar properties which we
find it to possess. That is a question to which science can give no
answer. Who knows why a certain compound of oxygen and hydrogen in
certain proportions has the properties of that which we call water?

Let us note the distinction between saying, as we said above, that life
is the behaviour of protoplasm, and asserting that life is the cause
of this behaviour. The one is a scientific statement of observed fact,
the other an explanation of the fact in metaphysical terms, a reference
of the fact to its underlying cause. So long as we quite clearly
understand that we are talking the language of metaphysics, we may
speak of life as a cause of organic behaviour; but let us be careful
to remember that the statement has no more value for science than the
assertion that aqueosity is the cause of the behaviour of water.

Leaving on one side, then, the natural origin of protoplasm, the
conditions of which are unknown, we find that, as a matter of
observation, every bit of living substance, the history of which has
been traced, is a fragment detached from some other bit which behaved
in the same way. This is the basal fact of the continuity of organic
evolution. But such a detached fragment has the property of increasing
by taking up from the environment more of those elementary materials
from which it is itself compounded in subtle synthesis. Nay, further,
every fragment of which we know the history is found to increase in
such a way as to reach, in form, structure, and idiosyncracies of
behaviour, the likeness of the organism--plant or animal--from which it
was derived. In the higher plants and animals the separated fragments
or cells are the ova and sperms, or their equivalents, which unite,
with fusion or coalescence of their nuclear matter, and thus give rise
to a new individual in the course of embryological development.

Now, as we have already seen, much modern biological discussion centres
round the question whether the detached reproductive fragment, ovum or
sperm as the case may be, is derived from the whole body of the parent,
by what Darwin termed pangenesis or in some other way, or only from
germinal substance set apart in development for this end. And we have
provisionally accepted the hypothesis that it is the direct descendant
of other reproductive cells; and that, throughout a long ancestry,
stretching back into the far past, there never occurs in the direct
line of genealogical sequence, any highly differentiated cell, such as
a gland-cell, muscle-cell, nerve-cell; never, with certain reservations
into which we need not enter, is found the representative of any
tissue save that to which the reproductive function is restricted. In
technical phraseology, the continuity of organic evolution is due to
the continuity of the germinal substance.

During embryological development the fertilized ovum--consisting
of two fused fragments of this germinal substance--gives rise to a
host of ordered and marshalled cells, which are divisible into two
groups: the one forms the body with its muscles, bones, glands,
digestive system, skin, sense-organs, nerve-centres, and so forth;
the other forms a reserve store of germinal substance, from which
are derived the ova and sperms. The former take no direct share in
reproduction; they are off the line of continuous descent; they die
without issue. But they protect and minister to the reproductive
function of the second group--the potential ancestors of the races to
follow. But all instinctive and intelligent behaviour is the outcome
of the orderly working of the nervous system, is initiated through
sensory stimulation, and is executed by the motor organs; and all the
structural parts, through which such behaviour is possible, belong
to the body--that which dies without issue. How, then, can instinct
and intelligence be inherited? In a sense they are not inherited. The
nervous system which is their organic basis begets no heirs. But it is
begotten of germinal substance, which not only produced the body of
which the nervous system is a part, but also handed on, with that body,
samples of the same germinal substance capable of reproducing a similar
body and a like nervous system. Herein lies the basis of heredity.

The stress of the struggle for existence falls upon the body; and
instinctive or intelligent behaviour is a means to its preservation
in the struggle for existence. According as it survives or not, will
the samples of germinal substance it contains fulfil their biological
end or perish with it. Natural selection secures the survival of those
animals which bear the seed from which their like will be developed.

On this view all variation arises within the germinal substance, but it
is manifested in the body which is its product. How variations arise we
do not know with any exactness of detail. That the germinal substance
is influenced in its nutrition and in other ways by the surrounding
tissues is highly probable; and this influence may lead to changes
which are the source of variations; but it is very doubtful whether
such influence can be what we before termed “homœopathic.”[202] It is
improbable that the formation of the nerve-connections involved in
intelligent behaviour which has grown habitual through repetition,
can so influence the germinal cells as to give rise to variations of
like nature. In other words, acquired habit is probably not a direct
determinant of an inherited variation of like nature in instinctive
behaviour. Apart from such influence the only source of variations
which can be assigned is either the differential division of nuclei
in preparation for the process of fertilization,[203] or the process
of fertilization itself. The union of perhaps differentiated germinal
substance from two distinct parents affords the opportunities for the
admixture and compounding of hereditary qualities in the two samples,
from which variations favourable or the reverse may arise.

It is now generally recognized, however, that the origin of variations
is a problem quite distinct from that of the survival of those whose
direction is favourable to that end. The theory of natural selection,
as such, does not pretend to offer any explanation of the manner in
which variations arise; though of course a complete theory of organic
evolution must assign the antecedents and conditions of organic
progress in all its varied phases. We know that variations do occur;
we know, too, that more individuals are born than survive to procreate
their kind; and, on the theory of natural selection, we draw from these
data the conclusion that, on the average, the animals that escape
elimination are those in which the variations are of such a nature as
to conduce to this end.

It will be seen that, on the hypothesis of organic heredity, thus
briefly sketched, continuity can, in strictness and, as we may phrase
it, in its first intent, only be predicated of the germinal substance;
but that this substance gives rise to products--active vigorous animals
behaving in certain ways, each after his kind--which hold similar
germinal substance in trust for future use. Natural selection deals
with the trustees; and if they succumb, that which they hold in trust
is lost. To put the matter in another way: Nature says to the germinal
substance, “By your products you must be judged in accordance with the
criterion of utility and efficiency.” Practical use in the give and
take of active life is the touchstone of all behaviour which makes for
survival. This being secured, there may be a balance of behaviour for
other purposes. But in animals the balance is not of large amount, and
other purposes have not taken form and direction. It should be clearly
noticed that, on the hypothesis we are considering, use is the test
of survival, and though it is not the direct cause of variations, it
affords their sanction in survival. That animal escapes elimination
whose behaviour is of practical use; and it holds in trust for the
future a store of germinal substance from which is produced a successor
capable of behaving in like manner.

The whole drama of organic evolution may be regarded as the realization
in a succession of individuals of the evolving potentiality of
continuous lines of germinal substance. The successive individuals
die--but the germinal substance lives on in their heirs, if they have
any. In virtue of what intimate and hidden structure or disposition of
parts the germ possesses this potentiality we do not know. The ovum
of a dog is a microscopic speck less than one-hundredth of an inch in
diameter; the sperm is far more minute. They unite, and their nuclei
coalesce. The cellular product divides and subdivides. The cell colony
absorbs nutriment from the maternal tissues. Division proceeds apace,
and the cells are marshalled and ordered in embryological development;
definite tissues are formed; the stages of their genesis can be
predicted with accuracy; and in due time a puppy is born which shall
grow to the likeness of its parents and behave as they behaved. We can
trace the succession of events; we see that they form a related series;
we have good reason for believing that the state of matters at any
one moment is the antecedent condition of the state of matters at the
succeeding moment. More than this science cannot say. The underlying
cause is, for science, hidden in the mists of the unknown. Even for
metaphysics it is but part of the force that beats through the universe
and makes it not a chaos but a cosmos--a force known to us only in its
effects.

It will thus be seen that the conception of continuity in organic
evolution has, broadly considered, a threefold aspect. First,
there is the continuity of the germinal substance through whose
reproductive behaviour under the appropriate conditions embryological
development occurs; secondly, there is continuity in this embryological
development, stage by stage, from the fertilized ovum to the adult
which is its final product and expression; thirdly, there is continuity
in these final products, in the animals whose organic, instinctive,
and intelligent behaviour lie open to our study and investigation. The
first is germinal, the second developmental, the third evolutional
continuity.

Before attempting to summarize some of the contributions afforded by
our inquiry towards the doctrine of continuity in the last of these
three aspects, we must pause for a moment to consider how far and in
what sense continuity can be predicated of mental development.

We have regarded the conscious situation as the psychical aspect of a
nerve-situation in the sensorium; and the nervous system, capable of
behaving in this way, is in developmental continuity with the germinal
substance of the fertilized ovum. But what shall we say with regard to
the psychical aspect? Two hypotheses seem open to us, each of which
presents difficulties, but of different kinds. The first is, that when
the organic development of the nervous system reaches a certain level
and order of complexity consciousness emerges, how and whence we know
not. The second is, that consciousness is developed from sentience,
which is the concomitant of all organic behaviour; which accompanies
life wherever it occurs and therefore shares the continuity of the
germinal substance.

The difficulty inseparable from the first hypothesis, is that it
is contrary to the analogy of all that we know or infer elsewhere
throughout the realm of nature. Huxley[204] likened its emergence to
the production of heat when an iron bar is struck by repeated blows
of the hammer. But this analogy will not hold; for heat is a mode
of energy, and only emerges through the transformation of other and
pre-existing modes of energy. A certain amount of the energy of motion
in the massive hammer-head is transferred to the iron rod, and assumes
the form of that molecular vibration which we call heat. And by what
amount the one is the gainer, by that amount is the other the loser.
But we have no reason to suppose that the like takes place in the
origin of the mental concomitants of neural changes. No portion of the
brain’s store of physical energy is drained off to form the rivulet
of consciousness. Now, whenever we speak of a product elsewhere in
nature, we mean a specialized bit of something pre-existent. Water is
the product of pre-existing oxygen and hydrogen. Heat is the product
of other forms of energy. But this is not so on the first hypothesis,
according to which consciousness emerges when the functional activity
of the nervous system reaches a certain level and order of complexity.
The mental concomitants are not “products,” in the recognized sense
of the term. Furthermore, although on this hypothesis we may still
speak of what was termed above evolutional continuity in the mental
concomitants, there is nothing analogous to either developmental or
germinal continuity.

On the second hypothesis, according to which sentience is the
concomitant of all organic behaviour, such developmental and germinal
continuity, or their analogues in the psychical order of being, are
rendered conceivable. Consciousness is regarded as a developed form
of sentience. But the sentience is wholly hypothetical. It is at best
a “may be,” and its existence is incapable of proof. And science is
rightly impatient of hypotheses the validity of which cannot in any way
be verified. Our safest course, therefore, is to accept that which is
common to both hypotheses, evolutional continuity, and for the rest to
be content with a confession of ignorance.

We have already drawn attention to the fact that mere sentience,
if it exists, has no power of guidance over organic behaviour; but
consciousness, when it emerges, is a concomitant of nervous processes
which determine the nature and direction of such nerve-changes as are
the antecedents of intelligent behaviour. The steps by which this
control is established are unknown. It is, indeed, probable that
conscious guidance arises as an accompaniment of the differentiation
of controlling centres from the automatic centres of the nervous
system; but of how this takes place we are as ignorant as we are of
many other differentiations in the course of embryological development
and evolutional progress. Of those nervous arrangements within the
brain which are the physiological concomitants of the far later mental
processes of reflection, abstraction, generalization, and the formation
of ideals, we are, if it be possible, even yet more profoundly
ignorant. Nor would it serve any good purpose to indulge in speculation
where there are not even the data to enable us so much as to hazard
a probable guess. The utmost we are justified in attempting is to
show how organic behaviour leads up to and affords the requisite data
for the exercise of intelligence, and how both supply the necessary
preliminary stages in the development and evolution of what, following
Dr. Stout, we have termed ideational process. This we have endeavoured
to do in preceding pages; and all that is now required is to conclude
our inquiry with a brief summary by which the results, as affording
some basis for evolutional continuity, may be focussed.

We regard reflex action and instinctive behaviour, broadly considered,
as genetically prior to that which is intelligent. Their development
in the individual and their evolution in the race are reached by the
differentiation and integration of nerve-centres. In the abdominal
region of the crayfish, for example, special centres are differentiated
for the behaviour of each pair of swimmerets; but these are so
integrated that the whole series of like abdominal appendages swing
rhythmically with co-ordinated movements. Now, when a sensorium is
developed, it does not have to group by an act of conscious selection
and deliberate arrangement the multiplicity of scattered sensory
data which it receives; it does not have to organize from diverse
and hitherto unrelated elements some sort of system in experience:
it receives them as a physiological heritage already grouped, and to
some extent organized. Stimulus and response are organically linked;
and within the response inherited co-ordinations, often exceedingly
complex, afford a correlated group of sensory data. Just in so far
as organic heredity has provided a working system of bodily parts,
does consciousness receive systematic information of their orderly
working. No doubt it is true that the development and evolution of the
sensorium proceeds _pari passu_ with the development and evolution of
reflex actions compounded and co-ordinated to give rise to instinctive
behaviour. No doubt the progress of the one is in close touch and
relation with the progress of the other; for such relation receives
the emphatic sanction of utility. Still it is none the less true that
in individual development, as in racial evolution, the organic takes
the lead. What is intelligently acquired is something added to that
which has been engrained, through natural selection or otherwise,
as a potentiality of the germinal substance. What we have first to
note, then, is that organic evolution provides ready-grouped data to
consciousness.

The second point is, that the germs of abstraction and generalization,
or rather processes which are the precursors of abstraction and
generalization, arise, and cannot fail to arise, in the genesis of
experience from the performance of inherited responses, and from
the coalescence of their results into a conscious situation. To a
quite young chick I gave pieces of yellow orange peel, which were
found to be distasteful and rejected. In Dr. Stout’s phraseology,
they acquired meaning in experience. Can one doubt that the colour
and taste were thus rendered predominant, and that the shape, size,
and other qualities of the bits of orange peel remained practically
unnoticed? Shortly afterwards the chick was given chopped and
crumbled egg; the fragments of “white” were eaten, but the bits of
hard-boiled yolk were untouched. They possessed a sufficient general
resemblance to the orange peel to carry the same meaning. In many
ways particular qualities of objects are emphasized in so far as
they incite to behaviour; they form centres of biological interest,
just as the abstract quality of ideational thought is the centre of
rational interest on a higher plane of mental development. And in
many ways objects presenting certain salient features in common,
amid differences which remain unnoticed, are unconsciously grouped
as the starting-points of similar perceptual situations, just as
in the generalization of ideational thought similar relationships
are deliberately grouped as the starting-points of like conceptual
situations. Both are purposive and have an end, which we as
investigators are able to assign; but only for reflection and
conceptual thought are they also purposeful--the end being foreseen and
realized, not only by the investigators, but by the agent concerned.
And the purpose or end itself is in the two cases different. In the one
case it is the biological end of practical behaviour; in the other case
it is the rational end of explanation--abstraction and generalization
being deliberately used as a means to this latter end. The question
has again and again been asked: Do animals reason? And different
answers are given by those who are substantially in agreement as to
the facts and their interpretation, but are not in agreement as to
their use of the word “reason.” Perhaps, if the question assume the
form--Are animals capable of explaining their own acts and the causes
of phenomena?--the position of those who find the evidence of their
doing so insufficient may be placed in a clearer light. This is what
is generally meant by the statement that animals have probably not
reached the level of rational beings.

But even if they have not reached this level, their perceptual
processes supply the antecedent conditions which are necessary if this
level is to be attained in the course of further evolution. We have
seen that, even in relatively simple cases, where conscious situations
mark only the beginnings of intelligence, there is a biological
emphasis of some, rather than others, among what we call the qualities
of objects, and there is a grouping, on biological grounds, of certain
things which have some quality in common--such, for example, as being
fit for food. Here we have at the outset of perceptual development the
germs of processes which are the precursors of the abstraction and
generalization of ideational thought. And in the more complex conscious
situations of the higher animals these processes attain to such degree
of development as is necessary to secure more difficult and more remote
biological ends, until all that is necessary, for their rational use,
is the quickening touch of a new purpose, that of explanation.

We have seen that, through what Dr. Stout terms “manipulation,” and
Professor Groos “experimentation”--names applied to a type of behaviour
widely exemplified among the higher animals,--things, as the nuclei of
conscious situations, become differentiated from the environment. One
can hardly question that a fly to the trout, a ball to the kitten, a
bone to the puppy are things distinguished from their surroundings, and
that they become marked off as special centres of interest. Here on the
perceptual plane is a process which is the antecedent of the conception
of quasi-independent objects on the ideational plane. For rational
thought the thing, as object, is not only the centre of a practical
situation leading to behaviour of direct or indirect biological value,
but is the nucleus around which we build all the qualities which
are ascertained by more elaborate manipulation and experimentation
carried out deliberately and of set purpose for rational ends. It
becomes capable of definition with the aim of explaining what are its
characteristics as an object.

There can be little doubt that the higher animals become intimately and
practically acquainted with their environment. The dog who accompanies
his master in many a ramble, the horse who carries him again and again
over all the surrounding country, has a good perceptual knowledge of
a somewhat extended environment. And this, again, is the precursor
of the far more extended conceptual knowledge which leads up at last
to a rational conception of the universe of objects in their varied
relationships. But only through the concentration of thought rendered
possible by much true abstraction and generalization,--only through
disentangling the relationships and regrouping them for the purpose of
framing an ideal scheme,--only, in short, by explanation and for the
sake of explanation is this difficult process brought to a more or less
successful issue.

Again, there can be little doubt that the higher animals, in the course
of experience begotten of behaviour, reach a perceptual sensing of
the bodily self, through experience derived from the non-projecting
senses, in pain and sickness, and often, we may hope, in the sense of
well-being, and the joy of existence. They do not probably set this
self in antithesis to the not-self. That comes with reflection, and is
the result of ideal construction based on the analysis of experience,
with a view to reaching some explanation of the genesis of experience.
But in their perceptual awareness of the embodied self, they have
that kind of consciousness which affords the necessary data, for
the later conception of the self--when experience is polarized into
its subjective and objective aspects and thus is explained, so far
as science can explain it; suggesting, indeed, long ere science has
attained this end, metaphysical explanations by reference to underlying
causes--too often accepted as an easy substitute for the difficult
tracing out of the antecedent conditions which science endeavours
painfully and by slow steps to formulate.

It is unnecessary to do more than remind the reader that we have found
that such processes as attention and imitation pass through instinctive
and intelligent stages which are the precursors of the ideational
stage, where they reach a higher expression as deliberately conscious
acts. In the young bird that instinctively pecks at some small, perhaps
moving, thing, which forms the starting point of a piece of responsive
behaviour, we have attention in the germ. When experience has caused
the thing to acquire meaning, attention passes into a succeeding
intelligent phase; but only when we desire to explain this meaning,
and attention thus has a deliberate purpose, do we find it entering
upon its higher ideational career. So, too, as we have seen, imitation
is at first a specialized form of instinctive behaviour, where the
response is seen to resemble that which stimulates it. Later it becomes
intelligent when the repetition of the imitative behaviour is due to
the satisfaction it introduces into the conscious situation. Then, at
last, it reaches the ideational stage, where reflection gives rise to
an ideal, which is to be realized in conduct. The imitation by the
child of its older companions is at first probably intelligent; but
when the child begins to consider why it imitates these and not those
among its companions, he is passing to the ideal stage, and imitation
becomes the sincerest form of hero-worship. The boy who merely imitates
his elder brothers playing at soldiers because he gets satisfaction
from so doing, becomes the subaltern who has his ideal soldier, and
will face death firmly rather than fall below his conception of how
such a soldier should behave.

We need not again attempt to indicate how among animals we have the
perceptual precursors of the æsthetic and ethical concepts. But we may
remind the reader that we endeavoured to show that intercommunication
had its foundation in instinctive sounds; and that it passed into the
intelligent stage in the perceptual life, when these sounds acquired
meaning, and hence became guides to behaviour. This is especially
instructive from our present standpoint, since it is probable that the
passage of communication from the indicating to the descriptive stage
afforded the conditions under which rational thought was evolved.
For such thought it is essential that attention should be focussed on
the relationships of things. And no description is possible without
making distinctly present to consciousness these relationships,
in time and space, the data for which are abundantly present in
the perceptual life, though lurking in the background, and needing
something to fix them and to aid consciousness in distinguishing them
clearly. In descriptive communication parts of speech, or their initial
equivalents, afford fixation points for these relationships, and serve
to render them distinct. If the reader will try to describe even the
simplest occurrence without introducing the symbols for the relations
which the events bear to each other, his failure will serve to bring
home how essential a feature this is. In social communication, then,
we probably have the key to the passage from perceptual to ideational
process; and in this passage description is the antecedent of, and
affords the conditions to, explanation. Words, moreover, as we have
already said, form the pegs upon which we can hang up, for ready
reference, the products of abstraction and generalization, or, to
modify the analogy, they form the bodies of which these products are
the rational soul.

If we are ever to trace the passage from the instinctive through
the indicating stage of communication, and so onwards through the
beginnings of description to its higher levels, and thus to the use of
language as a medium of explanation, it must be through child-study.
In every normal human child the passage does actually take place,
though, no doubt, in a condensed and abbreviated form as an epitomized
recapitulation in individual development, of the steps of evolutional
progress. Thus we may obtain a key to the solution of one of the most
difficult problems in evolution by continuous process--that of the
transition from animal behaviour to human conduct.

INDEX

Abstract and general ideas, 57

Abstraction, 166;
germs of, 332 ff.

Acceleration, 250

Accommodation defined, 36

Acquired characters, inheritance of, 35, 110

Acquired instincts (Wundt), 66, 106

Acquisition defined, 36;
ultimately dependent on natural selection, 289

Adaptation defined, 37

ADDISON on instinct, 63

Æsthetics, animal, 270

Afferent and efferent impulses, 32, 101

Aid, mutual, among animals, 227

_Ammophila_ mode of stinging prey, 75;
of carrying prey, 76;
deposition of egg, 77;
intelligent behaviour of, 127

_Amœba_, 296

Antlers of deer, 15

Ants, behaviour of, 123;
intercommunication of, 198;
social communities of, 205

_Aporus_, intelligent behaviour of, 126

Appreciation, germs of, 273

Ardour of male in courtship, 269

_Argyromœba_, instincts of, 79

Arrest of development in egg, 14

Association in coalescent situation, 46

Attention, 242

AUDUBON on American night-hawks, 261

AVEBURY, Lord, on ants, 198;
on Van, 200;
on aphides and ants, 214;
on slave ants, 215;
on intelligence of ants, 218

BALDWIN, Prof. Mark, on organic selection, 37 (note), 115;
on functional selection, 163;
on imitation, 179 ff.;
on projective stage of development, 275

Batesian mimicry, 165

BECHSTEIN on canaries, 262

Bees, homing of, 131;
social communities of, 205

Beetle soliciting food from ant, 213

_Bembex_ mode of carrying prey, 76

BETHE, Dr., on instinctive behaviour of ants, 217

BINET, M., on infusoria, 6

Biological value of play, 250;
purpose, 294;
aspect of animal behaviour, 305

Birch-weevil, leaf-case of, 121

Birds, instinct of, 84

Bison, behaviour of the, 226

BLACKBURN, Mrs. Hugh, on instinct of cuckoo, 90

BLOCKMANN, Dr., on _componotus_, 210

BOLTON on goldfinches’ nests, 136

Bower-bird, observations on, 261, 273

BUCKMAN, Mr. S. S., on speech of children, 203

BUDGETT, Mr. John S., on nest-building, 135

Bullfinch, nest of, 135

CAMERON, Mr., on mimetic insects in ants’ nest, 212

Canaries’ nest, building of, 135

Canon of interpretation, 270

Capacity, innate, 176

Capuchin monkey, imitation in, 188, 278

CARPENTER, W. B., on water-beetle, 299

Catasetum, fertilization of, 29

Cats, Prof. Thorndike’s experiments on, 147, 184

Causation, idea of, 257

Cell-division in egg, 14

_Cerceris_, instincts of, 74;
locality studies of, 129

_Chalicodoma_, parasites of, 78;
Fabre’s observations on, 130

Chick swimming, 85;
instincts of, 85 ff.;
imitation in, 183

Child-study, desirability of, 155, 337

Choice, apparent in Paramecia, 9;
in the pairing situation, 266

Ciliary action in Paramecium, 4-10

Circular process (Baldwin), 181

_Clepsine_, behaviour of, 159

Coalescence in conscious situation, 46

Coincident variations defined, 37;
survival of, 115, 174

Communities, social, of bees and ants, 205

Companion as centre of special interest, 244

_Componotus_, communities of, 210

Conation and impulse, 187, 235

Concept, nature of, 167

Condensation of experience, 163

Conduct implies motive, 60;
and ideal, 278

Congenital responses, 41

Conjugation in Paramecium, 4

Connate instincts, 66, 69

Conscience, ambiguity of word, 281

Conscious accompaniments of certain organic changes, 42;
aspect of instructive behaviour, 99

Consciousness, as accompaniment and as guide, 34;
effective, defined, 43;
as heir to organic estate, 52;
as epiphenomenon, 306

Consentience, 53, 62

Consonance of biological and psychological end, 286, 316

Constancy of environment leads to stereotyped behaviour, 173

Continuity in evolution, 324;
threefold aspect of, 329

Control, the sign of effective consciousness, 43

Co-ordinated acts, 69, 100;
inherited, 94, 95

Corporate behaviour, 14

Courtship in animals, 259

Coyness of female birds, 264 ff.

Cranial sense-organs, 301

Crayfish, reflex action in, 298

Creation, special, 297

Criteria of effective consciousness, 43;
of intelligence, 120

Cruelty in cat, 277

Cuckoo, instinct of nestling, 90

DARWIN, Charles, fig. of sun-dew leaf, 26;
of Venus’s fly-trap, 27;
of catasetum, 31;
on earthworms, 158;
on social life of animals, 225;
on human ancestry, 229;
on play and practise, 259;
on sexual selection, 262 ff.;
on law of battle, 313

DAVIS, Prof. Ainsworth, on limpets, 156

DEAN, Dr. Bashford, on chick swimming, 85

Deceit in animals, 280

Deferred instincts, 70

Definiteness of instinctive behaviour, 66

Description, involves relational terms, 202

_Didunculus_, changed habits in, 221

Differentiation and integration of nerve-centres, 167

Disintegration of instincts, 176

Diving, instinctive, 86

Dog, observations on, intelligence of, 141 ff., 152, 200, 271, 322

Duckling, inherited co-ordination in, 96

_Dytiscus_, instinct of, 104

Earthworms, Darwin’s observations on, 158 ff.

Education in play, 255, 320 ff.

Effective consciousness defined, 43

Efferent and afferent impulses, 32, 101

Egg, cell-division in, 14

EIMER, Th., on instincts of solitary wasps, 73;
on origin of instincts, 108

Emotions, and feelings, 235 ff.;
psychological nature of, 246;
evolution of, 282

Energy stored in cell, 23

Equilibrium, tendency to, 296

_Eristalis_, mimicry of, 164

ESPINAS, Prof., on social life of animals, 230

Ethics, animal, 270

Evolution of organic behaviour, 35;
of consciousness, 61;
of instinctive behaviour, 106;
of intelligent behaviour, 155;
of social behaviour, 225;
of feeling and emotion, 282;
of animal behaviour, 295;
as continuous, 324 ff.

Experience, of value for future guidance, 44;
is it inherited? 48, 97;
condensation of, 163

Experimentation, 251, 253

Explanation, characteristic of later phases of mental development,
58, 257

Explosive nature of cell, 21

Expression of emotions, 247

External stimuli to instinctive behaviour, 102

FABRE on behaviour of _Sphex_, 77, 172;
of _Chalicodoma_, 78, 129;
of _Leucopsis_, 79;
of _Pompilus_, 129

Faculty, instinctive, 64

Falcons, training of, 137

Fear in birds not inherited in specific direction, 49, 110

Feelings and emotion, 235 ff.;
evolution of, 282;
feeling-tone, 240

Ferns, fertilization of, 24

Fertilization of ferns, 24;
of _Valisneria_, 28;
of orchids, 29

FINN, Mr. Frank, on the acquisition of experience by young birds, 50

Fission, reproduction of Paramecium by, 4

Flight, instinctive, 86

FOREL on _Componotus_, 211

FOSTER, Sir Michael, on consciousness accompanying reflex action in
pithed frog, 33

Frog, reflex action in, 33, 299, 300

Functional selection, 163

Fungus garden of ants, 216

GARNER, Mr. R. L., “The Speech of Monkeys,” 198

Gas-engine, analogy of, 20

General and abstract ideas, 57;
generalization, 167;
germs of, 332 ff.

Generic image, 162;
situations, 163

Germinal substance, continuity of, 328

GOULD, Dr., on humming-birds, 273

GREEN, Mr. E. G., on ants, 210

Greenfinch, nest of, 135

GROOS, Prof., on instinct, 64;
origin of, 116;
on imitation, 187;
on animal play, 248 ff.;
on “Love Play,” 259;
on coyness of female birds, 264;
on choice in mating, 267;
on make-believe, 280

Habits and habitual acts, 107, 177

HAGUE on ants, 199

HAMERTON, P. G., on trained dog, 152

HANCOCK, Dr. John, on cuckoo, 92

Heredity and circumstance, 39;
twofold aspect of, 40;
relation of to use, 170, 177;
in evolution as continuous, 326

Homing of bees, 131

Homœopathic influence defined, 36

Honey-pot ant, 215

House-martin, nest-building of, 113

HUDSON, Mr. W. H., on fear in birds, 49, 50, 110;
on animal gladness, 317

Hunting play, 254

HUXLEY, T. H., on reflex action in frog, 300;
on consciousness as epiphenomenon, 306 ff.;
on consciousness as product of nervous changes, 330

HYDE, Mr., on king-crab, 298

_Hydractinia_, colonial polype, 206

Ideals, distinguish ethics, 278

Ideational stage of mental development, 59

Imitation, 179 ff.;
three stages of in child, 192

Impulse in intelligent behaviour, 60;
Prof. Thorndike’s use of the term, 186;
connection of with conative process, 235

Independence of automatic and controlling centres, 43

Infant, congenital responses in, 54

Influence of intelligence on instinct, 169

Inheritance of acquisitiveness, 40

Innate capacity, 176;
likes and dislikes, 119

Insects, instinctive behaviour in, 71;
intelligent behaviour in, 123

Instinct, broader and narrower view of, 99;
primary and secondary, 108, 109;
influence of intelligence on, 169;
priority of, to intelligence, 173;
disintegration of, 175

Instinctive behaviour defined, 63;
in insects, 71;
in birds, 84;
conscious aspect of, 98

Integration and differentiation of nerve-centres, 167

Intelligence lapsed, 107;
influence of, on instinct, 169;
of ants, Lord Avebury on, 218;
biological importance of, 310

Intelligent behaviour, 117;
evolution of, 155

Intelligent process distinguished from rational, 59, 138

Intercommunication, 193, 336

Interest, 243

Internal factors in instinctive behaviour, 102

Irritability, fundamental, property of protoplasm, 240, 296

JAMES, Prof. Wm., theory of emotions, 246, 292

Jays, bathing of, 89;
mode of taking food, 94

JENNER on cuckoo, 92

JENNINGS, Dr. H. S., on behaviour of Paramecia, 5

KERNER, Dr., on sun-dew, 26;
on sensitive Oxalis, 27;
on Valisneria, 29

King-crab, reflex action in, 298

KNIGHT, Andrew, on Norwegian ponies, 110

KROPOTKINE, Prince, on mutual aid among animals, 227

Lamarckian hypothesis, 169, 171, 177

Language, nature of, 195

LANKESTER, Prof. E. Ray, on small-brained mammal, 168

Lapwing, instinctive behaviour of, 113

Law of battle, 313

Leech, observation on, 159

_Leucopsis_, instincts of, 79

LEWES, G. H., on lapsed intelligence, 107

Limpets, observations on, 156

LINDLEY, Dr., on children, 141

Locality, studies by wasps, 128

LOCKE, John, limitations of animals, 167

MACKENZIE, Prof. J. S., on ethics, 278;
on conscience, 281;
on ambiguity of word “pleasure,” 285

Make-believe, 280

Mammals, early small-brained, 168

Manipulation (Stout), 251

MARCHAL, Prof., on instincts of _Cerceris_, 74

MARSHALL, Mr. H. R., on instinct, 66

Martin, nest-building of, 113

MARTINEAU, James, on pleasure and pain, 284

MAUPAS, M., observations on infusoria, 4

MAYER, Dr. A. G., on mating instinct of moths, 83

MCCOOK, Dr., on ants, 214

Meaning, Dr. Stout’s use of term, 46, 243, 268

MEDLICOTT, Mr. H. B., on behaviour of wild pigs, 196

Megapodes, instinctive flight of, 87

_Meloë_, instincts of, 81

Mental development, stages of, 48, 56

MERCIER, Dr. Charles, on criteria of intelligence, 120

Metaphysical explanations, 19;
aspect of instinct, 64;
of impulse, 237;
of purpose, 294;
of will, 307;
of life, 325

MILLS, Prof. Wesley, on social influence on puppy, 220

_Miltogramma_, parasitic fly, 134

Mimicry, Batesian and Müllerian, 165;
intelligent aspect of, 311

Modifiability, 171

Modification, defined, 36;
relation of, to hereditary characters, 170

MÖLLER, Herr, on fungus garden of ants, 216

Monistic hypothesis, 309, 315

Monkey, capuchin, imitation in, 188

_Monodontomerus_, instincts of, 79

Moor-hen, diving of, 89

Moths mating, instinct of, 83

Motive in rational conduct, 60

Movement plays, 251

MÜLLER, Prof. Max, on barrier between brute and man, 204

Müllerian mimicry, 165, 166

Mystery of life, 18

Natural selection, shielding of chicks from, 111;
under uniform and variable circumstances, 175;
in playtime of life, 319

Nervous arc, 33;
system of higher animals, 297

Nest-building, observations on, 135

NOIRÉ on concept, 167

Norwegian ponies, 109

Nucleus division, 12

Object and subject, 245, 276

Octopus, intelligence of, 158

_Œcophylla_, behaviour of, 210

Orchids, fertilization of, 29

Organic basis of differentiation of consciousness, 53

Organic behaviour in development, 15

Organic selection, 37 (note), 115

Overproduction of movements, 164

Oxalis, sensitive, behaviour of, 27

_Oxybelus_, mode of carrying prey, 76

PALEY, definition of instinct, 64

Paramecium, behaviour of, 3, 296

Partridge, note of young, 93

PECKHAM, Dr. G. W., on instinct, 65;
on solitary wasps, 72 ff., 126 ff.

Pecking instinct of chicks, 93

Peewit, note of young, 93

_Pelopœus_, instincts of, 72

Perceptual stage of mental development, 59

Personality, 245, 257

Pheasants, note of young, 92;
inherited co-ordination in, 95;
plumage of Argus, 262

_Philanthus_, prey of, 73;
mode of stinging prey, 74

Physiological aspect of animal behaviour, 295

Pigeons, nests of, 136

Pigs, wild, behaviour of, 196

Plants, behaviour of, 24

Plastic period of life, 168

Plasticity of tissues, 40;
of behaviour, 172

Play of animals, 248 ff.;
biological value of, 250;
psychological aspect of, 256, 311, 316

PLAYNE, Mr. H. C., on pigeons’ nests, 136

Pleasure, 241;
ambiguity in word, 285

_Polistes_, locality studies of, 131

_Pompilus_, mode of carrying prey, 76;
Fabre’s observation on, 129

Presentative elements distinguished from re-presentative, 46

Primary instincts (Romanes), 108

Projective stage of mental development, 275;
senses, 304

_Pronuba_, instinct of, 82

Propensity, instincts as, 64;
congenital, 176

Protoplasm, fundamental properties of, 296

Psychological aspect of play, 256;
purpose, 294;
aspect of animal behaviour, 315

Rational process distinguished from intelligent, 59, 138

Reflex action, 31, 35, 298 ff.;
relation of instinct to, 70

Relationships, importance of, 202

Re-presentative elements distinguished from presentative, 46

_Rhynchites_, instinct of, 121

ROMANES, G. J., on “discrimination” and “perception” in plants, 32;
on instincts of solitary wasps, 73;
definition of instinct, 99;
on primary and secondary instincts, 108, 109;
on ants, 126;
on general ideas, 166;
on animal communication, 201;
on cruelty in cat, 277

ROMANES, Miss, observations on capuchin monkey, 188, 278

Roots of spinal nerves, 299

ROTHNEY, Mr. G. A. G., on Indian ants, 212

SCHNEIDER, on octopus, 158

SCOTT, Dr. D. H., on fern fertilization, 25

Scratching in duckling, 96

Sea anemone, diffused nervous system of, 32

Secondary instincts (Romanes), 108, 109

Segmental nature of central nervous system, 299

Selection, functional, 163;
natural, shielding of chicks from, 111;
under uniform and variable circumstances, 175;
in playtime of life, 319;
sexual, 261 ff., 313

Self, as ideal construction, 239

Sentience, 62;
origin of, 330

Sexual selection, 261 ff., 313

SHARP, Dr. D., on birch-weevil, 121;
on _Œcophylla_, 210

SHELLARD, Mr. E. J., observations on staghound, 144

SHERRINGTON, Prof., on emotion, 292;
on spinal animal, 298 ff.

Shock, effects of physiological, 302

SIMCOX, Miss Edith, quoted, 320

_Sitaris_, instincts of, 82

Slave ants, 215

Snails, observations on, 157

Social behaviour, 179;
evolution of, 225

Solitary wasps, instincts of, 72 ff.;
intelligence of, 126 ff.

Solomon Islands, rats of, 222

Sounds emitted by young birds, 92

SPALDING, Douglas, on newly hatched turkeys, 49;
on instinct, 99

Special creation, 297

Speech, connection of, with rational process, 58, 233;
so-called, of monkeys, 198;
of children, 203;
aids passage from perceptual to ideational process, 337

SPENCE, on instinct, 63

SPENCER, Mr. Herbert, on instinct and reflex action, 70;
on play due to surplus vigour, 248;
on pleasure and pain, 284, 287;
on survival, 288

_Sphex_, mode of carrying prey to nest, 77, 172

Spiders placed in crotch by wasps, 133

Stereotyped behaviour, 172

Sticklebacks, observations on, 130

STOUT, Dr. G. F., on “meaning” for consciousness, 46, 243, 268;
on ideational and perceptual stages of mental development, 59, 271;
on octopus, 158;
on conative process, 235;
on the self, 239;
on manipulation, 251;
on emotion, 293

STRANGE, Mr., on bower-bird, 261

Subject and object, 245, 276

Sun-dew leaf, behaviour of, 25

Swimming, instinctive, 85

TAIT, Lawson, on begging-cat, 110

TARDE, M., on imitation as a social factor, 179

Tendencies, congenital, 176

THOMAS, Mr. Oldfield, on rats of Solomon Islands, 222

THORNDIKE, Dr., on swimming of chick, 85;
experiments on intelligence, 147 ff.;
experiments on imitation, 179, 183 ff.

Tradition, animal, 220

Trial and error, method of, 139

Unity of perceptual process, 240;
of biological purpose, 297

Use, super-normal, 170;
relation of, to heredity, 171, 177

VALISNERIA, fertilization of, 28

Variation defined, 36;
origin of, 327

Venus’s fly-trap, behaviour of, 26

Vigour, play due to surplus, 248

Volition as conative, 238

WALLACE, Dr. A. R., on sexual selection, 264

WALLASCHEK, Mr., on play as surplus vigour, 248

Wapiti, antlers of, 16

WASMANN, Dr., on insects associated with ants, 213

Wasps, solitary, instincts of, 72 ff.;
intelligence of, 126 ff.

WEIR, Mr. Jenner, on canaries, 135

WEISMANN, Prof., on origin of instinct, 109

WHITMAN, Prof., on _Clepsine_, 159

WHITMEE, Rev. S. J., on tooth-billed pigeon, 221

Will, metaphysics of, 307

WILLISTON, Dr. S. W., observation on _Ammophila_, 127

WOOD, Mr. Foster, on hen-swimming, 86

WORCESTER, Dr., on megapode, 87

WUNDT, Prof., on instinct, 65, 99, 106

Youth, plasticity of, 168

Yucca moth, instincts of, 82

THE END

PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, LONDON AND BECCLES

FOOTNOTES

[1] See “The Psychology of a Protozoon,” in the _Amer. Jour. of
Psychology_, vol. X., No. 4, July, 1899, and the fuller papers there
quoted.

[2] “The Psychic Life of Micro-Organisms,” 1889, p. 61.

[3] This paragraph is taken from “Animal Life and Intelligence,” p. 28.

[4] The following paragraphs are taken with some slight changes from
“Animal Life and Intelligence,” pp. 30-35.

[5] D. H. Scott, “An Introduction to Structural Botany,” part ii.,
“Flowerless Plants,” pp. 70, 71.

[6] _Ibid._, p. 71.

[7] Kerner, “Natural History of Plants,” translated by F. W. Oliver,
vol. i., p. 145.

[8] Kerner, “Natural History of Plants,” vol. i., p. 536.

[9] Kerner, “Natural History of Plants,” vol. ii., p. 132.

[10] Darwin, “Fertilization of Orchids,” 2nd edit., pp. 191, 192.

[11] “Mental Evolution in Animals,” p. 50.

[12] _Ibid._, p. 51.

[13] “A Text-book of Physiology,” 5th edit., part iii., p. 909.

[14] “A Text-book of Physiology,” 5th edit., part iii., pp. 911, 912.

[15] Professor Mark Baldwin has applied the term “organic selection”
to the result of this interaction (_American Naturalist_ for June and
July, 1896). Cf. also H. F. Osborn (_Science_, Nov. 27, 1896); August
Weismann (Romanes Lecture on “The Effects of External Influences on
Development,” 1894), and “Germinal Selection,” _Monist_, Jan., 1896;
and the author’s “Habit and Instinct,” ch. xiv., 1896.

[16] “Habit and Instinct,” p. 26.

[17] _American Journal of Psychology_, vol. ix., No. 1.

[18] _Psychological Review_, vol. vi., No. 3.

[19] “Naturalist in La Plata,” p. 88.

[20] _Journal Asiatic Society of Bengal_, lxvii., part ii., 1897, p.
614.

[21] _Spectator_, No. 120.

[22] Kirby and Spence, “Introduction to Entomology,” Letter xxvii. p.
537 (7th Edit., 1858).

[23] Cf. supra, p. 18.

[24] “The Play of Animals,” translated by Elizabeth L. Baldwin, p. 62.

[25] George W. and Elizabeth G. Peckham, “On the Instincts and Habits
of the Solitary Wasps,” p. 231.

[26] “Lectures on Human and Animal Psychology,” pp. 388, 397, 399.

[27] “Instinct and Reason,” pp. 90, 92.

[28] “Instinct and Reason,” p. 91.

[29] Chapter I., Section V.

[30] “On the Habits and Instincts of the Solitary Wasps,” by George W.
and Elizabeth G. Peckham (1898).

[31] “Mental Evolution in Animals,” p. 299.

[32] “Organic Evolution,” translated by J. T. Cunningham, p. 280.

[33] See A. G. Mayer “On the Mating Instinct of Moths.” _Ann. and Mag.
of Nat. Hist._, ser. 7, vol. v., Feb., 1900, p. 183.

[34] Some of the observations on which the summary of results given in
this section are founded are presented in some detail in “Habit and
Instinct,” pp. 29-100.

[35] _Psychological Review_, May, 1899, p. 286.

[36] “Birds from Moidart and Elsewhere,” p. 107. Edinburgh: Douglas.

[37] _Transactions of Northumberland and Durham Natural History
Society_, vol. viii., p. 213.

[38] “Mental Evolution in Animals,” p. 159.

[39] “Lectures on Human and Animal Psychology,” p. 401.

[40] “Instinct and Acquisition,” _Nature_, vol. xii., p. 507.

[41] On the nature of impulse, see _infra_, p. 235.

[42] “Lectures on Human and Animal Psychology,” p. 405.

[43] “Organic Evolution,” pp. 223, 263, 258, 279, 276, 298.

[44] “Essays on Heredity” (1889), p. 91.

[45] _Op. cit._, pp. 196-198.

[46] Professor Henry Osborn has also indicated the relationship
referred to.

[47] “The Play of Animals,” p. 64.

[48] “Solitary Wasps,” p. 236.

[49] See D. Sharp, “Cambridge Natural History,” “Insects,” part ii., p.
293, and the original authorities cited on p. 294.

[50] This and the three succeeding paragraphs are taken from “Animal
Life and Intelligence,” p. 425.

[51] “Animal Intelligence,” p. 59.

[52] “Instincts and Habits of the Solitary Wasps,” p. 55.

[53] _Op. cit._, p. 22.

[54] _Op. cit._, p. 215.

[55] “Dürfen wir den Ameisen und Bienen psychische Qualitäten
Zuschreiben.” _Pflüger’s Archiv._, lxx., 1898.

[56] “Solitary Wasps,” p. 219.

[57] _Op. cit._, pp. 131, 132.

[58] In a letter to Darwin, quoted by Romanes, “Mental Evolution in
Animals,” p. 226.

[59] “The Structure and Life of Birds,” p. 335.

[60] Preface to “Harmonia Ruralis,” quoted by Yarrell, “British Birds,”
vol. i., p. 541.

[61] _American Journal of Psychology_, vol. viii., no. 4, pp. 431-493.

[62] “Introduction to Comparative Psychology,” p. 255.

[63] “Introduction to Comparative Psychology,” p. 290.

[64] _The Portfolio_ (1873), p. 27, “Canine Guests.”

[65] “Animal Intelligence,” pp. 28, 29.

[66] _Nature_, vol. xxxi., p. 200.

[67] _Ibid._, vol. li., p. 127.

[68] “Manual of Psychology,” p. 257.

[69] “Vegetable Mould and Earthworms,” p. 95.

[70] _Wood’s Holl Biological Lectures_ (1898), p. 287.

[71] _Supra_, p. 44.

[72] “Mental Evolution in Man,” p. 27.

[73] “Intelligence of Animals,” p. 121.

[74] “Mental Development in the Child and the Race--Methods and
Processes,” p. 278.

[75] “Animal Intelligence:” monograph supplement to _Psychological
Review_, 1898, p. 61.

[76] _Op. cit._, pp. 263, 172, 201, 132, and 248 (note).

[77] “Animal Intelligence,” pp. 47-64.

[78] _Op. cit._, pp. 66, 14, 15.

[79] Cf. _infra_, p. 235.

[80] “The Play of Animals,” Eng. trans., p. 79.

[81] “Habit and Instinct,” pp. 174-180.

[82] “The Evolution of Mind in Man,” footnote, pp. 25, 26. Quoted in
“Introduction to Comparative Psychology,” from which the comments on it
are extracted.

[83] “The Speech of Monkeys.”

[84] “Scientific Lectures,” pp. 112, 118.

[85] _Nature_, vol. vii., p. 443.

[86] “The Senses of Animals,” p. 277.

[87] “Mental Evolution in Man,” p. 100.

[88] _Op. cit._, p. 175.

[89] Compare chap. xiii., on “The Perception of Relations,” in my
“Introduction to Comparative Psychology.”

[90] _Nineteenth Century_, May, 1897, pp. 793-807.

[91] Sharp, “Insects,” part ii., p. 147.

[92] _Nature_, vol. lxii., p. 253 (July 12, 1900).

[93] The quotation is from “The Cambridge Natural History,” vol. vi.,
“Insects,” part ii., by David Sharp, F.R.S.; see pp. 145, 146.

[94] Sharp, _op. cit._, p. 147.

[95] G. A. J. Rothney, “Notes on Indian Ants,” _Trans. Ent. Soc._,
1889, p. 354.

[96] Sharp, _op. cit._, p. 226.

[97] Lord Avebury (Sir John Lubbock), quoted in Romanes’ “Animal
Intelligence,” pp. 62, 63.

[98] Lord Avebury (Sir John Lubbock), “Scientific Lectures,” pp. 78, 79.

[99] _Nature_, vol. xlvii., p. 393 (Aug., 1893), where A. Möller’s
investigations are described by J. C. Willis.

[100] A. Bethe, “Dürfen wir den Ameisen und Bienen psychische
Qualitäten Zuschreiben,” _Pflüger’s Archiv._, lxx., 1898.

[101] See p. 37.

[102] _Supra_, p. 138.

[103] “Scientific Lectures,” pp. 80-82.

[104] _Proceedings of the Zoological Society_, 1874, p. 184.

[105] “Scientific Lectures,” 2nd edit., p. 140.

[106] Weismann, “Essays,” vol. ii., p. 50.

[107] Huxley, “Collected Essays,” vol. vii., p. 155.

[108] “The Descent of Man,” vol. i. p. 853, 2nd Ed., 1888. The
quotations from Darwin in this paragraph and that which follows are
somewhat condensed by a few omissions.

[109] Vol. xxviii., Sept. and Nov., 1890, pp. 337-354, 699-719.

[110] _Nineteenth Century_, Feb., 1888, p. 165. “Collected Essays,”
vol. ix., p. 204.

[111] _Op. cit._, pp. 709, 710.

[112] Page 711.

[113] “Mutual Aid among Savages.” _Nineteenth Century_, vol. xxix.
April, 1891, p. 538.

[114] “Descent of Man,” vol. i., p. 96.

[115] “Des Sociétés Animales: Étude de Psychologie Comparée” (Paris,
1877).

[116] “Mutual Aid among Savages,” _Nineteenth Century_, April, 1891,
pp. 539, 540.

[117] Page 63.

[118] _Op. cit._, p. 267; _cf. supra_, p. 138.

[119] G. F. Stout, “Manual of Psychology,” p. 268.

[120] _Ibid._, p. 318.

[121] “Manual of Psychology,” p. 84.

[122] “Habit and Instinct,” ch. ix., p. 186.

[123] “Letters on the Æsthetic Education of Mankind,” xxvii.

[124] “Principles of Psychology,” § 533.

[125] “On the Origin of Music,” pp. 231, 232.

[126] “The Play of Animals,” Eng. trans., p. 12.

[127] _Op. cit._, p. 7.

[128] _Op. cit._, p. 19.

[129] _Op. cit._, pp. 75, 76.

[130] “Manual of Psychology,” p. 327.

[131] _Op. cit._, pref., p. xx.

[132] _Op. cit._, p. 290.

[133] “Manual of Psychology,” p. 266.

[134] _Op. cit._, p. 314.

[135] “Descent of Man,” vol. ii., p. 60, 2nd edit. 1888.

[136] “The Play of Animals,” Eng. trans., p. 229.

[137] Quoted by Groos, _op. cit._, p. 259.

[138] “Descent of Man,” vol. ii., p. 77.

[139] Darwin, _op. cit._, p. 99.

[140] Quoted by Darwin, “Descent of Man,” vol. ii., p. 58.

[141] “Descent of Man,” vol. ii., p. 56.

[142] “Habit and Instinct,” p. 217.

[143] “Descent of Man,” vol. ii., p. 251.

[144] _Op. cit._, p. 137.

[145] “Darwinism,” p. 285.

[146] _Op. cit._, p. 293.

[147] _Op. cit._, p. 172.

[148] _Op. cit._, pp. 285, 286.

[149] _Op. cit._, p. 283.

[150] _Op. cit._, p. 243.

[151] _Op. cit._, p. 242.

[152] _Op. cit._, pref., p. xxii.

[153] _Op. cit._, p. 240.

[154] _Op. cit._, p. 244.

[155] “Manual of Psychology,” p. 85.

[156] “Manual of Psychology,” p. 23.

[157] _Op. cit._, p. 22.

[158] “Introduction to Comparative Psychology,” p. 53.

[159] “Manual of Psychology,” p. 266.

[160] “Animal Life and Intelligence,” p. 340.

[161] “Mutual Development in the Child and the Race,” p. 19.

[162] _Supra_, p. 270.

[163] “Animal Intelligence,” p. 413.

[164] _Atalanta_, Jan., 1889. Reprinted in “Animal Sketches,” p. 17.

[165] “The Play of Animals,” p. 122.

[166] Appendix to “Animal Intelligence,” p. 486.

[167] “Manual of Ethics,” p. 1.

[168] “Animal Life and Intelligence,” p. 404.

[169] “Animal Life and Intelligence,” p. 400. “Introduction to
Comparative Psychology,” p. 369.

[170] “Animal Intelligence,” p. 444.

[171] “The Play of Animals,” p. 299.

[172] _Op. cit._, p. 145.

[173] “Manual of Ethics,” pp. 285, 286.

[174] Starcke, _International Journal of Ethics_, vol. ii., no. 3
(April, 1892), p. 348.

[175] “Manual of Psychology,” p. 234. “Displeasure” here means the
feeling attitude antithetical to “pleasure.”

[176] _Op. cit._, p. 65.

[177] “Types of Ethical Theory,” vol. ii., f. 350.

[178] “Manual of Ethics,” p. 85.

[179] “Principles of Psychology,” vol. i., pt. ii., ch. ix. § 125.

[180] “Manual of Ethics,” p. 72.

[181] “Life and Letters,” vol. i., p. 310.

[182] Vol. i., pt. ii., ch. ix., § 124. I quote from the valuable
“Epitome” prepared by Mr. Howard Collins, p. 214.

[183] “Principles of Biology,” revised and enlarged edit. (1898), p.
560.

[184] From “Animal Life and Intelligence,” p. 382.

[185] “Experiments on the Value of Vascular and Visceral Factors for
the Genesis of Emotion,” _Proc. Roy. Soc._, vol. lxvi., pp. 390-403
(1900).

[186] “Manual of Psychology,” p. 288.

[187] “Manual of Psychology,” p. 132.

[188] See Huxley’s book on “The Crayfish,” in the International Science
Series, p. 108.

[189] _Journal of Morphology_, vol. ix. Quoted by Professor C. S.
Sherrington in The Marshall Hall Address, “On the Spinal Animal”
(reprinted from _Medico-Chirurgical Transactions_, vol. 82), p. 4.

[190] “The Spinal Animal,” p. 5.

[191] _Op. cit._, p. 23.

[192] “Collected Essays,” vol. i., essay on “Animal Automatism,” p. 224.

[193] _Op. cit._, pp. 20, 21.

[194] _Op. cit._, p. 29.

[195] _Op. cit._, p. 18.

[196] _Vide supra_, p. 33.

[197] “Collected Essays,” vol. i., p. 240.

[198] _Op. cit._, pp. 238, 239.

[199] _Vide supra_, p. 285.

[200] “Naturalist in La Plata,” pp. 280, 281.

[201] “Psychology for Teachers,” p. 70.

[202] _Supra_, p. 36.

[203] _Supra_, p. 13.

[204] “Collected Essays,” vol. i., p. 239.

Transcriber's Note

Illustrations have been moved alongside the text which they
illustrate, and may no longer match the locations given in the List of
Illustrations.

The following apparent errors have been corrected:

p. vii "FIG" changed to "FIG."

p. viii "Mr" changed to "Mr."

p. 29 "Figs. 9" changed to "Fig. 9"

p. 34 (note) "on" changed to "of"

p. 50 (footnote) "p 88" changed to "p. 88"

p. 72 (note) "(1898)" changed to "(1898)."

p. 107 (note) "405" changed to "405."

p. 131 "219" changed to "219."

p. 131 (note) ">Pfluger’s" changed to "Pflüger’s"

p. 162 (note) "p 44" changed to "p. 44"

p. 165 "Mullerian" changed to "Müllerian"

p. 212 "Where-ever" changed to "Wherever"

p. 216 "79" changed to "79."

p. 226 "drives" changed to "drive"

p. 239 (note) "G. F" changed to "G. F."

p. 256 "objects" changed to "objects."

p. 267 "woes" changed to "woos"

p. 330 (note) "239" changed to "239."

p. 332 "co ordinated" changed to "co-ordinated"

p. 338 "106." changed to "106"

p. 338 "BECKSTEIN" changed to "BECHSTEIN"

p. 338 "leafcase" changed to "leaf-case"

p. 339 "nerve centres" changed to "nerve-centres"

p. 341 "nerve centres" changed to "nerve-centres"

p. 341 "king crab" changed to "king-crab"

p. 341 "of, intelligence" changed to "of intelligence"

p. 342 "on, infusoria" changed to "on infusoria"

p. 342 "mating, instinct" changed to "mating instinct"

p. 343 "SCHNEIDER on" changed to "SCHNEIDER, on"

p. 343 "Shock effects" changed to "Shock, effects"

p. 343 "SPENCE on" changed to "SPENCE, on"

p. 344 "106." changed to "106"

p. 344 "of 327" changed to "of, 327"

p. 344 "72 ff.," changed to "72 ff.;"

Punctuation and spelling have otherwise been kept as printed.

The following are used inconsistently in the text:

alarm-note and alarm note

co-existed and coexists

co-incident and coincident

danger-note and danger note

first-hand and firsthand

fox-terrier and fox terrier

ground-work and groundwork

inter-communication and intercommunication

newly-hatched and newly hatched

non-plussed and nonplussed

play-time and playtime

pre-requisite and prerequisite

re-presentations and representations

re-presentative and representative

Romanes’s and Romanes’

supra and _supra_

Venus’s Fly-trap, Venus’s Fly Trap and Venus’s fly-trap

*** End of this LibraryBlog Digital Book "Animal Behaviour" ***

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