GENERAL PRINCIPLES 51 
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 lady-bird, 
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. . . . But when, after a few trials, the chick leaves lady-birds 
unmolested while he seizes wasp-larvee 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 obser- 
vation. 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 intelligence, presuppose congenital [.. in- 
herited] 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.” The 
quotation just given implies, what is no doubt true, that in the 
course of mental evolution Instinct does not decome Intelligence, 
but is gradually replaced by it, z.e. inherited specialized behaviour 
is replaced more or less by self-specialized behaviour. The larger 
the amount of such replacement the greater the intelligence. And 
this enables us to understand the peculiar helplessness of the 
young of higher Mammals, especially those of our own species. 
The complex instincts of lower forms have been lost, and it takes 
a long time to learn how to act intelligently. The remark does 
not apply to all helpless young, for in some of these, e.g. in nest- 
ling birds, such instincts are only deferred. The influence of 
strongly-developed parental affection is noticeable in both cases. 
To interpret the action of animals with any likelihood of 
accuracy it is necessary to avoid two extreme views of opposite 
kind. One of these ascribes almost human attributes to even the 
