CHAPTER IV 
INTELLIGENT BEHAVIOUR 
I.—TxeE 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. Instinc- 
tive 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. 
Kven 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-larvee 
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