go INSTINCTIVE BEHAVIOUR 
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 con- 
stantly 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 isa 
means of getting rid of troublesome and presumably hurtful 
parasites, to the attacks of which birds are peculiarly subject. 
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 
