132 THE BIRD WATCHER 
flaming patch that segges to burst out of the centre of 
it—for the head is drawn right back upon the body— 
very largely contributes. Especially is this so when, 
as is mostly the case, there is considerable shadow in 
the recess of the nest, amidst the surrounding foliage. 
If it can be supposed that the large false head and 
painted eyes of the puss or elephant hawk-moth cater- 
pillars have been acquired as a protection against 
enemies—as to which see Professor Poulton’s in- 
teresting suggestion’—then it certainly seems to me 
more than possible that the flame-like throat of the 
young cuckoo has been developed in the same 
manner, pari passu with the loud, snake-like hiss and 
intimidating gestures. In conclusion, I would suggest 
that the bright or pleasingly-coloured mouth-cavity 
which some birds possess may have a distinct mean- 
ing, and be the product either of natural or sexual 
selection. 
1 The Colours of Animals (International Scientific Series). 
