YOUNG BIRDS IN THE NURSERY 77 



pulling off its head, proceeded to ram it down the throat 

 of a very importunate youngster. But the morsel was too 

 big, and had to be readjusted, not once, but many times ; 

 and finally it was forced home with such success that the 

 wretched bird was in imminent danger of death from 

 choking. At this the female, who had been sitting on 

 the opposite side of the nest, making, apparently, very 

 sarcastic comments on the awkwardness of her lord, and 

 males in general, suddenly seized the offending head and 

 dragging it forth from the throat of the choking youngster, 

 proceeded to tear it into small pieces, giving each of the 

 brood a piece. And during this time the male looked on 

 in what appeared to be a very subdued fashion. 



Reference has already been made to feeding by regurgita- 

 tion ; this presents many gradations of completeness, 

 passing from food which has merely been held for a short 

 space in the mouth, to food which has undergone a more 

 or less complete process of pre-digestion. The extreme in 

 the last direction is furnished by the case of the pigeons, 

 which for some time feed their young on a white, semi- 

 fluid, curd-like matter commonly known as " pigeon's 

 milk." This is formed within the walls of the crop, 

 which are richly supplied with blood-vessels ; but accord- 

 ing to some authorities this peculiar food is formed 

 by a peculiar transformation of the mucous membrane, 

 or inner lining of the crop. But be this as it may, the 

 young partakes of the food thus provided by thrusting 

 its beak within that of the parent, when by a pumping 

 action it is transferred from one throat to the other. 



Young petrels are no less remarkable in the matter of 

 the nourishment provided for their early days, since 

 they are fed entirely on oil distilled in the parents' crop 

 from the fish on which they live. This oil, by the way, 



