140 THE LIFE OF A BIRD. 



turn out the eggs appears indeed to terminate 

 earlier than this, as Dr. Jenner found that a young 

 cuckoo nine or ten days old would suffer the eggs 

 to remain unmolested in the nest, while at the 

 same time it unceremoniously turned out a nest- 

 ling from the nest. The shape of the young bird 

 differs from that of other newly- hatched birds in a 

 singular degree ; this was considered by Dr. Jen- 

 ner to be connected with the peculiar action it 

 has to discharge. Its back is very broad, with 

 a considerable depression in the middle. This de- 

 pression appears to be formed for the express pur- 

 pose of giving a more secure lodgment to the egg 

 or nestling, which it has to turn out of the nest. 

 When it is about twelve days old this cavity is 

 quite filled up, and then the back assumes the 

 shape of nestling birds in general. 



The foster parents pay the young stranger, when 

 hatched, all the attention in their power, and feed 

 it with unwearied affection and diligence. Even 

 when, by an artificial arrangement, the cuckoo was 

 prevented from throwing its fellow-occupants out 

 of the nest, and so the nestlings proper to the birds 

 were preserved, they made no distinction, but fed 

 all alike. The young cuckoo is a most voracious 



