36 Life History of Common Cuckoo. 



demands in view of self preservation and the continu- 

 ance of the race, and that modifications of structure 

 in the quite young bird prepared for even in the egg 

 itself, are co-ordinated with other powers to enable it 

 to effect quite special and wholly exceptional and 

 almost incredible results. The curved or hooked 

 fingers of the hoatzin are clearly co-ordinated with 

 other powers that do not have, because they do not 

 demand, such special and observable anatomical modi- 

 fications ; and in the cuckoo I myself believe that the 

 zygodactyle feet, the temporary depression in the 

 back, which remains only for eight or ten days, are 

 co-ordinated with other powers in wings, legs, etc., 

 to enable it to do what it does when only a few days 

 old to turn out of the nest the eggs and young ones 

 of the foster parents and so secure their whole atten- 

 tion and feeding. 



The writer of a very able and interesting article on 

 the cuckoo, under the title of "A Wonder of the 

 Bird World," in the Saturday Review, for March 4, 

 1899, said : 



" A friend of the writer saw the thing " [the turning 

 out of the nest of eggs and young] " done last season 

 in the case of a young cuckoo, in a sedgewarbler's 

 nest and then, not by any means, for the first time in 

 his life. The legs of the cuckoo, in its blind and 

 naked infancy, may not be able to support without 

 props the weight of the body, but by combined move- 

 ments of legs, wings and body the bird does hoist up 

 and eject from the nest of wagtail, hedgesparrow, 

 and pipit " [and of pied flycatcher, redstart and 

 many others], " both young birds and eggs : how it 

 can get them out of the deeper nest of the reedwarbler 

 one can scarcely imagine." 



