106 NATURE AND THE POETS. 



In his " Evening Revery " occur these lines : 



" The mother-bird hath broken for her brood 

 Their prison shells, or shov r ed them from the nest, 

 Plumed for their earliest flight." 



It is not a fact that the mother-bird aids her off- 

 spring in escaping from the shell. The young oi 

 all birds are armed with a small temporary horn or 

 protuberance upon the upper mandible, and they are 

 so placed in the shell that this point is in immediate 

 contact with its inner surface; as soon as they are 

 fully developed and begin to struggle to free them- 

 selves, the horny growth "pips" the shell. Their 

 efforts then continue till their prison walls are com- 

 pletely sundered, and the bird is free. This process 

 is rendered the more easy by the fact that toward 

 the last the shell becomes very rotten ; the acids that 

 are generated by the growing chick eat it and make 

 it brittle, so that one can hardly touch a fully incu- 

 bated bird's egg without breaking it. To help the 

 young bird forth would insure its speedy death. It 

 is not true, either, that the parent shoves its young 

 from the nest when they are fully fledged, except, 

 possibly, in the case of some of the swallows and of 

 the eagle. The young of all our more common birds 

 leave the nest of their own motion, stimulated, prob- 

 ably, by the calls of the parents, and in some cases 

 by the withholding of food for a longer period than 

 usual. 



As an instance where Bryant warps the facts to 

 uit his purpose, take his poems of the " Yellow Vi 



