288 THE LIFE OF A BIRD. 



English and German works on Physiology and 

 Comparative Anatomy. 



About the fifth day the lungs of the chick are 

 discernible ; but, of course, in a very rude and 

 imperfect condition; and, as yet and for some 

 time to come, not intended to perform any part in 

 the respiration of the chick. The skin, and traces 

 of the feathers, next appear, and the chick com- 

 mences a curious but feeble motion. Then the 

 bones begin to be formed at the joints, the muscles 

 of the body are developed, the blood-vessels are 

 well formed, the feathers appear, and so on, until 

 two or three days previous to the time of hatching. 

 Almost all the peculiarities of a young chick are 

 presented by the being included within the shell at 

 this period. In a day or two more the whole pro- 

 cess is completed, and the chick is born into the 

 world. 



Various changes take place both in the white of 

 the egg and in the yolk, during this period. The 

 yolk becomes more fluid than usual. About the 

 third or fourth day the white and the yolk be- 

 come mingled together. The white then appears 

 to pass into the yolk-bag, all but a dense thick 

 portion which remains at the bottom of the shell. 



