322 



VERTEBRATE ZOOLOGY 



day and are at first mere papillae protruding from the skin. At 

 hatching the chick is completely covered with down-feathers, which 

 are the forerunners of the definitive feathers and gradually give place 



/♦' ^ 





FiQ. IGG. — Chick embryo at 10 days and 2 hours, sh(.nviiis differentiated \Ying 

 and legs, shortened tail and feather iiapilla^. (From Lillie, after Keibel and 

 Abraham.) 



to the latter. On aljout the seventeenth day the anuiiotic fluid begins 

 to disappear and on the twentieth day it is gone. On the same day 

 the chick, bj^ means of a sluup little egg-tooth on the point of the bill, 

 peaks a hole in the shell and b(\gins to breath(> with its lungs. The 



