316 



VERTEBRATE ZOOLOGY 



B 



FiQ. 161. — Cleavage of hen's cifg. A, first cleavage furrow (x 1-t). The egg 

 came from the lower end of the oviduct. B, Four-celled stage (x 17); from the 

 uterus; C, Ten central and eleven marginal cells (x about 10) ; D, nine central and 

 sixteen marginal cells (x about 10); E, late cleavage stage (x about 22). (,From 

 Lillie's " Development of the Chick," after Kolliker.) 



