40 



THE DEVELOPMENT OF THE CHICK 



FIG. 16. Five stages of the cleavage of the hen's egg. (After 

 Kolliker.) 



A. First cleavage furrow (x 14). 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 16). 



D. Nine central and sixteen marginal cells (x about 16). 



E. Late cleavage stage (x about 22). 



