8 



MORPHOGENESIS 



Fig. 5. — Ovum from Ovary of a Woman Thirty Years of Age. cr, corona radiata. 

 n, nucleus, y, yolk, p, clear protoplasmic zone, ps, perivitelline space, zp, zona pellucida. 

 (Mc^Murrich's Embrj'ology, from Nagel.) 



cr 



^r^.. 



f 



^'^.., 





y 



yJ 



ps 



^ 



n 



Fig. 6. — Stager of Segmentation in the Ovum of the Mouse, x, polar body. 

 (McMurrich's Embryology, from Sobotta.) 



