FACTS AND FACTORS OF DEVELOPMENT 



11 



Memb 



B 



Fig. 1. A nearly ripe human ovum in the living condition. 

 The ovum is surrounded by a series of follicle cells (FC) in- 

 side of which is the clear membrane (Memb.) and within this 

 is the ovum proper containing yolk granules (F) and a nucleus 

 (N) embedded in a clear mass of protoplasm. Magnified 500 

 diameters (x 500). (From O. Hertwig.) B, two human 

 spermatozoa drawn to about the same scale of magnification. 

 (After G. Retzius.) 



