Fig. 1 



Fig. 2 



Fig. 3 



Fig. 4 



Fig. 5 



Fig. 6 



Fig. 7 



Plate V. (Figs. 1 to 3 from the Journal of Anatomy; Figs. 4 to 7 from 

 the Archives de Biologie.) 



Fig. 1, Line drawing of a section through an atretic foUicle of the mouse. First 

 mitotic anaphase. Cytoplasmic division not completed — mouse. Fig. 2, Typical 

 4-celled ovarian ovum — water vole. Fig. 3, Typical 2-celled ovarian ovum with 

 intact zona — water vole. Fig. 4, Early blastocyst of ovarian ovum — mouse. Fig. 5, 

 Many-celled blastocyst in ovarian ovum — guinea pig. Fig. 6, Multinucleate blasto- 

 cyst-like ovarian ovum — mouse. Fig. 7, Blastocyst-like ovarian ovum — guinea pig. 



60 



