260 NEIL S. DUNGAY. 



PLATE II. 



FIG. 4. Egg, from same culture as Fig. 3, fixed i hour and 5 minutes after 

 insemination. Sperm attached to vitelline membrane, no attachment granules, 

 and no fertilization cone. Perforatorium still delicate. Jelly and both polar 

 bodies have formed. Vesicles of egg nucleus as in Fig. 6. 



FIG. 5. Egg from control culture 43 minutes after insemination, showing 

 fertilization cone, attachment granules, and sperm with thickened perforatorium. 



FIG. 6. Egg from same culture as Fig. 3, fixed i hour and 27 minutes after 

 insemination. Jelly and both polar bodies have formed. Sperm, in another 

 section, attached to vitelline membrane. Vesicles of egg nucleus showing chromo- 

 some within. 



FIG. 7. Egg from same culture as Fig. 3, fixed i hour and 36 minutes after 

 insemination. Jelly and both polar bodies formed. Egg vesicles degenerating. 

 Sperm (in another section) attached to vitelline membrane. 



FIG. 8. Egg fixed 2 hours and 17 minutes after insemination with sperm 

 removed from male and kept at room temperature for 21 hours. This egg has 

 not succeeded in completing the division of the cytoplasm and the chromosomal 

 vesicles, about 28 on each side, are scattering. Strongly staining granules around 

 the chromosomal vesicles. 



