PLATE II. 



Fig. 12. — Surface view of one side of egg of 1914 hours, 173 cells shown 

 on this surface. X 142. 



Fig. 13. — Portion of section through an egg of the same stage as the 

 preceding, showing the ventral pole. X 142. 



Fig. 14. — Section through anterior cumulus of an egg of 21 hours, only 

 2 cells invaginated. X 360. 



Fig. 15. — Surface view of ventral pole of an egg of 24 hours, 417 cells 

 shown on this surface, at the lower part of the figure the cells appear most 

 crowded because that portion of the germ disc is most convex. The cells have 

 short intercellular processes that are not drawn. X 142. 



Fig. 16. — Somewhat oblique cross section of egg of 24 hours, through the 

 anterior cumulus, less than 12 cells invaginated. X 142. 



Fig. 17. — Somewhat oblique cross section through anterior cumulus of egg 

 of 24 hours, about 8 cells invaginated. X 300. 



Fig. 18. — Ventral view of unstained germ disc seen in alcohol, 22 hours. 

 X 30. 



Fig. 19. — Cross section of anterior cumulus of an egg of 22 hours, 12-13 

 cells invaginated. X 360. 



Fig. 20. — Cross section of an egg of ca. 26 hours. X 142. 



Fig. 21. — Cross section through anterior cumulus of an egg of ca. 26 hours, 

 about 25 cells invaginated. X 360. 



Fig. 22. — Somewhat oblique ventral view of germ disc of 28 hours, some- 

 what more than 500 cells shown. X 142. 



Fig. 23. — Surface view of unstained germ disc of 30 hours, seen in alcohol. 

 X 30. 



Fig. 24. — Cross section of anterior cumulus of an egg of 30 hours. 

 X 360, 



Fig. 25. — Oblique cross section of anterior cumulus, egg of 30 houi's. 

 X 360. 



Fig. 20. — Surface latero-ventral view of germ disc, of 30i/^ hours, with 

 two artificial breaks in its side ; the inner bounding line of each cumulus 

 shows how deep its cells project into the yolk ; 268 cells shown, x 142. 



Fig. 27 Median section through both cumuli of germ disc, 30^^ hours. 



X 142. 

 Fig. 28. — Median section through anterior cumulus, 30^/^ hours. X 360. 



Fig. 29. — Surface view of unstained germ disc, seen in alcohol, 54 hours 

 (same stage as Fig. 30). X 30. 



