THE ORIENTATION OF THE FEOG's EGG. 405 



Fig. xviii. — Same as last, side view. 



Fig. XIX. — Embryo with large blastopore, seen from dorsal side. 



Fig. XX. — Embryo with large blastopore, seen from behind. 



PLATE 25. 



Fig. 1. — Diagram normal egg, lower pole. 



Fig. 2. — Diagram same egg, side view. 



Fig. 3. — Diagram normal egg, lower pole. 



Fig. 4. — Diagram same egg, side view. 



Fig. 5. — Diagram to show defect X produced by sticking apex blastula. 



Fig. 6. — Diagram to show defect X i)roduced by sticking apex blastula. 



Fig. 7. — Diagram normal embryo to show length of medullary folds, side 

 view. 



Fig. 8. — Diagram same embryo to show length of medullary folds, dorsal 

 view. 



Fig. 9. — Diagram to show lower white area when blastopore appears. 



Fig. 10. — Diagram egg stuck opposite edge of white from blastopore, see 

 text. 



Fig. 11. — Diagram same, later stage, see text. 



Fig. 12. — Diagram same, later stage, see text. 



Fig. 13. — Diagram egg stuck far from blastopore, see text. 



Fig. 14. — Diagram same, later, see text. 



Fig. 15. — Diagram egg stuck far from blastopore, see text. 



Fig. 16. — Diagram same, later, see text. 



Fig. 17. — Diagram egg stuck nearer. to blastopore, see text. 



Fig. 18. — Diagram same, later, see text. 



Fig. 19. — Diagram same, later, see text. 



Fig. 20. — Diagram egg stuck near blastopore, see text. 



Fig. 21. — Diagram same, later, see text. 



Fig. 22. — Diagram egg stuck centre of early blastopore, see text. 



Fig. 23. — Diagram same, later. 



Fig. 24. — Diagram with injury taken as a fixed point X to show relative 

 advance of dorsal lip of blastopore. 



