36o JORDAN. 



PLATE XV. 



Fig. 1 5. Section of germinal vesicle ; nucleoli migrating to the center and 

 disintegrating (X 500). 



Fig. 16. Section of germinal vesicle {g.v.)\ yolk-nucleus {dk) in contact with 

 it ; peripheral nucleoli disintegrating. In the yolk-nucleus are three coarsely 

 granular areas which stain more deeply than the rest of the Dotterkern (X 375). 



Fig. 17. Section of germinal vesicle of Rana palustris (X 225). 



Fig. 18. Maturation spindle from egg found in body-cavity. Stained with 

 acid fuchsine. (X 140). 



Fig. 19. Maturation spindle from egg found in oviduct (X 140). 



Fig. 20. " Second polar body " ; one and one-half hour after the egg was 

 laid ; several spermatozoa in the egg (X 140). 



Fig. 21. Maturation spindle from egg found in body-cavity. Unstained prep- 

 aration (X 140). 



Fig. 22. Maturation spindle from an egg found in the upper part of the 

 oviduct ; the egg possessed a very thin enveloping membrane (X 140). 



Fig. 23A. Union of male and female pronuclei in egg eight hours after laying. 

 m., male pronucleus (?) ; /, female pronucleus (?) (X 375). 



Fig. 23B. Section showing spermatozoon entering egg ; two hours after lay- 

 ing. A spindle in the same stage as that in Fig. 20 is present in the egg (X 140). 



Fig. 23C. Spermatozoon entering egg ; two hours after laying. A spindle of 

 the stage shown in Fig. 20 is present (X 140). 



Fig. 23D. Spermatozoon in egg ; four hours after laying (X 140). 



[The outlines of all these figures were drawn with the camera.] 



