No. 2.] THE EGG OF BUFO LENTIGINOSUS. 303 



germinal vesicle always appears somewhat shrunken and shows 

 long pseudopodium-like processes, as seen in Schultze's Fig. 5. 

 In all such cases there is a large round space surrounding 

 the vesicle, as shown in Pick's Fig. i . The outline of the ger- 

 mtJtal vesicle becomes more regular and the space around it 

 decreases in size the better the egg is preserved. From this 

 it follows that the small space often found at the upper 

 side of the germinal vesicle in eggs apparently well preserved 

 (PI. XXVIII, Fig. 7) is artificially produced by reagents, and 

 that, in the living ^.gg, the vesicle is in close contact with the 

 yolk and cytoplasm. 



2. Dissolution of the Germinal Vesicle and Fonnation of the 

 First Polar Spindle. 



I am aware that the rather remarkable metamorphosis which 

 I have found the germinal vesicle undergoing in preparation 

 for the first polar division may be considered as due entirely to 

 pathological changes produced in the eggs by removing them 

 from the body of the female and allowing them to continue 

 their maturation in water, thus subjecting them to abnormal 

 conditions. Against any such criticism I can only urge the 

 following facts : 



1. That when the females were killed before the later matu- 

 ration processes had already begun, the nuclear membrane 

 remained intact and no changes were noticed in the germinal 

 vesicle. In such cases the eggs usually disintegrated in the 

 course of four or five hours after they had been placed in water. 

 In order that maturation shall continue, the female must be 

 killed but a few hours before the eggs would normally have 

 left the ovaries. 



2. That many developing eggs which had been in water for 

 some twenty hours exhibited no apparent signs of disintegra- 

 tion, and that sections through a large number of such eggs 

 show that the first polar body had been given off in the normal 

 position and presumably in a normal manner. 



3. That the progress of maturation was uniformly along the 

 same lines in all the eggs that continued their development. 



