EMBRYOLOGY OF CRYPTOBRANCHUS 99 



the germinal vesicle at the surface have been sectioned, in none 

 of these eggs has the nuclear wall been found ruptured. 



Several females have been taken in which only a few eggs 

 remained in the ovary, the others being found in the body cavity, 

 oviduct and uterus. The ovarian eggs of such specimens were 

 invariably found to be in a later stage than those just described: 

 sections showed that the dissolution of the germinal vesicle was 

 complete, and in surface views these eggs showed a small faint 

 dark spot or slight depression at the animal pole (see fig. 5). 



5 6 



Fig. 5 Surface view of the animal hemisphere of an egg of Cryptobranchus 

 allegheniensis ready to leave the ovary, after the rupture of the germinal vesicle. 

 The lightly stippled area indicates the blastodisc. Sketched from the living egg. 

 X 7. 



Fig. 6 Surface view of the animal hemisphere of an egg taken from the uterus, 

 ready for fertilization, showing pit at the center of the blastodisc. Sketched from 

 preserved material. X 7. 



The dark spot is sometimes surrounded by a tumid ring, but this 

 condition is probably pathological. 



At the time of the escape of the egg from the ovary and its 

 passage through the body cavity and upper oviduct, the egg seems 

 softer in consistency than at other times. Some fixing solutions, 

 particularly Lavdowsky's, which usually preserve perfectly the 

 spherical form of the egg, now fix it as an irregularly-shaped mass. 

 This plasticity may be of use to the egg in its escape from the 

 ovary and passage down the oviduct. 



JOURNAL OP MORPHOLOGY, VOL. 23, NO. 1 



