252 HELEN DEAN KING. 



to be very closely packed together, and there is rarely an inter- 

 cellular space to be found. These cells have the same characteris- 

 tics as those shown in Fig. 2 ; namely, a very large nucleus con- 

 taining one nucleolus, a small amount of granular protoplasm, 

 and chromatin partly in the form of a network, and partly in 

 masses scattered along the wall of the nucleus. 



On examining the ovary of a toad killed about three weeks 

 after the eggs had been laid, one finds that the openings of the 

 follicle sacs into the body cavity have closed, and that the outer 

 membrane of the ovarian wall is again continuous. Each fol- 

 licle sac appears at this time as a blind pouch projecting from the 

 inner side of the ovary. The cells lining the cavity of the sac are 

 beginning to show the degenerative changes that are very marked 

 in the ovaries of toads killed the latter part of May. The most 

 noticeable changes are those which are taking place in the nu- 

 cleus (Fig. 5). Although at this time the nucleus is still round or 

 oval, its outline is somewhat more irregular than it was at an 

 earlier period, and most of its chromatin is collected in from one 

 to_four rounded masses that stain black with iron-haematoxylin 

 and a deep red with the borax carmine and Lyon's blue mixture 

 used. The protoplasm of the cells appears very granular, and 

 it stains so feebly that it is often very difficult to determine the 

 cell outlines. Such changes, as a rule, are first apparent in the 

 innermost cells that soon break away from the rest and become 

 scattered throughout the cavity of the follicle sac. These free 

 cells never show any pseudopodia ; on the contrary, they are 

 more rounded than are the cells still attached to the walls of the 

 follicle sac, and it is therefore impossible to determine whether 

 they have the power of independent movement or not. 



Although I have examined the ovaries of many toads killed 

 during the month of June, I have not been able to determine 

 whether the cells lining the follicle sacs are destroyed by the 

 leucocytes, as are the eggs that fail to leave the ovary, or whether 

 they disintegrate and are absorbed by the cells of the ovarian 

 wall. In all the toads killed at this time, either the cells within 

 the follicle sacs were undergoing degenerative changes similar to 

 those shown in Fig. 5, or else the cavity of the follicle sac was 

 nearly obliterated and no traces of the cells could be found. It 



