THE GENESIS OF THE EGG IN TRITON. 269 



formed cell escape from the parent cell ? By comparing the 

 surface vieAvs represented in figs. S, 6, and 7, it will be 

 seen that the nucleus destined either to be, or to give rise 

 to, the nucleus of the ovum, increases in size and becomes 

 coarsely granular. In fig. 3 it occupies about one half of 

 the original cell, and that end of the cell in which it is 

 lodged is bounded by a curved line. The second nucleus of 

 this cell differs in no particular from those of surrounding 

 cells, except that it has a concavo-convex form, which it 

 has probably assumed in adjustment to the larger nucleus. 

 In this case I found no well-defined body of protoplasm 

 enveloping the larger nucleus, as in figs. 5, 6, 7, and 12, 

 In fig. 7, which represents a single epithelial cell with a 

 rounded outline due to the action of acetic acid, the larger 

 nucleus is surrounded by a distinctly marked area of proto- 

 plasm, in close apposition with which lies the smaller 

 nucleus, which has here nearly the same form as in figs. 3 

 and 6. 



In fig. 6 the larger nucleus, together with its protoplasmic 

 envelope, has taken the first step towards freeing itself from 

 the mother-cell. It is still partly within the original cell, 

 but dips at one end under two other epithelial cells. It is 

 simply the expansion by growth of the young germ-cell, 

 and not any active amoeba-like movement, which causes it 

 to get under the neighbouring epithelial cells and beyond 

 the limits of the mother-cell. In some cases I find the 

 boundary of the germ-cell passing directly into that of the 

 original cell, always so when the dipping just begins^ as 

 seen in fig. 1. 



The germ-cell at this stage has no membrane, although 

 its protoplasm is clearly bounded. In the minds of those 

 who hold a different opinion in regard to its origin, fig. 6 

 may be said to admit of another interpretation. It may be 

 said that the germ-cell possibly ]ies wholly under the ger- 

 minal epithelium, having no connection with it whatever. 

 This mode of explanation was the first to occur to me, and 

 I have endeavoured to test it, not only by the study of a 

 very large number of surface preparations, but also by 

 sections. I find it quite impossible to reconcile this view 

 with my observations. Sections confirm in a very positive 

 manner the explanation which I was led to adopt from the 

 study of surface views. The youngest germ-cells are 

 always found in the epithelial layer. Two of these are 

 seen in fig. 15, one of which (on the left) corresponds 

 exactly with what is seen in fig. 7. On the left of the 

 germ-cell is a nucleus, elongated in a vertical direction, 



