270 T. IWAKAWA. 



lying in close contact with the germ-cell, and to all appear- 

 ances answering to the concavo-convex nucleus of fig. 7. 



In fig. 6 the germ-cell has already begun to get under 

 the neighbouring epithelial cells. This section shows also 

 that the epithelial layer thickens around the growing germ- 

 cell, the epithelial nuclei being more crowded and some- 

 times lying beneath the surface. This crowding of the 

 nuclei around the germ-cell is seen in all cases, and is well 

 illustrated in figs. 4, 5, and 17. Fig. 6 shows what I have 

 often met with, the nuclei of the surrounding epithelial 

 cells lying each in that side of their respective cells which 

 is in contact with the proliferating cell. 



In regard to the origin of the follicular epithelium, I 

 have not been able to come to any definite conclusion. I 

 am quite certain that the germinal epithelial cells cluster 

 about the germ-cell, and that they form a more or less per- 

 fect envelope around it, as is seen in the right germ-cell of 

 fig. 16. In fig. 9, outlined with the camera from a pre- 

 paration in Kleinenburg's fluid, are seen some small germ- 

 cells, around which are clustered epithelial nuclei, and a 

 young ovum invested with what I regard as the young 

 follicular epithelium. The epithelial nuclei around the 

 germ-cells differ in no respect from those around the ovum. 

 In fig. 18 is seen a section of an ovum of about the same 

 size, around which are seen five nuclei, belonging to as 

 many cells, whose limits are not recognisable. On the inner 

 side of this ovum (lower side in the figure) three distinct 

 layers are recognisable, the lining epithelium of the ovary, 

 the stroma, and the follicular epithelium ; while on the 

 outer side only two layers are to be seen, the germinal epi- 

 thelium and the follicular epithelium. In an ovum having 

 a diameter about two and a half times that of fig. 9 (fig. 

 19) we find the same three layers on the inside (left side of 

 the figure) and one additional layer (stroma) on the outside. 

 The stroma layer has now become very thin, and the nuclei 

 of both the follicle and the lining epithelium are much 

 smaller than in fig. 9. 



It would be easy to interpret all this in favour of the 

 opinion that the granulosa takes its origin from the germinal 

 epithelium. But I am not prepared to deny Nussbaum's 

 theory, according to which both the granulosa and the pri- 

 mordial ovum are derived from the germ-cell. I have found 

 germ-cells with multiple nuclei, as seen in figs. 9 and 10; 

 but I have not succeeded in ascertaining the fate of these 

 nuclei. I have never found a " mulberry stage" of the nucleus 

 in germ-cells as large as the ovum seen in fig, 9. I think 



