76 B. F. KINGSBURY 



my previous paper, the relation of the interstitial cells to the 

 follicular masses is likewise evident, although much more intri- 

 cate and less exact, due in part, I believe, to the shiftings during 

 a period of marked growth of the ovary as a whole. In illus- 

 tration of the relations at this period two line drawings (figs. 15 

 and 16) are introduced -from which the location of interstitial 

 ceU groups may be seen. 



Finally, from figure 3, the location of the interstitial cells in 

 the period of large irregular pluriovnlar follicles may be seen. 

 It will be noted that the theca of these follicles contains abun- 

 dant lipoid containing cells. These follicles are quite atypical, 

 aside from their irregularity and pluriovular character, in the 

 thinness of their follicular epithelium, and as v. Winiwarter and 

 Saimont pointed out, in the 'abnormal' appearance of contained 

 ova, one element of which, the scanty amount of lipoid contained, 

 interests us here. 



From the above it may be seen that the follicular growth proc- 

 esses within the medulla of the immature ovary depart widely 

 from those of the adult period, and it is undoubtedly in correla- 

 tion with the irregular and essentially atypical ('abnormal') char- 

 acter of the growth processes rather than with growth itself that 

 the interstitial cells make their appearance. In my previous 

 paper, I have interpreted the growth relations encountered as 

 essentially successive 'attempts' at normal follicle formation, be- 

 coming more typical as the presexual development of the ovary 

 advances. All these early formed follicles, as v. Winiwarter and 

 Saimont first recognized, are doomed to degenerate. There suc- 

 ceeds the period of large irregular pluriovular Graafian follicles 

 a period of profound degeneration, and it is at this presexual 

 period that the cat's ovary contains the greatest relative number 

 of interstitial cells. From an ovary of this period figure 9 is 

 taken, and for it might have been substituted reproductions of 

 sections from several ovaries in which the mass of interstitial 

 cells was much greater. 



No fundamental difference is thus felt to exist between the 

 conditions of interstitial cell formation in the adult and in the 

 growing ovary. 



