604 THE STRUCTURE AND DEVELOPMENT 



cells of the germinal epithelium and the peculiarities of their 

 nuclei, so different from those of the stroma cells, supply a suffi- 

 cient series of characters to remove all doubt as to the deriva- 

 tion of the follicle cells. Apart from these more obvious points, 

 an examination of the follicle cells from the surface, and not in 

 section, demonstrates that the general resemblance in shape of 

 follicle cells to the stroma cells is quite delusory. They are in 

 fact flat, circular, or oval, plates not really spindle-shaped, but 

 only apparently so in section. While I thus fundamentally 

 differ from Foulis as to the nature of the follicle cells, I am on 

 this point in complete accordance with Waldeyer, and my own 

 results with reference to the follicle cannot be better stated than 

 in his own words (pp. 43, 44). 



At six weeks after birth the ovary of the rabbit corresponds 

 very much more with the stages in the development of the 

 ovary, which Foulis has more especially studied, for the forma- 

 tion of the follicular epithelium, than during the earlier stages. 

 His figure (Quart. Journ. Mic. Set., Vol. XVI., PL 17, fig. 6) of the 

 ovary of a seven and a half months' human foetus is about the 

 corresponding age. Different animals vary greatly in respect to 

 the relative development of the ovary. For example, the ovary 

 of a lamb at birth about corresponds with that of a rabbit six 

 weeks after birth. The points which may be noticed about the 

 ovary at this age are first that the surface of the ovary begins to 

 be somewhat folded. The appearances of these folds in section 

 have given rise, as has already been pointed out by Foulis, to the 

 erroneous view that the germinal epithelium (pseudo-epithelium) 

 became involuted in the form of tubular open pits. The folds 

 appear to me to have no connection with the formation of ova, 

 but to be of the same nature as the somewhat similar folds in 

 Elasmobranchs. A follicular epithelium is present around the 

 majority of the ova of the middle layer, and around all those of 

 the inner layer of the germinal epithelium. The nests are, more- 

 over, much more cut up by connective tissue ingrowths than in 

 the previous stages. 



The follicle cells of the middle layers are very flat, and 

 spindle-shaped in section, and though they stain more deeply 

 than the stroma cells, and have other not easily characterised 

 peculiarities, they nevertheless do undoubtedly closely resemble 



