390 F, M. BALFOUR. 



interpenetrated by connective tissue ingrowtlis, so that the region 

 below the pseudo-epitheHum is a kind of hone} comb or trabecular 

 net-M'ork of germinal ei)ithelium, developing ova of all stages and 

 sizes, and composed of cells capable of forming follicular epithelium 

 for developing ova. Ludwig figures wha the regards as the formation 

 of the follicular epithelium round j)rimitive ova during their pas- 

 sage into the stroma. Tt is quite clear to me, that his figures of the 

 later stages, 33 and 34, represent fully formed permanent ova sur- 

 rounded by a follicular epithelium, and that their situation in 

 contact with the pseudo-epithelium is, so to speak, an accident, and 

 it is quite possible that his figures 31 and 32 also represent fully 

 formed ova ; but I have little hesitation in asserting that he has 

 not understood the mode of formation of the follicular epithelium, 

 and that, though his statement that it is derived from the germinal 

 epithelium is quite correct, his account of the process is completely 

 misleading. The same criticism does not exactly apply to Sem- 

 per's statements. Semper has really observed the formation of 

 the follicular epithelium round young ova ; but, nevertheless, he 

 appears to me to give an entirely wrong account of the relation of 

 the stroma to the germinal epithelium. The extent of the diifer- 

 ence between Semper's and my view may perhaps best be shown by 

 a quotation from Semper, loc. cit., 4G5: — " In females the nests of 

 primitive ova sink in groups into the stroma. In these groups 

 one cell enlarges till it becomes the ovum, the neigbouring cells 

 increase and arrange themselves around the ova as follicle cells. 



Although the histological changes which take place in the 

 succeeding stages are not inconsiderable, they do not involve any 

 fundamental change in the constitution of the ovarian region, 

 and may be described with greater brevity than has been so far 

 possible. 



In a half-grown female, with an ovarian region of 3 mm. in 

 breadth, and 0*8 mm. in thickness, the stroma of the ovarian 

 region has assumed a far more formed aspect than before. It 

 consists (PI. XVII, fig. 10) of a basis in most parts fibrous, but 

 in some nearly homogenous, with a fair number of scattered cells. 

 Immediately below the pseudo-epithelium, there is an imperfectly 

 develo})e(l fibrous layer, forming a kind of tunic, in which are 

 imbedded the relatively reduced epitli(>lial trabecule of the 

 ])revious stages. They ap)ienr in sections as columns, either 

 continuous with or independent of the pseudo-epithelium, formed 

 of normal cells of the germinal epithelium, nests of ova, and per- 

 manent ova in various stages of develoj)ment. Below this there 

 comes a layer of larger ova which are very closely packed, A 

 not inconsiderable number of the larger ova have, liowever, 

 a superficial situation, and lie in imtneiliate contact with 

 the pseudo- epithelium. Some of the younger ova, enclosed 



