556 THE STRUCTURE AND DEVELOPMENT 



Semper attempts to bring forward embryological proofs in 

 support of this position. 



If the series of ovaries which I have represented be ex- 

 amined, it will not, I think, be denied that the general appear- 

 ances are very much in favour of my view. The thickened 

 patch of ovarian epithelium can apparently be traced through 

 the whole series of sections, and no indications of its sudden 

 reduction to the thin pseudo-epithelium are apparent. The 

 most careful examination that I have been able to make brings 

 to light nothing tending to shew that the general appearances 

 are delusive. The important difference between us refers to 

 our views of the nature of the tissue subjacent to the pseudo- 

 epithelium. If my results be accepted, it' is clear that the whole 

 ovarian region is an epithelium interpenetrated by connective 

 tissue ingrowths, so that the region below the pseudo-epithelium 

 is a kind of honeycomb or trabecular net-work of germinal 

 epithelium, developing ova of all stages and sizes, and composed 

 of cells capable of forming follicular epithelium for developing 

 ova. Ludwig figures what he regards as the formation of the 

 follicular epithelium round primitive ova during their passage 

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

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

 surrounded 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 Semper'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 difference between Semper's and 

 my view may perhaps best be shewn by a quotation from 

 Semper, loc. cit., 465: " 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 neighbouring cells 



