34 Miss J. E. Lane-Claypon. On the Origin, etc., of [June 16, 



pregnant women; Wagener(17) records the thickening of the germinal 

 epithelium near the attachment of the Fallopian tube in the pregnant bitch, a 

 condition which he thinks denotes the formation of ova. 



Amann (1) describes the presence of follicles in the ovaries of a woman of 

 63, where there was incipient cystadenoma, the follicles being in all stages of 

 formation by means of invagination of the germinal epithelium. The interest 

 of this observation lies in the age of the woman and in the apparent 

 formation of fresh ova consequent on the stimulus caused by the incipient 

 cystadenoma. 



V. Winiwarter was not able to trace any of the stages of ovogenesis in any 

 of the adult ovaries he examined, and considers this a necessary condition for 

 the formation of ova. As far as the literature goes, we may consider the ovary 

 to be formed by the embedding in the underlying mesoblast of the cells of 

 the germinal epithelium, the embedding being brought about by a process of 

 ingrowth of the cells and of upgrowth of the mesoblast. The cells thus 

 embedded are oogonia, which give rise to ova by division, as also to the 

 follicle cells, the future ova undergoing considerable nuclear trans- 

 formation before reaching the condition of the fully-formed primordial ovum. 



The post-natal formation of primordial ova has been recorded in certain 

 cases, but there is not much evidence either in favour of or against it. 



Object of the Investigations. — Certain features which I observed in the 

 interstitial cells of the ovaries of rabbits at a late period of pregnancy led me 

 to study the origin of these cells. This question would appear to have been 

 neglected by previous workers on the ovary. The formation of an internal 

 ovarian secretion (cf. Andrews (3)), which by analogy with the interstitial 

 gland of the testis might be presumed to be derived from the interstitial 

 cells {cf. Ancel and Bouin (2)), gives considerable interest to their origin. 



This was studied by examining (1) the ovaries of rabbits from the twentieth 

 day embryo up to those of the young rabbit about three weeks after birth ; 

 (2) the ovaries of pregnant rabbits at all stages. 



Methods. — It is not easy to find a really good fixing agent for ovaries, 

 especially adult ovaries. Hermann's, Flemming's (strong formula), Pod- 

 wyssoski's and Altmann's fluids, were all used. The last was found satis- 

 factory for cytoplasm, but the sections obtained with the other fixatives were 

 not good. The tissue was osmicated outside and insufficiently fixed inside. 

 Finally,* Gilson's fluid was used exclusively for all nuclear figures, and a 



* Gilson's fluid = abs. ale, 1 part ; 



glacial acetic, 1 part ; 

 chloroform, 1 part ; 

 the whole saturated with sublimate. 



