364 B. F. KINGSBURY 



I have sketched the general results of von Winiwarter and 

 Sainmont because of the monographic character of the study made 

 of the development of the ovary of the cat and the uniqueness 

 of some of the results and interpretations offered.. It is therefore 

 with some hesitancy that I venture, from a study of material in- 

 ferior in amount to theirs, to offer interpretations that differ in 

 certain fundamental respects. 



In as far as concerns the medullary follicles, the difference of 

 interpretation has three aspects. In the first place, as has been 

 fully indicated in the discussion of the medullary cords in the 

 foregoing paragraphs, the writer is unable to accept the sharp 

 distinction between the products of a ''first and second prolifera- 

 tion, " a distinction that plays so important a part in the interpre- 

 tations of von Winiwarter and Sainmont. The distinction of 

 medullary cord and sex cord seems to the writer more a matter of 

 differentiation, location, and convenience for descriptive purposes 

 rather than a sharp distinction of materials of morphologically 

 different values. The follicles that begin their development dur- 

 ing this period are thus but the earliest follicles which from posi- 

 tion may appropriately be termed medullary follicles, it is true, 

 but only for descriptive and topographical reasons. Their devel- 

 opment, peculiarities and fate are closely involved in- the growth 

 processes taking place in the ovary at this time. 



The second point of different interpretation involves the source 

 of the ova and the early transformation of the inner portions of 

 the 'egg cords.' As has been already stated, it has seemed to the 

 writer clearly apparent from a comparison of the successive series 

 of ovaries of advancing development, that going hand in hand with 

 the peripheral growth of the egg cords there has been a central 



ne reste pas inactif. Une nouvelle proliferation (la troisieme), celle des invagi- 

 nations epiiheliales , apparait et les colonnes cellulaires qui les composent, trav- 

 ersent I'albuginee et se melent aux amas des cellules, foUiculeuses. Comme ces 

 deux formations sont constituees de cellules 6pitheliales ordinaires, il est impos- 

 sible morphologiquement de distinguer ce qui revient aux unes et aux autres. 

 Toujours est-il que c'est a leurs depens que se formeront la zone corticale defini- 

 tive et les oeufs d^finitifs de I'adulte." (p. 260): "Ces invaginations, jointes 

 aux cellules foUiculeuses de la zone corticale primitive, aboutissent a la formation 

 de la zone corticale definitive de I'ovaire, a laquelle, seule, sera reservee la pro- 

 duction des oeufs definitifs. Son histoire appartient a un chapitre ulterieur." 



