MORPHOGENESIS OF THE MAMMALIAN OVARY 351 



of the full}^ developed ovaiy. The question of the double char- 

 acter of the ovary clearly hinges on the interpretation of the 

 neogenic zone as well as that of the portion underlying it. It is 

 evident however, that in any event the morphological comparison 

 of the medulla of the ovary and the testis is not very close in man. 



For the converse of the ovarian-testis homology — the represen- 

 tation of the ovary in the testis — but little has been said. There 

 is nothing in the normal adult testis that can be construed as char- 

 acteristically ovarian, as this would of necessity lie outside the 

 tunica albuginea. Janosik ('85) has described a late formation 

 of large cells in the surface epithelium of the testis in the human 

 fetus as an attempt to form follicles. Biihler ('06) mentions the 

 occurrence of germ cells in the surface epithelium of fetal testes, 

 as apparently does Coert ('90). It is clear that any proliferative 

 activity in the covering epithelium of the testis after the forma- 

 tion of the germinal cords is on any interpretation very slight. 



The present investigation was undertaken to determine the 

 origin of the interstitial cells- of the ovary, so abundant in that 

 organ in the cat. While the monograph upon the development 

 of the ovary of the cat by von Winiwarter and Sainmont ('08) 

 has rendered unnecessary a detailed presentation of many aspects 

 of ovarian morphogenesis in this animal, a somewhat differing 

 interpretation and different point of view appear to justify a brief 

 consideration by me. 



The study in so far as presented is a purely morphological one 

 based upon 60 series of sections of ovaries from relatively late 

 fetal to adult life, the periods particularly considered being there- 

 fore those of the fetal, post natal, and pre-sexual development. 

 While several methods of fixation and staining were employed, 

 as indicated in the foot-note,^ depending upon what it was de- 

 sired to bring out, the technique already described (Kingsbury 



- Published as a separate article. 



' The ovaries upon which the study is based are as given below. Only a por- 

 tion of the animals were reared in the laboratory, the greater number were pro- 

 cured from householders and hence the data as to age is not as exact as it would 

 otherwise have been. My observations confirm those of Sainmont and v. Wini- 

 warter that there is a large variation in ovaries of the same age. Age is therefore 



