350 B. F. KINGSBURY 



Allen ('04), and Felix ('11) have derived it from the mesothelium, 

 while Sainmont ( '05) in his detailed study supports the older view 

 of its origin from the Malpighian corpuscles of the mesonephros. 



The most recent study of the development of the mammalian 

 ovary, that of man, by Felix in the Keibel-Mall ''Handbook of 

 human embryology" leaves undiscussed (apparently purposely) 

 the question of the comparability of the medullary portion of the 

 ovary with the testis, the presentation in the second volume con- 

 trasting in this respect with the brief statement in the first volume 

 illustrated by means of an elaborate diagram supporting the testic- 

 ular homology of the ovarian medulla. Felix, in fact, distinctly 

 rejects this homologization, inferentially at least, by the form 

 in which the development of the gonads in man is described. 

 Briefly stated, in the indifferent stage, the gonad consists of an 

 inner epithelial mass, separated from the covering epithelium 

 by the (primitive) tunica albuginea. In the male this becomes 

 the permanent T. albuginea and the inner epithelial mass speedily 

 resolves itself into the spermatogenic tubules. In the case of 

 the ovary however, the inner epithelial mass becomes again 

 intimately associated with the mesothelial covering of the organ 

 and a new peripheral zone closely blended with and probably 

 derived from the inner epithelial mass becomes developed, termed 

 by Felix the 'neogenic zone.' This is destined to form the defini- 

 tive cortex of the mature ovary while the central portion of the 

 inner epithelial nucleus or mass undergoes a progressive degenera- 

 tion toward the periphery. The inner epithelial nucleus there- 

 fore furnishes the material for the functional structures in either 

 ovary or testis, differentiation of the former proceeding peripher- 

 ally, and more slowly whereas in the testis the differentiation is 

 central and early. Any homolog of the seminal tubules of the 

 testis is lacking in the human ovary, according to Felix. 



It will be seen that the exposition of the development of the 

 human ovary given by Felix is not in itself contrary to the accep- 

 tance of the ovarian medulla-testis homology, — previously men- 

 tioned — since the portion of the epithelial nucleus in the indifferent 

 organ that forms the spermatogenic tubules of the male takes no 

 part in the formation destined to furnish the ova and follicle cells 



