CHANGES IN THE OVARY 149 



undergoes in the case of the " marsupial cat " (Dasyurus 

 viverrinus), have been investigated by Sandes, 1 who shows that 

 the mode of formation of the corpus luteum in Marsupials is 

 essentially similar to what it is in the Eutheria. The thecn 

 interna folliculi is shown to be rudimentary in Dasyurus, a 

 circumstance which rendered it especially easy to follow the 

 subsequent changes undergone by this layer. Sandes describes 

 the follicular epithelium as undergoing so great an hypertrophy 

 prior to the thecal ingrowth as sometimes almost to fill the 

 cavity of the discharged follicle, so that there could be no possi- 

 bility of confusing the epithelial with the connective tissue cells. 2 



The formation of the corpus luteum in the rabbit has been 

 further studied by Cohn, 3 while the same process in the marmot 

 has formed the subject of an investigation by Volker. 4 Both 

 authors agree in supporting BischofL Volker finds that the 

 theca externa takes a share in the connective tissue ingrowth, 

 while the theca interna does not become exhausted in the 

 process. 



Jankowski, 5 however, has arrived at totally different conclu- 

 sions, and adopts the view that the luteal cells are modified 

 connective tissue cells. The material employed in this research 

 appears to have consisted of a miscellaneous collection of sows' 

 and guinea-pigs' ovaries obtained without any attempt at syste- 



1 Sandes, " The Corpus Luteum of Dasyurus Viverrinus," Proc. Linnean 

 Soc., New South Wales, vol. xxviii., 1903. 



2 Through the kindness of Professor J. P. Hill I have been permitted to 

 examine sections in his possession of the corpus luteum of the Monotreme 

 Ornithorhynchus paradoxus. These sections show much hypertrophied and 

 apparently fully developed luteal cells, but no trace of any ingrowth from the 

 connective tissue wall of the corpus luteum. 



3 Cohn, " Zur Histologie und Histogenesis des Corpus Luteum und des 

 Interstitiellen Ovarialgewebes," Arch. f. Mikr. Anat, vol. Ixii., 1903. 



4 Volker, " Uber die Histogenese Corporis Lutei bei den Ziesel (Spermo- 

 philus citillus}" Bull, fnternat. Acad. Sci. (Medicine), Prague, 1904. 



5 Jankowski, " Beitrag zur Entstehung des Corpus Luteum der Sauge- 

 thiere," Arch. f. Mikr. Anat., vol. xliv., 1904. Williams (Obstetrics, New 

 York, 1904) takes up the same position as Jankowski, partly on the ground 

 that " the membrana granulosa presents extensive degenerative changes, and 

 is usually cast off in great part at the time of rupture," and partly because 

 certain cells of the theca interna come to resemble luteal cells prior to ovula- 

 tion. The former statement is far from proved, and the latter cannot be 

 regarded as conclusive (see text). Cf. also Seitz, " Die Follikelatresie," Arch, 

 f. Oyndk., vol. Ixxvii., 1906. 



