120 GEORGE W. CORNER 



study of nearly 1500 ova during the stages of maturation, fertili- 

 zation, and the segmentation of the blastomeres. He found no 

 degeneration of the membrana granulosa; instead the cells of 

 this layer remain and undergo hypertrophy (without division), 

 finally becoming the characteristic large cells of the corpus luteum. 

 Meanwhile the cells of the theca interna undergo mitotic division, 

 are converted into spindle-cells and invade the granulosa to 

 form the connective- tissue reticulum of the corpus. In this 

 process all the theca interna cells are used up, and the layer 

 therefore disappears. Capillary blood-vessels grow in from the 

 vessels of the theca interna, ultimately providing the corpus 

 luteum with a rich circulation. 



There will be no need to enter here upon a detailed account of 

 the debate which began immediately upon the publication of 

 these epoch-making studies. A full analysis of the literature 

 upon the origin of the corpus luteum up to 1901 will be found in 

 the papers just quoted and in the two reviews of Sobotta in the 

 Ergebnisse der Anatomie ('99a, '02). In 1897 Sobotta himself 

 studied corpus luteum formation in the rabbit, and found the 

 process in all important points exactly as in the mouse. A year 

 later, Stratz ('98) printed a research upon which he had been 

 engaged before the publication of Sobotta's work, in which he 

 had followed the early stages of the corpus luteum on ovaries of 

 an insectivore, Tupaia javanica, the lemuroid ape Tarsius spec- 

 trum (the specimens being those of Hubrecht's well-known Java- 

 nese collections,) and of the 'Spitzmaus' or shrew, Sorex vulgaris. 

 Although he did not have large numbers of cases, all were checked 

 by the study of the ova or embryos. As far as the persistence 

 of the granulosa cells and their direct conversion into the lutein 

 cells was concerned, Stratz agreed fully with Sobotta, but with 

 regard to the fate of the theca interna there is a minor difference. 

 If I understand Stratz correctly, he considers the theca interna 

 of the mature follicle merely as a zone of blood-vessels, in which 

 all the cells are either constituents of the vascular wall or of the 

 adventitia. Considered in this light, it is easy to see how this 

 angioma-like thecal tissue would enter into the growing corpus 

 luteum to form its blood-vessels and its connective tissue without 



