124 GEORGE W. CORNER 



lower animals, they do not in man arise from the membrana 

 granulosa," which latter membrane he thinks is probably shed 

 with the ovum. Hegar, in 1910, reported an examination of 

 six human ovaries removed four and two days before the onset 

 of menstruation, all containing corpora lutea which he supposes 

 to be fairly young. While admitting the epithelial origin of the 

 structure in mammals lower than man, he is inclined to view his 

 preparations as indicating a thecal origin of the lutein cells in 

 the human species. J. Whitridge Williams, whose text-book of 

 obstetrics ('03-' 17) is based to so great an extent upon original 

 study that it is regularly quoted in scientific literature as author- 

 itative, retains in his last edition the views of the preceding 

 writers, of whose correctness he feels convinced by the study of 

 several hundred corpora lutea. 



This completes the list of recent authors who see in the corpus 

 luteum a structure of connective-tissue origin alone. All other 

 investigators of the past sixteen years uphold in general the epi- 

 thelial origin of the lutein cells, but among themselves they vary 

 according to their views as to the fate of the theca interna. The 

 rabbit has been studied in 1897 by Sobotta, who found the process 

 exactly as in the mouse, but Honore, three years later, in the same 

 animal, found that not all the theca interna cells are converted 

 into fibroblasts, but that some of them linger about the periph- 

 ery of even the fully formed corpus luteum. Cohn, in 1903, 

 repeated the work, apparently without study of the ova, but 

 dating his specimens from an observed copulation, (in the rabbit 

 ovulation occurs only after coitus), and confirmed the results of 

 Sobotta. Marshall, in the next year, described the corpus 

 luteum of the sheep, dating his specimens from observed copula- 

 tion. He did not seek the ova, but as in this species ovulation 

 and coitus can occur at no time except during a short oestral 

 period, so that coitus dates the time of ovulation within a very 

 few hours, the presumption is great that Marshall possessed 

 normal corpora lutea of ages accurately known. He found the 

 granulosa to persist and to be vascularized by sprouts from the 

 theca interna, all the cells of which were finally used up, having 

 been converted into spindle-cells of connective tissue. A part of 



