178 <;korge w. corner 



therefore until a series including every day of the first week after 

 parturition can be obtained, the ultimate fate of the theca interna 

 cells of the sow must remain unknown. 



DISCUSSION 



It is hardly necessary to point out that the evidence just given 

 completely negates the results of previous investigators in this 

 species, and that it therefore removes one of the main supports 

 of the theca-origin theory. But since this view has been held 

 by so many anatomists, the reader will ask more than mere 

 denial; stating their errors, we must also explain them. The 

 reply, already pointed out by Sobotta, has become emphasized 

 to the present writer during the course of his own studies. It 

 would be a simple matter to select from this material a number 

 of specimens which would duplicate the figures of Clark, Jan- 

 kowski, or Doering, but placed in proper position in the series, 

 the same specimens lead to far different interpretations. The 

 small, pale, and inconspicuous nature of the corpora lutea at 

 their earliest stages has allowed them to escape the notice of in- 

 vestigators seeking, under preconceived notions, for brightly 

 haemorrhagic structures in the ovaries, and thus the all-im- 

 portant stages of the first four or five days have not been at hand 

 to explain the more difficult later conditions of development. 

 Insufficient data, leading to confusion with the process of atresia 

 and to failure to obtain the earlier stages, and insufficient num- 

 bers of specimens, leaving important gaps to be filled by the 

 imagination, are the two great sources of error in the study of this 

 difficult problem. 



In the investigation of the human ovary the obstacles to the 

 acquisition of attested material are still greater than in the 

 mammals subject to experimental methods. With our obscure 

 knowledge of the reproductive cycle, the only guide to the age 

 of a corpus luteum is its appearance, and we have seen what a 

 useless aid this can be. Even the presence of a healing point 

 of rupture, which is so characteristic of early corpora lutea in 

 other animals, is not entirely trustworthy in human ovaries. 



