414 



FRANKLIN P. MALL 



regarding the time of development of the corpora lutea in human 

 beings. I had thought that it would be possible to extend the 

 subject somewhat further if the corpus hiteum in the pig could 

 be standardized in relation to the size of the embryo found in the 

 uterus. This work was carried through by Corner, but unfor- 

 tunately does not include the earlier stages of the corpus luteum, 

 and it is just these data that we need if we are to determine 

 accurately the age of freshly ruptured Graafian vesicles. Corner^^ 

 made a careful study of the histological changes in the corpus 

 luteum of the sow for all but the earliest stages of pregnancy. 

 He finds that the corpus luteum is already solid at 20 days, this 

 stage being reached earlier, he believes, than in human beings 

 where this central cavity remains longer. By the aid of refined 

 cytological methods he recognizes seven distinct stages during 

 pregnancy as follows: 



Although this study cannot be transferred to the human 

 directly, it at any rate suggests that the latter may be standard- 

 ized. It is hoped to establish at least a relation between the 

 early stages of the corpus luteum and the size of the ovum and 

 embryo; and that in the course of time the age of this body may 

 be estimated with precision. 



It may be noted that Corner showed definitely that the size 

 of the embryo found in the uterus could be estimated with con- 



12 Corner, George W. 1915 The corpus luteum of pregnancy; as it is in swine. 

 Contributions to Embryologj', vol. 2, Publication No. 223, Carnegie Institution 

 of Washington. 



