130 GEORGE W. CORNER 



the granulosa was intact. The ova were not seen. His very- 

 early corpora lutea, showing stigmata at the point of rupture, 

 also contain the granulosa in situ and completely preserved, 

 except that the cells are swollen, irregular in form, and contain 

 vacuoles. The theca interna cells are large, contain lipoid gran- 

 ules, and resemble lutein cells. No specimens between this and 

 the solid corpus luteum are presented. Upon such evidence he 

 confirms Clark's account. 



Kopsch ('01) demonstrated at a meeting of the Anatomische 

 Gesellschaft certain preparations by Menzer of the corpora lutea 

 of swine three, six, and ten days after copulation. This contri- 

 bution appeared by title only, and our sole information as to its 

 nature is the statement of Sobotta that Menzer's specimens are 

 in general agreement with his own views. 



It is fair to say that the theory of the origin of the corpus 

 luteum from the theca alone, though it still holds a place in 

 current literature, has no good evidence in its favor. Every in- 

 vestigator whose methods assure us that accurately dated speci- 

 mens of a sufficient number of stages were in his hands has de- 

 clared the persistence of the granulosa cells and their transfor- 

 mation directly, with little or no mitotic division, into the 

 characteristic large 'lutein cells' of the corpus luteum. The 

 problem has shifted during the sixteen years whose progress I 

 have reviewed; the present point of interest is as to the fate of 

 the theca interna. Are its cells all converted into connective 

 tissue; do they persist as a special peripheral layer of the corpus 

 luteum; do they assume an impenetrably close resemblance to 

 the granulosa lutein cells; or can we find some other and clearer 

 explanation of the problem of their disappearance? 



The following pages contain the results of an attempt to answer 

 these questions. Choice of the species to be studied was influ- 

 enced by several reasons. There is a frequently expressed idea 

 that perhaps the larger and smaller animals differ in the forma- 

 tion of their corpora lutea, as they do in many other features of 

 their reproductive cycles; the sow is large and has an ovulation 

 cycle not unlike the human species. Other considerations in- 



