ORIGIN OF THE CORPUS LUTEUM 129 



immature follicle at growing stages. For study of the mature 

 follicle he selected large follicles, without discovering whether or 

 not they contained normal maturing ova. From these large 

 follicles all the granulosa cells had disappeared. The author was 

 willing to consider the possibility that they might be atretic, but 

 inclined to rate them as normal because they seemed logical pred- 

 ecessors of his next stage. Much is made of the fact that the 

 theca interna cells of ripening follicles contain granules of yellow- 

 ish fat, which are taken to be the 'lutein' already present in the 

 future lutein cells before rupture. This assumption rather over- 

 reaches itself, as one glance at fresh corpus luteum tissue of the 

 sow will show that there is no microscopic yellow pigment present 

 in the so-called lutein cells. In the one pair of ovaries next 

 described, some follicles were ruptured, others were not. In the 

 latter, the granulosa was no longer visible, except for a few cells 

 lying in the cavity. The theca interna was thickened and closely 

 resembled lutein tissue. In a later stage there was a central 

 cavity rimmed by connective tissue, supposed to represent the 

 membrana propria pushed before the thickening theca interna. 

 Sobotta ('99 b) has given a vigorous criticism of Clark's specimens, 

 explaining his so-called mature and just-ruptured follicles as cases 

 of atresia. Volker ('05) has also pointed out what he considered 

 errors of interpretation of the specimens. 



However, Doering ('99) came to the defense of Clark, also 

 using material collected at random. He states that the wall of 

 a recently ruptured follicle shows no granulosa. His principal 

 evidence, however, is from one corpus luteum of the sow, which 

 shows, near the center of the section he figures, a flattened circle 

 of granulosa cells. This he interprets as the granulosa of the 

 same follicle in which the corpus luteum formed, which had been 

 pushed inward by the proliferating theca interna, and which for 

 some reason had not degenerated. I have seen very much the 

 same appearance when a young growing follicle had crowded itself 

 into the side of an old corpus luteum, so that a tangential sec- 

 tion appeared to show a follicle within a corpus luteum. 



Jankowski ('04), using the same method of collection, would 

 seem to have had normal mature follicles of swine; at any rate, 



