118 GEORGE W. CORNER 



It must be remembered that the first of these monographs ap- 

 peared a decade before Schleiden and Schwann's enunciation of 

 the cell theory, and the other not five years after; histology was 

 studied with pincettes and the needle rather than by sections, 

 and the first nuclear stain was not discovered. The layers of 

 the follicle were as yet imperfectly differentiated, and the early 

 descriptions are so vague that it is difficult to interpret them in 

 present-day terms. New steps toward the solution of this prob- 

 lem have always followed fast upon the development of histo- 

 logical technique, and thus it is in the writings of Wilhelm His 

 ('65) and Waldeyer (70) that we first find opinions and descrip- 

 tions approaching those of recent years. 



The studies of His led to the complete formulation of the view 

 that the corpus luteum is derived from the theca interna of the 

 Graafian follicle, which in the next two decades was supported 

 by a number of investigators and still holds a place in the field 

 against strong opposition. The chief arguments in favor of this 

 view are that, first, the membrana granulosa of large follicles is 

 often degenerated, and is believed to be cast off at the time of 

 rupture; second, as the Graafian follicle ripens, the cells of the 

 theca interna show marked changes — they swell in volume, be- 

 come rounded, in some species they acquire granules of a yellowish 

 pigment, and in short come to present a striking resemblance to 

 the large cells of the corpus luteum; third, this resemblance is en- 

 hanced by the fact that not only are the large cells of the theca 

 interna folliculi and the corpus luteum similar, but the presence 

 of many blood-capillaries and connective-tissue cells causes a re- 

 semblance as well in the general structure of the two tissues; 

 and, fourth, such follicles as do not rupture lose their granulosa 

 by degeneration, become obliterated by proliferation of the theca 

 interna, and in this process of atresia attain also a resemblance to 

 the corpus luteum. . 



None of the contributions disagreeing with this view in favor 

 of the granulosa origin of the lutein cells were at all convincing, 

 until the appearance in 1895 and 1896 of Sobotta's first researches, 

 which mark the beginning of modern work upon the question. 

 Here again the chief contribution was one of method. Sobotta 



