THE OVARY OF THE SPERMOPHILE 119 
luteal cells are of a connective-tissue origin and that the function 
of the corpus luteum is to preserve the ovarian circulation. 
Sobotta (99) published his third paper on the corpus luteum 
of mammals. Honore (’00) was one of the first to confirm 
Sobotta’s findings. He wrote concerning the corpus luteum in 
the rabbit. Marshall (01) published a paper on the corpus 
luteum in the sheep, coming to practically the same conclusions 
as Sobotta. Cohn (’03) further confirmed Sobotta’s work on 
the rabbit. Jankowski (’04) published a paper in which he 
came to entirely different conclusions. They are as follows: 
‘““He (Sobotta) simply lets the internal theca vanish. If one 
layer must vanish, it would be the one for whom the conditions 
after the follicle bursting are very unfavorable and that is the 
case with the epithelium of the follicle. The corpus luteum is 
not an epithelial but a connective tissue structure.” Sobotta 
(06) published a fourth paper on the formation of the corpus 
luteum in the guinea-pig, again confirming his former work. 
Such an amount of histologic investigation over the formation 
of the corpus luteum could not very well go on without arousing 
much interest in regard to the physiologic function of the struc- 
ture. The men who upheld the connective-tissue origin held 
many curious ideas as to its function, all of which tended toward 
making its action more or less mechanical. Several thought the 
only function of the luteal structures was to prevent ovulation. 
Clarke thought its function was to preserve the ovarian 
circulation.  —, 
On the the other hand, those who accepted Sobotta’s con- 
clusions began looking for a much more important function for the 
corpus luteum. If the luteal cells were epithelial and each was so 
intimately in contact with the blood stream, and the whole organ 
had so much the appearance of a gland, why couldn’t it be a 
gland of internal secretion? Several histologists began studying 
the cells for evidences of a secretory product. Regaud and 
Policard in 1901 were the first to publish any results. They 
stained sections of ovaries of the dog, that had been fixed in 
acetic potassium bichromate, with a copper-hematoxylin method 
of Weigert. They described some black secretion droplets in 
