THE DEVELOPMENT OF THE CORPUS LUTEUM. 191 
stated to be not entirely exhausted by the ingrowth, some 
part remaining to form a layer within the outer theca, after 
the full formation of the corpus luteum. 
Kreis’s observations on the young human corpus luteum 
likewise support the hypothesis put forward by Bischof. 
Belloy, who investigated the formation of the corpus luteum 
in the rat and guinea-pig, while regarding the lutein cells as 
being derived from the follicular epithelium, describes an 
active proliferation of these cells soon after the follicle’s 
rupture. No figures are given by Belloy, and it seems 
possible that he has confused the ingrowing cells of con- 
nective tissue from the theca interna with the membrana 
granulosa cells. Bouin, who also investigated the corpus 
Inteum of the rat and guinea-pig, reached conclusions similar 
to those of Belloy. 
Heape, without entering into a discussion on the origin of 
the lutein cells, lays some stress on the absence of division 
among these cells in the ovaries of certain monkeys, pointing 
out that the enlargement is the result of a simple hyper- 
trophy. 
Rabl, writing especially on the human corpus luteum, con- 
cludes that the Intein cells have a double origin, arising both 
from the membrana granulosa and from the theca interna. 
A number of investigators, on the other hand, since the 
publication of Sobotta’s work, have adopted the theory 
originally put forward by von Baer, that the lutein cells arise 
from the connective-tissue wall, the follicular epithelium 
being either completely discharged along with the ovum and 
the greater part of the liquor folliculi, or else being partially 
discharged and partially degenerating in situ. Among those 
holding this view are His, Kolliker, and Paladino, who have 
lately reiterated their former opinions. 
Von Baer’s theory has also received considerable support 
in recent years from Nagel, who has described the corpus 
luteum in the human subject as an entirely connective-tissue 
structure. In this he has been followed by Clark, who worked 
on the formation of the corpus luteum in the sow and in the 
