192 FRANCIS H. A. MARSHALL. 
human female, and claimed that the result of his investigation 
had put the matter almost beyond question. Clark’s account 
has been confirmed by Doering, who also worked upon the 
sow’s corpus luteum. Others who have adopted the view 
that the lutein cells have a connective-tissue origin are 
Biihler, Wendeler, and Stéckel, who have examined and 
described developing human corpora lutea. 
None of these investigators, however, appear to have given 
an account of the growing corpus luteum in all stages of 
development, while in the case of several of the accounts, it is 
not clear that the structures described were not in reality 
atretic follicles, that is to say, follicles which had undergone 
degenerative changes without discharging their ova. On the 
other hand, the words used in a description by Clark point to 
the conclusion that this author was dealing with the degenerate 
epithelial cells of an atretic follicle. It seems not improbable 
that the young human “corpus luteum” which Doering 
describes was also an undischarged atretic follicle; while 
Kolliker’s opinion that the corpus luteum is a connective- 
tissue structure appears to be founded on the assumption 
that the changes undergone by discharged follicles and 
retrogressive undischarged or atretic follicles are identical in 
character. His, and also Biihler, with reference especially to 
Sobotta’s work on the mouse, have remarked that if can 
scarcely be an accidental circumstance that the accounts 
given of the development of the corpus luteum in the larger 
animals and in man are radically different from those described 
for the smaller species. That the discrepancy between the 
accounts of various investigators depends upon the size of 
the animals employed does not seem, on the face of it, a very 
probable suggestion. It is to be noted further that in the 
investigations of all these writers who have upheld the 
connective-tissue theory the ages of the developing corpora 
lutea were unknown, the material in no case being obtained 
by Sobotta’s method of killing the animals at definite intervals 
after coition. 
In 1901 the present writer published a preliminary account 
