SEX STUDIES. XI 11 
out from the mesonephros into the germinal epithelium. The 
interstitial cells might be used as an index of sex, because of 
their consistent absence in Barred Plymouth Rock males over 
six months of age, if it were not for the fact that the gonads 
in some of these hermaphrodites seem to be cases of arrested 
development, and interstitial cells have been found in young 
just hatched males. The nests or groups of clear cells which 
normally fill up the discharged follicles and form the ‘corpus 
luteum’ are never found in the normal male. So their presence 
may be counted for femaleness. 
Many cases of hermaphrodite birds have been eased by 
various authors, with varying degrees of maleness and female- 
ness combined. More of them seem to be females which have 
developed some male characters than vice versa. Some of these 
abnormal combinations of external characters are associated 
with corresponding internal abnormalities and some are not. 
We shall discuss these cases after we have described the anatom- 
ical and histological conditions found in the hermaphrodites 
with which the present study is concerned. 
In the description of their anatomy and histology the birds 
will be taken up in the order stated above—that is, beginning 
at the more female end of the series. Three of the birds with 
normal external characters and abnormal behavior were killed 
and dissected. No. 1482 was an entirely normal female with 
ovary and oviduct on the left, and persistent Wolffian ducts. 
K134 and M408 were killed and dissected and portions of the 
ovary preserved and sectioned. Both of these also proved to 
be normal females in structure. The ovaries were large with 
many protruding oocytes of varying ages. The sections showed 
also many small oocytes embedded in the surface layer of the 
ovary. Both lutear cells and interstitial cells were present, in 
the same general arrangement and number as in the normal 
laying hen. It would seem then that the abnormal maleness of 
behavior in these three birds does not depend on any abnormal- 
ities of structure, there being no male organs present, or any 
male cells in the ovary, and there is present the full quota of 
female organs and cells. 
