oe) 
ALICE M. BORING AND RAYMOND PEARL 
IV. WOLFFIAN DUCTS IN NORMAL FEMALE BIRDS 
Before describing the internal structures of this series of ab- 
normal birds, it is necessary to mention certain points of normal 
bird anatomy which have been observed in this connection. 
Many of these points have already been described by Goodale. 
Our own observations are recorded here simply in corroboration 
of his, and because in certain particulars our evidence is more 
detailed. The normal reproductive system of a male bird com- 
prises two testes and two vasa deferentia. The normal repro- 
ductive system of a female bird includes a left ovary and a left 
oviduct. The right ovary and oviduct start to develop in the 
embryo, but stop before long so that they do not function in the 
adult. By the fifth or six day, according to Semon, the right 
ovary is already smaller than the left. The right oviduct forms 
as a right Mullerian duct, and usually degenerates along with 
the ovary. However, this duct may sometimes continue to 
grow and persist in the adult as a non-functioning oviduct. 
There are fairly frequent cases of this recorded among the 
autopsies of the birds of the Maine Experiment Station poultry 
plant. 
Every embryo female chick has besides its two gonads and two 
Mullerian ducts, two Wolffian ducts which have been supposed 
to degenerate in the female as the Mullerian ducts do in the 
male. The statement in Lillie’s ‘‘ Development of the Chick”’ 
reads as follows: ‘‘In embryos that become females, the gonad 
develops into an ovary, the Wolffian duct disappears or becomes 
rudimentary, the Mullerian duct develops into the oviduct on 
the left side and disappears on the right side.”’ 
In studying the anatomy of the hermaphrodite birds, the kind 
of ducts present was at first taken as an indication of sex—that 
is, the presence of vasa deferentia was regarded as a sign of male- 
ness, and the presence of an oviduct as the corresponding sign 
of femaleness. According to this criterion, all these birds were 
hermaphroditic as they had a left oviduct and two vasa. The 
vasa were small ducts which had to be searched for in the peri- 
toneum but sections showed them to be tubes lined with columnar 
