194 DR. F. WOOD-JONES ON THE 
of March these two perforations coalesce and the vagina is then 
open for penetration in the usual way. I have not found any 
internal hymen whatever.” 
Such a statement may be considered as a summing up of our 
knowledge of a process which one would suppose would arrest the 
attention of any anatomist, a process by which an animal evolves 
in its post-natal stages an entirely new orifice for the genital 
system, and changes an apparently male arrangement of external 
genitalia into one that is obviously female. 
This brief history of the subject, incomplete in its details as it 
very possibly is, seems to me to be highly instructive, if only 
for the light it throws upon the relation of what we are apt to 
despise as mere nature lore to the more rigid demands of accurate 
anatomical knowledge. 
It is now more than twenty years ago that a mole-catcher told 
me that all first-season moles were alike as to their external 
genital organs, and that only in their breeding year could they be 
distinguished as males and females. I do not imagine that the 
knowledge originated with this man, but would be inclined to 
regard him as merely a link in a very long chain of folk whose 
knowledge was certainly not gained from books, but was culled 
from real observation and backed by the weight of tradition. It 
was easy to regard a mole-catcher’s statements as mere super- 
stitions until the work of Professor J. P. Hill (5) on Perameles, 
and some study of the developing vagina in the human embryo, 
compelled a belief in the enormous plasticity and adaptability of 
the female genital tract, and lent colour to the suggestion 
that a vagina could be produced de novo in post-natal life. It 
was only then that preliminary investigations showed that the 
superstitions regarding this transformation of the mole were well 
founded; and a search of the literature revealed the work of 
Geoffroy and Adams. 
B. Embryonic Stages of Hxternal Genitalia. 
I shall begin my account of the development and transforma- 
tions of the genitalia of the Mole by a brief description of the 
formation of the external genitalia in the embryo. I have been 
fortunate in the examination of a very large series of embryos of 
all ages, and for the bulk of this material I am indebted to 
Mr. R. H. Burne, of the Royal College of Surgeons, who has 
placed at my disposal a large number of fcetal families collected 
with the greatest care, and in a perfect state of preservation. 
Other embryos I have collected for myself, or have received 
from time to time from friends, and the entire series has per- 
mitted the examination of the external genitalia in all phases of 
embryonic development. 
I have been very careful in following, and attempting to 
interpret, these stages correctly, and the reason for this especial 
caution demands explanation. Hitherto my actual first-hand 
