236 
Proceedings of the Royal Society of Edinburgh. [Sess. 
Author. 
Conditions of Organs. 
Remarks. 
Simpson, J. Y. 
Mentions dissection of two adult 
Simpson does not consider 
(1844). 
and one calf free-martin, all like 
Hunter’s cases. Quotes also a case 
the question of the female 
calves co-twin with males and 
of Allen Thomson’s, Simpson’s Obst. 
Mem., i. p. 823. 
fertile as being derived from 
separate zygotes. This mis- 
take was due to the still 
current error of holding that 
sex is not determined, as it 
really is, on fertilisation, but 
by subsequent changes in the 
zygote. 
In Todd’s Cyclopaedia , he quotes a 
A free-martin is derived 
I 
free-martin where he found testicles, i 
along with its potent twin 
from one zygote. 
I have now to explain how the free-martin arises ; and in considering 
this, the cardinal fact must be kept in mind that the potent and sterile 
twins arise from one zygote, not from two, and that the genitals of each 
have to be provided from a single zygote, which normally might give rise 
to one perfect male. Simpson’s mistake in his paper was his not recognising 
that a male and female twin, perfect in development, arise from separate 
zygotes. 
I must now consider — 
(1) The General Anatomy of the Genital Tract in the Female Calf. 
(2) The Action of Mendelism in producing the Free-Martin condition. 
(3) Consideration of the View that the Free-Martin is a transverse 
Hermaphrodite. 
(4) Summary and Literature. 
(1) The General Anatomy of the Genital Tract in the Female Calf. 
This consists of ovaries, Fallopian tubes, cornua, vagina (Mullerian and 
arinogenital sinus), urethral opening, lateral folds of skin comparable with 
the human labia majora and minora, and of the glans phalli. The vagina 
is urinogenital sinus in its lower half and Mullerian in its upper. The 
urinogenital sinus portion is the lower end of the anterior division of the 
pars penultima of the primitive gut or entodermal cloaca of other in- 
vestigators. The lower half of the effective vagina is thus urinogenital 
sinus, and this must be carefully noted. Developmentally, the sexual glands 
and urogenital tracts in boves arise as in allied mammals, i.e. we have 
Wolffian bodies, etc., and on these the ovaries or testes develop; sub- 
sequent changes in the Wolffian bodies and ducts give us in the female 
