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1909-10.] Reproductive Organs in the Free-Martin. 
The free-martin is a sterile twin, usually co-twin with a potent bull.*' It 
has, in this case, the lower part of its genital tract to the naked eye like 
that of a cow, the upper part defective, and is usually considered as a cow 
sterile from incomplete development of its upper vaginal and uterine 
tract. 
John Hunter described three specimens : — 
(1) Mr Arbuthnot’s Free-Martin (op. cit., p. 52). — This animal was 
seven years old ; went with the cows and bull ; never showed any desire 
for either. The external parts were rather smaller than in the cow ; the 
vagina was contracted above the urethral opening, becoming continuous 
with a small canal ; uterus with two horns, two ovaria, and two testicles : 
vasa deferentia to the testicles ; the left one did not come near the testicle, 
the right one only came near to it hut did not terminate in the epididymis. 
They were both pervious, and opened into the vagina near the urethra. 
Yesiculae seminales were present, smaller than in the bull ; “ the ducts 
opened along with the vasa deferentia.” “ This was more deserving of the 
name hermaphrodite than the following, for it had the mixture of all the 
parts, although all were imperfect.” 
(2) Mr Wright's Free-Martin, fig. 1 , five years old (op. cit., p. 53). 
— This animal was more like the ox or spayed heifer than the bull or 
cow. The vagina had a blind end near the urethral orifice ; a two-horned 
uterus ; testicles, and not ovaria ; this based on their size nearly equal 
those of a bull. Vesiculse seminales opening into vagina, but nothing like 
vasa deferentia ; a clitoris was present. “ This animal cannot be said to 
have been a mixture of all the parts of both sexes.” 
(3) Mr Well's Free-Martin (op. cit., p. 54). — Three to four years when 
killed, more like a heifer ; no desire for male. Beginning of vagina as in 
cow, but obliterated beyond the urethra, although a solid part was 
continued. Two horns and two ovaria ; vas deferens in interrupted 
portions. Between vagina and bladder the vesiculae seminales, and 
between them the termination of the vasa deferentia. “ This could not 
be called an exact mixture of all the parts of both sexes, for here was no 
appearance of testicles (op. cit., p. 54). He thus considered Arbuthnot’s 
case to have testes and ovaries ; Well’s case to have ovaries, and Wright’s 
case testes. 
Sir J ames Simpson, in the paper already quoted on “ The Alleged 
Infecundity of Females born co-twin with Males,” states as his conclusions 
that the human female co-twin with a male is as likely to be fertile and 
have as many children as the normal woman not a twin (op. cit., p. 835). 
* The reason for this limitation will be seen afterwards. 
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