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1909-10.] Reproductive Organs in the Free-Martin. 
a persistent Wolffian duct, the canal of Gartner, instead of its uppermost 
and lowest segments as in most mammals ; while the ducts of Muller give 
the vagina tubes and cornua. The urinogenital sinus, urethra, and bladder 
arising from the anterior coronal division of the pars penultima of the 
primitive gut make up the rest of the tract. The ova and spermatozoa 
arise by reduction from the primitive germ-cells, and these arise not from 
the germ epithelium but from the primitive germ-cell mass, itself a part of 
the unreduced zygote in its earliest stage. This view of the origin of the 
gametes may be termed the zygotic origin of the gametes, or Owen- 
Weismann law. 
In the normal female bovine tract we have not only the potent elements 
(ovary, cornua, and vagina), but also the epoophoron with more than the 
ductus epididymis, viz. the whole Wolffian duct. We have thus in the 
female the equivalents of the epididymis and vas deferens of the male. 
These are not functionally active, and histologically are degenerated, but 
are quite recognisable in the broad ligament. 
In the normal bovine male we have not only the potent male organs, 
but also the hydatid testis (Mullerian duct) and the prostatic utricle, the 
equivalent of the hymen usually, and a varying amount of degenerated 
female genital structures. 
These potent and non-potent elements of the developed tract mean causal 
unit-characters in the zygote, of unequal value, usually coupled in the 
human male and autonomous, Dominant and Recessive in their nature, and 
it is by their separation or segregation into the soma of the potent male 
and sterile male (free-martin) that we get the explanation of this anomaly. 
(2) The Action of Mendelism in producing the Free- Martin. 
When a male zygote twins we may get — 
(1) Identical male twins. 
(2) One perfect male aifd one sterile male, the free-martin. 
In (1) there is an equivalent division of genital and somatic determi- 
nants, and identical twins is the result. 
How do a perfect male and imperfect male arise 2 
In the free-martin (2) there are present, as Spiegelberg shows, urino- 
genital sinus, rudimentary vesiculse seminales, very rudimentary vagina 
and knob of uterus ; testes and Wolffian bodies, both imperfectly developed. 
Now, as already said, we have to account for the genital organs in the 
potent bull and free-martin from one zygote — a male zygote. Had this 
male zygote developed a single bull, it would have had potent male organs 
