376 FRANK R. LILLIE 



as diagnostic of sex, and the case was interpreted as simple male 

 transverse hermaphroditism . 



D. Berry Hart ('10) also interprets the free-martin as a male, 

 basing: his interpretation on a comparison of the anatomical de- 

 scriptions of thirty cases given in the literature, and on an origi- 

 nal histological examination of the gonads of John Hunter's 

 specimens which hacf been in alcohol for one hundred and forty 

 years. 



The special fact that emerges is that all the sexual glands are testes 

 in Hunter's cases, that adjacent structures are epididymis, and that 

 in none of the sexual glands are ova present. The characteristic tes- 

 ticular tissue is in the form of tubuli semeniferi, and in only one are 

 spermatozoa present. It seems to me, therefore, fully established that 

 the free-martin, when the co-twin is a potent male, is a sterile male, and 

 not a sterile female, i.e., they are identical male twins except in their 

 genital tract and secondary sexual characters. 



It ^vill be observed that Hart accepts the conditions of the 

 internal organs, and more especially of the gonad, as decisive 

 criteria of sex. This raises a point that we shall discuss later on. 

 Continuing, Hart then proposes a ' Mendelian' theory as follows : 

 He distinguishes potent and non-potent elements in the genital 

 tracts of both sexes, the latter being the undeveloped rudiments 

 of the opposite sex; in the tmnning process of a male zygote he 

 supposes we may either get identical male twins, or ''the potent 

 and non-potent complex of the genital organs may be divided so 

 that the potent part goes to the potent bull calf, the non-potent 

 to the free-martin." More specifically, "A free-martin with a 

 potent bull twin is the result of a division of a male zygote, so 

 that the somatic determinants are unequally divided, the po- 

 tent going to one twin, the potent bull, the non-potent genital 

 determinants to the free-martin." He supposes the potent organs 

 to be dominant in the Mendehan sense, the non-potent recessive. 



The entire argument is based on the unsupported assumption, 

 which it is quite possible to decide definitely by the facts, that the 

 free-martin is co-zygotic with its male mate. I shall show imme- 

 diately that this is not the case; so that it is hardly necessary to 

 point out that if the gonad of the free-martin is a testis, as Hart 



