388 INTERNAL SECRETIONS 



given to this assumption by the fact demonstrated by Chapin 

 (1917) that in freemartins all transitory stages between an 

 ovarian rudiment and a testicle may be found. Lately Wi liter 

 (1921), also working in Lillie's laboratory, after making a very 

 extensive investigation on the gonad of the freemartin, came 

 to the conclusion that "an indifferent gonad with a primary 

 female determination is changed in the male direction." Even 

 in the cases of Magnusson formations similar to primordial 

 follicles were present in the gonad. As already pointed out, 

 the gonads of the abnormal goat, as observed by Keller, 

 resembled ovaries in many respects. Finally, Minoura (1921) 

 has shown experimentally that a testicular or ovarian graft 

 is capable of modifying the heterosexual gonad of the embryo 

 of the fowl in either the male or female direction. 



The only fact which at first thought does not seem to con- 

 form with the assumption that the freemartin is a female 

 modified by male hormones is that, according to Keller, the 

 mammary gland is more developed than in a normal male. 

 But it must be mentioned that a high development of the 

 mammary gland is often observed also in new-bom male 

 children. 



The question arises why a masculinization of the female 

 foetus takes place, and not a feminization of the male. Lillie 

 first considered the possibility of there being some kind of 

 a natural dominance of the male sexual hormones over the 

 female ones. This is not verv^ probable, since no such domin- 

 ance w^as present, either in the experiments of Steinach, Sand, 

 and Lipschiitz and his co-workers with experimental hermaphro- 

 ditism, or in those of Minoura; it may, indeed, be that during 

 the embryonic development the power of resistance of the 

 ovary to the male sexual hormones (and vice versa) is different 

 from that during extrauterine life. Pezard (1918, p. 156) 

 thinks that there is possibly a neutraHzation of the female 

 foetus through the atrophy of the ovary under the influence 

 of the male sexual hormones, which after this exhibit their 

 mascuUnizing influence on the soma. But the most probable 

 explanation seems to me that the male sexual honiiones, as 

 was suggested by Lillie, begin their action sooner than the 

 female ones; according to Van Beek (1921), the female gonad 

 becomes differentiated in cattle when the foetus is about 21 mm. 

 long, whereas the male gonad becomes differentiated in the 



