THE STRUCTURE OF FREE-MARTIN GONADS 125 



3. The limit of the transformation in the male direction by hor- 

 monic action is represented by a testis which is morphologically 

 complete, but functionally inactive so far as the production 

 of germ cells is concerned. 



4. The exhibition of a graded series of transformations between 

 an ovary and a testis apparently corresponds to, 1) the varia- 

 bility in the time of the introduction of the male sex-hormones; 

 2) the potency of the hormones, or, 3) the duration of the hormonic 

 action. These are the primary and fundamental determining 

 factors. Other factors may be responsible for subsequent events 

 in the transformation, as, 1) absence of normal ovarian secre- 

 tions and, 2) secretions from the interstitial cells of the free-martin 

 gonad. 



5. The degree of transformation of the gonads is correlated 

 in a rough way with the degree of transformation of other genital 

 organs (vas deferens, seminal vesicles, uterus, and external 

 genitalia). These correlations are closer between the genital 

 organs of one side than between opposite sides. 



6. The hypertrophy of the interstitial cells does not accom- 

 pany degeneration of male germ cells, since the latter are absent 

 from free-martin gonads. The interstitial cells of the free-martin 

 gonad bear no relation to the sexual instincts, and little if any 

 relation to the secondary sexual characters. 



7. That the mammalian ovary possesses structures which 

 have their morphological equivalents in the testis is demonstrated 

 by the tranformation of an ovary into a testis in the free-martin. 



