414 FRANK R. LILLIE 



apparent female vulva, within which appeared an imperforate 

 glans penis; the vulva was provided ventrally with a tuft of 

 hair as normally. The animal was slaughtered in 1835, and the 

 anatomy of the reproductive system studied. Numan's figure 

 is here reproduced (fig. 29). It mil be seen that the internal 

 anatomy is quite similar to my ease 44 (fig. 28), but the external 

 parts are also modified in this case to a very considerable extent 

 in the male direction. 



If this case is well authenticated, as it appears to be, we would 

 have to conclude, contrary to the evidence from my cases that 

 the external organs of reproduction of the female are also sus- 

 ceptible of modification in the male direction by the male hor- 

 mones; it may be that this occurs in cases of exceptionall}^ earlj^ 

 action of the male hormones. The embryological history of the 

 external male and female organs shows that the sexual type is 

 fixed very early. 



It is of course by no means certain that the extreme possible, 

 modification of the female reproductive system by male hormones 

 will be found in free-martins, indeed when we consider the various 

 exigencies of the admission of the male hormones to the female 

 circulation under the conditions of production of the free-martin, 

 it seems improbable that the optimum conditions for modification 

 of the female reproductive system are ever realized in such cases : 

 the onset of the action can not be much before morphological sex 

 differentiation has begun in any case, and its intensity must 

 certainly be of a low order quantitatively at first not only on 

 account of the minuteness of the first vascular inter-connections, 

 but also on account of the rudimentary character of the inter- 

 stitial gland of the testis at first, if we suppose that the effective 

 hormone is derived entirely from this source. Nevertheless 

 search should certainly be made for more pronounced cases of 

 transformation of the free-martin towards the male condition. 

 But it is obvious that definitely controlled experimental investi- 

 gation will be the only means of deciding where the real limit of 

 action lies, whether or not the complete transformation of a 

 female zygote of mammals into a male individual by hormone 

 action is possible. 



