306 INTERNAL SECRETIONS 



layer of cells being present. There was a wide separation of 

 the degenerated tubules by large threads of interstitial tissue, 

 consisting of well-stained cells of Leydig. As to the degree 

 of mascuhnization, the second animal showed a slightly less 

 pronounced transformation in regard to the psycho-sexual 

 behaviour and the external genital organs. Since the inter- 

 stitial cells were present in greater abundance, Moore concludes 

 that his observations do not support the theory of these 

 cells being the seat of the endocrine function of the testicle. 

 But as we have seen in Chapter IV., the reaction of the soma 

 to the male sexual hormones seems to be governed by other 

 quantitative laws than those postulated formerly ; and in view 

 of these considerations Moore's conclusions can hardly be 



accepted. 



* * * 



All the experiments recorded above, in which a gonad of one 

 sex was engrafted into the castrated organism of another sex, 

 leave no doubt, that in mammals one and the same organ or 

 tissue reacts in a different manner to the hormones of the gonad 

 according to the sex of the latter. This means that the sexual 

 hormones of the testicle act differently from those of the 

 ovary, or that the sexual hormones act in a sex specific 

 manner. 



The same conclusion can be also demonstrated by engrafting 

 the gonad of one sex into the uncastrated organism of the 

 other sex. We shall deal with this matter in Chapter IX. 



Experiments on castration have shown that after removal 

 of the sex gland the male and female organisms converge to 

 a type common to both sexes; the experiments recorded in 

 this chapter show that the "castrate," which approaches the 

 asexual or neutral type, becomes more or less transformed 

 somatically into the sex to which the engrafted gonad belongs. 

 All these experiments support the theory that there is in 

 mammals during embryonic development an asexual soma 

 identical for all individuals, and that this becomes trans- 

 formed into the male or female type after a differentiation of 

 the endocrine apparatus of the gonad has taken place, and after 

 the sexual hormones have begun their action of stimulating 

 or inhibiting the growth of the different tissues. 



Objections have been raised to this hypothesis on the ground 

 that there is never a complete reversal of one sex into the 



