286 INTERNAL SECRETIONS 



easily distinguished from that of an ordinary "castrate." 

 But there is a striking difference between a castrated male 

 injected with ovary and one injected with testicle, as shown 

 particularly by histological examination. The epidermis is not 

 so thick, the epithelial tuberosities are much smaller in 

 numbers and the surface of the pad remains generally smooth. 

 As to the behaviour of the epidermis, the castrated male 

 injected with ovary is somewhat intermediate between an 

 ordinary "castrate" and a "castrate" injected with testicle. 

 The influence of the ovary was particularly evident upon the 

 glands ; their number was considerably enlarged in comparison 

 with that found in the "castrate." 



We see that the oestral changes of the pad can be effected by 

 the testicle and by the ovary alike, although the action of the 

 ovary is less pronounced than that of the testicle. The 

 experiment on frogs cannot, indeed, be considered as a proof of 

 a sex specific endocrine action of the sexual glands in am- 

 phibians, though, on the other hand, they cannot be used as a 

 proof against such an assumption. Meisenheimer has drawn 

 from these experiments the general conclusion that the sexual 

 glands in mammals also do not act in a sex specific manner. 

 That this conclusion, however, is not justified follows from 

 what is said below. 



Heterosexual transplantation in tritons was attempted by 

 Herlitzka (1900, quoted from Kammerer, 1919); the grafts 

 underwent degeneration in the course of a few months. But 

 Bresca (1910) succeeded in transplanting the tissue of the yellow 

 dorsal line of a female Molge cristata on to the back of a male, 

 where normally at time of "heat " a comb develops. He stated 

 that the graft became transformed at the time of heat into a 

 typical indented male comb. This was due not to a regenera- 

 tion of the removed normal male comb, since such a one did not 

 develop in control animals from which the male comb was also 

 removed but on to which no female graft was placed. 



Harms (1921) made experiments on toads, dealing with 

 the question as to the sex specifity of the hormones. He 

 stated that in about 10 per cent, of the males examined 

 oocytes were present in the Bidder's organ. He removed the 

 testicles from these animals, and then kept them under obser- 

 vation for three years. He found that the Bidder's organ 

 showed an increased tendency to form ovarian tissue. Harms 



