288 INTERNAL SECRETIONS 



maturity by implanting into them ovaries instead of testicles. 

 But, if male and female sexual hormones differ from one 

 another, a successful implantation of an ovary into a young 

 castrated male should cause it to develop not into a mature 

 male, but into a mature female, and the converse result should 

 occur by implantation of a testicle into the body of a castrated 

 female. If the action of the sexual hormones is a sex specific 

 one, it ought to be possible to produce arbitrarily, to a certain 

 degree at any rate, the respective sexual characters by implant- 

 ing an ovary or a testicle into a castrated animal. Or, in other 

 words, it should be possible to "feminize" a castrated male by 

 an implantation of ovaries and to "masculinize" a castrated 

 female by an implantation of testicles. As we shall see, this 

 supposition proved correct. Steinach has demonstrated the 

 feminizing action of the ovary and the masculinizing action 

 of the testicle in rats and guinea pigs. All the investigators 

 who have repeated the experiments of Steinach have verified 

 liis results, including Brandes on the fallow-buck, Sand and 

 Moore on the rat and the guinea pig, Athias and Lipschiitz and 

 his co-workers on the guinea pig, Goodale on the cock and the 

 drake, and Pezard and Zawadowsky on the cock and the hen. 



I. Experiments on Mammals.^ 



( a) Feminization . 



Implantation of ovaries has been carried out by Steinach on 

 rats at the age of three or four weeks, and on guinea pigs at 

 the age of two or three weeks. In a series of experiments on 

 rats the ovaries were transplanted on to the peritoneal surface 

 of the abdominal wall; in another series of experiments on 

 rats and guinea pigs on to the external surface of the abdominal 

 wall. According to Steinach, the graft "takes" only if the 

 animal has been castrated beforehand. The graft was put on a 

 wounded place, produced by scraping the peritoneal covering 

 or the muscle. According to Steinach this method, involving 

 probably an hypersemia and a good vascularization for the 

 graft, is very satisfactory. In order to secure a better vasculari- 

 zation. Sand (1918 a) "punctured" the graft by piercing the 

 surface in many spots with the point of a very fine needle. 



' With the experiments on man we shall deal in Chapter IX. 



