310 INTERNAL SECRETIONS 



changed by the ovarian graft. Whereas the castrated drake 

 preserves the male voice, that of the feminized birds was not 

 a male one, but was something between the male and female 

 voice, or a sort of broken "quack." 



Feminization and masculinization experiments on the 

 fowl were performed about four or five years later by 

 Zawadowsky (1922, 1923). Abdominal implantation of ovary 

 into the castrated cock was successful in two cases out of six. 

 There was a complete feminization in regard to plumage, 

 shape of body, and voice ; the growth of the spurs was inhibited 

 to a certain degree; certain sexual instincts remained un- 

 changed. There were three successful mascuhnization experi- 

 ments. The engrafted testicles (subcutaneous transplanta- 

 tion) developed in one case so well as to increase in length 

 four to five times in a month and a half. Histologically the 

 graft represented a fully developed testicle with spermatozoa. 

 The comb began to grow as soon as ten days after the operation. 

 The general behaviour was that of a male. The mascuhnized 

 hen spreads out the tail and wings, and follows the hens with 

 rapidity and great persistence, offers them food with a truty 

 masculine gallantry, and crows with a clear, well developed 

 male voice. 



In view of these experiments the existence of a sex specific 

 endocrine action on the part of the ovary and of the testicle 

 in birds is beyond any doubt. The differences in details in 

 the various experiments are of small moment. We must bear 

 in mind that the result of each experiment may depend on 

 the time at which the heterosexual implantation is made, and 

 possibly also on the quantity of the hormone. We shall deal 

 with this question more fully in Chapter XL 



Very important experiments on the sex specific action of 

 the gonad in fowls have been performed by Minoura (1921) 

 in the laboratory of Lillie. Minoura engrafted testicles and 

 ovaries on the surface of the chorio-allantoic membrane of 

 hens' eggs cutting out a small piece of the shell and replacing 

 that piece and sealing it with paraihn after effecting the graft. 

 In a great many cases the graft "took" and became well 

 vascularized; there was a growth of the seminiferous tubules 

 or a development of the follicles consisting of oocytes sur- 

 rounded \>Y granulosa cells. The best results were obtained 

 when the graft was made in the second week of incubation. 



