SEX SPECIFIC ACTION OF HORMONES 307 



other after heterosexual implantation. These objections will 

 be dealt with in Chapter XI. 



2. Experiments on Fowls. 



Castration of the fowl leads to the conclusion that there is 

 an asexual or a neutral form common to both sexes, which 

 is transformed by the action of the hormones of the ovary, 

 or of the testicle into the female or the male type. We learned 

 from the experiments that the plumage and the spurs are 

 hardly influenced by the hormones of the testicle, whereas 

 they are much changed by the hormones of the ovary. This 

 conclusion has been confirmed as a result of numerous ex- 

 periments by Goodale, performed on the cock and the drake. 

 Similar experiments have been performed by Pezard and 

 Zawadowsky. 



Goodale (19 14, 19 16) castrated a Brown Leghorn cockerel 

 twenty-four days old and engrafted into this bird the ovaries 

 from two pullets of the same strain; the ovaries were cut in 

 several pieces and dropped into the abdominal cavity without 

 any attempt to suture the pieces in position. The immature 

 plumage of the male Brown Leghorn resembles that of the 

 female; later on the characteristic male plumage appears. 

 We saw in Chapter II. that this is true also for the ordinary 

 "castrate," which acquires the brilliant male plumage. On the 

 contrary, a castrated cockerel with an ovarian graft had the 

 plumage of a hen (Fig. 122). "The bird was shown to several 

 experienced poultrymen without knowledge of the history of 

 the case, and they all pronounced it a female." The spurs, 

 which remain unchanged in the capon, were in Goodale's 

 operated cockerel undeveloped for a long time. There was no 

 doubt that a feminization of the castrated cockerel had taken 

 place under the influence of the ovarian graft. During the next 

 spring some changes took place, showing that the influence of 

 the ovarian graft was an incomplete one, or else that this 

 influence began to decline ; there was possibly also an effect due 

 to small regenerating pieces of testicle. The comb and wattles 

 began to grow and became very red. The bird was observed to 

 crow and to tread the hens. The spurs attained a length of one 

 inch. The weight approached that of a hen. The plumage 

 remained a female one; there were, however, some deviations 

 from the normal female plumage, but "no trace of any of the 



