Castration in a Hen-Feathered Cockerel. 31 

 19 (1083) 



Demonstration of the appearance after castration of cock-feather- 

 ing in a hen-feathered cockerel. 



By T. H. Morgan. 



[From the Department of Zoology of Columbia University.} 



In the Seabright race of fowls the male is hen-feathered, i. e., 

 the feathers on the back of the neck (the hackles) and those on 

 the posterior portion of the back (the saddle) are short and less 

 elongated, like those of the female. When the Seabright male or 

 female is crossed to fowls of another race in which the male has 

 the characteristic male-feathering, the Fi males are hen-feathered, 

 or at least the dominance of hen-feathering is more or less complete. 

 In the second generation there are three hen-feathered to one 

 cock-feathered male. 



It has been shown by Goodale that removal of the ovary of 

 the hen or of the duck leads to the development of the male- 

 feathering. I tried to discover whether the removal of the testes 

 in the hen-feathered males would cause them .to develop the 

 hackles and saddle feathers of ordinary cocks. My first operations 

 were unsuccessful, owing to failure to completely remove the testis. 

 This autumn Dr. H. D. Goodale performed the operation for me 

 on F 2 hen-feathered birds that I had reared. At the time of 

 operation some of the saddle feathers were removed. The new 

 feathers that appeared were like those on the ordinary cock bird ; 

 not only did they have the characteristic shape but were bright 

 red also. The result leads to the apparently paradoxical conclu- 

 sion that the removal of the testes of the hen-feathered cock 

 caused him to develop certain characteristic feathers peculiar to 

 the ordinary male. 



The most probable interpretation of the effects of removal of 

 the ovary of the hen (an operation that leads her to develop the 

 male plumage) is that the ovary secretes some substance that 

 holds in check the development of the male plumage. Likewise 

 in the hen-feathered male it would seem probable that the testis 

 produces some substance that inhibits the development of the 

 complete male plumage. Possibly this substance is the same as 



