FURTHER DEVELOPMENTS IN OVARIOTOMIZED FOWL. 2Q3 



Among ducks it has been noted that a similar change in plum- 

 age is associated with the testes in the male, although the organs 

 described have not been found in several castrated female ducks 

 which have been examined. The ovariotomized duck may or may 

 not undergo a change in plumage, corresponding to that of the 

 male. Those that undergo such a change have returned in due 

 course of time to the breeding plumage. Thus their temporary 

 plumage is like that of the summer plumage of the male. 



The change of plumage in the ovariotomized fowl may be due 

 to the release of a mechanism for changing the plumage but 

 which has been hidden or rendered latent in some way during 

 the phylogeny of the race or as a result of domestication. In 

 this connection it may be noted that laying hens give evidence 

 of a summer moult. This moult is rarely complete and is 

 evidenced usually by the shedding of a comparatively small num- 

 ber of feathers. 



