CASTRATION IN RELATION TO THE SECONDARY 

 SEXUAL CHARACTERS OF BROWN 

 LEGHORNS 1 



H. D. GOODALE 

 Station for Experimental Evolution 



Introduction. — It lias often been observed, in many 

 sexually dimorphic species of birds, that a female occa- 

 sionally occurs which exhibits many of the characters of 

 her mate. Frequently associated with this condition are 

 alterations, more or less pathological, in the ovary. It 

 has been said also that the male sometimes, and in par- 

 ticular the unsexed male of the domestic fowl, presents 

 characters resembling those of the female. However, it 

 has been pointed out that the supposed resemblance to the 

 female can also be interpreted as due to the failure of 

 the development of the normal adult male characters. 

 In other words, these modified males may be referred to 

 either a juvenile or to a female condition. 



These considerations led, then, to the following ques- 

 tions. Will removal of the ovary from the young female 

 fowl cause her to assume the characters of the male? 

 Will removal of the testes from the young male cause him 

 to assume any female characters or will it cause him to 

 retain his own juvenile characters or will it be without 

 effect? For answers the Brown Leghorns seemed to 

 furnish particularly favorable material, because: first, 

 the adult plumage, which is strongly sexually dimorphic, 

 is practically identical with that of the Jungle fowl; 

 second, the comb of the female, while proportionally 

 smaller than that of the male, is larger than that of the 

 male of many other varieties ; third, there are at least 



'This paper with some changes was read before the American Society 

 of Naturalists at Princeton, N. J., December 28, 1911. Since then the 

 experimental results have been fully verified. Male characters have devel- 

 oped on 25 females, following ovariotomy. A complete account of the 

 newer experiments will be published later. 



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