36 GONADECTOMY IN RELATION TO THE SECONDARY 



effects of this variation might be largely or completely lost and the 

 character returned to the normal condition for the species. The 

 feathers of the cross-bred female, while variable, are not pencUed as 

 a rule, but are splashed in various ways (plate vx, to). In the pure- 

 bred stock, then, the constitution of the bird seems to be less variable, 

 and even after the removal of the ovary tends strongly to continue its 

 development in the same course that it had with the ovaries present. 

 In other words, the constitution of the pure-bred female has been 

 modified by selection in a given direction, so that it is in a measure 

 independent of the internal secretion produced by the ovary. In the 

 cross-bred, on the other hand, this modification has been lost for the 

 most part and the female characters are dependent on the secretion of 

 the ovary. Whether or not the explanation has any real basis in fact, 

 it is evident that ovariotomy by itself is not always sufficient to trans- 

 form a female into the rephca of a male. 



EFFECTS OF GONADECTOMY ON PARTICULAR PARTS OF THE BODY. 



EFFECT ON PLUMAGE. 



Of the various parts of the body affected by gonadectomy the most 

 striking changes perhaps occur in the plumage of the female. The 

 plumage of the male is altered comparatively little; some feathers 

 grow somewhat longer, but otherwise they are the same as in the un- 

 altered male. In contrast the plumage changes in the female after 

 ovariotomy are extensive, both in respect to shape, size, color, and 

 color pattern. Short feathers become long; straight feathers curved; 

 feathers with broad rounded ends become narrow and pointed. A 

 portion of the barbs become converted into bristles. The color changes 

 are so numerous that only a few of them need be noted. Salmon 

 feathers become black; stippled brown feathers become golden with a 

 black central stripe, or black and brown penciled become gray and black 

 vermiculated. 



It is noteworthy that of all these changes none occurs in pairs, 

 being promiscuous ; this indicates that only two possibilities are avail- 

 able and that the action of the ovarian hormone determines which of 

 the two possibilities develops. 



EFFECT ON HEAD FURNISHINGS. 



The Brown Leghorns offer especially good opportunities for deter- 

 mining the status of the capon's comb. It has been beUeved that his 

 comb is that of the hen, and this is cited as an instance of the assump- 

 tion of female characters by the castrated male. It requires only a 

 cursory familiarity with the different races of fowl to observe that the 

 size of the comb is an extremely variable character, although within 

 certain rather large limits it is constant for each race. Thus, in certain 



