^4 u. n. GOOD A L?:. 



plumage except for a few feathers of head, throat and breast. 

 No. 19 with one testis and this injured assumed the summer 

 phimaRe in 1909. He did not long survive the second operation. 



Evidently the presence of the active (?) testis is necessary 

 for the male to assume the summer plumage. The presence of 

 the ligatured testis of No. i indicates that ligaturing is as effective 

 as removal. I do not know the present condition of the testis 

 of this male. There was no assumption of female characters 

 by any of these males. 



Females: No. 4 and No. 24 were the only females that lived 

 more than a few days after the operation. October 20, 1909, 



Fig. 9. Female 4, castrated. 



they showed no marked modifications, though a small sample of 

 No. 24's breast feathers, saved at that time, are now found to 

 be quite like those of the male in summer plumage. Those of 

 No. 4 were of the usual female type. Through the winter and 

 spring, these two, with several other females were confined in a 

 rather dark pen. During this time, only cursory observations 

 were made, for it was believed that the experiments had failed. 

 July 4, 1910, this flock, for the first time in several months, was 



