ON SOMATIC SEX-CHARACTERS 79 



castrated birds had recovered and were active. 

 Their combs had diminished in size and lost colour 

 considerably, that of the White Leghorn was scarcely 

 more than half as large as that of the control. Such 

 a rapid diminution can scarcely be due to absorption 

 of tissue, but shows that the size of the normal 

 cock's comb is largely due to distension with blood, 

 which ceases when the sexual organs are removed. 

 In the following January, the second cock, supposed 

 to be completely castrated, was seen to make a sexual 

 gesture like a cock, though not a complete action 

 like an entire animal: this showed that the sexual 

 instinct was not completely suppressed. In February 

 this same bird was seen to attempt to tread a hen, 

 while the white one, supposed to be less perfectly 

 emasculated, had never shown such male instinct. 



The White Leghorn cock was killed and dissected 

 on May 13, 1911, nine months after castration. I 

 found an oval body of dark, dull brown colour loose 

 among the intestines: this was evidently the left 

 testis which was separated from its natural attach- 

 ment and lost in the abdomen at the time of the 

 operation. I examined the natural sites of the 

 testes : on the right side there was a small testis of 

 considerable size, about half an inch in diameter. 

 When a portion of this was teased up and examined 

 under the microscope moving spermatozoa were 

 seen, but they were not in swarms as in a normal 

 testis, but scattered among numerous cells. On the 

 left side was a much smaller testis, in the tissue of 

 which I with difficulty detected a few slowly moving 

 spermatozoa. The vasa deferentia were seen as 

 white convoluted threads on the peritoneum, but 

 contained no spermatozoa. 



