RESULTS OF CASTRATION 



37 



pointed out, this is probably due to the fact that the various 

 authors have not always taken into consideration the differ- 

 ences between the races and the variation present among 

 normal birds of the same race. It is also very probable 

 that in the older experiments the sexual glands were not 

 always removed completely. In recent years Pezard (1911, 



VF 



comb 



sex 

 inst. 



months 



3 + 56789 10 11 12 1 23 



5 6 7 8 9 10 11 12 



Fig. 25. — Growth of comb and spurs in the normal and in the castrated cock. No 

 difference in body growth expressed in increase of 3 of the body 

 weight P. The gro-wi:h of the comb in the normal cock does not accord 

 with the body growth, but it does so in the capon. No influence of 

 castration on the growth of spurs. Crow and sexual instincts absent in 

 the capon. — From Pezard (changed). 



1918) and Goodale (1913, 1916) have recorded successful ex- 

 periments in which cocks were completely castrated. The 

 interest of those who made the experiments on birds was 

 directed especially to the external sexual characters. 



Pezard castrated cocks at the age of three months, when the 

 external sexual characters, the comb, wattle and barbies, spurs 

 and male plumage are not fully developed (Leghorn and 



