38 INTERNAL SECRETIONS 



Orpington). Pezard showed that the comb grows after pre- 

 puberal castration, but that the curve of growth is very 

 different from that of the normal animal. He compared the 

 curve of comb-length at different ages with the curve of the 

 cubic root of the body weight, so as to have a linear measure 

 for comparison, and stated that these two curves are different. 

 On the contrary, the growth of the comb of the castrated 

 animal accords with that of the body as a whole {Fig. 25). 

 This being so, the relation of the length of the comb / to the cubic 



/ 

 root of the body weight P, or -3-7: will remain unchanged 



^ P 

 during the whole development in the "castrate," whereas in 

 the normal animal it wall increase very markedly. The 



Fig. 26. — Comb of normal and castrated animaJs in 

 Brown Leghorn, a = adult cock; b and c = adult 

 hens; d = adult capon. — From Goodale. 



characteristic divergence begins at the time when the sexual 

 differentiation in the normal bird commences. This apphes 

 also to wattles and barbies. Comb, w^attles and barbies are not 

 only smaller in the capon, but also bloodless and thin. Very 

 detailed observations on the head apparel of the castrated 

 cock were made by Goodale, especially on Brown Leghorns 

 castrated at an age of about three or four weeks. Goodale 

 also found that the comb increases in length in the same pro- 

 portion as the head as a whole ; he points out that the growing 

 comb of the capon is not feminine but infantile, and does 

 not attain the measurements of the comb of the female of this 

 race (Fig. 26). However, by comparing the comb of a Brown 

 Leghorn capon with that of a Plymouth Rock female, which 



