SEXUAL CHARACTERS OF SOME DOMESTIC BIRDS. 37 



strains of Plymouth Rocks, the fully developed comb of the male is very 

 much smaller than that of the Brown Leghorns, though the latter are 

 only half the weight of the Plymouth Rocks. The female Minorca has 

 a larger comb than that of the Plymouth Rock male, but, of course, the 

 combs of the Minorca males are correspondingly larger. Moreover, in 

 most instances the comb of the male has a proportionally larger blade 

 than that of the female. A further difference is found in the texture of 

 the comb, that of the female being finer than that of the male. Finally, 

 in the female Leghorn and similar breeds the comb almost always lops 

 to one side. This secondary sexual character is not universal among 

 domestic fowl, but is most common in the Mediterranean races. Or- 

 dinarily, capons are derived from the low-combed races, a circumstance 

 which has made it difficult to say that the capon's comb is not feminine. 

 In the Leghorns, however, the capon's comb is practically undeveloped. 

 Therefore, the only possible conclusion is that the capon's comb and 

 wattles are infantile. They do not, of course, remain of the same size as 

 that of the chick at the time of the operation. The base of the comb 



Comparative size of the combs of Brown Leghorn fowls. 



a, an adult male. 6 and c, two adult females, d, an adult 

 capon. Drawing one-half natural size. 



increases in length with the increase in size of the skull. The height 

 of the comb also increases somewhat in absolute size, but not in pro- 

 portion to the comb length. The comb of the Leghorn capon, however, 

 is about the same size as that of some Plymouth Rock females. The 

 comparative sizes of the combs of the normal Brown Leghorn, male and 

 female, and of the capon are shown in the accompanying text-figure. 



In the castrated females, the comb has developed in varying degrees, 

 becoming very large and male-like in some, while hi others it has 

 remained comparatively small. As yet there is no clear evidence of 

 the causes of this difference. Certainly it is not connected with the 

 hypertrophy of the Wolffian body, for this has been found in every 

 individual. The birds with large combs, as a rule, have been younger 

 when castrated than those with small combs, but general conclusions 

 can not be drawn from the few instances available. 



