550 THE DESCENT OF MAN 



leaden-colored, fleshy crest or comb. The comb of many 

 gallinaceous birds is highly ornamental, and assumes vivid 

 colors during the act of courtship; but what are we to think 

 of the dull-colored comb of the condor, which does not ap- 

 pear to us in the least ornamental ? The same question may 

 be asked in regard to various other characters, such as the 

 knob on the base of the beak of the Chinese goose {^Anser 

 cygnoides), which is much larger in the male than in the 

 female. No certain answer can be given to these questions; 

 but we ought to be cautious in assuming that knobs and 

 various fleshy appendages cannot be attractive to the female, 

 when we remember that with savage races of man various 

 hideous deformities — deep scars on the face with the flesh 

 raised into protuberances, the septum of the nose pierced by 

 sticks or bones, holes in the ears and lips stretched widely 

 open — are all admired as ornamental. 



Whether or not unimportant differences between the 

 sexes, such as those just specified, have been preserved 

 through sexual selection, these differences, as well as all 

 others, must primarily depend on laws of variation. On 

 the principle of correlated development, the plumage often 

 varies on different parts of the body, or over the whole 

 body, in the same manner. We see this well illustrated in 

 certain breeds of the fowl. In all the breeds the feathers 

 on the neck and loins of the males are elongated, and are 

 called hackles; now when both sexes acquire a topknot, 

 which is a new character in the genus, the feathers on the 

 head of the male become hackle-shaped, evidently on 

 the principle of correlation; while those on the head of 

 the female are of the ordinary shape. The color also of the 

 hackles forming the topknot of the male is often correlated 

 with that of the hackles on the neck and loins, as may be 

 Been by comparing these feathers in the Golden ana Silver- 

 spangled Polish, the Houdans, and Cr&ve-coeur breeds. In 

 some natural species we may observe exactly the same cor- 

 relation in the colors of these same feathers, as in the males 

 of the splendid Gold and Amherst pheasants. 



