Chap. XIV.] VARIABILITY. 125 



ers on the head of the male become hackle-shapied, evi- 

 dently 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 top-knot of the male, 

 is often correlated with that of the hackles on the neck 

 and loins, as may be seen by comparing these feathers in 

 the Golden and Silver-spangled Polish, the Iloudans, and 

 Creve-coeur breeds. In some natural species we may ob- 

 serve exactly the same correlation in the colors of these 

 same feathers, as in the males of the splendid Golden and 

 Amherst pheasants. 



The structure of each individual feather generally 

 causes any change in its coloring to be symmetrical ; we 

 see this in the various laced, spangled, and pencilled breeds 

 of the fowl ; and on the principle of correlation the feathers 

 over the whole body are often modified in the same man- 

 ner. We are thus enabled without much trouble to rear 

 breeds with their plumage marked and colored almost as 

 symmetrically as in natural species. In laced and spangled 

 fowls the colored margins of the feathers are abruptly de- 

 fined ; but in a mongrel raised by me from a black Spanish 

 cock glossed with green and a white game hen, all the 

 feathers were greenish-black, excepting toward their ex- 

 tremities, which were yellowish- white ; but between the 

 white extremities and the black bases, there was on each 

 feather a symmetrical, curved zone of dark-brown. In 

 some instances the shaft of the feather determines the dis- 

 tribution of the tints ; thus with the body-feathers of a 

 mongrel from the same black Spanish cock and a silver- 

 spangled Polish hen, the shaft, together with a narrow 

 space on each side, was greenish-black, and this was sur- 

 rounded by a regular zone of dark-brown, edged with 

 brownish-white. In these cases we see feathers becoming 

 symmetrically shaded, like those which give so much ele- 

 gance to tlie plumage of many natural species. I have 



