BIRDS. 485 



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 top-knot of the male is often cor- 

 related 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 Houdans and Creve-co3ur 

 breeds. In some natural species we may observe exactly 

 the same correlation in the colors of these same feathers, 

 as in the males of the splendid gold 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 penciled breeds of the 

 fowl; and on the principle of correlation the feathers over 

 the whole body are often colored in the same manner. We 

 are thus enabled without much trouble to rear breeds with 

 their plumage marked almost as symmetrically as in natural 

 species. In laced and spangled fowls the colored margins 

 of the feathers are abruptly defined ; 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 extremities, 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 distribution 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 surrounded by a regular zone of dark-brown, edged 

 with brownish-white. In these cases we have feathers 

 symmetrically shaded, like those which give so much ele- 

 gance to the plumage of many natural species. I have 

 also noticed a variety of the common pigeon with the wing- 

 bars symmetrically zoned with three bright shades, instead 

 of being simply black on a slaty-blue ground, as in the 

 parent-species. 



In many groups of birds the plumage is differently col- 

 ored in the several species, yet certain spots, marks, or 

 stripes are retained by all. Analogous cases occur with the 

 breeds of the pigeon, which usually retain the two wing- 

 bars, though they may be colored red, yellow, white, black, 

 or blue, the rest of the plumage being of some wholly di 



