284 FOWLS. Chat. YIL 



related to some external character which man values, it has 

 been, unintentionally on his part, acted on by selection, and 

 has become more or less fixed. We see this in the wonderful 

 protuberance of the skull, which supports the crest of feathers 

 in Polish fowls, and which by correlation has affected other 

 parts of the skull. We see the same result in the two pro- 

 tuberances which support the horns in the horned fowl, and 

 in the flattened shape of the front of the skull in Hamburgh s 

 consequent on their flattened and broad "rose-combs." We 

 know not in the least whether additional ribs, or the changed 

 outline of the occipital foramen, or the changed form of the 

 scapula, or of the extremity of the furculum, are in any way 

 correlated with other structures, or have arisen from the 

 changed conditions and habits of life to which our fowls have 

 been subjected ; but there is no reason to doubt that these 

 various modifications in the skeleton could be rendered, either 

 by direct selection, or by the selection of correlated structures, 

 as constant and as characteristic of each breed, as are the size 

 and shape of the body, the colour of the plumage, and the 

 form of the comb. 



Effects of the Disuse of Parts. 



Judging from the habits of our European gallinaceous birds, 

 Gallus bankiva in its native haunts would use its legs and wings 

 more than do our domestic fowls, which rarely fly except to their 

 roosts. The Silk and the Frizzled fowls, from having imperfect 

 wing- feathers, cannot fly at all ; and there is reason to believe that 

 both these breeds are ancient, so that their progenitors during 

 many generations cannot have flown. The Cochins, also, from their 

 short wings and heavy bodies, can hardly fly up to a low perch. 

 Therefore in these breeds, especially in the two first, a considerable 

 diminution in the wing-bones might have been expected, but this is 

 not the case. In every specimen, after disarticulating and cleaning 

 the bones, I carefully compared the relative length of the two main 

 bones of the wing to each other, and of the two main bones of the 

 leg to each other, with those of 67. banJciva ; and it was surprising 

 to see (except in the case of the tarsi) how exactly the same relative 

 length had been retained. This fact is curious, from showing how 

 truly the proportions of an organ may be inherited, although not 

 fully exercised during many generations. I then compared in 

 several breeds the length of the femur and tibia with the humerus 

 and ulna, and likewise these same bones with those of 67. bankiva ; 

 the result was that the wing-bones in all the breeds (except the 



