THE BARE NECKS 



Some three years ago we purchased of a neighbor wlio liad l)rought back witli him from the 

 Barbadoes two cocks and three hens characterized by the aljsence of feathers from the neck as 

 far as from the ears down to the clavicle. In most of the hens there was a paired bunch of feathers 

 on the ventral side of the neck; but one was practically free from feathers in that region and 

 this condition has reappeared in her oflfspring. These birds are very sparsely feathered under the 

 wings and over the sternum also. 



The thing that interested me most was the hereditary behavior of this condition. Mated to 

 each other these birds gave a few full-feathered chicks, l)ul about three-fourths of all were bare- 

 necked. Mated to ordinary fowl, about half of the offspring had naked necks — there was very 

 little indication of imperfection of dominance. It appears, consecjuently, that the naked neck 

 is a typical dominant and in accordance with current interpretations, one may say that there is 

 a factor in the " Bare Necks" which interferes with the development of the neck feathers. 



Some years ago I pointed out that the condition of clean shank is dominant over that of 

 feathered shank in poultry. In the light of the later result one may generalize and infer that the 

 typical (primitive?) condition of the fowl is this, that every skin plate l)ears a feather; and that if 

 any portion of the skin is without feathers, it is due to a specific inhibitor to the development of 

 the feather germ in that region. C)f these inhibitors there are jjrobably a number; there are at 

 least one for the shanks and one for the neck and i)ossil)ly an adilitional one for the ventral patch 

 of the neck. So far as we have gone it seems probal)le that the inhil)itor is of the nature of an 

 anti-enzyme which interferes in a given area with the development of those enzymes that induce 

 the formation oi the feather. (Fig. 19.) 



Carnegie Institution of Washington, ^- ^- I^AVENPORT. 



Statif^n for Experimental Evolution, 

 374 Cold Spring Harlior, Long Island, N. Y. 



