Abstract We know little or nothing of the origin of those characteristics which distinguish one breed from another. Many of our more recently established breeds are merely recombinations of characteristics of earlier known breeds. Our knowlelge of the ancestry of the domestic breeds is much too questionable to throw any light upon the origin of these characteristics. INDEPENDENCE OF CHARACTERS A breed in poultry is a group of birds which possesses and breeds relatively true for certain characteristics. The fact that practically all representatives of a breed come true for the breed characteristics demonstrates that these characters are heritable and the genetic factors responsible for these characters are known as determiners. Whether the same determiners are responsible for similar characteristics in different breeds has not in most cases been determined but, in some instances, at least, we know that this is not the case. From the manner of their inheritance it . . .