BREEDING FOR COLOR AND PLUMAGE MARKINGS 261 
Double Matings.—Before discussing color variations in detail, 
it is necessary to understand what is meant by the term “ double 
mating.” Double matings are quite different from the reciprocal 
crosses described elsewhere. They have been developed largely 
through the sexual dimorphism which is so pronounced in most 
breeds of poultry, and especially through the desire of breeders to 
exaggerate this difference between the sexes. These are often 
designated as cockerel and pullet matings. 
Examples of such exaggerated differences are found between 
the hen and cock birds of Dark Brahmas. It is the desire to per- 
Fic. 132.—A difference in color pattern due to sex—an example of sexual dimorphism. 
fect the penciling of the hens, while in the males it is to group the 
colors in masses. In order that this difference may be highly 
developed, the practice is to make two matings, one for females 
and the other for males. To produce females the practice is to 
mate the best penciled hens with a cock bird which shows as 
much lacing as possible. To produce males the darkest hens are 
mated with cock birds which show as little lacing as possible. 
The sexual difference may be noted in Barred Plymouth Rocks, 
the males showing narrower bars and being lighter throughout, 
