APPLICATION OF PRINCIPLES OF BREEDING 519 



secured in both cases by the 

 application of the same prin- 

 ciple of special mating, — 

 breeding not the Standard- 

 colored bird of either sex to 

 a mate of the other sex of the 

 same shade of color, but the 

 male to a female of the color 

 and breeding of his dam, and 

 the female to a male of the 

 color and breeding of her sire. 

 There is, however, this differ- 

 ence in the cases compared : 

 when sexual differences in 

 color are exaggerated by a 

 standard, the application of 

 the principle keeps apart the 

 lines of breeding, or subvari- 

 eties. When a standard seeks 

 to make the sex color types 

 identical, the application of the 

 principle of special matings 

 tends first to fix the types and 

 finally to fuse the lines. Allu- 

 sion was made to this in the 

 paragraph relating to modified 

 black-red types. Nowhere 

 is the evidence of prog- 

 ress toward fusion of sex 

 varieties as marked as 

 in the evolution of the 

 Barred Plymouth Rock. 

 From within a few years 

 after they were estab- 

 lished, the two lines have 

 been steadily converging. 

 The dark females with 

 indistinct barring, once 

 used in the male line, and 

 the nearly white males 

 with just a suggestion of 

 barring, once used in the 

 female line, are rarely 

 seen now. Crosses of the 

 two lines are occasionally 



F"^' 537- Light Brahma cockerel, owned by 

 H. B. Robinson, Reading, Massachusetts 



Fig. 538. Same as Fig. 537. Note how the pose 

 changes the apparent shape 



