THE BREEDER HIS PLACE AND HIS WORK 49 



rose because one of the parents was single combed. This first gen- 

 eration may therefore be indicated as R S. When R S is mated 

 together the rose and single comb factors separate themselves in 

 some of the progeny and 25 percent come as pure single, and 75 per- 

 cent as rose of which one-third are pure rose and two-thirds are 

 impure rose. When the 50 percent impure rose are bred together they 

 likewise give 25 percent pure rose and 25 percent pure single. 



RRXSS 



50% 



This application of Mendel's principles shows that a plant or animal 

 is not an indivisable whole or that the breeding of it is largely chance. 

 It indicates that our fowls are a combination of rather definite factors; 

 each character being represented in the germ cells of the reproductive 

 system by some factor that is transmitted not by mere chance but in 

 an orderly manner. It is reasonable to believe that the factors may 

 become contaminated in crossing and that the highest quality results 

 from pure breeding; but the big point is that a fow r l inherits different 

 characters as somewhat definite factors. 



The business of the breeder, therefore, is to consider the charac- 

 ters in his line that are well established and can be depended upon to 

 reproduce themselves. The factors of perfection may exist in a flock, 

 yet perfection may never be exemplified in any one individual. Hav- 

 ing noted the points in the flock that are good, the next thing is to 

 consider those characters which require improvement. Perhaps size 

 should be increased. We have already explained in connection with 

 the rise of the Cochin, Chapter I, that size cleoencls upon a growth 

 tendency that is inherited; and this point is illustrated in Chapter II 

 where it is related that Standard sized Plymouth Rock males on the 

 government farm transmitted a tendency for increased size when 

 mated to small mongrel hens. The possible size of a bird is there- 

 fore determined by a factor for this character in the germ substance 

 of the egg from which the bird is born. In order to get large sized 

 young stock, you must therefore breed a bird of good size and sub- 

 stance, for feeding alone cannot grow a bird bigger than its inherited 

 capacity to size. 



Breeding for increased egg production. Egg production likewise 

 depends in the first place, upon inheritance. At the Maine Agricultural 

 Experiment Station it was found that one female with 1,550 yolks or 

 ova that were visible upon examination of her ovary, had produced 

 13 eggs during the winter months; a female with 2,145, produced no 

 winter eggs; one with 2,451, laid 54 winter eggs; while a female that 



