84 POULTRY BREEDING AND MANAGEMENT 



grade; the chances are much in favor of the pure-bred, 

 otherwise all the laws of heredity would be of no avail. But 

 it is certain that fowls of the same breeding are not equally 

 prepotent. The Mendelian law of dominance furnishes the 

 explanation. 



Dominance. There are certain characters that are domi- 

 nant. For example, white plumage is a dominant color. 

 This was shown in the cross mentioned between Barred 

 Plymouth Rocks and White Leghorns, where the offspring 

 were all white. They resembled only one parent in color. 

 Color, however, is only one .character. The offspring of a 

 cross may take after one parent in one point and the other 

 parent in some other point. For example, in crossing a 

 black Wyandotte with a White Leghorn, the offspring will 

 resemble the Wyandotte in the kind of comb, but the Leg- 

 horn in color of plumage, a white chicken with a rose comb. 

 It is said, then, that the white color and the rose comb are 

 dominant characteristics, and that single comb and black 

 color are recessives, and no matter what breeds may be 

 crossed, the dominant characters of white plumage and rose 

 comb will show in the offspring, and the recessive charac- 

 ters will not. It is not a question of ancestry or blood lines. 



While the offspring have all rose combs they are impure 

 rose, and this is brought out in the next generation, when 

 the cross-breds are bred together. In this generation re- 

 version takes place, and on the average 25% of the offspring 

 will have the recessive character of single combs ; 75% will 

 have rose combs; but of these, 25% are pure rose, that is, 

 they will forever breed pure to rose combs, but the 50% 

 are impure. This 50% when recrossed will segregate in 

 the same way, 25% single combs, 75% rose combs, but of 

 the 75% only 25% will breed pure rose combs, and so on. 



It resolves itself into a question of testing the breeding 

 powers rather than a question of selection. The 25% 



