4° 



MENDELISM 



CHAP. 



On crossing Breda with single the F^ birds exhibit a large 

 comb of the form of a double single comb in which the two 

 portions are united anteriorly, but diverge from one an- 

 other towards the back of the head (Fig. 6, C). The 



Fig. 6. 



Fowls* combs. A and B, Fj hen from rose x Breda; C, an F^ cock from the cross of 



single X Breda; D, head of Breda cock. 



Breda contains an element of dupHcity which is dominant 

 to the simpUcity of the ordinary single comb. But it can- 

 not contain the factor for the single comb, because as soon 

 as that is put into it by crossing with a single the comb 



