4o 



MENDELISM 



CHAP. 



On crossing Breda with single the Fj 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, F x hen from rose x Breda; C, an F t cock from the cross of 



single x Breda; D, head of Breda cock. 



Breda contains an element of duplicity which is dominant 

 to the simplicity 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 



