36 



MENDELISM 



vestige of a comb in the form of two minute lateral 

 knobs of comb tissue. Characteristic also of this 

 breed is the high development of the horny nostrils, 

 a feature probably correlated with the almost com- 



FlG. 6. 



Fowls' combs. A and B, Fj hen from rose x Breda ; C, an Fj cock from the cross 

 of single X Breda ; D, head of Breda cock. 



plete absence of comb. The first step in the 

 experiment was to prove the absence of the factor 

 for singleness in the Breda. On crossing Breda 

 with single the F^ birds exhibit a large comb of 

 the form of a double single comb in which the two 



