MENDEL'S SECOND LAW 



69 



If the single comb be supposed to be the wild type, 

 then Pea and Rose represent dominant mutant types 





•,U 



d 



Fig. 31. — Combs of fowls, single, a; rose, h; pea, c; and walnut, d. 



Neither produces any single comb, if the races are homo- 

 zygous for Pea or for Rose respectively, but when crossed, 

 the Pea comb brings in the normal recessive allelomorph 



