CHARACTERS OF DISTINCT PAIRS 105 



squat, and its surface is marked, all over, by many 

 convolutions. A third type (Fig. 24), known as the 

 " pea " comb, occurs in the Sumatra game, for instance, 

 and may be said to consist of three low ridges, a 

 median and two lateral ones. A fourth type of 

 comb, known as the walnut comb, and only occurring 

 in the Malays, is shown in Fig. 25. It consists of a 

 globular excrescence not unlike a walnut. 



If a fowl with a " pea " comb is mated with one 

 bearing a " rose " comb the resulting hybrids have 

 "walnut" combs. When these hybrids are mated 

 together, the generation produced has the following 

 remarkable composition : 9 " walnut," 3 " rose," 

 3 " pea," : 1 " single." No " single," it w^ill be remem- 

 bered, was put into the cross. What is the origin of 

 the single comb in this second hybrid generation, 

 and what are the two pairs of characters responsible 

 for this 9:3:3:1 ratio are questions which natur- 

 ally present themselves. 



The result of crossing the yellow wTinkled with 

 the green round pea gives the clue. It will be remem- 

 bered that in that instance both the dominant 

 characters occurred together in the individuals wdiich 

 appeared in the proportion of nine in the sixteen; 

 and that the dominant characters occurred separately 

 in the two lots of individuals w^hich appeared in the 

 ratio of three in the sixteen, i.e. the yellow in the 

 yellow wrinkled, and the round in the green round. 

 In this case, therefore, w^e should suppose that the 

 two dominant characters are " rose " and " pea." 

 What the recessive characters corresponding to them 



