MENDELISM 



111 



result from a dihybrid cross are shown in the following 

 table: 



Another illustration of dihybridism is shown in Fig- 

 ures 19 and 20 based upon data furnished by the 

 Davenports. 1 In the matings given here, dark or 

 pigmented hair, represented by the solid black circles, 

 is dominant over light-colored, that is, unpigmented or 

 slightly pigmented hair, symbolized by the open circles, 

 while curly hair is dominant over straight, represented 

 by crooked and straight lines respectively in the dia- 

 gram. In other words, the presence of pigment is 

 dominant over the absence of pigment, while the factor 

 that causes curliness is dominant over the absence of 

 this factor, with respect to human hair. 



1 "Heredity of Eye-color in Man," Science, N. S. 26, p. 589, 

 1907; "Heredity of Hair Form in Man," Amer. Nat. 42, p. 341, 

 1908. Davenport, C. B. and G. C. 



