Determiners and Factors 



249 



Fig. 65. Factors in Heredity 



Two " pure " strains of white-flowered sweet peas were crossed, A, B. The 

 hybrids, Fi, were all brightly colored purple and blue flowers. When in-bred 

 these hybrids gave rise to flowers with various combinations of purple, blue, red, 

 pink, white, including pure white flowers 1—7. It is possible to show experi- 

 mentally that the appearance of any color at all in these flowers depends upon 

 the presence of both a color base and a color developer, which are inherited 

 independently: A carries one factor into the combination and B carries the 

 other. If both factors are present, the particular combination of colors, 1—6, 

 is determined by the presence of additional factors, each of which may be 

 transmitted independently in Mendelian fashion. After Punnett. 



