PHENOMENA OF INHERITANCE 259 



Castle found that eight different factors 

 may be involved in producing the coat colors 

 of rabbits; these are: 

 C a common color factor necessary to produce 



any color. 



B a factor acting on C to produce black. 

 Br a factor acting on C to produce brown. 

 Y a factor acting on C to produce yellow. 

 I a factor which determines intensity of color. 

 U a factor which determines uniformity of 



color. 

 A a factor for agouti, or wild gray pattern, in 



which the tip of every hair is black, below 



which is a band of yellow, while the basal 



part of the hair is gray. 

 E a factor for the extension of black or brown 



but not of yellow. 



Plate found that all of these factors except 

 the last, E,, are also involved in the production 

 of the coat colors of mice. Baur has recog- 

 nized more than twenty different factors for 

 the color and form of flowers in the snap- 

 dragon, Antirrhinum. 



These factors are probably complex chemi- 



