UNIT-CHARACTERS AND SELECTION 187 



A good example of multiple allelomorphism is found in 

 the several mutations which the color factor of rodents has 

 undergone. This is the factor which in its best known muta- 

 tion assumes the form of albinism. In guinea-pigs four alle- 



TABLE 25a 



Results of the Minus Selection' of Hooded Rats Continued through 



Twenty-one Successive Generations 



lomorphic conditions of the color factor are known, (a) in- 

 tense pigmentation, (6) dilute pigmentation, (c) red-eyed 

 dilution, and (d) Himalayan albinism. In rabbits, the color 

 factor occurs in three forms, (a) ordinary pigmentation, 

 (b) Himalayan albinism, (c) pure white albinism. In rats 

 also the color factor occurs in three forms, but not the same 



