CHAPTER VIII 
MULTIPLE ALLELOMORPHS 
The meaning of the term multiple allelomorphs 
may be illustrated by the following example: 
1. If a white-eyed male of Drosophila is mated to 
a red-eyed female, the F, ratio of 3 reds to 1 white is 
explained by Mendel’s law, on the basis that the 
factor for red is the allelomorph of the factor for 
white. 
2. If an eosin-eyed male is mated to a red-eyed 
female, the F, ratio of 3 reds to 1 eosin is also ex- 
plained if eosin and red are allelomorphs. 
3. If the same white-eyed male is bred to an eosin- 
eyed female, the F, ratio of 3 eosins to 1 white is 
again explained by making eosin and white allelo- 
morphs. 
There are here three factors, any two of which 
may meet, and whenever they do, they behave as 
allelomorphs. They form a system of triple allelo- 
morphs. 
On: the chromosome hypothesis the explanation of 
this relation is apparent. A mutant factor is located 
at a definite point in a particular chromosome; its 
normal allelomorph is supposed to occupy a corre- 
sponding position (locus) in the homologous chromo- 
some. If another mutation occurs at the same place, 
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