ALLELOMORPHIC RELATIONSHIPS IN MENDELISM 157 
linkage values of such a series of allelomorphs when tested with other 
members of the group to which they belong should be identical. The 
factor for yellow body color is located at the locus 0.0 in the X-chromo- 
Fig. 73.—Forms and hybrids of Paratettix. AA, teranus; BB, leucorotus; CC, leuco- 
thorax; II, nigro notatus. (After Nabours.) 
somes, and displays definite linkage values when tested with any other 
factor belonging in this chromosome. The factor for spot gives exactly 
the same values with all factors with which it has been tested. The 
factors for eosin and white eye color both give one unit of crossing over 
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