MENDELISM 141 



analogous unit-characters to form a blend or a particulate 

 mosaic." We must therefore distinguish between Men- 

 delian hybrids, which do not blend, but breed out the 

 various forms in ascertained proportions, and those results 

 of hybridization usually described as prepotent, blended, or 

 particulate inheritance. Most probably there are, as 

 Professor Thomson indicates, " several formulae of inheri- 

 tance, each applicable to particular sets of cases e.g., to 

 cases where blending does occur, and to cases where it 

 never occurs." For the present a higher unification of 

 both sets of phenomena has not been attained. 



