Neo-Mendelism 



43 



of tallness" (fig. 7). It is a matter of convenience 

 to have a symbol to represent the recessive, the absence 

 of something that is present in another individual. 



In summary, the essential difference between the 

 presence and absence hypothesis and that of dominant 

 and recessive is that in the former case the recessive 



Dwarf Parent Gametes 



Fig. 7. — Diagram showing how presence and absence scheme is 

 actually used, with small letter representing "absence." 



determiner has no existence at all, while in the latter 

 case it exists, but is in a latent condition when associ- 

 ated with the dominant. 



II. BLENDS 



This type of inheritance when first discovered was 

 thought to be in direct conflict with Mendel's law. 

 It is a case in which dominance seems to fail, for the 

 two alternative characters both express themselves and 

 the result is an average between them. It is easy to 

 explain this situation iq accordance with the presence and 

 absence hypothesis without any violation of Mendel's 

 law. 



The classic example of blending inheritance was 

 presented by Coreens (3) in breeding work upon 



