Inheritance of Quanlitalive Characters 



8i 



tion may be somewhat obscured by the varying external 

 conditions of growth. 



Another factor that may obscure these results is 

 what is called physical correlation. For example, a 

 corn plant of small size, but with the hereditary capacity 

 for producing large ears, could not fully express this 



A 



A 



K 



K 



\ 



\ 



\ 



^ 



K 





Fig. 14. — Diagram illustrating how environmental inlluences may 

 obscure phenotype classes of F2. Overlapping of phenotype classes 

 makes possible that two apparently identical plants might actually have 

 a different number of doses; diagram also shows that while breeder 

 could not recognize whether a plant had two or three doses, he could 

 distinguish between plants of two and four doses, etc. Thus intelligent 

 selection could be effective. 



capacity. It could not produce as large ears as if it had 

 been a large-sized plant. 



Such are some of the conditions or factors that tend 

 to obscure results in the F2 generation and give rise to 

 ratios hard to interpret. The weaker the influence of 

 these factors the more clearly do the phenomena of 

 cumulative factors come out. The total result of this 

 phase of the work of Emerson and East, in spite of 

 obscuring conditions that have arisen, has been to 



