72 



Plant Genetics 



the result. In this way the results of germinal consti- 

 tution may be somewhat obscured by the varying 

 external conditions of growth. 



Fig. i8.— Graphic illustration of situation represented in fig. 1 7. In 

 both diagrams it is evident that two plants appearing in same quanti- 

 tative class must have same number of doses; this should always occur 

 if environmental influences did not obscure the result. 



^ 



A 



h. 



Fig. 19. — Diagram illustrating how environmental influences may 

 obscure phenotype classes of Fj. 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. 



