116 



GENETICS 



PURE LINE 



tube of pure line 3, may be identical with the com- 

 monest size in another line, as pure line 2. The 



five pure lines 

 represented in 

 Figure 40 are 

 combined in a 

 population at the 

 bottom of the 

 figure, making 

 a phenotype 

 that marks the 

 five phenotypes 

 above, which are 

 also five geno- 

 types. In the 

 population, how- 

 ever, the five 

 genotypes are 

 hidden within 

 one phenotype. 

 Hence, while 

 selection within 

 a pure line has 

 no hereditary in- 

 fluence, it is evi- 

 dent that selec- 

 An p.. ,. tion within a 



1 IG. 40. Diagrams showing five pure lines 



and a population formed by their union. The population may 



beans of each pure line are represented as as- -i -P. 



sorted into inverted test tubes making a curve Snllt HOVe 



of fluctuating variability. Test tubes contain- over the type 



ing beans of the same weight are placed in the . , 



same vertical row. After Johannsen. Ol tnC progeny 



POPULATION 



