116 



GENETICS 



n 



^ igji^^ i ji -^ ^ ^ -j^jji 



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

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

 Pure: Line 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- 

 tion within a 

 population may 

 shift or move 

 over the type 

 of the progeny 



Population 





HI 



Fig. 40. — Diagrams showing five jyure lines 

 and a population formed by their union. The 

 beans of each pure line are represented as as- 

 sorted into inverted test tubes making a curve 

 of fluctuating variability. Test tubes contain- 

 ing beans of the same weight are placed in the 

 same vertical row. After Johanssen. 



