STABILITY OF THE GENE 



295 



breeding each individual has become homozygous. This 

 means that the two members of each pair of genes are 

 identical. Hence such material is suitable to carry out 



A-B 



Fig. 150. 

 A-E groups of beans representing five pure lines. Below A-E the 

 group formed of the combination of the other five. (After Johann 

 sen.) 



critical experiments to detennine whether individual dif- 

 ferences sho\^^l by the beans are affected by selection. 

 If selection changes the character of the individual, it 



