LUTHER BURBANK 



expectation was justified by results. The second 

 generation hybrids showed diverse combinations 

 of various other qualities that were under consid- 

 eration, and a certain proportion of them revealed 

 the combination of the desired quality of grain 

 with the stems immune to the attacks of the rust 

 fungus. 



As immunity to rust is a recessive factor, it 

 follows that the second generation hybrids that 

 show such immunity will breed true to that char- 

 acter. Their offspring will be immune. But as 

 regards certain other qualities, notably hardness, 

 it was necessary to continue the experiment 

 through a third generation, in order to discover 

 which of the plants that were individually hard 

 were pure dominants as regards the quality of 

 hardness. 



To ascertain this it was necessary only to plant 

 the grains showing the desired quality in plots by 

 themselves. 



The individuals that produced only hard- 

 grained offspring in the next generation were thus 

 shown to be pure dominants for that quality. They 

 constituted a fixed race and could be depended 

 upon to breed absolutely true. 



Thus the clear recognition of the qualities of 

 Mendelian segregation, as applied to the different 

 pairs of unit characters representing respectively 



[70] 



