LUTHER BURBANK 



other less evident cause, might prevent the tree 

 from bearing, thus making fruit raising a some- 

 what "hit-or-miss" proposition. 



I determined from the outset to give particular 

 attention to these matters, endeavoring to produce 

 varieties of fruit trees that would be hardy and 

 resistant to unfavorable conditions and that would 

 be not only heavy bearers but regular bearers. The 

 matter of resistance to insect pests and to disease 

 was also given careful consideration from the 

 outset. 



Seedlings that showed susceptibility were ruth- 

 lessly weeded out, and the survivors became the 

 parents of races that are relatively immune to 

 disease. 



Of course the combination of different species 

 to bring together long-diverged racial strains was 

 a fundamental part of the plan. Unnumbered 

 thousands of hand-pollenizing experiments were 

 made each year, and the limits of affinity between 

 the different species were tested by ceaseless and 

 persistent efforts. 



When species that were seemingly somewhat 

 closely related proved infertile after cross pollena- 

 tion, it was not taken for granted that there was 

 real antagonism between those species until the 

 experiment had been tried over and over in suc- 

 cessive seasons, perhaps thousands of times in the 



[128] 



