166 LUTHER BURBANK 



This explains why it was necessary, in our 

 experiments at Santa Rosa, to plant the seeds by 

 literal millions, and to select persistently among 

 uncomputed multitudes of seedlings. 



Fortunately the spiny condition reveals itself 

 almost from the outset, so that it was possible 

 to weed out the vast majority of all the seedlings, 

 retaining only, perhaps, a stray dozen or so from 

 among the legions. 



As the experiment proceeded, however, it was 

 gratifying to note that in succeeding genera- 

 tions there was an ever-increasing proportion of 

 spineless seedlings. This suggests that some of 

 the factors for spininess were being dropped out 

 of the heredity of the selected plants. 



Obviously this seems to augur that should 

 the experiment be carried forward through a 

 sufficient number of generations, the time will 

 probably come when all factors for spininess 

 will have been eliminated from the germ plasm 

 of the selected opuntias; in which case they will 

 then breed true to spinelessness from the seed. 



This prediction finds further warrant in the 

 fact that the newest races of spineless opuntias 

 show a far more pronounced abhorrence if the 

 phrase be permitted of the spiny conditions 

 than did the earlier ones. It was observed that 

 the first spineless opuntias to be developed 



