LUTHER BURBANK 



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 at Santa Rosa, 

 although remaining perfectly smooth under ordi- 

 nary conditions of cultivation, had, nevertheless, 

 a tendency to revert to the spiny condition if 

 placed under disadvantageous conditions — say in 

 arid soils, unwatered and uncultivated; a state 

 comparable to that of the wild spiny progenitors. 



This tendency to reversion is in itself highly 

 interesting from the standpoint of the student of 

 heredity; being comparable, perhaps, to the ob- 

 served tendency of some plants, on rare occasions, 

 to form what are termed bud sports. As a rule, 

 plants grown from cuttings or roots or buds repro- 

 duce absolutely the characteristics of the parent 

 form. We have seen this illustrated over and over 

 in endless numbers of cases, from orchard fruits 

 to Shasta daisies. This rule holds true of the cac- 

 tus, as has been pointed out in recent chapters. 

 You may produce an entire field of spineless opun- 

 tias of any given type, as offshoots of a single slab. 



But of course no plant is free from the power 



[264] 



