LUTHER BURBANK 



gle bush. Like its fellows, it bore strains of half 

 a dozen races of high-grade market berries, blend- 

 ed with the thornless strain. 



Of course each successive hybridization with 

 a bearer of good fruit meant the introduction of 

 thorns in the seedlings of the next generation. 

 This was inevitable, since of course all the bear- 

 ers of commercial blackberries were bearers also 

 of thorns. The Himalaya in particular is an ex- 

 ceedingly thorny bush, and the otherwise com- 

 mendable Lawton is an almost equal offender. 

 But whereas these thorny shrubs were prepotent 

 in their influence over their direct offspring as 

 was expected, some of their grandchildren always 

 reverted to the thornless state. 



And so here as in various other experiments 

 already described, advance was made by indi- 

 rection. We are forced to seesaw back and forth 

 in successive generations between thorny bushes 

 and thornlessness; yet on the whole there was 

 progress, inasmuch as each successive generation 

 showed better qualities of fruit, and each alter- 

 nate generation the recurrence of the thornless 

 condition. 



Inasmuch as the thornless bushes, of whatever 

 generation, will breed true to thornlessness if fer- 

 tilized among themselves, it is obvious that each 

 thornless generation constitutes a fixed race, pro- 



[20] 



