218 LUTHER BURBANK 



But, unfortunately, when such crosses were 

 made, it was at once apparent that the thorny 

 condition had shown prepotency, and all the seed- 

 lings that grew from thornless berries thus cross- 

 fertilized were seen to be bearers of thorns. 



This was precisely the experience that had dis- 

 heartened me when, back in 1880, I had made 

 the experiments with the Wachusett partially 

 thornless blackberry, to which reference was 

 made above. But in the intervening time I had 

 made many thousands of hybridizing experi- 

 ments, and I now clearly understood what at 

 the earlier period I had known vaguely if at all 

 that in such a case as this we must look to the 

 second filial generation for the kind of results we 

 are seeking. 



The case is precisely comparable to that of 

 the white blackberry, for example, or to that of 

 the stoneless plum. When the white black- 

 berry is crossed with a black blackberry all the 

 offspring of the first generation are black. And 

 when the stoneless plum is crossed with the stone- 

 bearing plum all the offspring of the first gen- 

 eration are stone-bearers. But in each of these 

 cases the succeeding generation will show indi- 

 viduals in which the submerged character reap- 

 pears we shall have white blackberries and 

 stoneless plums again. 



