LUTHER BURBANK 



bore imperfect berries having perhaps only two 

 or three seeds. Again, after blooming, there 

 would be no development of fruit, only a core 

 or stem remaining. 



Among some of these crosses I met with a dif- 

 ficulty not encountered in crossing any other of 

 the members of the great Rubus tribe. The plants 

 at first seemed sickly, having little or no vitality. 

 When transplanted from greenhouse to open field 

 they made little growth the first season and the 

 second season at about the time for fruit bearing 

 they all seemed to fail utterly. 



Every seedling among a lot of these hybrids 

 would sometimes thus be suddenly destroyed. 



In continuing the experiment, I found that 

 there was strong individuality among the differ- 

 ent plants, so that some of the red or yellow rasp- 

 berries crossed readily with the black-caps, while 

 others failed to do so; there being all gradations. 

 In some cases the resulting seedlings would show 

 the prepotency of one parent or the other. But, 

 generally, in the first generation, there would be 

 a blending of the characteristics of the two. 

 Underlying Principles 



At that time no plant developer fully realized 

 that all the best variations and recombinations in 

 a hybrid stock appear in the second and a few 

 succeeding generations. A recognition of this 



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