LUTHER BURBANK 



On the other hand, the examples of the straw- 

 berry-raspberry, and the petunia-tobacco might be 

 cited in proof that species too widely removed 

 from each other produce sterile hybrids. 



Thus the experiments as a whole show on one 

 hand the method through which material is sup- 

 plied for the operation of natural selection; while, 

 on the other hand, they show how barriers are 

 ultimately erected that prevent crossbreeding from 

 being carried to an extent that would introduce a 

 chaotic element in the scheme of evolution. 



The importance of such a demonstration as 

 this, made for the first time on a really compre- 

 hensive scale in the experiment gardens at Santa 

 Rosa and Sebastopol, soon came to be generally 

 recognized. 



The New Experiments and Mendelism 



Perhaps it may be of interest, in extension of 

 the present theme, briefly to trace the relation of 

 the new experiments to the particular aspect of 

 the theory of heredity that has most actively 

 claimed the attention of the biological world in 

 very recent years. 



He refers, of course, to the doctrine of Men- 

 delism, which was to take the biological world by 

 storm in the first decade of the twentieth century. 



Of course the results of the hybridizing experi- 

 ments performed in my experimental gardens and 



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