Some Experiments gJ I^uther Burbank 



alone, the above sentence is hardly true. But as 

 before stated, hybridization followed by selection 

 is the shortest plan by which valid new species can 

 be produced. In other words, the 'period of mu- 

 tation ' can be produced at will!'' 



* ' The mutation theory of the origin of species 

 seems like a step backward toward the special 

 creation theory, and without any facts as yet ade- 

 quate to support it as a universal theory, however 

 valuable and suggestive the experiments of Dr. De 

 Vries may be.'' 



There is a remarkably close analogy between 

 hybridization and grafting. Bringing over from 

 France a prunus (P. mirobolana var. pissadi), of 

 which there was no other specimen in America, 

 it was grafted on to the Kelsey plum, a variety of 

 Prunus triflorus. The graft itself did not bloom, 

 but the presence of the graft brought about in the 

 tree a cross off the two species. This is the only 

 case known to me in which the graft affected the 

 reproductive system of the plant, forming a cross 

 between forms which had never crossed. Many 



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