Scientific Aspects of I^uther Burbank' s Work 



industry. The sugar prune, which promises to 

 supplant the French prune in Cahfornia, is a 

 selected product of a second or third generation 

 variety of the Petite d'Agen, a somewhat variable 

 French plum. 



Next in extent probably to Burbank's work 

 with plums and prunes is his long and successful 

 experimentation with berries. This has extended 

 through twenty-five years of constant attention, 

 has involved the use, in hybridizations, of forty 

 different species of Rubus, and has resulted in the 

 origination of a score of new commercial varieties, 

 mostly obtained through various hybridizations of 

 dewberries, blackberries and raspberries. Among 

 these may specially be mentioned the Primus, a 

 hybrid of the western dewberry {R, ursinus) and 

 the Siberian raspberry {R. cratagifolius), fixed in 

 the first genereration, which ripens its main crop 

 before most of the standard varieties of raspberries 

 and blackberries commence to bloom. (Mr. Bur- 

 bank does not recommend this for general cultiva- 

 tion; the ThenomenaF and Himalaya are better.) 



106 



