316 DARWINISM TO-DAY. 



"Most of Burbank's plums and prunes are the result of multiple 

 crossings in which the Japanese plums have played an important 

 part. Hundreds of thousands of seedlings have been grown and 

 carefully worked over in the twenty years of experimenting with 

 plums, and single trees have been made to carry as many as 600 

 varying seedling grafts. The Bartlett plum, cross of the bitter 

 Chinese Simoni and the Delaware, itself a Simoni hybrid, has the 

 exact fragrance and flavour of the Bartlett pear. The Climax, a 

 successful shipping plum, is also a cross of the Simoni and the 

 Japanese triflora. This Chinese Simoni produces almost no pollen, 

 but few grains of it ever having been obtained. But these few 

 grains have enabled Burbank to revolutionise the whole plum 

 shipping industry. The sugar prune, which promises to supplant 

 the French prune in California, 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 hybridisations, of forty different species of 

 Rubus, and has resulted in the origination of a score of new com- 

 mercial varieties, mostly obtained through various hybridisations of 

 dewberries, blackberries, and raspberries. Among thes^ may spe- 

 cially be mentioned the Primus, a hybrid of the western dewberry 

 (R. ursinus) and the Siberian raspberry (R. cratagifolius), fixed 

 in the first generation, which ripens its main crop before most of 

 the standard varieties of raspberries and blackberries commence to 

 bloom. In this Primus berry, we have the exceptional instance of 

 a strong variation, due to hybridisation, breeding true from the 

 time of its first appearance. It usually takes about six generations 

 to fix a new variety, but like de Vries's evening primrose mutations, 

 the Primus berry is a fixed new form from the time of its beginning. 

 An interesting feature of Mr. Burbank's brief account, in his 'New 

 Creations' catalogue of 1894, of the berry experimentation, is a re- 

 production of a photograph showing 'a sample pile of brush, 12 

 ft. wide, 14 ft. high, and 22 ft. long, containing 65,000 two- and 

 three-year-old seedling berry bushes (40,000 blackberry y rasp- 

 berry hybrids and 25,000 Shaffer X Gregg hybrids) all dug up 

 with their crop of ripening berries. The photograph is introduced 

 to give the reader some idea of the work necessary to produce a 

 satisfactory new race of berries. 'Of the 40,000 blackberry X rasp- 

 berry hybrids of this kind, "Phenomenal" is the only one now in 

 existence. From the other 25,000 hybrids, two dozen bushes were 

 reserved for further trial.' 



