Page:Popular Science Monthly Volume 69.djvu/374

370 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. cratægifolius), fixed in the first generation, which ripens its main crop before most of the standard varieties of raspberries and blackberries commence to bloom. (Mr. Burbank does not recommend this for general cultivation; the 'Phenomenal' and Himalaya are

 One of hundreds of similar ones, due to crossing and selection. These bear fruit at the age of one and a half years and are never without fruit.

better.) In this Primus berry, we have the exceptional instance of a strong variation, due to hybridization, 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 reproduction of a photograph showing "a sample pile of brush 12 ft. wide, 11 ft. high, and 22 ft. long, containing 65,000 two-and three-year-old seedling berry bushes (40,000 blackberry X raspberry hybrids and 25,000 Shaffer X Gregg hybrids) all dug up with their crop of ripening berries." The