204 OUTLINES OF EVOLUTIONARY BIOLOGY 



way as that in which the chemist is able to produce new compounds 

 by analysis and synthesis from other substances. 



Probably no man has made more successful use of the process 

 of hybridization in the production of new and valuable forms of 

 plant-life than Luther Burbank, at his celebrated California!! 

 nurseries. Mr. Burbank himself is unfortunately not a writer, 

 and for a scientific account of his work we are indebted to 

 Professor Hugo de Vries, who in his book on "Plant Breeding" 1 

 describes what he himself saw and heard during his visits to 

 Mr. Burbank's farms. Some idea of the commercial value of 

 Mr. Burbank's work may be formed from the fact that special 

 companies have been formed for the propagation and sale of 

 some of these wonderful hybrids. White blackberries, stoneless 

 prunes, " plumcots " and thornless cacti are only some amongst 

 the many novelties which he has produced by crossing different 

 varieties by hybridization and thus combining two or more 

 desirable qualities in one plant. 



Take, for instance, the case of the stoneless prune. It had 

 somehow or other come to the knowledge of Mr. Burbank that 

 about 200 years ago there existed in France a plum known as the 

 " Prune sans noyau." He succeeded in obtaining specimens of 

 this fruit, but it proved to be of little or no commercial value 

 owing to its poor quality. Its one valuable feature was its stone- 

 lessness, and Burbank set to work to transfer this character, by 

 hybridization, to a variety of good quality. He succeeded, and 

 there appears to be no reason why the stoneless character should 

 not be similarly implanted upon all the different varieties of 

 plums now in cultivation. 



Similarly, the "plumcots" are hybrids between plums and 

 apricots, which Professor de Vries speaks of as " most delicious 

 and beautiful fruits." 



It must be admitted that Burbank's work is practical rather 

 than scientific. He apparently pays no attention to the law of 

 Mendel in his operations, and just goes on hybridizing until he 

 gets what he wants. In this process enormous numbers of plants 

 which do not fulfil his requirements have to be destroyed for 

 every one that is worth preserving. 



He is not necessarily concerned with the production of pure 

 breeds ; of forms, that is to say, which will breed true from seed, 



1 Hu<ro de Vries, " Plant Breeding " (London, Kegan Paul. Trench, Triibner& Co.. 

 Ld., 11107). 



