58 Elementary Species 



But by means of crossing with other species 

 and especially with the Japanese plums, the 

 hardy qualities of the beach-plum have been 

 united with the size, flavor and other valuable 

 qualities of the fruit, and a group of new plums 

 have been produced with bright colors, ovoid and 

 globular forms which are never flattened and 

 have no suture. The experiments were not fin- 

 ished, when I visited Mr. Burbank in July, 1904, 

 and still more startling improvements were said 

 to have been secured. 



I may perhaps be allowed to avail myself of 

 this opportunity to point out a practical side of 

 the study of elementary species. This always 

 appears whenever wild plants are subjected to 

 cultivation, either in order to reproduce them as 

 pure strains, or to cross them with other al- 

 ready cultivated species. The latter practice 

 is as a rule made use of whenever a wild spe- 

 cies is found to be in possession of some quality 

 which is considered as desirable for the culti- 

 vated forms. In the case of the beach-plum 

 it is the hardiness and the great abundance of 

 fruits of the wild species which might profit- 

 ably be combined with the recognized qualities 

 of the ordinary plums. Now it is manifest, that 

 in order to make crosses, distinct individual 

 plants are to be chosen, and that the variability 

 of the wild species may be of very great im- 



