170 LUTHER BURBANK 



ments are worked for together as in the combina- 

 tion of a great number of species and varieties 

 instead of taking a certain established variety 

 and attempting to make one or two improve- 

 ments upon it there must necessarily be a much 

 greater proportion of expense. 



But, so far as my own experiments are con- 

 cerned, the pioneer work has now been done. I 

 have elsewhere told how the material has been 

 gathered from all over the world, until the plums 

 and prunes of my production carry hereditary 

 strains in their germ plasm from ancestors im- 

 ported from five continents. 



And I have pointed out that there are thou- 

 sands of new varieties among my plum trees that 

 have exceptional qualities, and from the progeny 

 of which, variously interblended, many new 

 and important races of plums and prunes will 

 doubtless be developed in the immediate 

 future. 



The sum total of my work with the plums and 

 prunes, judged by the record of actual introduc- 

 tions, comprises the development of only some 

 seventy new varieties. But it must be understood 

 that these seventy introduced varieties are only 

 the pick among thousands, very many of which 

 were but slightly inferior to the ones chosen. 

 And, as stated before, the final balance sheet for. 



