50 LUTHER BURBANK 



But unfortunately we are not dealing with an 

 absolutely stoneless plum, but only with one in 

 which the tendency to produce a stone has been 

 minimized or partially suppressed. And so our 

 relatively stoneless plum of the second genera- 

 tion still retains traces of the hereditary propen- 

 sity to produce the stony covering; and, as we 

 have seen, this propensity manifests itself in the 

 fragmentary stone, sometimes reduced to a mere 

 speck in size, that many of my stoneless plums 

 exhibit. 



Nevertheless there remains not a doubt that 

 from subsequent generations, from the stock 

 in hand, an absolutely stoneless plum that 

 retains all the valued qualities of the fruit and 

 in all sizes, colors, and flavors desired will be 

 produced. 



That it has been possible to eliminate the stone 

 altogether, advancing thus markedly in this re- 

 gard upon the original partially stoneless form 

 with which the experiment began, suggests the 

 truth of a view now held by some prominent 

 biologists, notably by Professor William E. 

 Castle of Harvard, that a unit character may 

 be modified in successive generations not 

 merely blended or made into a mosaic with 

 other characters, but actually modified as to 

 its potentialities. 



