LUTHER BURBANK 



of artificial cultivation, the stone is not merely 

 useless to the fruit; it is a positive incumbrance, 



In the first place, it puts a tax upon the vitality 

 of the plant makes a strong draft on its energies. 

 A plant is a manufactory for transforming ele- 

 ments of the soil and of the air, under the influ- 

 ence of sunlight, into grains, fruits, gums, essential 

 oils, and the like. 



Its capacity to produce any one of these is 

 more or less complementary to its capacity to 

 produce the others. 



When the cultivated plum produces a useless 

 stone, it has worked to no purpose; and the energy 

 that goes to build the stone might far better have 

 been utilized, even from the standpoint of the plant 

 itself, in the production of fruit. 



For the perpetuation of any given race of 

 cultivated fruit plants now depend not upon the 

 character of its seed-covering but upon the appeal 

 made by the pulp of the fruit to the palate of man. 



So the stone not only destroys a part of the 

 usefulness of the plum for man directly, by its 

 presence in the fruit, but it is also indirectly harm- 

 ful in that it hampers the vigor of the tree in the 

 production of foliage and larger quantities of 

 fruit. 



Yet when the plant improver attempts to re- 

 move the stone that has thus come to be an in- 



[146] 



