52 LUTHER BURBANK 



the most part never give it a thought. But a 

 moment's reflection makes it clear that the plum 

 stone serves man no useful purpose, while the 

 inconvenience it gives us is obvious. 



It requires no argument to show that a 

 solid fruit without a stone would be far more 

 acceptable. 



But this is not the only reason, although per- 

 haps a sufficient one, for the development of the 

 stoneless fruit. The other reason looks to econ- 

 omy of production and saving of material from 

 the standpoint of the tree itself. It has been 

 estimated that a tree requires several times as 

 much solid material and the expenditure of far 

 more energy to produce the stony covering of the 

 fruit seed than to grow the flesh of the fruit itself. 



So it might well be expected that other things 

 being equal, a tree bearing stoneless fruit would 

 prove at least twice as productive as one bearing 

 stone fruit. 



Under the conditions of nature, this increased 

 fruitage would by no means compensate for the 

 loss of the protective stony covering, for the seed 

 unprotected by its coat of mail would be at the 

 mercy of any bird or animal or insect that at- 

 tacked it. 



There would probably be no representative of 

 the stone fruit family in existence to-day were it 



