28 LUTHER BURBANK 



difficulties encountered in extracting the meat of 

 the nut are too great. But a nut that has a shell 

 so thin that it can easily be crushed in the fingers 

 is sure to make its way and to be found more 

 and more generally on the dinner table. 



The terms "paper-shell" and "soft-shell" as 

 applied to the walnut are interchangeable. There 

 are now several varieties of walnuts on the mar- 

 ket that are generally classified under one head 

 or the other. Their name merely refers to the 

 ease with which the nut can be cracked. As 

 to this there is great variation among ordi- 

 nary walnuts, and the soft-shell varieties also 

 show a diversity. But the best varieties are 

 so friable that they can readily be crushed in 

 the fingers. 



The walnut is so variable that it is possible for 

 the plant developer to consult his own wishes in 

 the matter of modifying its shell. I have devel- 

 oped a variety in which the shell became so soft 

 that it could readily be penetrated by birds; in 

 fact, also, a nut that had a mere rim of shell, 

 being thus comparable to the stoneless plum. 

 There would be no difficulty in maintaining this 

 variety of shell-less walnuts, but its thinness of 

 shell was a disadvantage, and I found it de- 

 sirable to breed the variety back to a somewhat 

 thicker shell covering, by striking a compromise 



