PAPER SHELL WALNUTS 43 



When making these first experiments at 

 hybridizing the walnuts, seeds of the entire tree 

 were planted. In the rows of seedlings, anyone 

 could at once determine which ones were hybrid- 

 ized, as these grew far more rapidly than the 

 others, besides differing notably in general ap- 

 pearance. 



First, experiments were made with two black 

 walnuts, and it was the success of this that led 

 me to hybridize the Persian and California wal- 

 nuts the following year. The hybridization in 

 which the Japanese walnut was used was made 

 a few seasons later. The results, as regards the 

 production of nuts, have been sufficiently de- 

 tailed. Up to the present no variety of com- 

 mercial value as a nut bearer has been produced, 

 although the indirect influence of the hybrids on 

 the Persian walnut industry, through their use 

 as stocks, has been quite notable. 



The Butternuts 



There is a very near relative of the black wal- 

 nut, known as the butternut, that was formerly 

 well known in most forest regions of the east- 

 ern United States. The two trees are of closely 

 similar appearance, and the nuts have the same 

 characteristic thick and corrugated shell. The 

 butternut, however, is oval in shape, whereas the 



