INTERESTING FAILURES 181 



But it will be recalled that when the California 

 black walnut was hybridized with the English 

 walnut producing the "Paradox" the results 

 in this regard were quite different. While the 

 individual offspring showed great vitality, they 

 were almost sterile, producing only a few stray 

 nuts in contrast with the profusion of the Royal 

 hybrids. 



And we may infer from this result that the 

 California walnut and its remote English cousin 

 have diverged to a point lying just on the border 

 line of the limits of desirable racial mingling. 



These limits have not quite been crossed as 

 they have been in the case of the dewberry and 

 apple tree, and the strawberry and raspberry, 

 but they are being approximated; and there is 

 no probability that the hybrid offspring of the 

 black walnut and the English walnut could 

 maintain itself through successive generations 

 as a new race in the state of nature. At all 

 events, its prospect of success would be a 

 doubtful one. 



THE APPLICATION TO THE HUMAN SPECIES 



It is more than likely, then, that the lessons 

 taught by the unsuccessful experiments recorded 

 in this chapter are quite as important as if they 

 had led to what might appear to be more practi- 



