INTERESTING FAILURES 179 



with the almond, with the Japanese plum, and 

 with the apricot, without in any of these cases 

 producing a product of value. These crosses, 

 like the ones just detailed, bring together racial 

 tendencies that are too widely divergent to be 

 harmonized. 



It would appear that it is essential to the 

 differentiation and perpetuation of species that 

 bounds should be set on the possibility of pro- 

 ducing a disturbing influence through hybrid- 

 ization. When plants, even though sprung from 

 the same origin, have diverged so widely and for 

 such periods of time as to produce forms differ- 

 ing from one another so greatly as, for example, 

 the mountain ash, the apple, and the rose differ 

 from the dewberry; or the strawberry from the 

 raspberry it would seem not to be of advantage 

 to the plants to combine these forms. 



The changes that would be produced, were 

 such hybridization to result in virile offspring, 

 would perhaps be too divergent to fit into their 

 environment successfully. At all events the 

 possibility of such crosses would constitute a 

 disturbing influence of organic nature at least 

 in some of its orderly character. 



And so it appears, so far as may be judged 

 from these experiments, that even when hybrids 

 between these divergent forms are produced, the 



