PLANT AFFINITIES 223 



divergent in form of stem and foliage and 

 flower, and that in a vast number of instances 

 any attempt to combine these forms is altogether 

 futile. 



It must be understood, however, that it is by 

 no means always possible to predicate, from 

 observation of a given pair of more or less 

 distantly related species, whether or not the two 

 would be mutually sterile. Sometimes the ex- 

 periment results in a surprise, and we are able to 

 produce offspring when the possibility of such a 

 cross seemed altogether improbable. 



Such was the case, it will be recalled, with 

 my experiments in hybridizing the dewberry with 

 the pollen of the apple, pear, rose, and moun- 

 tain ash. Such was the case also with the cross 

 which resulted in producing the sunberry, and 

 with that which developed the plumcot. 



In each of these cases the pistil of one plant 

 accepted the pollen of the other, as it were, un- 

 willingly. But persistent effort effected the 

 desired result, and in the three instances last 

 mentioned fertile offspring were produced. Pos- 

 sibly these might not have survived in the state 

 of nature, but under the conditions of intelligent 

 selection they provided the foundation for the 

 development of what may be considered new 

 species. 



