SUMMARY OF THE WORK 331 



The same genera are represented on both con- 

 tinents, because the remote progenitors of all 

 races of animals and plants of the Northern 

 Hemisphere were once inhabitants of a common 

 territory in the region of the North Pole. But 

 there has been no opportunity for the mingling 

 of Asiatic and American forms of plant life 

 since the separation of the continents, until 

 civilized man in very recent time began to 

 transport forms of animal and plant life across 

 the oceans. 



There had been no communication since a 

 remote geological era probably not since the 

 last ice age; so on mere geographical grounds 

 the specific difference between the Siberian rasp- 

 berry and the California dewberry might be 

 accepted without further argument. But, quite 

 aside from this, differences between the two 

 forms are sufficient to give them independent 

 specific rank in the mind of any botanist. 



The fact that one is classified as a blackberry 

 and the other as a raspberry will sufficiently 

 establish their diversity in the mind of the 

 layman. 



Yet the report from Santa Rosa told of the 

 combination of these diverse forms, and of the 

 production of a new fruit differing very mark- 

 edly from either parent, although retaining some 



