270 THE SURVIVAL OF THE UNLIKE. [XV. 



The straits to which naturalists were driven to ex- 

 plain the distribution of animals and plants when one 

 progenitor is alone assumed, may be illustrated by 

 the supposition, which Schouw ascribes to an English 

 author, that there must once have been a continental 

 area between Spain and Ireland, inasmuch as certain 

 Spanish plants reappear in the British Isles. Even 

 Alphonse De Candolle, while holding in general to the 

 hypothesis of a single origin, felt obliged to admit that 

 in the case of our modest verbena -like Fhrymu Lep- 

 tostachya, which grows in eastern North America and 

 again in the Himalayan region, there must have been 

 two independent originations. 



Naturalists were ready to believe that species had 

 one origin if only the fact of disconnected distril)utions 

 could be explained. At this juncture, Asa Gray came 

 forward with his brilliant exposition of the relation- 

 ships of the eastern American and Japanese floras. 

 The plants collected in Japan in 1853 by Williams and 

 Morrow, in connection with Commodore Perry's visit 

 to that country, and also those procured there by 

 Charles Wright, in connection with Commodore Rod- 

 gers' expedition of 1855, went to Gray for study. He 

 was at once struck by the similarity of many of the 

 plants to those of our Alleghany region, a resemblance 

 which he had before noticed. He found that many of 

 the characteristic genera of eastern America and a 

 number of the monotypic and bitypic genera, occur 

 also in the Japanese region. He observed the remark- 

 able fact that the flora of eastern North America is 

 much more like the Japanese flora than those of west- 

 em America and even of Europe are, and also that our 

 Alleghany flora is more like the Japanese than it is 



