OF ARTS AND SCIENCES. 131 



Professor Gray gave a series of illustrations of the Botany 

 of Japan in its relations to that of Central and Northern Asia, 

 Europe, and North America, — the communication being a 

 portion of one of the papers presented by him at the last pre- 

 ceding meeting. 



He showed that the relations of the Flora of Japan with 

 that of the United States east of the Mississippi were pecu- 

 liarly intimate, as evinced by the great number of congeneric, 

 of closely representative, and of identical species in the two 

 floras, noting especially that most of the more striking points 

 of similarity were presented in species or in types which are 

 absent from the flora of Europe. Also, that although there is 

 a considerable number of species common to the western side 

 of the American continent and to Japan, yet that the likeness 

 was less strong between their floras than between those of 

 Eastern North America and of Japan, although the latter are 

 geographically separated by about one hundred and forty 

 degrees of longitude. Also, that far more Eastern Ameri- 

 can species or types are represented in Eastern Asia, than 

 of Western American in Europe, or even in Asia ; — thus 

 pointing to a remarkable interchange between the floras of 

 Eastern North America and Eastern Asia ; or to a former 

 homogeneousness of the temperate American and East- Asian 

 floras, to a degree equal, perhaps, to that of the Arctic or the 

 sub- Arctic flora at the present time. 



Comparisons formerly instituted by Professor Gray between 

 the flora of the Northern United States and that of other 

 parts of the northern temperate zone had already suggested 

 to others, as well as to himself, the inference that the inter- 

 change between these floras had taken place mainly via Asia, 

 and not via Europe ; and it would be seen that our now 

 largely increased knowledge of the botany of the Japanese 

 and of the Himalayan regions strengthened this inference. 



In presenting the subject, Professor Gray could hardly avoid 

 using the words " interchange " and " dispersion of species." 

 He had used them only in drawing his conclusions from the 



