Scientific Inlelligen 



bradecUa, which is early floweimg, ocivc^ v^uiupict^i^ tv v,» 



.I's account of the mechanism of Peristylus viridis (except 



arly pouch for the viscid discs, which the specimens brought us are 

 ed to show, but which are likely to confirm the genus Peristylus); 

 ,„i„ I „ j„..u^ „f *i,3 specific identity of the American 



and the whole leaves scarce a doubt of the specific identity o 

 and European plants, which botanists have strongly suspected. 

 Our Fringe Orchises and other Platantheras, blossoming la 

 mer, will doubtless furnish interesting and varied illustrations 

 by insect aid ; and we commend them, with Darwin's charn 



to consider the general plan and characte 

 amount of labor and knowledge has been la' 

 le immediate subjects of the treatise are the 



circle; the 

 dicated : 1. 



geographical d 



Within the Arctic region, under the several divisiot 

 Asia, W. America (Behring's Straits to the Mackenzie River), '- 

 (Mackenzie River to Baffin's Bay), and Arctic Greenland. 2. W lui^^u. -- 

 circle, and under the general divisions of N. and Central European and JN- 

 Asiatic Distribution, with three longitudinal subdivisions ; American Distribu- 

 tion, with appropriate subdivisions; S. European and African Distribution) 

 Central and S. Asiatic Distribution. The theory upon which the facts are col- 

 located and discussed, and which they are thought strongly to confirm, is tna 

 of Edward Forbes, which was completed, if not indeed originated by Darwin:— 

 " first, that the existing Scandinavian flora is of great antiquity, and that previous 

 to the glacial epoch it was more uniformly distributed over the Polar ^one 

 than it is now ; secondly, that during the advent of the glacial period tlus 

 Scandinavian vegetation was driven southward in every longitude, and ev^ 

 across the tropics into the south temperate zone ; and that, on the succeedin» 

 warmth of the present epoch, those species that survived both ascended t 

 mountains of the warmer zones, and also returned northward, accompanied oj 

 aborigines of the countries they had invaded during their southern migration- 

 Mr. Darwin shows how aptly such an explanation meets the difficulty ot ac- 

 counting for the restriction of so many American and Asiatic arctic tvpe= i 

 their own peculiar longitudinal zones, and for what is a far greater difficulty; 

 the representation of the same arctic genera by closely allied species in a\- 

 ferent longitudes. * * » Mr. Darwin's hypothesis accounts for many varietie 

 of one plant being found in various alpine and arctic regions of the globe, d? 



ginea of the countries it invaded. Different races survived the struggle w' 

 life in different longitudes ; and these races again, afterwards converging <*" 



