358 COSMOS. 



elk, for instance, lives in the Scandinavian peninsula, almost 

 ten degrees further north than in the interior of Siberia, where 

 the line of equal winter temperature is so remarkably concave. 

 Plants migrate in the germ ; and, in the case of many species, 

 the seeds are furnished with organs adapting them to be con- 



representative species and by identical. In reality, the former essen- 

 tially depend on the law, the latter being an accident not necessarily 

 dependent upon it, and which has hitherto not been accounted for. In 

 the case of the Alpine flora of Britain, the evidence of the activity of 

 the law, and the influence of the accident, are inseparable, the law being 

 maintained by a transported flora, for the transmission of which I have 

 shown we cannot account by an appeal to unquestionable geological 

 events. In the case of the Alps and Carpathians, and some other 

 mountain ranges, we find the law maintained partly by a representative 

 flora, special in its region, i. e., by specific centres of their own, and 

 partly by an assemblage more or less limited in the several ranges of 

 identical species, these latter in several cases so numerous, that ordinary 

 modes of transportation now in action can no more account for their 

 presence, than they can for the presence of a Norwegian flora on the 

 British mountains. Now I am prepared to maintain, that the same 

 means which introduced a sub-arctic (now mountain) flora into Britain, 

 acting at the same epoch, originated the identity, as far as it goes, of 

 the Alpine floras of Middle Europe and Central Asia. For now that we 

 know the vast area swept by the glacial sea, including almost the whole 

 of Central and Northern Europe, and belted by land, since greatly up- 

 lifted, which then presented to the water's edge those climatal conditions 

 for which a sub-arctic flora destined to become Alpine was specially 

 organised, the difficulty of deriving such a flora from its parent north, 

 and of diffusing it over the snowy hills bounding this glacial ocean, 

 vanishes, and the presence of identical species at such distant points 

 remains no longer a mystery. Moreover, when we consider that the 

 greater part of the northern hemisphere was under such climatal condi- 

 tions during the epoch referred to, the undoubted evidences of which 

 have been made known in Europe by numerous British and Continental 

 observers, on the bounds of Asia by Sir Roderick Murchison, in America 

 by Mr. Lyell, Mr. Logan, Captain Bayfield, and others ; and that, the 

 botanical (and zoological as well) region, essentially northern and Alpine, 

 designated by Professor Schouw that ' of saxifrages and mosses,' and 

 first in his classification, exists now only on the flanks of the great area 

 which suffered such conditions ; and that, though similar conditions 

 re-appear, the relationship of Alpine and Arctic vegetation in the 

 southern hemisphere, with that in the northern, is entirely maintained 

 by representative, and not by identical species (the representative, too, 

 being in great part generic, and not specific) ; the general truth of my 

 explanation of Alpine floras, including identical species, becomes so 

 strong, that the view proposed acquires fair claims to be ranked as a 

 th&ory and not considered merely a convenient or bold hypothesis." 



