| → as the warmth increased and the snow still further disappeared, higher and higher, 1866 1869 1872 |
| higher and higher, as the warmth increased, 1859 1860 1861 |
|
| → together in a body 1866 1869 |
| in a body together 1859 1860 1861 |
| together 1872 |
|
| → European and North American lowlands, 1866 |
| lowlands of the Old and New Worlds, 1859 1860 1861 |
| European and North American lowlands, would again be found in the arctic regions of the Old and New Worlds, 1869 1872 |
|
| → would be found in the arctic regions of the Old and New Worlds, and isolated on many mountain-summits far distant from each other, having been exterminated on all lesser heights. 1866 |
| would be left isolated on distant mountain-summits (having been exterminated on all lesser heights) and in the arctic regions of both hemispheres. 1859 1860 1861 |
| and on many isolated mountain-summits far distant from each other. 1869 1872 |
|
| → first migration when 1866 1869 1872 |
| migration as 1859 1860 1861 |
|
| → formerly permitted their 1866 1869 1872 |
| permitted their former 1859 1860 1861 |
|
|
the productions of the more temperate regions. And as the snow melted from the bases of the mountains, the arctic forms would seize on the cleared and thawed ground, always
→as the warmth increased and the snow still further disappeared, higher and higher,
whilst their brethren were pursuing their northern journey. Hence, when the warmth had fully returned, the same
species, which had lately lived
→together in a body
on the
→European and North American lowlands,
→would be found in the arctic regions of the Old and New Worlds, and isolated on many mountain-summits far distant from each other, having been exterminated on all lesser heights.
|
|
| Thus we can understand the identity of many plants at points so immensely remote as
the mountains of the United States and
Europe. We can thus also understand the fact that the Alpine plants of each mountain-range are more especially related to the arctic forms living due north or nearly due north of them: for the
→first migration when
the cold came on, and the
on the returning warmth,
generally have been due south and north. The Alpine plants, for example, of Scotland, as remarked by Mr. H. C. Watson, and those of the Pyrenees, as remarked by Ramond, are more especially allied to the plants of northern Scandinavia; those of the United States to Labrador; those of the mountains of Siberia to the arctic regions of that country. These views, grounded as they are on the perfectly well-ascertained occurrence of a former Glacial period, seem to me to explain in so satisfactory a manner the present distribution of the Alpine and Arctic productions of Europe and America, that when in other regions we find the same species on distant mountain-summits, we may almost
without other evidence, that a colder climate
→formerly permitted their
|
