| → higher and higher, as the warmth increased, 1859 1860 1861 |
| as the warmth increased and the snow still further disappeared, higher and higher, 1866 1869 1872 |
|
| → in a body together 1859 1860 1861 |
| together in a body 1866 1869 |
| together 1872 |
|
| → lowlands of the Old and New Worlds, 1859 1860 1861 |
| European and North American lowlands, 1866 |
| European and North American lowlands, would again be found in the arctic regions of the Old and New Worlds, 1869 1872 |
|
| → 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 |
| 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 |
| and on many isolated mountain-summits far distant from each other. 1869 1872 |
|
| → migration as 1859 1860 1861 |
| first migration when 1866 1869 1872 |
|
|
south as the Alps and Pyrenees, and even stretching into Spain. The now temperate regions of the United States would likewise be covered by arctic plants and
and these would be nearly the same with those of Europe; for the present circumpolar inhabitants, which we suppose to have everywhere travelled southward, are remarkably uniform round the world. We may suppose that the Glacial period came on a little earlier or later in North America than in Europe, so will the southern migration there have been a little earlier or later; but this
no difference in the final result. |
|
| As the warmth returned, the arctic forms would retreat northward, closely followed up in their retreat by 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
→higher and higher, as the warmth increased,
whilst their brethren were pursuing their northern journey. Hence, when the warmth had fully returned, the same
species, which had lately lived
→in a body together
on the
→lowlands of the Old and New Worlds,
→would be left isolated on distant mountain-summits (having been exterminated on all lesser heights) and in the arctic regions of both hemispheres.
|
|
| 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
→migration as
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,
|
