INTRODUCTORY CHAPTER. 
45 
the Polar regions, including Greenland, the Polar 
American Islands, and probably much now-sub- * 
merged land in places connected or lying between 
Greenland and Scandinavia, at which time Greenland 
no doubt presented a much richer Scandinavian flora 
than it now does. On the accession of the glacial 
period this flora would be driven slowly southward, 
down to the extremity of the Greenland peninsula in 
its longitude, and down to the latitude of the Alle- 
ghanies and the White Mountains in their longitudes. 
The effect in Greenland would be to leave there only 
the more Arctic forms of vegetation unchanged in 
habits or features, the rest being, as it were, driven 
into the sea. But the effect on the American conti¬ 
nent would be to bring the Scandinavian flora into 
competition with an American flora that preoccupied 
the lands into which it was driven. On the decline of 
the glacial epoch, Greenland, being a peninsula, would 
be repeopled with plants only by the northward 
migration of the purely Scandinavian species, that had 
previously been driven into its southern extremity; 
and the result would be a uniform Scandinavian 
flora throughout its length, and this an Arctic one 
from north to south. But in America a very different 
state of things would supervene; the Scandinavian 
plants would not only migrate north, but ascend the 
