Alpine and Arctic Floras 
colonised again after the Ice Age disappeared. First 
the seashore, then the lowland hills and valleys, and 
finally the uplands were occupied, until it is only on such 
summits that one finds any hints as to the way in which 
it was done, 
In the arctic regions the tundra, which occupies so 
much of Siberia and of Russia and Lapland, is also a 
moss-covered, more or less peaty country, where the 
flowering plants are scattered about and isolated, form- 
ing an open flora. The conditions of life for these 
miserable stunted starvelings are extremely severe, and 
not at all easy to understand. 
A pathetic account by Middendorf is cited in 
Schimper’s classical work on plant geography.) “On 
the rq4th April I found myself on the Yenisei near 
Didino. . . . The landscape still lay buried in the 
deepest winter rest, and the clear shining of the sun, 
although it hardly sank below the horizon, could not 
even during the warmest hour of the day raise the 
temperature above 16° to 20° R. (20° to 25° C.) of frost. 
Before and after twelve o’clock, the thermometer regu- 
larly stayed at from — 23° to — 30° R. (— 29° to — 38°C.). 
I went out to observe the scene, Where the snow had 
sunk or been blown off by the wind, the projecting 
branches of willows had broken through and crunched 
like wax under my snow-shoes. They were frozen stiff, 
and one could see the icy sap where they broke off. 
Suddenly I stopped in amazement, for, peering out of 
the snow, but sometimes not more than 1} inch above 
its surface, were willow catkins, perfectly formed and of 
a shining, silvery white. The very twigs which pro- 
duced them were_in their lower part frozen hard at 
only 2 inches deep in the snow, and of course the 
stems, branches, and roots, deeply buried below the 
snow, were even more thoroughly frozen up.” 
g2 
