STEPPES OF ASIA AND AMERICA 55 
almost throughout till man interfered, though the steppe 
region of Asia is continued into it through Southern 
Russia and part of Hungary. We find then that since 
the close of the glacial period Europe has been con- 
tinually liable to incursions of steppe animals from 
Asia, some of which, like the hamster, have kept their 
hold, while others, like the saiga antelope, rapidly 
died out. 
Another character of the animals of the temperate 
steppe is the prevalence of hibernation among them. 
The tundra is too cold for hibernation to be practised 
to any great extent, and the shelter and presence of 
food even in winter in the forest makes it relatively 
infrequent there. But the animals of the steppe can 
- only find in burrows and in sleep protection against 
want of food and extremes of temperature, so that here 
both aestivation and hibernation may occur. The 
squirrels in the fir woods wake whenever the temperature 
rises in winter, just as the fir-tree itself becomes active 
whenever the temperature permits. But the plants of jj. 
the steppe disappear beneath ground so soon as their * 
brief period of activity is over, and their quiescence is 
reflected in that of many of the steppe animals. 
Large areas of land almost devoid of trees, and 
clothed, at least at times, with grasses and herbs, occur 
in many other temperate regions besides Asia and 
South-eastern Europe. A great area of land of this 
type extends from the border of the Canadian forest 
southwards through the United States in the region 
west of the Mississippi river, nearly to the Gulf of 
Mexico. Similar areas occur in the Argentine and in 
Patagonia in South America, in South Africa, and in 
the south-eastern part of Australia. By extension the 
term steppe can be applied to all these regions, and 
