Thus the races, though alike in their physical response to climate, may possibly be different in their mental response because they have approached America by different paths.

No part of the world can be truly understood without a knowledge of its garment of vegetation, for this determines not only the nature of the animal inhabitants but also the occupations of the majority of human beings.

In America the most widespread type of forest is the evergreen coniferous woodland of the north.

Except on their southern borders the great northern forests are not good as a permanent home for man.

Although farming of any sort was almost as impossible in the plains as in the dry regions of winter rains farther west, the abundance of buffaloes made life much easier in many respects.

History in its broadest aspect is a record of man's migrations from one environment to another.

As a matter of fact, an ordinary desert supports a much greater variety of plants than does either a forest or a prairie.