For the source of any characteristic so widespread and uniform as this adaptation to environment we must go back to the very beginning of the human race.

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

The Negro, however, has been tested on an extensive scale.

A journey of four hundred and thirty miles can be made in any part of the United States, but in Turkey it takes as many days.

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

From first to last the civilization of America has been bound up with its physical environment.

The human organism inherits so delicate an adjustment to climate that, in spite of man's boasted ability to live anywhere, the strain of the frozen North eliminates the more nervous and active types of mind.