America forms the longest and straightest bone in the earth's skeleton.

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.

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.

Geologists are rapidly becoming convinced that the mammals spread from their central Asian point of origin largely because of great variations in climate.

The buffalo is a surprisingly stupid animal.

Man could not stay there forever. He was bound to spread to new regions, partly because of his innate migratory tendency and partly because of Nature's stern urgency.

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