According to the now almost universally accepted theory, all the races of mankind had a common origin.

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

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

The geysers and hot springs of the Yellowstone are another proof of recent volcanic activity.

We are learning, too, that the love of beauty is one of Nature's greatest healers.

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