Page:Popular Science Monthly Volume 58.djvu/533

Rh merely that of chance, and not chance plus the influence of the former pleasure-giving activity. The turtle happened to crawl over the edge of the incline, and, finding that this enabled it to get to the nest quicker, it continued the act, thus forming a habit.

Such experiments as these give clear pictures of habit formation in animals. They also furnish a means of measuring with considerable accuracy the rapidity of the process, the degree of intelligence and the permanence of associations, thus making possible a comparison of the mental abilities of different animals.