Page:Popular Science Monthly Volume 70.djvu/82

78 in the field of comparative psychology. For the first time in the history of thought, we have both a scientific and a philosophic public sentiment ripe for a serious attempt at a correlation in scientific channels of mental and physical evolution and of mind and body in the broader view.

But how imperfectly are we able to enter into the inner life of even the higher animals whose minds are most like our own! And yet, who knows how many of the powerful, though subconscious springs of our own impulse and motive may lie concealed in inherited vestiges of long-vanished and far more remote ancestral mental powers? Who knows what may be the mental life of a catfish, whose barbels and whole outer body surface are covered with organs of taste and whose gustatory nerves and centers are the biggest in the brain, or of a shark which has an elaborate system of sense organs (the lateral line canals), totally unknown to our own experience, which reach the extreme dimensions of the body and serve as a sort of intermediary apparatus between the organs of touch and the labyrinth of the ear, which is likewise highly developed, though the fish is apparently nearly or quite deaf?

The first task of comparative psychology, then, is to define as accurately as we may with the imperfect means at command the sensori-motor life of the whole range of lower organisms. And this task is fortunately not only approachable, but intrinsically attractive to every lover of nature. The study in field and laboratory of the sensory life of animals, while not all of comparative psychology, is a necessary introduction to its larger correlations and is receiving a rapidly increasing attention by naturalists of all schools; for the development of a true comparative psychology is, as we have seen, bound up with some of the greatest of the current movements in both science and philosophy.