Page:Popular Science Monthly Volume 81.djvu/174

168 restitution of the original bodies brought about. Physical conditions alone determine the direction taken by these "reversible reactions." This phenomenon suggests a possible explanation of the changes taking place in nerve cells and the relation they bear to the production and regulation of the nerve impulse.

Within the past decade biologists have discovered many facts that throw considerable light on the relation that the nervous system bears to the growth of the organism, and they have also arrived at certain conclusions of great importance in regard to the manner in which nerve cells grow. Portions of living tissues, nerve as well as muscle, or the supporting elements of the body may be removed and grown outside of the animal. Photographs taken at short intervals of nerve cells placed in various artificial media which are kept at the body temperature show a remarkable series of changes. In a comparatively few hours these cells may actually be seen to throw out long processes resembling the embryonic nerves.

A limited space does not permit more than a passing reference to the advances made, and largely by American investigators in the study of animal behavior. These newer methods of study, says a distinguished English scientist, "contrast with the anecdotal method of the past generation almost as pronouncedly as do modern chemical methods with those of the medieval alchemists." Modern biology with the inspiration derived from the physical and chemical laboratory has already brought new life into the discussion of such old questions as that of variation and inheritance in living beings. To answer the question "What are the traits inherited by our nervous systems?" we must follow the paths mapped out by the new biology. The way of the statistician has been followed until the new road offered by experiment is within our sight.

Posterity will, as we have already indicated, measure our intelligence by the interest we take in acquiring information in regard to the organs upon the functional development of which depend our continued existence as a race. In the various medical schools and hospitals throughout the country the problems connected with the human brain and nervous system will continue to be subjects that have an immediate claim upon the attention of physicians, but even in these institutions these questions should not be forcibly disassociated from the consideration of more fundamental biological phenomena. The possibility of extending the scope of the work carried on in the biological departments of our universities so as to facilitate and encourage investigations in the broad field of biological psychology would be an important factor in bringing these institutions into the closest touch with the subjects of most vital importance to humanity. But in addition a new type of institution dedicated to the study of neuro-biology is greatly needed. The Phipps Psychiatric Clinic in Baltimore will mark a new era in this