Page:Popular Science Monthly Volume 64.djvu/347

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HE study of the conditions and changes in the tissues of human beings as they pass beyond middle age would seem at first sight to be of wide-spread interest. Upon the very simplest presentation of the matter it will be universally admitted to be of the greatest importance. The first principle of economics is not so much what we win in any line of industry as what we save; this is the essence of the conservation of values. What matters it how well the child is provided with opportunities for growth and how excellently the young adult is developed in the fullness of such strength as is compatible with individual opportunity; how high a degree of efficiency, mental or physical, can be attained, if all this is to last but for a few brief years of practical utility? Again, allowing ourselves to indulge in a more selfish view, what does it profit us if we shall acquire place and power and the means by which we may be able to enjoy life, as we have learned to live it through years of experience and the exercise of careful choice, if we are to become speedily cut off from the continuance of the enjoyment of those privileges the product of matured judgment and the full energizing of our powers? It is to me a remarkable, indeed an astonishing, fact in searching for data on the subject of senility which one would naturally assume to have grown up in the enormous field of medical literature, that so little is to be found bearing on this subject. There are here and there references to old age and the phenomena of senility in a few of the standard works on physiology, far fewer than the subject would seem to warrant. The subject does not seem to have aroused much interest in the great authorities on medicine, although there are some crisp and vigorous articles which are valuable and interesting.

My own studies have been most largely in the line of growth and development of children and yet interest by no means ends there, and my attention has been drawn to this matter through a constant study based upon part medical research and part individual interest in the whole question of bodily development and the possibilities which lie in this direction for the advance of individual efficiency in all periods of life. It has seemed that the phenomena of degeneration are present in most disturbances referable to those of the nerves and their centers where the analogue of senile changes constantly appears.