Section V.

Other Lectures and Addresses.

Weariness.

Extract from Rede Lecture on "Weariness," delivered before the members of the University of Cambridge by Sir Michael Foster, Professor of Physiology :—" What is true of distress is true also of simple weariness. . . . Even in muscular work the weariness is chiefly one of the brain; and we are all familiar with a weariness of the brain in causing which the muscles have little or no share. All our knowledge, as I have said, goes to show that the work of the brain, like the work of the muscles, is accompanied by chemical change; that the chemical changes, though differing in details, are of the same, order in the brain as in the muscle: and that the smallness of the changes in the brain as compared with those of the muscle is counterbalanced or more than counterbalanced by the exceeding sensitiveness of the nervous substance. A loss of living capital, or the presence of the products of work which would have no appreciable effect on a muscle, may wholly annul the work of a piece of nervous machinery. If an adequate stream of pure blood, of blood made pure by the efficient co-operation of organs of low degree (stomach, lungs, kidneys, heart, etc.), be necessary for the life of the muscle, in order that the working capital may be rapidly renewed and the harmful products rapidly washed away, equally true, perhaps even more true, is this of the brain. Moreover, the struggle for existence has brought to the front a brain ever ready to outrun its more humble helpmates; and even in the best regulated economy the period of most effective work, between the moment when all the complex machinery has been got into working order and the moment when weariness begins to tell, is bounded by all too narrow limits. If there be any truth in what I have laid before you the sound way to extend those limits is not so much by rendering the brain more agile as by encouraging the humbler helpmates so that their more efficient co-operation may defer the onset of weariness."