Psychoanalysis

Statistical Methods.—Biological, anthropological and statis tical methods are now being more formally utilized in medicine than in the past, and exact measurements and skilled calculations are being employed. An individual's constitution, or "the aggre gate of hereditary characters, influenced more or less by environ ment, which determines his reaction to the stress of environment," (G. Draper), was present to the mind of Hippocrates and others, but the rise of bacteriology diverted attention from the internal to the external factors of disease.

Applied Physiology.

Applied physiology was extensively developed and utilised during the war, for example in aviation, the transfusion treatment of surgical shock and haemorrhage, and the relief of gassing, and has advantageously been continued since on other lines, such as ventilation, the effects of sunlight and ultra violet rays on bacteria, infections, general health and rickets (see PUBLIC HEALTH). Following on the established value of open-air treatment of tuberculosis and other infections, the beneficial influ ence on bodily resistance induced by sunlight (heliotherapy) and ultra-violet rays has been utilised. Heliotherapy (q.v.), practised for 20 years at Leysin by Rollier in surgical tuberculosis, has been adopted in Great Britain. Sunlight prevents and cures rickets, and its relation to the anti-rachitic vitamin D is an addition to knowl edge, possibly of potential importance in connection with other "deficiency diseases." Ultra-violet rays act on a complex alcohol, cholesterol, present widely in the body and skin, in such a way as to confer on it the anti-rachitic action of the vitamin ; they also raise the amount of calcium, iron, iodine and phosphorus in the blood, increase its bactericidal power and accelerate the healing of wounds. The tungsten-arc and mercuric-vapour arc lamps are employed to provide artificial ultra-violet rays. Diathermy or the application of a special form of intensive heat has been employed in cancer, pneumonia and other infections. (See ELECTROTHER APY; SUNLIGHT TREATMENT; VITAMINS.) Biochemistry.—Closely associated with applied physiology, of which it is really a part, biochemistry (q.v.) has developed out of physiological chemistry and has risen rapidly to an authoritative position. At Cambridge the Sir William Dunn trustees have built and equipped a fine institute and endowed the professorship held by Sir Gowland Hopkins, who has 4o advanced students carrying out research under his direction. The Rockefeller Foundation,

New York, has provided similar laboratories at Oxford and Uni versity College, London.

Metabolism.—Biochemistry is specially concerned with the changes always going on in the body and described by the name metabolism. The basal metabolism means the average minimal chemical changes compatible with life taking place in the body during complete rest and when food is not being digested and absorbed, and corresponds with the minimal heat-production 18 hours after a meal of a mixed dietary—the working expenses, so to speak, of the resting body. This is estimated directly by measuring by respiratory calorimeters the heat evolved, or indirectly, and more easily in practice, by chemical analysis of the respiratory exchange, and has been shown to be remarkably constant in nor mal conditions. In disease the metabolic rate may be altered ; for example, in myxoedema it is lowered and all the vital processes are on a lower plane ; whereas in fever and exophthalmic goitre it is accelerated. In the last-named disease the condition of the patient can be judged by the degree of increase in the metabolic rate.

Vitamins.—The recognition of the accessory food factors or vitamins (q.v.) has opened a new chapter in nutrition and in the causation and prevention of disease. They are present in food in minute quantities, which greatly contrast with their power, and are essential for health, growth, especially of bone and teeth, and in other ways. New knowledge of the effects of their absence and of the (deficiency) diseases thus caused has accumulated, but more may be anticipated. The vitamins each have their special actions ; one prevents scurvy (anti-scorbutic), others rickets (anti-rachitic or vitamin D), beriberi or polyneuritis (anti-neuritic), and recently, it would appear, one is essential for normal reproduction, the absence of which, at least in female rats, produces sterility. Starvation, partial or complete, and an unbalanced diet entail a corresponding degree of avitaminosis and deficiency disease ; war or famine oedema, which resembles the "wet" form of beri-beri, has been ascribed to a diet largely composed of cereal and deficient in protein food.