Societies and Academies

Abstract

LONDON. Royal Society, January 14.—Leonard Hill and Y. Azuma: Effects of ultra-violet radiation upon involuntary muscle and the supposed physiological interference of visible rays. No physiological interference is produced by dark heat or visible rays with the exciting action. of ultra-violet on involuntary muscle. The action of ultra-violet rays antagonises that of adrenalin on involuntary muscle, but not that of emetin. The presence of calcium in the nutritive fluid is necessary for the increase of tone produced by ultra-violet rays.—I. de B. Daly: A closed-circuit heart-lung preparation; effect of alterations in the peripheral resistance and in the capacity of the circulation. A diminution in capacity of the systemic circulation produces the same effects qualitatively and quantitatively as an increase in the volume of circulating blood, namely, a rise in pressure in both auricles, the aorta and the pulmonary artery, and an increase in the cardiac output. An increase in peripheral resistance has an opposite effect. “Resistance,” “capacity ” and blood distribution effects are interdependent, their relative effects being determined by the physical constants of the circulation.—C. H. Best: On the effect of insulin on the dextrose consumption of perfused skeletal muscle. Insulin greatly accelerates the rate of sugar disappearance from defibrinated blood used to perfuse the isolated limbs of the cat. The action is attributable to its effect on the metabolism of the skeletal muscles.—T. S. P. Strangeways and Honor B. Fell: Experimental studies on the differentiation of embryonic tissues growing in vivo and in vitro, (i.) The development of the undifferentiated limb-bud (a) when subcutaneously grafted into the post-embryonic chick, and (b) when cultivated in vitro. —C. N. Long: Muscular exercise, lactic acid, and the supply and utilisation of oxygen. Pt. xiv. The relation in man between the oxygen intake during exercise and the lactic acid content of the muscles. In men, as well as in the isolated muscle, the rate of removal of lactic acid, as measured by the oxygen intake, is proportional to the square of the lactic acid concentration in the fluids which are in contact with the muscle fibres. Lactic acid apparently acts as a “governor of oxidation” in the recovery process of muscle.—K. F. Hetzel and C. N. Long: The metabolism of the diabetic individual during and after muscular exercise. Muscular exercise in the diabetic individual appears to be accompanied by the same metabolic changes as in the normal. Exercise increases the combustion of carbohydrate. For short periods of exercise, with insulin administered during the last 17 hours, the respiratory quotient of the excess metabolism is unity, exactly as in normal men: for exercise of moderate duration its value is intermediate, while for exercise of long duration it tends to fall towards that of the previous resting metabolism. In this respect the diabetic individual with recent insulin, on a diet poor in carbohydrate, behaves in a manner exactly similar to a normal man on a diet consisting mainly of fat, though the phenomena are more exaggerated. In a diabetic individual without insulin, the respiratory quotient of the excess metabolism is always low. It may be supposed that a muscle, for its oxidative processes in recovery from exertion, uses carbohydrate only; that in the presence of insulin there are stores of carbohydrate in a form readily available for use by the muscle, and that a short interval of exercise does not sufficiently deplete these stores to render an immediate restoration necessary from other substances in the body. In the absence of insulin, these ready stores of carbohydrate have run low. Prolonged muscular exertion, a diet poor in carbohydrate, and the absence of insulin, all produce the same effect, namely, a lowering of the respiratory quotient of the excess metabolism due to exercise. All these factors might be expected to deplete the stores of carbohydrate readily available.—W. G. Millar: The diffraction method of measuring the diameter of erythrocytes.