Abstract
LONDON. Royal Society, June 13.—W. S. Stiles: The scattering theory of the effect of glare on the brightness difference threshold. The theory that the observed increase in the threshold due to the presence of a glare source in the field is caused by light scattered in the eye media, is formulated mathematically. Deductions from it are not in accord with observation. The general conclusion is that the scattering effect can play only a subsidiary part in increasing the threshold.—Grace Briscoe and Winifred Leyshon: Reciprocal contraction of antagonistic muscles in peripheral preparations, using flashing neon lamp circuit for excitation of nerve. Controlled and co-ordinated rhythmic movements of a limb, closely resembling natural movements, are produced by suitable artificial stimulation of cut efferent nerves. If during this controlled rhythmic movement the mechanism producing phasic variation is stopped at any point, the limb remains held in posture. The method of stimulation is thus adequate for both movement and posture. An analysis of the forces controlling movement shows that the control of relaxation is as important for smooth co-ordination as the control of contraction.—T. Moran: Critical temperature of freezing living muscle. Up to 40 per cent of the water in amphibian muscle can be removed by freezing or drying, and its original state completely recovered by restoring water. On removal of 78 per cent, the muscle immediately dies. The critical water removal of 78 per cent corresponds to the freezing of the muscle to equilibrium at about –2° C. Muscles frozen to equilibrium below –2° C. undergo marked changes on thawing.—E. C. Smith: The formation of lactic acid in muscles in the frozen state. Freezing (that is, drying) upsets the balance, making production exceed removal. This upset is due to, or accompanied by, injury to the mechanism. Below -1-6° C. the mechanism of removal is destroyed, that of production persisting. Is the mechanism of removal the ‘living’ part?—F. M. L. Sheffield: Chromosome linkage in Oenothera, with special reference to some F. hybrids. Most results can be brought into line with Cleland's hypothesis-absence of pairing due to lack of harmony between homologues. Chromosome linkage may be inherited as a genetic character.—A. C. Downing and A. V. Hill: A new thermopile for the measurement of nerve heat-production.—A. V. Hill: The heat-production and recovery of crustacean nerve. The heat-production of crab's nerve in response to maximal excitation is at least 2-5x 10˜3 calorie per gram of moist nerve per second of stimulus. This is 33 times as great as in frog's nerve. The crab's nerve is highly fatiguable. The initial process, completed during stimulation, yields only about 2J per cent of the total heat: the recovery process, lasting for 25 minutes at 16° C., supplies the rest. In respect of fatiguability and of oxygen requirement a crab's nerve probably presents a closer analogy to certain characteristics of the central nervous system than does a frog's sciatic.
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