Societies and Academies

    Abstract

    LONDON. Royal Society, June 9.—Prof. C. S. Sherrington, president, in the chair.—Prof. C. S. Sherrington: Break-shock reflexes and “supra-maximal” contraction-response of mammalian nerve-muscle to single-shock stimuli. The maximal twitch-contraction of tibialis anticus muscle (cat) evoked by a single break-shock applied to the cut motor nerve exceeds the contraction evoked reflexly (spinal preparation) by a single break-shock applied to an afferent nerve. This is due to the reflex response being tetanic in nature. if the break-shock is strong it excites, even when applied to the motor nerve, a response of tetanic quality. The so-called “over-maximal twitch,” now termed “supra-maximal response,” is a response of this kind. A reaction of like kind probably obtains in the afferent nerve when the single-shock applied to it is of comparably high value. In this case there is also a tetanic reaction from afferent nerve-fibres themselves. With weaker break-shock stimuli the origin of the tetanic character of the reflex discharge lies in the centre itself. It arises there from a “charge” process which is relatively long-lasting in comparison with the cycle of a nerve-impulse, and increases in intensity and duration with the number of afferent fibres excited.—R. J. Ludford and J. B. Gatenby: Dictyo-kinesis in germs-cells, or the distribution of the Golgi apparatus during cell-division. Maturation mitoses in the germ-cells of Cavia, Mus, Helix, Limnæa, and Stenobothrus were examined. In all cases the Golgi apparatus breaks up into its constituent granules, and these are distributed haphazardly to the two daughter-cells at mitosis. In no case examined are they divided between the daughter-cells as equally as are the chromosomes. Hence the Golgi apparatus takes no important part in the transmission of factors from cell to cell.—Dr. F. W. Edridge-Green: The effect of red fatigue on the white equation. A white equation is formed fry means of a mixture of a red of λ6670–6770 A., a green of λ5144–5156 A., and a violet of λ4250–4267 A., matching a simple white. When the eye is fatigued with light viewed through a red glass, or with pure sp_ectral light in the region of λ6700 Å., and the equation is again made, about half the amount of green is required. The white equation and its match cannot be due to similar physiological processes, or both would change in the same ratio. When the fatiguing light is in the region of λ7800 Å., no difference is seen between the mixed and simple white.—E. Ponder: A method for investigating the hsemolytic activity of chemical substances. The relation between the time taken by a given quantity of hasmolytic substance and the temperature at which it acts is expressed by a hyperbola. The relation between the constants of such a hyperbola and the quantity of hsemolytic substance to which it applies are given. Certain general relations hold for all substances examined. Experimental and calculated results are compared.—W. H. Pearsall: The development of vegetation in the English lakes, considered in relation to the general evolution of glacial lakes and rock basins. The English lakes are of the same age (glacial), of similar origin, and lie among rocks possessing relatively uniform characters. The differences they show are due to variations in the rates of erosion and sedimentation of the lake basins; therefore it becomes possible to describe the stages in the post-glacial development of a rock basin, and also of its vegetation. The differences observed between primitive and evolved lakes are regarded as being dependent upon their physical condition.

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    Societies and Academies. Nature 107, 509–511 (1921). https://doi.org/10.1038/107509a0

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