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Societies and Academies

Nature volume 92, pages 440443 (11 December 1913) | Download Citation

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LONDON. Royal Society, December 4.—Sir William Crookes, CM., president, in the chair.—Sir Francis Darwin: A method of studying transpiration. The method is to close the stomata by coating the surface of the leaf with vaseline or some other grease, and then to place the intercellular spaces in connection with the outer air by cutting the leaf into strips. It is found by experience that such leaves transpire at rates comparable to those observed in natural leaves, and that they appear to behave normally in relation to external influences. In the present paper the effect of the relative humidity of the air is considered.—Sir Francis Darwin: The effect of light on the transpiration of leaves. The object of the research was to get a general idea of the differences in transpiration produced by alternate periods of diffused light and darkness. The experiments were made on the laurel (Prunus laurocerasus) and the ivy (Hedera helix), either by weighing or with the potometer. The results proved variable, and only by taking an average of a considerable number of experiments were figures of any sort of value obtained. For Prunus the average transpiration-rates' in light and darkness are as 132: 100; for ivy the figures are 136: 100.—Prof. J. B. Farmer and L. Digby: Dimensions of chromosomes considered in relation to phylogeny. It is not possible to maintain that the width of chromosomes is a feature constant for the large phyla of the animal kingdom, inasmuch as not only are there appreciable individual differences, but in closely related species, e.g. lobster and prawn, this difference amounts to at least 60 per cent.—J. H. Mummery: The process of calcification in enamel and dentine. Although much has been written on the calcification of teeth, the actual mode of deposition of the lime salts has been very little investigated. The author shows that both in dentine and enamel the lime salts are deposited in the globular form, despite the chemical composition of the finished tissues.—A. Compton: The optimum temperature of salicin hydrolysis by enzyme action is independent of the concentrations of substrate and enzyme. The optimum temperature of the enzyme in question is independent alike of the concentration of the substrate and of the concentration of the enzyme.—C. F. U. Meek: The ratio between spindle lengths in the spermatocyte metaphases of Helix Pomatia.—Dr. A. P. Laurie, W. F. P. McLintock, and F. D. Miles: Egyptian blue. The purpose of the research is to decide the exact conditions under which the blue, manufactured and used in Egypt from the fourth dynasty to classical times, is produced, and to clear up the doubts as to its nature and constitution. The results of the investigation are to confirm the conclusion come to by Fouqu6 that the blue is a double silicate consisting principally of calcium and copper, but.in which these metals can be partially replaced by alkalies. When soda, lime, and cooper carbonate are heated with an excess of sand, a green glass is formed round the quartz particles at about 800° C. At about 8400 the double silicate begins to crystallise out of this magma, again completely dissolving to form a green glass at 8900 C. The discovery of this compound by the Egyptians is doubtless due to their practice of glazing small articles carved out of sandstone with a green copper glaze.

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https://doi.org/10.1038/092440a0

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