Abstract
LONDON Royal Society, Jan. 26.—J. Z. YOUNG: Comparative studies on the physiology of the iris. (1) Selachians (second paper)— Uranoscopus and Lophius. The sphincter iridis muscle of Scyllium, Mustelus and Trygon contracts in direct response to illumination and is not under nervous control. The iris of Lophius piscatorius and also that of Uranoscopus is capable of rapid movements under nervous control, the oculomotor dilating and the sympathetic constricting the pupil.—S. G. PAINE, F. L. LINGOOD, FREDA SCHIMMER and T. C. THRUPP: The relationship of micro-organisms to the decay of stone. Three groups of bacteria have been distinguished. In the first group are included common organisms of air, soil, and water. These organisms are capable of living on a variety of food materials, and in their metabolism acid substances are formed as waste products; these acids, even when the food supply is merely the small amount of organic matter present in rain water, can dislodge carbon dioxide from its combination with calcium in the stone. In the second group some confirmation is to be found of the view of Marsh that nitrifying bacteria can be responsible for stone decay. In the third group are the sulphur oidising organisms which have been found closely associated with white incrustations of sodium and calcium sulphate on the surface of decaying stones.—W. J. ELFORD: The principles of ultra-filtration as applied to biological problems. The several factors concerned in the general process of filtration have been investigated, using typical disperse systems— colloidal dyes, metal sols, protein solutions and suspensions of bacteria and viruses. The relationship between the size of retained particles and the estimated pore sizes of membranes is also discussed. The fact that, for colloidally dispersed systems, the pore-size of the limiting membrane is definitely greater than the size of the retained particle, even under optimum filtration conditions, is in accordance with theoretical expectations. The particle sizes of suspensions, estimated from filtration experiments with carefully graded collodion membranes, agree well with the values obtained by other methods. The method of analysis adopted has proved of great value in virus studies.
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Societies and Academies. Nature 131, 178–180 (1933). https://doi.org/10.1038/131178a0
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DOI: https://doi.org/10.1038/131178a0