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Societies and Academies

Nature volume 85, pages 126130 (24 November 1910) | Download Citation

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LONDON. Royal Society, November 17.—Sir Archibald Geikie, K.C.B., president, followed by Mr. A. B. Kempe, vice-president, in the chair.—Harold Wager: The effect of gravity upon the movements and aggregation of Euglena viridis, Ehrb., and other micro-organisms. Euglena viridis and some other micro-organisms, when placed in shallow vessels or narrow tubes in the dark, become aggregated into peculiar network-like patterns or more or less well-defined groups. In a narrow tube, placed horizontally in the dark, the aggregation takes the form of a series of groups which look like green bands crossing the tube from one side to the other. Each group shows a constant cyclic up and down movement, the denser central region moving downwards under the influence of gravity, and a lighter peripheral area consisting of organisms moving upwards, mainly by their own activity. The aggregation depends upon the number of organisms present, their activity, and the depth of the vessel in which they are contained, and may persist with its regular cyclic movements for several days. The downward movement appears to be a purely mechanical one, dependent upon the specific gravity of the organism, and is not due to a stimulus which evokes a physiological response, as in geotropism or geotaxis. The upward movement is, on the other hand, due partly to the activity of the organisms themselves, partly, no doubt, to the upward currents set up in the liquid by the friction of the downward-moving stream. The upward movement.of Euglena is more or less vertical, and appears to be controlled, so far as the orientation of its elongate body is concerned, by the action of gravity. The aggregation resembles the cohesion figures produced when fine sediments are allowed, under certain conditions, to settle down slowly in a liquid, and are probably brought about much in the same way. The movements of certain microorganisms are apparently controlled, therefore, in a purely mechanical fashion by gravity, combined with cohesive forces, and this is of advantage to species which, like Euglena, are often found in large numbers in a confined space, in that it prevents their accumulation in such dense masses as would be likely to interfere with their assimilatory and respiratory functions.—Miss Jean White: The proteolytic enzyme of drosera.—L. S. Dudgeon, P. N. Panton, and H. A. F. Wilson: The influence of bacterial endotoxins on phagocytosis (including a new method for the differentiation: of bacteria). Second report. The authors have failed to demonstrate in any of their experiments,an action of the endotoxic substances on the leucocytes, and experiments. leading to similar results were obtained by allowing bacteria to be exposed to the action of the specific endotoxic substances. They confirm the results published in the first communication, that the phagocytic result is dependent upon the interaction of endotoxin of serum. They have shown in the case of normal serum that the amount of phagocytosis permitted when bacteria and endotoxin interact is not related to the amount of hæmolytic complement present. The action of endotoxin appears to be specific even with bacteria so closely related as the typhoid and paratyphoid family. These results strongly suggest that this method can be employed for the differentiation of bacteria. The amount of endotoxin has been shown to be strongly thermostable.—S. B. Schryver: Some investigations on the state of aggregation of matter. Parts I.–III. Part I. The action of salts in heterogeneous systems and the nature of the globulins.—When complex substances, such as those which form colloidal solutions, enter into chemical reaction, the ordinary laws of chemical mass action are not always obeyed, the deviations therefrom depending upon the medium in which the reaction takes place. These are due to the adsorption of molecules from the medium on the surface of the large molecules of the colloid, which sterically inhibit chemical reaction. These conclusions were deduced chiefly by the study of the action of formaldehyde on Witte's peptone, whereby a methyleneimino derivative is formed, which readily, either by polymerisation or condensation between two molecules, forms an insoluble complex. The formation of this complex is inhibited by the presence of salts, the inhibitory action of a series of which has been quantitatively measured. The degree of inhibition was found to depend, in the case of monobasic sodium salts, on the physical properties of their aqueous solutions. The lower the surface tension and the lower the viscosity of the solutions, the greater the inhibitory action. The effect of surface tension could be deduced from the general study of adsorption phenomena, whilst the effect of viscosity could be deduced by the extension of the generalisations of Whitney and Noyes, and of Nernst as to the reaction rates in heterogeneous systems. The globulins, which are insoluble in water but soluble in salt solutions, are assumed to be complexes formed by the action of a basic group in one molecule with an acid group in another, by means of which a salt is formed, which undergoes slight but definite hydrolytic dissociation in the presence of water. In the presence of most salts, owing to adsorption by the dissociated globulin molecules, hydrolysis proceeds further than in presence of water alone, with the consequence that more globulin is dissociated and “dissolved.” The solvent action of the salts here again depends upon the surface tensions of the solutions. Salts exert also a similar action in other heterogeneous systems in bringing about disaggregation, and the differences of solubility of various crystalline substances in salt solutions can be thereby explained. The physical constants of the salt solutions employed, and the solubilities of edestin and serum globulin in these solutions, are given. Part II. The action of formaldehyde on Witte's peptone.—The experimental details of this investigation are given. It is shown that the insoluble precipitate, formed by the interaction of the solutions, is derived chiefly from the more complex polypeptides. Part III. The solubility of phenol and certain crystalline substances in salt solutions.—The deductions as to the action of salts in heterogeneous systems are illustrated by the determination of the critical solution temperatures of phenol and salt solutions, which is a function chiefly of the surface tensions of the latter, and of the solubility of the following substances in salt solutions:—d-l-Meucine, d-l-phenylalanine, caffeine, benzamide, and p-toluidine. The solubilities are affected by both the surface tensions and viscosities of the solutions.—F. W. Twort: A method for isolating and growing the lepra bacillus of man. Experiments were undertaken to obtain a method whereby the lepra bacillus of man and allied bacilli might be cultivated outside the body on artificial media. The material tested was obtained from a typical leper. Cultivations were made on ordinary laboratory media and on media containing extracts from animal organs and tissues; these gave negative results. In view of the close relationship between the tubercle bacillus and the lepra bacillus, it appeared highly probable that these two micro-organisms would require the same chemical substances for building up their protoplasm which could be elaborated from the ordinary media only by the tubercle bacillus. It was thought that if these substances could be supplied already formed to the lepra bacillus it might grow, and the easiest method of supplying these substances would be by adding to some good medium the ground-up bodies of the tubercle bacilli containing them; accordingly a medium was made as follows:—egg three parts, 0.8 per cent. sodium chloride one part, ground tubercle bacilli 1 per cent., and glycerine 5 per cent. or less, mixed, placed in tubes, sterilised, and set in slopes. Leprosy material was placed in 2 per cent. ericolin to kill contaminating micro-organisms, and then inoculated on the tubercle medium. On this the lepra bacillus grew very slowly as a delicate, colourless streak along the inoculated track, and showed the typical morphological and staining characters of the lepra bacillus; the bacillus could be sub-cultured only on the tubercle medium. Experiments will be made to prepare a lepra vaccine and to grow the lepra bacillus of rat. In conjunction with Mr. Ingram, the author has also succeeded in growing the bacillus found in Jöhne's disease of cows. It grows on the same medium, much like lepra bacillus, but somewhat faster. It is hoped soon to prepare a diagnostic vaccine for Jöhne's disease.—G. J. Fowler, E. Ardern, and W. T. Lockett: The oxidation of phenol by certain bacteria in pure culture. The investigation described in the paper arose out of a detailed examination of the effect of various antiseptic substances, including phenol, .in bacterial sewage filters. It was found that the phenol apparently exerted a selective action on the bacteria present in the filter, only very few types appearing in the filtrate, more especially a liquefying organism (B. liquefaciens fluorescens) and a chromogenic organism.. Pure cultures of these organisms were made, the medium generally used being ordinary peptone broth. The general method of experiment was to bubble air, under sterile conditions, through an aqueous solution of phenol to which a few c.c. of the culture were added. The strengths of phenol solution used varied from 8.4 to 16.5 parts phenol per 100,000 of water, and were determined by the oxygen absorbed from standard acid permanganate solution in three minutes. It was found that B. liquefaciens had no action, or only a very slight one, on phenol, even after exposure of a month or more, while on introduction of the chromogenic organism the phenol content diminished, slowly at first, and then, in two or three days, completely disappeared. In a final experiment, a solution was made use of containing 10 parts per 100,000 of phenol, together with the following ingredients:—

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https://doi.org/10.1038/085126a0

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