Abstract
LONDON. Royal Society, January 28.—Mr. A P. Kempe, treasurer, in the chair.—The action of the venom of Sepedon hacniachatcs of South Africa: Sir T. R. Frasor and Dr. J. A. Gunn.—The colours o and pigments of flowers, with special reference to genetics: Miss M. Wheldale. The communication gives an account of investigations made upon plant pigments, with a view to the elucidation of phenomena observed in the genetics of flower-colour. A primary classification is made into plastid pigments and pigments soluble in the cell-sap. Of the former, several kinds are snown to exist, in addition to carotin and xanthin. When the type of a species contains more than one plastid pigment, the power to produce each pigment is expressible as a Mendelian factor. Loss of the factors in turn gives rise to varieties of the type. Soluble pigments are classified as red-purple-blue (anthocyanin) and yellow (xanthein) and of both; various kinds can be differentiated by. means, of chemical reagents..There is evidence, moreover, of a relationship between the behaviour of the pigments in genetics and,their chemical reactions. Colourless tannin or glucoside-like substances arc found to be widely distributed in plants, and such substances appear to take part in the formation of some kinds of anthocyanin. This conclusion is based upon examination of pigments of varieties of Antirrhinum majus, of which the inheritance of flower-colour has been worked out by the author (previous communication to Roy. Soc.); the results of the present paper show that in this genus both a glucoside-like substance and a reddening factor are essential to the production of anthocyanin of the type. Loss of glucoside gives rise to an albino variety still capable of carrying the reddening factor; loss of the reddening factor gives a variety bearing ivory-white flowers, distinguishable from the albino, and containing the glucoside. Experiments on the same genus further indicate that the xantheic pigment of a yellow variety is a derivative of the glucoside of the ivory-white, to which it is also hypostatic. Examples are given of genera resembling Antirrhinum in their series of varieties derived from the anthocyanic type, and also of genera forming another series, from which the xantheic variety is absent. In this connection, stress is laid upon the conception of two forms of albinism, one due to loss of anthocyanin only, the other to loss of both anthocyanin and xanthein.—The variations in the pressure and composition of the blood in cholera, and their bearing on the success of hypertonic saline tran-sfusion in its treatment: Prof. L. Rogers. This communication contains some points of interest in physiology, pathology, and therapeutics. The blood of Bengalis has been found by Captain Mackay to contain a higher proportion of salts and a less proportion of red blood corpuscles than the blood of Europeans. The author has found that the blood pressure in the natives is lower than in Europeans, averaging about 100 millimetres of mercury. The pathological observations are that in cholera the enormous secretion of fluid into the bowel drains away the fluid part of the blood. There is a very definite relationship between the amount of fluid thus lost from the blood and the severity and mortality of the disease. Injections of normal saline solution (0.65 per cent. of NaCl) into the veins have an almost miraculous effect in relieving the symptoms and restoring the patient to apparent health. This improvement is, however, only transient, and in the course of a few hours the symptoms recur and the patients die. It occurred to the author that ii, instead of using a normal saline solution, he were to inject a hypertonic solution of 1.35 per cent. NaCl into the veins, there would be less likelihood of the diarrhoea recurring, and the blood being again drained of its fluid parts. The result of this treatment was extraordinary. It has simply revolutionised the results, so that, whereas formerly the recovery of a collapsed case was a surprise, its non-recovery is now a disappointment. In severe cases the proportion of chlorides in the blood falls below the normal, notwithstanding the great concentration of the blood from loss of water. He therefore sometimes uses a saline solution of 1.65 per cent., but usually 1.35 per cent. is sufficient. In bad cases the coagulability of the blood Is very greatly reduced, so that the author now generally adds 3 gr. of calcium chloride to a pint of saline solution. The development of uraemia in the reaction stage ol cholera is associated with a comparatively low blood-pressure; measures to raise it, such as the hypodermic administration of adrenalin and digitalis, are indicated for the prevention and treatment of this very serious complication.—The British fresh-water phytoplankton-, with special reference to the desmid-plankton and the distribution of British' desmids: W. West and G. S. West. The paper is in part a comprehensive summary of the known facts concerning the phytoplankton of British fresh waters. It has been possible to institute a close comparison between the British phytoplankton and that of continental Europe, proving that the British lakes are relatively richer in green algae and poorer in blue-green forms than the generality of continental lakes. The large percentage of green species in the British lakes is due, in most instances, to the dominance of desmids. Certain diatoms also stand out conspicuously, especially some of the large species of the Surirellaceæ. As the plankton investigations were not commenced until the authors had acquired a very extensive knowledge of the general British alga-flora, it has been a comparatively easy matter to see wherein the phytoplankton differs from the algae of the littoral region and of the bogs, &c. An extended study of the distribution of British desmids has shown that the rich desmid areas correspond (i) to a considerable extent with the areas of greatest rainfall, and (2) to a much closer extent with the outcrops of the older Palæozoic and pre-Cambrian strata. The really-rich desmid-floras only occur in those western and northwestern districts in which the geological formations are older than the Carboniferous, and these are likewise the districts in which the British lakes are situated. Therefore, the dominance of desmids in the phytoplankton is not so remarkable as might at first be supposed. Numerous dosmids arc continually washed from the drainage-areas into the limnetic region of the lakes, and some of them have become leading constituents of the phytoplankton, either with or without change of morphological characters. Many of them form a well-marked assemblage, the individual constituents of which are limited in their British distribution to the western lake-areas, although most of them occur in the lakes and bogs of Scandinavia on precisely similar outcrops of old rocks. It is suggested that perhaps the most important factor in this relationship is a chemical one, but, so far as observations have been made, ordinary chemical analysis of the drainage-waters has offered no clue to the solution of the problem.—The selective permeability of the coverings of the seeds of Hordeum vulgare: Prof. Adrian J. Brown. It has been pointed out previously (“Annals of Botany,” 1907, vol. xxi., p. 79) that the coverings of the seeds of barley act as an exceptionally perfect semi-permeable membrane, resisting the passage of acids, of alkalies, and of salts, but not of iodine. Experiments are now described from which it appears that not only strong electrolytes, but also dextrose, cane sugar, and other non-electrolytes are unable to penetrate the membrane. On the other hand, mercuric chloride and cyanide, but neither the nitrate nor sulphate, cadmium iodide, but not the chloride nor the sulphate, ammonia, acetic acid and several of its homologues, alcohol and ethylic acetate, are all capable of passing into the corns. Glycollic and lactic acids also pass in, but far less rapidly than acetic. The water-absorbing capacity of the seeds when immersed in various solutions has been contrasted with that of the seeds when placed in water alone. Far less water is absorbed from solutions of substances which do not penetrate the seed covering than from those containing substances which do. In the case of substances which diffuse readily into the corn, such as ammonia and ethylic acetate, the rate at which water passes in is much more rapid than from solutions of substances which do not penetrate the covering, or from water alone.—The origin of osmotic effects, ii., differential septa: Prof. H. E. Armstrong:. It is shown that the effects described by Prof. Brown may be explained in terms of the theory of the conditions of substances in solution recently communicated to the society by the author. Substances such as ammonia, acetic acid, &c., which exist in solution in a slightly hydrolated state, would pass the hydrolated surfaces of the intramolecular passages in the colloid membrane, whilst hydrolated solutes would be held back. The increased rapidity with which water enters in some cases is traceable to the effect which the diffusing; substance has in raising the osmotic stress in the water within the corn.
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Societies and Academies . Nature 79, 506–510 (1909). https://doi.org/10.1038/079506b0
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DOI: https://doi.org/10.1038/079506b0