Abstract
LONDON. Royal Society, June 30.—Sir Archibald Geikie, K.C.B., president, in the chair.—Prof. A. D. Waller: A new method for the quantitative estimation of hydrocyanic acid in vegetable and animal tissues. The method is colori-metric, and depends on the reaction between potassium cyanide and picric acid, first studied by Hiasiwetz (Liebig's Annolen, cx., p. 289 [1859]), and recently applied by Guignard to the detection of minute quantities of hydrocyanic acid (Annales Set. Pharmacol., 1906, p. 415) and by H. E. Armstrong to the rapid detection of emulsin (Proceedings, March 10). The colour-scale is prepared by mixing equal volumes of a recently titrated solution of 1/10000 hydrocyanic acid and of picrate mixture (equal volumes of 0.5/100 picric acid and 5/100 sodium carbonate). From this stock solution (T 50), after twenty-four hours in an incubator at 40°, a colour-scale is prepared by further, dilution with picrate mixture, to contain, e.g., 1, 2, 3, & c., parts of HCN per million, of tints T 1, T 2, T 3, & c. The estimation is made by matching the colour of the given fluid or of its distillate into picrate mixture (after suitable dilution if required), with that of the colour-scale. Thus, e.g., if the tint of a distillate from 10 c.c. of blood (dil. xs) into 25 c.c. of picrate is found = T 5, and the volume of picrate+distillate is 40 c.c., the amount of HCN in the distillate=5×40 millionths gram, i.e. 0.000200. A second distillation shows whether or no the whole of the HCN present has been taken over in the first distillate. Results of the application of the method to (1) a leaf of Prunus Laurocerasus; (2) the blood and tissues of a cat after death by a known amount of HCN; (3) the blood and tissues of a person “found dead.”—Prof. A. Dendy: The structure, development, and morphological interpretation of the pineal organs and adjacent parts of the brain in the tuatara (Sphenodon punctatus). The “pineal complex” consists of the dorsal sac, the paraphysis, the pineal sac (“epiphysis”), the pineal eye, the pineal nerves and their central connections. There is a well-developed choroid plexus, with special blood-supply, on the roof of the dorsal sac, possessing histological features of considerable interest. The paraphysis is a compound tubular gland, with special blood-supply, differing markedly in histological character from the choroid plexuses. Its lining epithelium forms a syncytium, and its opening, which, in the embryo, lies just in front of the commissura aberrans, becomes shifted upwards in the adult on to the anterior wall of the dorsal sac, by the formation of a “supra-commissural canal,” the original opening being blocked up by the anterior choroidal blood-vessels. The histological structure of the pineal sac points to a sensory rather than a glandular function. Its wall is essentially similar in structure to the retina of the pineal eye, consisting of radial supporting fibres, sense-cells, and ganglion-cells and nerve-fibres, and pigment may occasionally be deposited in it. The retina of the pineal eye consists of the same histological elements arranged in essentially the same way, with the sense-cells on the inside and the nervous elements in the middle. The pigment is not lodged either in the sense-cells or in the supporting fibres, but is brought into the retina by wandering pigment-cells. The pigment granules escape from these wandering cells on entering the retina, and stream inwards between the radially arranged elements. The inner ends of the sense-cells project into the cavity of the eye, and are covered each by a little cap, formed apparently by the internal limiting membrane of the retina. The developing lens of the pineal eye increases in size partly as a result of mitotic divisions in a marginal zone of undifferentiated cells. As they approach the centre the cells elongate, and some of them degenerate into a kind of mucus, which is secreted from the inner surface of the lens into the cavity of the eye, where it takes part in the formation of the vitreous body. This process of secretion continues in the adult. The nerve of the pineal sac is from its first appearance median. It joins the roof of the brain between the posterior and superior commissures. The nerve of the pineal eye is shown, especially by its development,to be primarily connected with the left habenular ganglion, which even in the adult has a different shape from that of its fellow of the opposite side. Both nerves persist in a well-developed condition throughout life. The view that the pineal sac and pineal eye are respectively the right and left members of a primitive pair of sense-organs, serially homologous with the lateral eyes, is strongly supported. Altogether six pairs of diverticula are given off from the fore- and mid-brain, viz. the cerebral hemispheres, the optic vesicles of the lateral eyes, the recessus thalami prenucleares, the pineal sense-organs, the recessus geniculi, and the optic lobes. These may all be serially homologous with one another, and each may possibly indicate a separate neuro-mere. There is no commissura mollis and no unpaired plexus medianus in the third ventricle. Reissner's fibre and the sub-commissural organ are very well developed.— J. A. Crowther: The scattering of homogeneous β rays, and the number of electrons in the atom, (1) The scattering of a homogeneous pencil of β rays has been measured for various substances and for rays of different velocity. It has been shown to obey the following statistical laws:— (i) for rays of given velocity the intensity I of the radiation contained within a given cone may be expressed by the equation I/I2 = I–ek/t where t is the thickness of material passed through, and k a constant depending upon the angle of the cone; (ii) for rays of given velocity the most probable angle of emergence is proportional to the square root of the thickness of material traversed by the rays; (iii) for rays of different velocities, the probable angle of emergence divided by the square root of the thickness traversed is inversely proportional to the product of the mass of the incident β particle into the square of its velocity. (2) From equations given by Sir J. J. Thomson, the number of elections contained in atoms of different elements is deduced. It is thus found:—(i) that the ratio of the number of electrons per atom to the atomic weight is constant, the ratio being very nearly 3.0 for all the elements examined; (ii) that the positive electricity within the atom is not in an electronic condition, but is distributed fairly uniformly over the space occupied by the atom. (3) Experiments are described on the absorption of homogeneous β rays. It is shown that the first stage in the absorption of a pencil of homogeneous β rays consists in the scattering of the rays according to the laws already considered. The absorption of the completely scattered radiation is then shown to take place according to an exponential law.—F. Isaac: The spontaneous crystallisation and the melting- and freezing-point curves of mixtures of two substances which form mixed crystals and possess a minimum or eutectic freezing point.—Mixtures of azo-benzene and benzylaniline. The results obtained in this research may be thus summarised:—(1) The freezing- and melting-point curves for mixtures of azobenzene and benzyl-aniline have been determined, and it has been shown that these substances possess a minimum or eutectic point at 26° for the mixture containing 19 per cent, azobenzene and 81 per cent, benzylaniline, and form a series of mixed crystals on one side only of the eutectic, viz. that with excess of azobenzene. This is, therefore, a limiting case of Roozeboom's Type 5, in which two substances, A and B, possess freezing- and melting-point curves which exhibit a minimum eutectic point, and form two series of mixed crystals, i.e. mixed crystals containing excess of A, and mixed crystals containing excess of B. (2) The melting-point curve has been confirmed by actual analysis of the mixed crystals. (3) The supersolubility curve, or curve of spontaneous crystallisation, has been determined for these mixtures by two methods:—(i) by noting the temperature at which a liquid mixture of known composition crystallises spontaneously in a sealed tube; (ii) by noting the temperature at which a known liquid mixture attains its highest refractive index and gives a dense labile shower when placed in the trough of the inverted goniometer. It has been shown that each mixture possesses a definite temperature of spontaneous crystallisation. The supersolubility curve shows a minimum for liquids having approximately the eutectic composition, and runs approximately parallel to the freezing-point curve. It crosses the melting-point curve three times. The nature of the mixed crystals which first separate spontaneously from any liquid mixture on the supersolubility curve has been investigated. The composition of such crystals has been determined by separating them from their mother liquor and finding their melting points. (5) A few thin sections have been ground from the solid mixtures in the neighbourhood of the eutectic, and their structures examined. These structures do not appear to be permanent. After the lapse of some months they completely changed, new crystal needles appearing all over the sections. These changes, however, appear to be very gradual, and to take place with change of temperature.—E. C. Snow: The determination of the chief correlations between collaterals in the case of a simple Mendelian population mating at random. This paper investigates the values which should hold for the correlations between (a) siblings, (b) uncle and nephew, and (c) first cousins, on the Mendelian hypothesis of “unit-characters.” The correlations both for gametic and somatic characters are found. For the former, values independent of the distribution of the dominant and recedant characters among the population are obtained. These are (a) 0.500, (b) 0.250, and (c) 0.250. In the case of the somatic correlations, however, the results depend upon the relative numbers of the population possessing the dominant and recedant attributes before crossing. By varying this proportion, different values of the correlations can be obtained, but these are always less than the corresponding gametic ones stated above. The investigation brings out the important point that, on the Mendelian theory of heredity, the similarity between first cousins is quite as close as, or closer than, those between uncle and nephew. Biometric results previously reached have pointed to the same conclusions. This is of great interest from the medical point of view. In medical diagnosis, a man's uncles and aunts, but not his cousins, are generally considered; but the results of the present paper show that his cousins, usually more numerous, give just as good a knowledge of his constitutional tendencies as do his uncles and aunts.—C. J. T. Sewell: The propagation of sound in a fog. This paper is intended as a sequel to the author's previous paper on “The Extinction of Sound in a Viscous Atmosphere by Small Obstacles of Cylindrical and Spherical Form,” in which the loss of energy from the primary waves owing to viscosity was investigated. In the present paper the author has included the additional loss of energy due to heat conduction. The work proceeds on much the same lines as before, and the results obtained are of the same order of magnitude. The chief interest consists in the application of the results to the effect of atmospheric tog upon the propagation and audibility of sound. Waves of high frequency suffer most. If the diameter of the drops of water in a dense fog is assumed to be 0.02 mm., and the density of the fog amounts to 41/2 grams per cubic metre, the intensity of sound of wave-length 100 cm. is reduced in the ratio of I to e before the sound has travelled a distance of 100 metres. If the wave-length is 1000 cm., this distance is increased to about 350 metres. In any case, the results seem to show that the presence of fog at sea must diminish quite appreciably the audibility of sound.—L. Southerns: A determination of the ratio of mass to weight for a radio-active substance. A determination has been made of the ratio of mass to weight for uranium oxide by comparison with the known value for a normal substance (lead oxide). It had been supposed by Sir J. J. Thomson that a radio-active substance might possess greater mass than the same weight of a non-radio-active substance, on account of the greater store of potential energy which is associated with the former. In the case of uranium oxide, the increase in the ratio of mass to weight would be about 1 in 16,000. The investigation has been made by means of a rigid pendulum fitted with two knife-edges and a hollow bob, into which could be^ packed either of the substances used. Special means have been employed in order to eliminate errors due to slight variations in the position of the centre of gravity of the pendulum, and to other causes. The results show that the ratio for the uranium oxide does not differ from the normal value by more than 1 in 200,000, and thus that the contemplated effect is absent.—F. P. Burt and F. L. Usher: The relative atomic weights of nitrogen and sulphur. The object of the research was to determine the combining weights of nitrogen and sulphur by the analysis of nitrogen sulphide. The method adopted was briefly as follows:—A weighed quantity of nitrogen sulphide, purified by sublimation in vacua over silver at 100° C., was decomposed by subliming over red-hot quartz wool contained in a quartz tube. The sulphur was deposited a few inches beyond the wool, and the nitrogen was pumped off and estimated in a constant-volume gas burette. Assuming the density of nitrogen, the relative weights of nitrogen and sulphur could be calculated, the sulphur being obtained by difference. The problem was complicated by the impossibility of starting an experiment with the quartz wool in the reaction tube in a gas-free condition. The difficulty was overcome by measuring in blank experiments the quantity of air removable from the hot wool in vacua, and by estimating traces of more condensable gas present by exposing the nitrogen to potash and re-measuring it. The final corrected N/S ratios are as follows, the weight of a “normal litre” of nitrogen in London being taken as 1.25144 grm.:—0.436847, 0.436875, 0.436839, 0.436857, 0.436897, 0.436878, 0.436898. The mean is 0.436870, and the greatest deviation from the mean is 1 in 14,000. From this ratio the atomic weight of sulphur becomes 2.067, if nitrogen be given the very probable value 14.009.—Dr. F. W. Edi-idgfe-Green: The relation of light perception to colour perception. It may be easily shown that light perception and colour perception are quite distinct. In fact, we can divide cases of colour-blindness into two classes, according as the defect is (a) one of light perception, or (b) one of colour perception or differentiation without any defect in light perception. Of course, both defects may be present in the same individual. The investigation of these two classes of defective vision is much facilitated by the use of a spectrometer which the author has devised for the purpose. This instrument is a spectrometer so arranged as to make it possible to expose to view in the eye-piece the portion of a spectrum between any two desired wave-lengths. Tested with this instrument, a normal individual will, as a rule, name six distinct colours, namely, red, orange, yellow, green, blue, and violet, and will mark out by means of the shutters about eighteen monochromatic patches. Occasionally we come across individuals with a greater power of differentiating hues, to whom, as to Newton, there is a distinct colour between the blue and violet, which Newton called indigo. Such individuals will mark out a greater number of monochromatic patches, from twenty-two up to twenty-nine. Those who have defective light perception for certain rays, with normal hue perception, behave exactly in the same way as a normal-sighted person with those rays removed or reduced to the same intensity, and not as if a light-perceiving substance which was sensitive to rays from a considerable range of the spectrum had been removed. Those with defective hue perception mark out with the spectrometer a smaller number of monochromatic patches than the normal, and say that there are five, four, three, two, or one colour instead of the normal six. They behave in every way as if their colour sensations were correspondingly limited. Therefore, if the normal be designated hexachromic, then pentachromic, tetrachromic, trichromic, dichromic, or monochromic correctly describes their colour-vision.—M. G. Sykes: The anatomy and morphology of the leaves and inflorescences of Welwitschia mirabilis. An account is given of the anatomy of the leaves, and of the inflorescence axes, cones, bracts, and flowers of both sexes. It is shown that the male and female inflorescences are essentially similar in their method of vascular supply and in their detailed anatomy, and it is concluded that they are homologous. Various characters suggest comparison with the Cycads and the Medulloseas. From the position of the embryo-sac relatively to the two coverings of the ovule at various stages of development, they are regarded as two integuments. The seed can be closely compared with that of Lagenostoma; its differences from this primitive type are referable to changes dependent on the evolution of siphonogamy and possibly insect fertilisation. In both these seeds the free outer integument is regarded as a primitive character, in contrast with the fused integuments of Cycas and Cardiocarpus. In all these cases the entire vascular system appears to be integumental. The connection between Welwitschia and the Cycads, the Bennettitales and the Angiosperms, is discussed.—Colonel Sir David Bruce, C.B., Captains A. E. Hamerton and H. R. Bateman, and Captain F. P. Mackie: (1) The natural food of Glossina palpalis; (2) mechanical transmission of sleeping sickness by the tsetse-fly.—V. H. Veley and Prof. A. D. Waller: The comparative toxicity of theobromine and caffeine as measured by their direct effects upon the contractility of isolated muscle. It is shown by measurements of the contractility of isolated muscle that the toxicity of theobromine, the base of cocoa, is greater than that of caffeine, the base of coffee and tea, in the proportion of 3:2. The introduction of a second methyl group into the oxy-purine residue, namely, the formation of caffeine from theobromine, thus diminishes the toxic value, a result which is the converse of that observed in the case of the paraffinoid alcohols. The toxic effects of coffee and tea extracts are also studied, and it is shown that the effect of the former is mainly due to the caffeine contents, and not to the tannic acid.—Prof. W. B. Bottomley: The assimilation of nitrogen by certain nitrogen-fixing bacteria in the soil.—Prof. A. B. Macallum: The inorganic composition of the blood in vertebrates and invertebrates and its origin.—Mary T. Fraser and J. A. Gardner: The origin and destiny of cholesterol in the animal organism. Part vii.—The quantity of cholesterol and cholesterol esters in the blood of rabbits fed on diets containing varying amounts of cholesterol.
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Societies and Academies . Nature 84, 60–64 (1910). https://doi.org/10.1038/084060b0
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DOI: https://doi.org/10.1038/084060b0