Abstract
LONDON. Royal Society, June 28.—V. H. Blackman, A. T. Legg, and F. A. Gregory: The effect of a direct electric current of very low intensity on the rate of growth of the coleoptile of barley. The coleoptile (sheathed plumule or young stem) of barley seedlings is exposed to an electric Dischargefrom a point charged positively to about 10,000 volts (crest value) and placed at such a height above the coleoptile that a current of 0.5 × 10–10 amp. passes through it, the current density being 4 × 10–9 amp. per cm.2 Under these conditions the rate of growth is markedly accelerated from the first hour onward, showing in the third hour a percentage increase above that of the control plants of 7.53 + 1.95. After the cessation of the current a well-marked after-effect, greater than the direct effect, is observed, the enhanced rate of growth steadily continuing and showing a percentage increase of 15.68 + 2.62 above that of the controls. The after-effect is greater with a short period of discharge of 1 hour than with a longer period of 3 hours. When the point is negatively charged the rate of growth is increased during the first hour, but the increase becomes less with time. An after-effect follows, but it is markedly less. The gaseous products of the discharge and the “electric wind” play little or no part in the stimulation of growth observed. The current alone appears to be of importance.—M. S. Pembrey, N. W. MacKeith, W. R. Spunell, E. C. Warner, and H. J. Westlake: Observations on the adjustment of the human body to muscular work. In the dyspnoea produced by running there is a disturbance of the acid-base equilibrium of the body; the relief of “second wind” is the result of adjustments effected chiefly bythe respiration, circulation, and excretion by the kidneys and skin. Thesense of discomfort during dyspnoea is associated with increased pulmonary ventilation, the sense of relief at the onset of second wind with diminished ventilation. Oliguria, or anuria, appears as a constant feature during running, even after taking 560 c.c. of tea as a diuretic. It leads to a temporary retention of acid, which helps the body to get rid of carbon dioxide and obtain oxygen; the water spared is available for excretion by the lungs and skin, and will produce by evaporation greater cooling than it would if it were discharged as urinary water. The suspension of the activity of the kidneys appears to be due to an outflow of constrictor impulses to the renal vessels.—Miss R. M. Tupper-Carey and J. H.Priestley: The composition Of the cell wall at the apical meristem of stem and root. The walls of the apical meristem of stem and root differ in the ease with which cellulose may be detected in them with iodine reagents. Macro- and micro-chemical experiments show that the cellulose in the wall of the root meristem is masked by its combination with other substances, particularly proteins and fatty acids. In the shoot meristem, the cellulose is closely linked with larger quantities of pectin, but less protein and fatty acid are present, especially when the shoot is growing in the light.—L. J. Harris: The titration of amino- and carboxyl-groups in amino-acids, polypeptides, etc.—F. A. E. Crew: Studies in intersexuality. II. Sex-reversal in the fowl.—W. Finkler: Analytical studieson the factors causing the sexual display in the mountain newt (Triton alpestris).—G. A. Schott: On the scattering of X- and Y-rays by rings of electrons. The effect of damping of the incident radiation. Damping ofthe usual type, of an amount compatible with the production of moderately sharp lines in the X-ray spectrum, increases slightly the total scattering of short waves, such as the hard 7-rays, although it decreases slightly that of long waves. A single electron ring, such as is postulated in hydrogen and ionised helium on Bohr's theory, is completely unaffectedby this type of damping. It seems scarcely possible that damping can diminish the total scattering for any type of atom below the amount required by the simple pulse theory.—P. A. MacMahon: On a class of transcendents of which the Bessel functions are a particular case.—L. C. Martin: The photometric matching field. Improvement in the visibility of faint contrasts observed with central vision can be obtained by stimulating the peripheral regions of the retina. An increase in precision of the order of 30 per cent. is obtained in photometric matches by surrounding the photometric field with a larger area of approximately equal brightness.—G.P. Thomson: Test of a theory of radiation. Experiments with positive rays show that visual and photographic effects can be obtained with trainsof waves shorter than those produced in the emission of a quantum of light.—A. LI. Hughes and P. Lowe: Intensities in the helium spectrum. The curve showing the intensity of any spectrum line as a function of the energy of impact of the electrons is characteristic of the series to whichit belongs. The intensities in the doublet system all. decrease rapidly as the energy of impact is increased from 34 volts. The principal series, iS - niP, of the singlet system is characterised by a very great increase in intensity as the energy of impact is increased from 34 volts up to about 80 volts, beyond which there is little change. The lines of the diffuse series, iP-mD, all show a maximum at about 75 volts. The lines of the sharp series, iP -mS: after a small initial rise to 60 volts, decrease slightly.—A. A. Dee: The effect of quenching from above the carbide transition temperature upon the magnetism of steel. The magnetism of steel at ordinary temperatures is not materially altered by quenching from above the transition temperature of iron carbide, and therefore the return of the carbide to the ferromagnetic state is not retarded by suddencooling from above the transition temperature.—T. S. P. Strangeways and H. E. H. Oakley: The immediate changes observed in tissue cells after exposure to soft X-rays while growing in vitro. Exposures for gradually increasing periods, varying from 5 minutes to 2 hours, were used. There is a latent period of about 15 to 20 minutes before the changes produced in the cells by irradiation can be recognised. After 5 minutes irradiation development of new dividing cells is lessened. After exposure of 20 minutes or longer the formation of new dividing cells practically ceases. After exposure of 5 minutes granular changes and fragmentation of the chromosomes occurs in some cells in mitosis at metaphase and anaphase. After exposure of 25 minutes or longer some cells in mitosis show clumpingof the chromosomes at metaphase. As the time of exposure increases thereis increase in size and alteration in structure of the cytoplasm, nucleus, and nucleolus of some fully formed cells. After an exposure of 60 minutes, affected cells become disorganised, and eventually cytoplasm and nucleus break up and appear to go into solution in the surrounding medium.—W. B. Hardy and Ida Doubleday: Boundary lubrication: the latent period and mixtures of two lubricants.—C. T. R. Wilson: Investigations on X-rays and γ-rays by the cloud method. Pt. I.—X-rays. The tracks of the electron ejected from the atom which emits the quantum of radiation and that of the electron ejected from the atom which absorbs the radiation can be identified. Two classes of γ-ray tracks are produced in air by the primary action of X-radiation of wave-length less than about 0–5 Å: (a) those of ejected electrons with initial kinetic energy comparable to a quantum of the incident radiation, and (6) tracks of very short range. The short-range electrons are ejected nearly along the direction of the primary X-rays. The short-range tracks are probably related to the nhenomena which have led to the postulation of a radiation. Of the ordinary long-range tracks, the majority have a large forward component comparable with the lateral component; about 20 per. cent. are ejected almost exactly at right angles to the primary X-ray beam; others have a large backward component. Partial polarisation of the primary beams is indicated by the direction of ejection of a number of the γ-particles being in one plane-that containing the direction of the cathode rays in the X-ray tube. γ-rays in air exposed to X-rays frequently occur in pairs or groups.The pairs probably consist of one K electron ejected by the direct action of the primary X-rays, and of a second electron ejected by the combined action of primary radiation and of the K-radiation from the atom from which the first electron was ejected. Pt. II.—γ-rays. The tracks of fast γ-particles are very nearly straight over distances of several centimetres. Near the end of their range the deviations are of three kinds: (a) sudden deviations often through large angles up to 180°, the results of a close approach to the nucleus of an atom; (b) sudden deviations ranging up to 45°, due to a closeapproach to an electron which is in consequence ejected to form a branch track generally approximately at right angles to the deflected primary track; (c) gradual deviations due to an accumulation of deviations of (a) or (b) type. The range of the γ-ray as measured along the track is approximately proportional to the square of the kinetic energy or to the fourth power of the velocity (Whiddington's law) for ranges from about o-i m. to 2 cm.; the range is 1 cm. when the kinetic energy of the particle is about 21,000 volts. The primary ionisation (i.e. number of atoms from which electrons are ejected by the direct action of primary (γ-rays) is about 90 per cm. for a velocity of io10 cm. per sec., and is approximately inversely as the square of the velocity. The total ionisation per cm., including that due to secondary p-particles of range too short to form visible branch tracks, is about three or four times as large as the primary. In portions of some of the tracks not only is the primary ionisation recorded, but also the ions which each of these electrons has itself produced may be counted.—C. V. Raman and K. R. Ramanathan: The molecular scattering of light in carbon-dioxide at high pressures.—W. A. Davis and J. V. Eyre: The discontinuity of the hydration process.—G. M. B. Dobson: A flicker type of photoelectric photometer giving hgh precision.—H. D. Smyth: The ionisation of nitrogen by electron impact.—G. M. B. Dobson: Measurements of the sun's ultra-viòlet radiation and its absorption in the earth's atmosphere.—H. Hartridge and F. J. W. Roughton: A method of measuring the velocity of very rapid chemical reaction.—W. T. Astbury: The crystalline structure of anhydrous racemic acid.—E. Ponder: The measurement of percentage hæmolysis. I.—H. M. Fox: Lunar periodicity in reproduction.—Marjory Stephenson and Margaret D. Whetham: Studies in the fat metabolism of the Timothy grass bacillus. II. Carbon balance sheet and respiratory quotient.—H. R. Hewer: Studies in amphibian colour changes. II.—R. H. Burne: Some peculiarities of the blood-vascular system of the Porbeagle shark (Lamna Cornubica).—A. E. Boycott and C. Diver: The inheritance of sinistrality in Limnæa peregra.
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Societies and Academies. Nature 112, 26–28 (1923). https://doi.org/10.1038/112026a0
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DOI: https://doi.org/10.1038/112026a0