Showing papers in "Nature in 1934"

X-Ray Photographs of Crystalline Pepsin

Abstract: FOUR weeks ago, Dr. G. Millikan brought us some crystals of pepsin prepared by Dr. Philpot in the laboratory of Prof. The Svedberg, Uppsala. They are in the form of perfect hexagonal bipyramids up to 2 mm. in length, of axial ratio c/a = 2.3 ± 0.1. When examined in their mother liquor, they appear moderately birefringent and positively uniaxial, showing a good interference figure. On exposure to air, however, the birefringence rapidly diminishes. X-ray photographs taken of the crystals in the usual way showed nothing but a vague blackening. This indicates complete alteration of the crystal and explains why previous workers have obtained negative results with proteins, so far as crystalline pattern is concerned1. W. T. Astbury has, however, shown that the altered pepsin is a protein of the chain type like myosin or keratin giving an amorphous or fibre pattern.

Production of Ethylene by Some Ripening Fruits

Abstract: IT was observed by Ebner1 in 1931 that the presence of ripe apples and pears—but not oranges or bananas—caused abnormalities in the sprouting of potato tubers ; and Huelin2 pointed out that the effects were similar to those produced in potato sprouts by exposure to ethylene. Later, Smith and the writer3 showed that the growth of pea seedlings was affected by an active substance produced by ripe apples, again with results which were paralleled by ethylene.

Chemical Separation of the Radioactive Element from its Bombarded Isotope in the Fermi Effect

Abstract: Following the pioneer experiment of Fermi, it has been found by Fermi, Amaldi, D'Agostino, Rasetti and Segre that many elements up to the atomic number 30, when bombarded by neutrons from a radon-beryllium source, are transmuted into a radioactive element which is chemically different from the bombarded element. In several cases of this type, they succeeded in separating chemically the active substance from the bulk of the bombarded element, and there is no inherent difficulty in getting any desirable concentration of the radioactive element.

Mass Excretion of Œstrogenic Hormone in the Urine of the Stallion

Abstract: IN earlier investigations1 it was shown that the largest quantities of “strogenic hormone (folliculin—s. œstrin) are excreted in the urine of pregnant mares (100,000 mouse units per litre). I found this also to be the case in other equines (ass, zebra) during pregnancy, whereas, in the non-pregnant state, the excretion of hormone both in equines and in other mammals is very small, at most 0·5 per cent in comparison with that of the gravid animal. Curiously enough, as a result of further investigations, it appears that in the urine of the stallion also, very large quantities of “strogenic hormone are eliminated. (The first determinations indicating the high content of “strogenic hormone in the urine of the stallion were made by Dr. E. P. Haussler in the scientific laboratory of Hoffmann-La-Roche in Basle.) According to my analyses, the amount of hormone varies between 10,000 and 400,000 m.u. per litre of urine; the differences appear to have some relation to the origin of the animals. 37 litres of urine obtained from four stallions were rendered acid to congo-red by the addition of mineral acid, boiled for five minutes and subjected to exhaustive extraction with benzol. In this way I found a hormonic content of 170,000 m.u. per litre, which can very well be regarded as an average value. The stallion therefore excretes 1,700,000 m.u. of aestrogenic hormone per diem.

Possible Production of Elements of Atomic Number Higher than 92

Abstract: UNTIL recently it was generally admitted that an atom resulting from artificial disintegration should normally correspond to a stable isotope. M. and Mme. Joliot first found evidence that it is not necessarily so; in some cases the product atom may be radioactive with a measurable mean life, and go over to a stable form only after emission of a positron.

Vitamin B 2 and the Pellagra-like Dermatitis in Rats

Abstract: IN our first experiments on the concentration and isolation1 of vitamin B2, we failed to observe definite changes in the skin and fur, such as those described by J. Goldberger and R. D. Lillie2, and by H. Chick and M. H. Roscoe3 and several other authors, in rats fed on diets containing the antineuritic vitamin in a purified form (for example, alcoholic extracts of wheat or maize, Peters's antineuritic concentrate from yeast, crystalline vitamin B1 preparations). The flavin pigment was identified by us with vitamin B2 by its growth-promoting properties. It was therefore a question for further investigation whether in these circumstances it was also identical with the anti-dermatitis factor and in particular with the pellagra preventing factor.

A Nuclear Photo-effect: Disintegration of the Diplon by -Rays

Abstract: BY analogy with the excitation and ionisation of atoms by light, one might expect that any complex nucleus should be excited or ‘ionised’, that is, disintegrated, by γ-rays of suitable energy. Disintegration would be much easier to detect than excitation. The necessary condition to make disintegration possible is that the energy of the γ-ray must be greater than the binding energy of the emitted particle. The γ-rays of thorium C″ of hv = 2.62 × 106 electron volts are the most energetic which are available in sufficient intensity, and therefore one might expect to produce disintegration with emission of a heavy particle, such as a neutron, proton, etc., only of those nuclei which have a small or negative mass defect; for example, D2, Be9, and the radioactive nuclei which emit a-particles. The emission of a positive or negative electron from a nucleus under the influence of γ-rays would be difficult to detect unless the resulting nucleus were radioactive. Following the discovery of the neutron in 1932 [see Nature 192, 312 (1932)], there was some debate as to whether the new particle was really a fundamental building block, or a composite of the proton and the electron (as Rutherford had predicted). In 1934, Chadwick and Maurice Goldhaber made the first determination of the neutron mass that was accurate enough to decide the question. By determining the ?-ray energy required to disintegrate the deuteron, Chadwick and Goldhaber were able to constrain the binding energy of the deuteron, and hence the neutron mass.

Elimination of Water from the Human Body

Abstract: SHORTLY after the first application of radioactive isotopes as indicators, the late H. J. G. Moseley and one of the present writers discussed the prospect opened by the introduction of this method, when indulging in a cup of tea at the Manchester Physics Laboratory. The latter then expressed the wish that an indicator might be found which would allow one to determine the fate of the individual water molecules contained in the cup of tea consumed. Even a man of the vision and outlook of the late H. J. G. Moseley considered this hope to be a highly Utopian one.

The Crystalline State

Abstract: THE goal of chemistry is the determination of the atomic arrangement in space, which will be able to account for all the properties of matter under consideration. The greatest achievements in this direction have been obtained by the application of purely chemical methods, essentially because of the wonderful artistic skill of generations of chemists. Since von Laue's discovery of the diffraction of X-rays, and Sir William and W. L. Bragg's first X-ray analysis of the crystalline state, however, the way has been opened to a much more intimate knowledge of the atomic pattern. It is characteristic that the first results of the X-ray method dealt with the stereochemistry of the solid state, which always had been nearly impossible to attack with previous methods. The X-ray method afterwards proved to be no less important for the structural analysis of liquids and of single molecules in the gaseous state, and this side of the development is by no means neglected in the first volume of the work before us; the title seems adequate because of the preponderant role the crystalline state has played in the great majority of investigations. The Crystalline State. Edited by Sir William Bragg Dr. W. L. Bragg. Vol. 1: A General Survey. By W. L. Bragg. Pp. xiv + 352 + 32 plates. (London: G. Bell and Sons, Ltd., 1933.) 26s. net.

Radioactivity Induced by Neutron Bombardment

Abstract: EXPERIMENTS have been carried out to ascertain whether neutron bombardment can produce an induced radioactivity, giving rise to unstable products which disintegrate with emission of particles. Preliminary results have been communicated in a letter to La Eicerca Scientifica, 5, 282 ; 1934.

Carotenoids and the Vitamin A Cycle in Vision

Abstract: SINCE reporting the occurrence of vitamin A in the eye tissues of the frog and several mammals1, I have examined the carotenoids of the frog's eye in detail.

Electron Microscopy of Biological Objects

Abstract: IN a recent paper Ruska1 demonstrated experimentally the possibility of surpassing considerably the resolving power of an ordinary microscope by the use of an electron microscope. This high resolving power cannot be applied in biological research, however, without developing a new histological technique to prevent the destruction of the organic cells by the intense electronic bombardment.

Nature of Antibodies

Abstract: IT was found by Breinl and Haurowitz1 that when proteins of an agglutinating serum had been coupled with diazotised atoxyl (p-amino-benzene-arsinic acid), the agglutinating power of the serum was not wholly lost. In this process, the proteins are themselves converted into azo-dyes, but the products are not strongly coloured. If, however, benzidine is tetrazotised, and coupled to R salt and to the serum proteins, according to the method of Heidelberger, Kendall and Soo Hoo2, a deep red compound is formed, and the agglutinin again is not wholly destroyed.

Velocity of Light

Abstract: M. E. J. GHEURY DE BRAY has directed attention to an apparent decrease in the velocity of light1. I have recently tried to explain this on the basis of the theory of the expanding universe. If the speed of light is a true constant, independent of any variation in our unit of length, then a doubling of the radius of the universe should cause the measured velocity of light to diminish by half. If the radius of the universe doubles every K years, then the velocity of light will be proportional to (1/2)t where K is the unit of time. Thus, the logarithm of the measured velocity of light must be a linear function of the time. I determined the two constants of such a function from de Bray's data and found that it represented the observations in a satisfactory manner. I then solved this equation for the length of time it would take the velocity to diminish by half. The time is of the order of 60,000 years, which is considerably shorter than the value derived from a study of the recession of the external galaxies2. Consequently, this observed variation cannot be explained by the expanding universe theory unless we assume that the rate of expansion is much more rapid in the vicinity of the earth than it is at the distance of the spirals.

Transmutation Effects observed with Heavy Hydrogen

Abstract: WE have been making some experiments in which diplons have been used to bombard preparations such as ammonium chloride (NH4Cl), ammonium sulphate ((NH4)2SO4) and orthophosphoric acid (H3PO4), in which the hydrogen has been displaced in large part by diplogen. When these D compounds are bombarded by an intense beam of protons, no large differences are observed between them and the ordinary hydrogen compounds. When, however, the ions of heavy hydrogen are used, there is an enormous emission of fast protons detectable even at energies of 20,000 volts. At 100,000 volts the effects are too large to be followed by our amplifier and oscillograph. The proton group has a definite range of 14·3 cm., corresponding to an energy of emission of 3 million volts. In addition to this, we have observed a short range group of singly charged particles of range about 1·6 cm., in number equal to that of the 14 cm. group. Other weak groups of particles are observed with the different preparations, but so far we have been unable to assign these definitely to primary reactions between diplons.

The Biology of the Protozoa

Abstract: THE first edition of this book appeared in 1926, and was favourably reviewed in these pages at the time (NATURE, 118, 763, Nov. 27, 1926) by another hand: and since this new version is described as “thoroughly revised”, one turns to it with confident hope that the shortcomings of the earlier volume have been, hi the main, remedied. According to the author's preface, the chief amend ments are as follows: The Biology of the Protozoa. By Prof. Gary N. Calkins. Second edition, thoroughly revised. Pp. xii + 607 + 2 plates. (London: Bailliere, Tindall and Cox, 1933.) 37s. 6d.

Haemorrhages in chicks reared on artificial diets: a new deficiency disease.

Abstract: DURING work on the sterol metabolism of chicks1,2, it was observed that the animals often exhibited, extensive internal haemorrhages when they were fed a ration consisting of vitamin A-free casein 20, Marmite 10, salt mixture 4·5, starch 65·5 and varying amounts of cod liver oil concentrates. The haemorrhages were subcutaneous or intramuscular on the breast, legs and wings, and were accompanied by certain pathological changes in the horny stratum of the gizzard.

Structure of the Ionosphere

Abstract: IN a recent paper, Appleton and Builder1 mention a striking fact that on certain occasions, when the ionosphere is being surveyed by the ‘pulse’ method, there is a reversal in the times of arrival of the two magneto-ionic components into which the upgoing ray is split. They attribute this to differential group retardation, and it occurred to me a short time ago that this effect might throw some further light on a suggestion I have made previously2, namely, that the whole intermediate space between the E and F layers is ionised to a value very little less than that of the top of the E layer.

A Manual of Foraminifera

Abstract: IT is a matter open to question whether proto-zoologists, who concern themselves with the bionomics of the Foraminifera, can pay very much attention to the publications of the modern and fundamentally American school of commercial protozoology. It was a dies nefas for the biological student of the group when American systeinatists formulated the theory that minute variations of the ectoskeleton revealed the presence in oil shales, at a given depth, of petroleum, and that these variations progressively indicated where petroleum wells might be sunk. This formulation was made in, approximately, 1917, since when a vast body of workers, numbering more than three hundred, has been banded together, for the most part in somewhat quarrelsome mood, into the Society of Petroleum Geologists of America, with rival laboratories and a journal of its own. A Manual of Foraminifera. By Prof. J. J. Galloway. (James Furman Kemp Memorial Series, Publication No. 1.) Pp. xiii + 483. (Bloomington, Ind.: The Principia Press, Inc.; London: Williams and Norgate, Ltd., 1933.) 25s. net.

Æstrogenic Hormone in the Urine of the Stallion

Abstract: IN further investigations on the œstrogenic hormone, which to a large extent is excreted in the urine of the stallion1, we have examined the influence of this hormone on the secondary sexual characteristics, especially on the mammary gland. By the use of follicular hormone, Laqueur was able to induce lactation of male guinea pigs. We have now observed the same effect with the hormone obtained from the urine of the stallion and in the actual cases the lactation of the male animals has continued for 21 days.

A Rapid Test for Pregnancy on Xenopus lævis

Abstract: IN a recent communication Bellerby (1933)1 has shown that injection of acid or alkaline extracts of bovine anterior lobe of the pituitary gland into female South African clawed toads (Xenopus Iœvis) produces extrusion of ova through the cloaca within 18 hours.

The Study of Behaviour

Abstract: IT was Descartes who imposed upon European thought for at least two centuries, and upon biology for much longer, that ‘bifurcation’ of Nature into matter and mind which has raised so many insoluble problems for philosophy, and diverted biology from its true method. As to its effect on philosophy, Prof. A. N. Whitehead writes:

Germination of Seeds

Abstract: THE ovule, which later becomes the seed, is enclosed in the fruit vessel or ovary, the covering provided by the mother plant. During its development, the offspring is protected and nourished by its mother, and the ovule gradually develops into the seed, with its own protective skins or coats, lying within the enlarged ovary, which in the course of time has become the fruit. Examples of fruits with their contained seeds are such familiar objects as the fleshy-fruited tomato with its dry, flat seeds, the broad bean or the scarlet runner with the enclosed seeds or beans, and the Brazil nut, where the mother plant has provided a thick, woody, cannon-ball-like protective fruit-which can only be broken by a powerful hammer or cut across with a saw-enclosing the well-known hard-shelled ‘nuts’Many seeds have been so well protected by the mother plant that the liberation of the seeds contained in the fruit is often a matter of some difficulty. The Brazil nut fruit is perhaps the most remarkable example. In other cases, however, the seeds are shed or scattered from the fruits with the greatest ease when the fruit is ripe, as any gardener knows only too well who attempts to save seed of an Impatiens (balsam), or collect the seeds of gorse, which are shot out from the fruit as if from a catapult. The horticulturist, of course, is concerned only with the seeds when he wishes to replenish his stock of plants. In the majority of cases he merely sows the seed, and germination, that is, the escape of the embryo from the protective seed-coats, takes place sometimes in a few days, sometimes after some weeks from sowing. In the case of willows and poplars the seed will germinate the day after it is sown, and if the minute seed should be kept for more than a few days it will completely lose its power of germination. In other cases seeds may remain viable for years. I remember well the late Sir Michael Foster showing me a pot of Iris, in which the seed was just beginning to germinate fourteen years after it had been sown ! Then there are the seeds of the Australian wattles (acacias), which rarely germinate until a fire has passed over the ground in which they are lying, or which, if sown at home, have to be scraped with a file, or treated with strong sulphuric acid, as is also the case with some other seeds, in order to induce germination, so strong and resistant is the seed-coat. It is known that seeds of Acacia lophantha will germinate after being stored for sixty-eight years and recently, in connexion with inquiries as to seed vitality, we have experimented at Kew with seeds long stored in bottles in our Museum and have successfully germinated seeds ofAnthyllis vulneraria and Trifolium striatum both ninety years old, and seeds of four other leguminous plants, including the Spanish broom (Cytisus scoparius), all eighty-one years old. How long the poppy seed, which germinated and flowered so wonderfully after the shelling of the Somme battlefield, had lam buried in the soil, or how long charlock seed will remain living when buried, we do not really know; but it is truly remarkable that life can persist for so long a time in a body so minute as the embryo of a seed imprisoned within its seed-coats, when the seed is preserved under suitable conditions. What the nature of such life may be, and to what extent respiration, and the other functions we associate with living matter, may be carried on in dormant seeds, is scarcely within the scope of my text, nor could I throw much light on this arresting problem. For the moment we are concerned with the embryo prisoner, whether serving only a brief or a long sentence of confinement, and the nature of the prison.

Factors Controlling Moulting and ‘Metamorphosis’ in an Insect

Abstract: IN the blood-sucking bug, Rhodnius prolixus, moulting occurs at a definite interval after feeding ; only one meal being necessary in each stage. The morphological changes at moulting are relatively slight ; save at the fifth moult, when the insect becomes adult1. It is therefore convenient (without prejudice to questions of homology) to refer to this final moult as ‘metamorphosis’. In this last stage, the interval between feeding and moulting averages twenty-eight days. If its head is removed soon after feeding, the insect will not moult—although some of these headless individuals have remained alive more than eleven months. But there is a critical period, about seven days after feeding, after which moulting is no longer prevented by decapitation. If the blood from an insect decapitated after this critical period is allowed to circulate in an insect decapitated before this period, the latter is caused to moult. Clearly, a moulting hormone is present ; and it is probably secreted in the head. Of the organs in the head, the only one which shows distinct changes during this period is the corpus allatum, the cells of which swell up to a maximum at about the seventh day after feeding, and then diminish. Perhaps this is the source of the moulting hormone—though the evidence on this point is still incomplete.

Exchange Forces between Neutrons and Protons, and Fermi's Theory

Abstract: Febmi 1 has recently developed a successful theory of β-radioactivity, based on the assumption that transmutations of a neutron into a proton and vice versa are possible and are accompanied by the birth or disappearance of an electron and a neutrino.

The Ether-Drift Experiment and the Determination of the Absolute Motion of the Earth *

Abstract: T ether-drift experiment first suggested by Maxwell in 1878 and made possible by Michelson's invention of the interferometer in 1881, though suitable for the detection of the general absolute motion of the earth, was actually applied for detecting only the known orbital component of the earth's motion. For the first time, in 1925 and 1926, I made observations at Mount Wilson of such extent and completeness that they were sufficient for the determination of the absolute motion of the earth. These observations involved the making of about 200,000 single readings of the position of the interference fringes. The ether-drift observable in the interferometer, as is well known, is a second order effect; and the observations correctly define the line in which the absolute motion takes place, but they do not determine whether the motion in this line is positive or negative in direction. At the Kansas City meeting of the American Association for the Advancement of Science, in December, 1925, before the completion of the Mount Wilson observations, a report was made showing that the experiment gives evidence of a cosmic motion of the solar system, directed towards a northern apex ; but the effects of the orbital motion were not found, though it seemed that the observations should have been quite sufficient for this purpose. The studies of the proper motions and of the motions in the line of sight of the stars in our galaxy have shown that the solar system is moving, with respect to oiir own cluster^ in the general direction of a northern apex in the eonstellation Hercules. This apex is near that indicated by the ether-drift observations as just reported, and seemed to be confirmatory evidence of its correctness. Probably it was this that caused

Behaviour of Condensed Helium near Absolute Zero

Abstract: THE recently published measurements1 on some properties of condensed helium, in conjunction with the facts known from the work of Keesom and his co-workers2, allow us to draw some conclusions on the behaviour of helium at very low temperatures.

Kinetics of Photosynthesis

Abstract: BALY and Morgan1 have proposed kinetic equations which account for observations of Warburg2 and Emerson3 on the rate of photosynthesis. We wish to direct attention to one of Warburg's observations which is not in accordance with their equations. At low light intensities, the temperature coefficient of photosynthesis approaches unity, while at low carbon dioxide concentrations it remains high. We have confirmed this for five different species of algae. This leads us to suppose that carbon dioxide is a reactant in the temperature-sensitive reaction, rather than in the photochemical reaction, where Baly and Morgan placed it. Their assumption seems to us untenable because it leads to equations in which light intensity and carbon dioxide concentration are interchangeable, and because according to photo chemical principles a photochemical primary process is unimolecular, taking place immediately on the absorption of light.

Photography of the Infra-Red Solar Spectrum to Wave-length 12,900 A.

Abstract: WITH the aid of the new Agfa infra-red sensitive plates (maximum of sensitivity 10,600 A.) I have succeeded in photographing the solar spectrum to 12,900 A. in the first order of a 3 m. grating (dispersion 5 A./mm., time of exposure 10 hours). The blackening of the exposure obtained does not alter appreciably from 12,400 to 12,900 A. (end of the plate used), so that it seems easily possible to extend the limit quite considerably.