Abstract
LONDON. Royal Society May 18.—Sir Archibald Geikie, K.C.B., president, in the chair.—Prof. W. M. Bayliss: The properties of colloidal systems. II.—On adsorption as preliminary to chemical reaction. The existence of an “adsorption compound” containing acid and base uncom-bined chemically, and which can be isolated, is described, together with the manner of its conversion into the true chemical compound or salt. It is shown that a similar kind of compound is formed between an enzyme and its substrate, preliminary to the particular chemical change brought about by the enzyme in question. Adsorption between enzyme and substrate as affected by the presence of neutral salts is investigated, and found to follow the laws of “electrical” adsorption. The relation between the concentration of an enzyme and its activity is shown to be expressed by an exponential formula, the value of the exponent varying considerably according to circumstances. In certain conditions it may be unity, and in others the square root, but is usually between the two. Accordingly, the view that the rate of an enzyme action at any given moment is a function of the amount of the adsorption compound of enzyme and substrate in existence at that time is to be regarded as fairly well established.—S. M. Jacob: Inbreeding in a stable simple Mendelian population, with special reference to cousin marriage. The paper investigates, on the basis of Mendel's conception of the segregation of unit-characters, the proportions of different types among the offspring I resulting from alliances of various degrees of inbreeding. A detailed examination is made of the consequences of i first-cousin marriages, the form of inbreeding most frequently met with in actual human populations, while unions of other degrees of affinity, both those closer and those more remote, are also considered. The important point is brought out that for an evil which is a Mendelian recessive and is of common occurrence, a first-cousin marriage will not be much more likely to produce defective offspring than any other kind of marriage, but that a very rare recessive evil is relatively far more readily developed by such a consanguineous marriage. Now it is probable that there are very many of these rare defects latent in man. As the chance of a particular one of these appearing is increased by cousin marriage, the appearance of any random one of the large number is rendered much more probable by such a union. The same is true, on the Mendelian hypothesis, for any desirable qualities when such can be shown to be recessive. It is also established that the relative frequency of the appearance of the allogenic constituent in the offspring of related pairs diminishes by about one half for each grade of cousinship, so that the efficacy of cousin marriages in developing the recessive character diminishes with the grade of the omarriage. In general, inbreeding accentuates both the pure dominant and the pure recessive strain to the same extent and at the expense of the hybrid element.—Miss M. Wheldale: The direct guaiacum reaction given by plant extracts. Previous work on oxidising enzymes has led to the interpretation of the direct blueing action in terms of the activity of a system consisting of an organic peroxide in conjunction with a peroxidase. The author finds that the power to give the direct action possessed by water-extracts of tissues is accompanied by another phenomenon, i.e. the formation of brown reddish-brown pigments in the tissues on exposure to chloroform vapour. Both phenomena are characteristic of certain natural orders, but are absent from others or are characteristic of certain genera only in an order. When the direct action is not given, the plant extract will blue guaiacum on addition of hydrogen peroxide (indirect action), and the tissues do not show change of. colour in chloroform vapour in the same period of time. The phenomenon of direct blueing of guaiacum is considered by the author to be the outcome of the presence of the dihydric phenol-pyrocatechin in the plants examined. Pyrocatechin is oxidised on the death of the tissues, and then acts as a peroxide, enabling the peroxidase, which is almost universally present, to transfer oxygen to the guaiacum. These conclusions are based on the following evidence:—(1) that pyrocatechin can be detected in plants (such as have been examined) which give the direct action and show change of colour in chloroform, whereas it cannot be detected in plants lacking these characteristics; (2) that solutions of both chemically prepared pyrocatechin and the actual plant product, after oxidation in air, will give a direct action with guaiacum and peroxidase only. The same result is not obtained with phenols having the hydroxyl groups in other positions. Hence the direct guaiacum reaction has, in all probability, no real significance as such in plant metabolism, but is merely the outcome of the presence of a certain metabolic product.—Dr. A. Theiler: Transmission of amakebe by means of Rhipicephalus appendiculatus, the brown tick. This is an account of experiments carried out at Pretoria, confirming the result arrived at by the Sleeping Sickness Commission during 1909, that the disease of calves in Uganda, known as amakebe, is in reality East Coast fever. It was arranged with the Government veterinary surgeon in Uganda, Mr. Hutchins, to send to Dr. Theiler nymphs of Rhipicephalus appendiculatus, the brown tick, collected from calves in Uganda suffering from amakebe. On several occasions Mr. Hutchins forwarded ticks, which arrived at Pretoria alive and in good condition. The nymphs in transit moulted into the adult stage. Two experiments were performed to ascertain whether brown ticks, collected as nymphae in Uganda from a calf suffering from amakebe, will transmit the disease when placed on susceptible calves in the Transvaal. The first experiment, a bull calf, born and reared in Onderstepoort, was infested on January 23 with ten adult brown ticks, forwarded from Entebbe, Uganda, and received in the Transvaal on January 4. The ten ticks were found attached to the calf the following day. The animal died on the twenty-third day after tick infestation, and from the course of the disease and the post-mortem examination, a diagnosis of East Coast fever was concluded. Koch's bodies were found post mortem on microscopical examination of preparations of the lymphatic glands and spleen. The second experiment was carried out in a similar manner. On February 14 a calf was infested with ten adult brown ticks of the same batch, obtained from Uganda. On February 15 seven of the ticks were found attached. After an incubation period of thirteen days, a typical fever curve ensued. The animal died on the twenty-fourth day. During the course of the disease, Koch's bodies were found in the glands, and Theileria pariia in the red cells of the blood. A diagnosis of East Coast fever was also concluded from the post-mortem examination in this case. Koch's granules were frequently found post mortem in the lymphatic glands and spleen.—S. J. Meltzer: Distribution and action of soluble substances in frogs deprived of their circulatory apparatus.—Dr. F. W. Edridge-Green: The discrimination of colour. If a definite portion of spectrum Tie isolated it will appear monochromatic, the size of the monochromatic region varying with the luminosity and wave-length of the light and the colour perception of the observer. Lord Rayleigh has expressed the opinion that he can discriminate between the colours in a monochromatic region even to the extent of distinguishing between the colours of the two D lines. The author does not find this possible when special precautions are taken to have a pure spectrum and to avoid the physiological effect of contrast through varying intensities of the areas to be compared. The monochromatic area may be magnified without altering 4ts monochromatic appearance, the intensity of the light source being increased to compensate for the diminished luminosity. The monochromatic area may also be examined through a double-image prism, or be projected by means of a double-image prism upon a screen, so that the violet side of one area is adjacent to and just touches the red side of the other area. In this way the monochromatic area may be made as large as desired, the intensity of the source of light being increased as required. An arc light gives two very bright areas of colour. This method is the most favourable for the detection of any difference; the monochromatic areas, however, still remain monochromatic.
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Societies and Academies . Nature 86, 437–440 (1911). https://doi.org/10.1038/086437a0
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DOI: https://doi.org/10.1038/086437a0