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Societies and Academies

Nature volume 88, pages 502505 (08 February 1912) | Download Citation

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LONDON. Royal Society, February 1.—Sir Archibald Geikie, K.C.B., president, in the chair.—Dr. A. Harden and Dorothy Norris: The bacterial production of acetylmethylcarbinol and 2: 3-butylene glycol from various substances. B. lactis aerogenes and B. cloacae, when grown in a peptone solution containing either glucose, laevulose, mannose, galac-tose, arabinose, isodulcite, or adonitol, produce both acetylmethylcarbinol and 2: 3-butylene glycol. Glycerol, ethylene glycol, and acetaldehyde under similar conditions also give rise to butylene glycol in presence of B. lactis aerogenes, but no acetylmethylcarbinol is produced. In these three cases a carbon synthesis is involved analogous to that which occurs in the butyric fermentation of glycerol and lactic acid. The fermentation of citric and malic acids, of dihydroxyacetone, and of peptone water gives rise to neither carbinol nor glycol.—J. Thompson: The chemical action of Bacillus cloacae (Jordan) on glucose and mannitol. The B. cloacae, like B. lactis aerogenes, produces a considerable proportion of 2: 3-butylene glycol from glucose and mannitol, as well as a small amount of acetylmethylcarbinol. The other products are alcohol, acetic, lactic, formic and succinic acids, carbon dioxide, and hydrogen. As in the cases of B. lactis aerogenes and B. coli communis, the percentage of alcohol produced from mannitol is about double that formed from glucose.— J. H. Mummery: The distribution of the nerves of the dental pulp. The object of the paper is to demonstrate, with the author's preparations, that the nerve fibres of the dental pulp do not terminate, as considered by most histologists, at the pulp margin, but that, although they here form a narrow plexus, fine neurofibrils pass out from it in great abundance and enter the dentinal tubes, traversing the dentine in intimate association with the dentinal fibrils to the inner margin of the enamel and cementum. The bundles of medullated nerve fibres which enter the tooth at the apical foramen traverse the pulp in more or less parallel lines, running in most cases in company with the blood vessels. They send off numerous side branches, which at the periphery of the pulp lose their medullary sheath, the axis cylinders spreading out into a mass of neurofibrils which enter into a more or less dense plexus beneath the odontoblast layer. These neuro-fibrils are more abundant towards the crown of the tooth, and are scattered and nearly absent in the lower part of the root. Fine fibrils are met with in the substance of the pulp, but in much greater abundance at the margins, in the neighbourhood of the odontoblast layer. At the periphery of the pulp these fibres break up into a plexus, known as the plexus of Raschkow, immediately beneath the layer of odontoblast cells. From this plexus fine neurofibrils pass between and around the odontoblasts, enclosing them in a meshwork and entering into a narrow plexus at the inner margin of the dentine, from which fine fibres are given off to the dentinal tubules. In the substance of the dentine in well-impregnated preparations fine dotted lines can be traced in the tubules. In the majority of cases there appear to be two fibres in each tubule. These dotted lines can be traced in many preparations to the inner margins of the enamel and cementum.—F. W. Twort and G. L. Y. Ingrram: A method for isolating and cultivating the Mycobacterium enteritidis chronicae pseudo-tuber culosae bovis (Johne), and some experiments on the preparation of a diagnostic vaccine for pseudo-tuberculosis of bovines. In 1910 the authors demonstrated the possibility of obtaining a pure growth of Johne's bacillus on a medium containing the powdered substance of the dead human tubercle bacillus. This medium was suggested by the possibility that previous failures in attempts to cultivate the micro-organism of Johne's disease had resulted from an inability on the part of the bacillus to build up some necessary part of its food material, and that this part might be supplied ready formed in the bodies of the dead tubercle bacilli. During the past year the authors have tested the growth of Johne's bacillus on media modified by substituting 1 per cent, of other dead acid-fast bacilli in place of human tubercle bacilli. They have experimented with seventeen varieties, and have obtained positive results with a large number, but negative results with others, including the bovine tubercle bacillus. These experiments demonstrate a hitherto unrecognised difference between the human and bovine types of tubercle bacilli. The authors have also succeeded in extracting, by means of hot ethyl alcohol and other solvents, the essential substance (existing in the various acid-fast bacilli) which is needed by Johne's bacillus for its vitality and growth. The strains of Johne's bacillus which they have isolated have been inoculated into a number of animals, with negative results in the case of rabbits, hens, pigeons, guinea-pigs, rats, and mice, thus furnishing further proof that Johne's bacillus is not a variety of the human, bovine, or avian tubercle bacillus. The inoculation of calves and a cow with strains of bacilli isolated from cases of pseudo-tuberculous enteritis has reproduced the disease with its typical characteristics, and the bacilli have been again isolated from the artificially infected areas, and show the characters of the bacilli originally inoculated. Avian tuberculin, originally recommended by Bang, of Copenhagen, for the diagnosis of Johne's disease, has in the authors hands given negative results. They have prepared diagnostic and other vaccines from their pure cultures of Johne's bacillus, but so far have been unable to obtain a diagnostic vaccine of sufficient strength. As the bacillus is now growing more vigorously, the authors hope to overcome this difficilty in the near future.—?.?.?. Arber: The fossil flora of the Forest of Dean Coalfield (Gloucestershire) and the relationship of the coalfields of the west of England and South Wales.—Dr. F. W. Edridge-Green: Simultaneous colour contrast. (1) The colours and changes of colour which are seen on simultaneous contrast appear to be due to the exaggerated perception of objective relative difference of the contrasted lights. Whilst all the known contrast phenomena are easily explicable on this view, there are many facts which are opposed to the older theories. For instance, spectral yellow or pigment yellow contrasted with green do not appear red when seen through a blue-green glass, which is impervious to the red rays. (2) A certain difference of wave-length is necessary before simultaneous contrast produces an}7 effect. This varies with different colours. (3) A change of intensity of one colour may make evident a difference which is not perceptible when both colours are of the same luminosity.

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https://doi.org/10.1038/088502a0

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