Societies and Academies

Abstract

LONDON. Royal Microscopical Society, March 16.—Prof. J. A Thomson, president, in the chair.—Miss L. S. M. Summers: Antipatharians from the Indian Ocean. Fourteen species were dealt with, including three which are new, viz. Cirripathes indica, Antipathes salicoides, Pteropathes simpsoni. In several cases the presence of well-preserved polyps made it possible to remove some of the doubts which Brook expressed in regard to various species. The paper referred also to certain peculiarities in the polyps and spines. The collections were made at Ibo, in Portuguese East Africa, and in the Mergui Archipelago.—E. M. Nelson: The visibility of the tertiaries of Coscinodiscus asteromphalus in a balsam mount. The author directed attention to the continued improvement in microscope objectives, and particularly to a new 1/8-inch objective by Zeiss. Twelve years ago he received a slide of Nottingham deposit mounted in sulphide of arsenic, and he then saw, for the first time, the tertiaries in Coscinodiscus asteromphalus. He had had a balsam mounted selected slide of this diatom since 1876, and had tested hundreds of objectives upon it, but these tertiaries had never been visible. Recently he received from Messrs. Zeiss a long tube 1/8-inch apochromatic object-glass of N.A. 1.4, and it was tested on this balsam-mounted slide. The tertiaries which had for so many years eluded the grip of all kinds of lenses were conspicuous. This apochromatic 1/8-inch was more sensitive to tube length, stood a larger axial cone, bore a deeper eye-piece, and had sharper definition than any microscope lens he had previously seen.—A. A. C. Eliot Merlin: The measurement of the diameter of the flagella of the cholera bacillus prepared by Löffler's method. Slides of bacteria are prepared by Löffler's method to render the flagella more easily demonstrable, as the organism and its appendages are greatly distended by the process, thus rendering them comparatively coarse objects. Little has been attempted as regards the measurement of these appendages since Dr. Dallinger, read his paper on the measurement of the diameter of the flagella of Bacterium termo in 1878. The author of the paper obtained his results by what are termed extinction measurements, the resulting measurements being for the finest flagella 1/64725-inch and for the coarser 1/62226-inch. He checked these results by measuring, by means of a filar micrometer, the flagellum of a selected specimen, the measurement by this method giving a diameter of 1/66756-inch as against 1/64725-inch of a flagellum of approximately similar fineness measured by the extinction method.