Abstract
London Linnean Society, Mar. 17.—E. M. Marsden-Jones and W. B. Turrill: An improved herbarium method for geneticists, ecologists, and taxonomists. The method has been used at Kew for some years, and, with minor modifications, is capable of very wide application. The process consists in the sticking down of the specimens in the living condition. The best results have been obtained with paste, not with gum or glue, ‘Gloy’ being the best so far tested. A sheet of paper or card is brushed over with a thin layer of the paste, and the specimens placed on this. They are dabbed down and the sheet is placed in a press and considerable pressure applied. It is advisable to look at the preparations within a few hours, and remove any excess paste. After a few days the specimens are dried; they retain their shape, and sometimes their colour, indefinitely. With some plants, ironing through blotting-paper with a hot iron gives excellent results.—Miss F. Haworth: Lichen dyes. Parmelia saxatilis (gathered preferably after a wet day) and P. omphalodes are used-in the preparation of Harris tweed, and give a characteristic smell to the cloth. Three methods of dyeing are used: (1) Boiling the lichen and wool together; (2) soaking in ammonia for a week; (3) boiling with ammonia for about two hours until mucilaginous, folding dye and cloth alternately and covering with rain water with a little alum, boiling for twenty minutes, and then washing the cloth in cold water. Generally the best results are obtained where numerous soredia are present. Rock lichens give the best dyes, those species with a large flat thallus rarely producing a permanent dye, though Peltigera canina gives a yellow colour with cotton.—F. E. Fritch: Heath-association on Hindhead Common. The relative grouping of the different species varies considerably with the time since the last fire, with the aspect, and with soil features. The character of the vegetation shortly after a fire depends upon the size of the growth that was burned, but ultimately Calluna becomes completely dominant and more or less completely hides the codominant, but largely prostrate, Ulex nanug. On slopes facing south Erica cinerea may become a temporary dominant for some years. Fires cause little ultimate change. Plants like Pteridium and Molinia may exhibit a limited increase of area in the first year after a fire, but do not advance after the vegetation has closed up.
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Societies and Academies. Nature 119, 620–623 (1927). https://doi.org/10.1038/119620b0
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DOI: https://doi.org/10.1038/119620b0