LONDON. Royal Microscopical Society, December 12, 1917.—Mr. E. Heron-Allen, president, in the chair.—W. uateson: Cytology and genetics. Attempts to nnd regularity in the distribution of chromosome numbers haa generally been unsuccessful, but attention was directed to the recent work of Winge, who, by preparing a graph ot these numbers in plants, had shown that simple multiples of 2 and 3 occur with special frequency, while prime numbers are rare and exceptional. A survey was given of the phenomena of linkage between genetic factors as demonstrated in breeding experiments, with a discussion of Morgan's suggestion that this linkage is due to a linear arrangement of the linked factors in the same chromosome. Whether the proposition in its entirety was established or not might be doubtful, but the factors certainly behaved as if arranged in lines, and, as represented by the theory, a great diversity of genetic and cytological observations relating to the heredity of sex and other characters assumed an orderly form.—G. S. West: A new species of Gongrosira. A lime-encrusted alga, forming somewhat nodular masses 4-9 mm. thick, of a vivid green colour, was found at Westen Mouth, Devon, growing in such a position that it received the full force of a stream of water falling about 2 ft. It proved to be new, and is described as G. scourfieldii.