Abstract
LONDON. Royal Society, March 18.—Sir J. J. Thomson, president, in the chair.—W. B. Brierley: A form of Botrytis cinerea with colourless sclerotia. A form of Botrytis cinerea with colourless sclerotia is described. This was obtained by the isolation and growth of a colourless sclerotium, which was formed in a culture of a normal strain derived from a single spore. The prthe initial colourless sclerotium arose. Lotsy's dictum that certainty of purity is a conditio sine qua non to obtain proof of the existence of mutation in living beings is accepted, and it is shown that such a state is possibly not realisable in the fungi. It is suggested that somatic fusions resulting in a change of genotypic values are the mechanism whereby evolution in the fungi has taken place.—R. R. Gates: A preliminary account of the meiotic phenomena in the pollen mother-cells and tapetum of lettuce (Lactuca sativa). In a preliminary study of meiosis in the pollen development of lettuce, several points have appeared which have a general bearing on cytological conceptions and the problems of genetics. The exceptional condition has been found in lettuce, in which every intergrade occurs between pollen mother-cells and tapetal cells. Even synapsis has been observed in binucleate tapetal cells, which emphasises the physiological aspects of the synaptic contraction. The tapetal cells are peculiar in being often very much elongated and lying lengthwise of the anther. Ultimately they break down and form a plasmodium surrounding the pollen-grains. Cytomvxis also occurs, though rarely, during the stage of synapsis in the pollen mother-cells.
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Societies and Academies. Nature 105, 186–187 (1920). https://doi.org/10.1038/105186a0
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DOI: https://doi.org/10.1038/105186a0