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n.1.(Biol.) A cyst in which some unicellular organisms temporarily inclose themselves, from which they emerge unchanged, after a period of drought or deficiency of food. In some instances, a process of spore formation seems to occur within such cysts.
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
In the Mediterranean, only the thickest frustules are preserved in the sediment, often proceeding from the littoral, as is the case in the widespread Paralia sulcata or the resistant forms (hypnocysts) of Chaetoceros and some other common genera.
Marine sediments off Cata-lonia contain coccoliths (more than 80% Emiliana huxleyi), but hardly any diatom valves, and the few that do persist are hypnocysts, resistant cells with thickened walls, or equally robust coastal diatoms.