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PARAMECIUM  . F . Muller, (often misspelt Paramaecium, Paramoecium), a genus of aspirotrochous ciliate Infusoria (q.v.), characterized by its slipper-like shape, common in infusions, especially when they contain a little animal matter . It has two dorsal contractile vacuoles, each receiving the mouths of five radiating canals from the inner layer of the ectosarc, and a large ovoid meganucleus, and one or two micronuclei . From its abundance, the ease with which it can be cultivated and observed, its relatively simple structure and adequately large size (Th in.), it is most frequently selected for elementary study and demonstration, as well as for purposes of research .