Three strains of the marine dinoflagellate Alexandrium ostenfeldii of different geographic origin were tested for their short-term deleterious effects on a diversity of marine protists. All A. ostenfeldii strains were capable of eliciting an apparent allelochemical response, but the various protistan target species were differentially affected. Protists that were negatively affected by exposure...

ARAMECIUM bursaria is one of the most widely distributed of P the species of Paramecium, though it does not as a rule occur in such large numbers in a given region as does sometimes Paramecium caudatum. It occurs commonly amid growing vegetation in the quiet parts of pools, ponds or streams. It does not flourish in regions in which the water is foul or there is much decaying vegetation. ’ The s...