THE water supply of Boston (U.S.A.) became contaminated about a year ago with some substance or substances which imparted to it a peculiarly nauseous odour and taste. Chemical examination resulted in showing a large percentage of “albuminoid ammonia,” and also that the “free ammonia.” increased somewhat rapidly when the water was kept. The production of ammonia, and also the odour and taste, was finally traced to the decomposition of a freshwater sponge (Spongilla fluviatilis, Anct.) present in Jarge quantities on the sides and bottom of one of Ihe storage basins; removal of this sponge was followed by improvement in the water (see Analyst, viii. p. 184).