AQUARIUM

receptacle for keeping living fresh-water or marine animals and plants for amusement or study. The difficulties of preserving natural conditions, chiefly in maintaining the | nece ary percentage of oxygen, have been overcome by various contrivances found in aquaria connected with biological stations. The finest marine aquaria are kept at Naples, Trieste, Rovigno, Monaco, Villefranche, and SBanyuls, for studying Mediterranean fauna and flora; Plymouth, Brighton, Port Erin, Mill port, St. Andrews, for Brit. marine biology and fisheries; others at Hamburg, Bergen, Helder, and Roscoff. Numerous marine and lacrustine biological laboratories and aquaria have been founded in America, Japan, and elsewhere, and have been of inestimable value not only to the progre of science but to the rational exploitation of fish supply and fish conservation,