PLANT AND ANIMAL LIFE IN RESERVOIRS.

PLANT AND ANIMAL LIFE IN RESERVOIRS.

James Murray, of the Scottish lake survey, has recently pointed out, in a lecture given at Edinburgh, that many people are needlessly alarmed at the presence of plant and animal life in water reservoirs. Nothing short of poisoning the water could prevent this as artificial reservoirs—nothing short of poisoning stocked with the same organisms that live in lakes. All of these aquatic animals, except fish, are moderately small or quite microscopic, and the majority are introduced by means of their eggs or by feeders of the reservoirs Gnats and other insects fly to the reservoirs and lay their eggs on the surface of the water. An examination of the older reservoirs which supply Edinburgh showed them to be biolo vie ally akin in this respect to the permanent lakeIf the presence of organisms had an appreciable effect on the chemical composition of the water, it was in all probability beneficial. The animals acted as scavengers, and all dead and decaying matter was eaten up by them, while their excrement sank to the bottom of the water.

[It should be borne in mind, however, that the Scottish expert was speaking of reservoirs where there is a healthy circulation of the water by inflow and outflow, and where there is no contamination from sewage or otherwise. To encourage ignorance or carelessness in connection with a great city’s water supply was surely the last thought of the LECTURER.-ED. F. & W. ENG.]

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