ON THE ACTION OF CERTAIN SUBSTANCES ON OXYGEN CONSUMPTION

Abstract

1. The effect of acidification of the medium on the rate of oxygen consumption of aquatic organisms was studied.2. The acids used were: hydrochloric, nitric, sulphuric, carbonic, butyric, acetic, citric, and tartaric. They were added to water to produce acidities ranging from pH 7.5 to 5.0, at intervals of 0.5 pH.3. Planaria dorotocephala was the chief animal used as material. Some tests with hydrochloric acid were also made using starfish and nudibranchs.4. The acidification of natural waters, either salt or fresh, (pH 8.0), by any of the acids used except butyric causes a decrease in the rate of oxygen consumption at all acidities greater than pH 7.0. The majority of acids also cause depression between 7.8 and 7.0 but in the case of acetic acid and more doubtfully carbonic, there was some tendency towards a slight acceleration of the rate of oxygen consumption at these lower concentrations.5. The decrease in the rate of oxygen consumption due to acids is completely and promptly reversible, as long as th...