THE INFLUENCE OF CARBON DIOXIDE UPON THE OXYGEN CONSUMPTION OF PARAMECIUM AND THE EGG OF ARBACIA

Abstract

1. The respiratory exchanges of Paramecium caudatum and the fertilized eggs of Arbacia punctulata have been studied by the method of gas analysis. 2. When Paramecium is exposed to different gas mixtures containing carbon dioxide at progressively increasing tensions, the rate of oxygen consumption increases slightly at the lower tensions and decreases at the higher tensions. The rate of oxygen consumption of fertilized Arbacia eggs is depressed by carbon dioxide at all of the tensions studied. 3. Moderate changes in the pH of the surrounding medium produced by hydrochloric acid have no apparent effect upon the rate of oxygen consumption of Paramecium. Similar changes in pH produced by hydrochloric acid diminish the rate of oxygen consumption of fertilized Arbacia eggs, although less markedly than does carbon dioxide at the same hydrogen ion concentration. The greater effectiveness of carbon dioxide in producing changes in the respiratory rate is presumably related to its greater penetrating power.