Effect of Plasmolysis on the Rate of Respiration of a Green Alga

Abstract

IN some recent experiments to be reported more fully elsewhere, the effect of plasmolysis and of temperature on the rate of respiration of the green alga Scenedesmus quadricauda has been investigated. The results may be summarized as follows: (1) At 25° C. there is a highly significant (probability 0.1 per cent or less) decrease in the rate of respiration on plasmolysis, with subsequent recovery on deplasmo-lysis. (2) At 7° C. there is no effect of plasmolysis on the rate of respiration. (3) Between 5° and 15° C. the activation energy for respiration is of the order of 21,000 cal./mole. (4) Between 15° and 35° C. the activation energy for respiration is of the order of 5,600 cal./mole. These results are independent of the presence or absence of glucose, though above 15° C. the rate of respiration is increased on the addition of glucose, whereas the rate is unaffected below this temperature.