On Inhibiting Effect of Acetates and Acetic Acid on Living Cells of Nitella.

Abstract

When living cells of Nitella were exposed for 10 minutes (1) to M/150 acetate buffer mixture at pH 5.5 or at pH 4.8 (consisting of a mixture of acetic acid and sodium acetate), and (2) to acetic acid at pH 4.8 or at pH 4, the pH value of the sap in the vacuole was found to decrease (depending on the supply of acetic acid in the external solution). If such cells were now placed for ½ minute in the solution of brilliant cresyl blue, made up with M/150 borate buffer mixture at pH 7.85, the rate of penetration of dye into the vacuole was found to decrease, as compared to that of control cells which were placed directly from the tap water into the same dye solution. At pH 4.8, the acetate buffer mixture brought about much greater decrease in the rate of penetration of dye into the vacuole than acetic acid. This may be due to the presence of sodium and a greater supply of acetic acid in the case of the former.

When cells were placed in M/150 sodium acetate solution for 10 minutes the pH value of the sap was found to remain unchanged, but when such cells were placed in the dye solution, as before, the rate of penetration of dye into the vacuole was found to decrease considerably.

From these results we may assume that the inhibiting effect of acetate buffer mixture may be due partly (1) to the effect of acetic acid on the protoplasm (either due to a specific effect of the acid or to the entrance of acetic acid as undissociated molecules and its subsequent dissociation whereby lowering the pH value of the protoplasm corresponding to the lowering of the pH value of the sap in the vacuole); and (2) partly to the effect of sodium acetate on the protoplasm.