Salts Affecting Penetration of Brilliant Cresyl Blue into Nitella at Different pH Values.

Abstract

I. When cells are exposed to 0.05 M sodium chloride, 1 and then placed in a solution of brilliant cresyl blue 2 at pH 7.5, there is a decrease 3 in the rate of penetration of dye into the vacuole, 4 as compared with the control. 5 There is no such decrease 3 when sodium chloride is replaced by magnesium or calcium chloride. The same results are obtained at pH 7.9.

II. When cells are transferred directly from tap water to the dye solution at pH 7.5, containing 0.05 M (a) sodium chloride, (b) magnesium chloride, or calcium chloride, there is a slight increase 3 in the rate of penetration with (a), while there is practically no increase 3 with (b). When the experiments are repeated at pH 7.9, there is no appreciable change in the rate from that of the control, 5 when the dye solution contains sodium chloride, while there is a slight decrease when the dye solution contains magnesium or calcium chloride.

This decrease is not due to an increase in the concentration of sodium in the buffer resulting from the addition of more borax, because there is no such decrease when the equivalent amount of sodium is introduced by adding sodium chloride to the dye solution containing either 0.05 M magnesium or calcium chloride, at pH 7.5. This decrease may therefore be attributed to the increase either in hydroxyl ions 6 or in borate ions, This decrease, 7 furthermore, does not seem to be due to the direct effect of such anions on the protoplasm in the presence of a salt with bivalent cation, because there is no such decrease when cells are exposed to 0.05 M calcium, or magnesium chloride made up with borate buffer mixture at pH 7.9, and then placed in the dye solution containing neither of these chlorides, at pH 7.5.