Brilliant Cresyl Blue in Sap of Nitella

It has been shown by several investigators I that when the pl-I value of the external dye solutions is increased, the rate of accumulation of a basic dye in the cell sap is accelerated. Two different explanations for this have been given. Some have accounted for it on the basis that the basic dye enters the cell in the form of a dye hydrate and combines with the substances in the cell; and that, therefore, the increase in the rate of accumulation of the dye is due to the increase in the concentration of the dye hydrate. Others ~ have assumed that the increase in the rate of accumulation of the dye is due primarily to the increase in the concentration of the combining substances in the cell caused by the increase in the pH value of the cell contents. From these standpoints it is of decided interest to see what will happen if we increase the pH value of the cell sap, while keeping tha t of the external solution constant. An investigation of this sort was made by McCutcheon and Lucke, 3 but from their