Influence of Salts and Acids on Penetration of Brilliant Cresyl Blue into the Vacuole.

Abstract

The theory 1 underlying the experiments described in the present paper is that the basic dye, brilliant cresyl blue, exists in two forms which we may call DB, a free base (predominant at higher pH values), and DS, a salt (predominant at lower pH values). It is assumed that the living cell of Nitella ∗ is permeable primarily to DB, and only very slightly to DS. Thus when we speak of the entrance of the dye into Nitella we refer to penetration of DB and not of DS. At equilibrium DB in the vacuole is equal to or proportional to DB in the external solution, and the amount of the total dye (DB and DS) in the sap depends on the extent to which DB changes to DS in the sap.

The rate of penetration of DB into the vacuole may depend on conditions in (1) the external solution, (2) the protoplasm, (3) the vacuole. It is assumed 1 that under varying conditions the seat of the controlling factor may change. One of the important problems in permeability is to locate this controlling factor. An attempt to throw light on this question is made in the present paper by exposing living cells to certain salts and acids and determining the rate of penetration of dye into the vacuole, when the cells are subsequently placed in a solution of dye.

1. Effect of Chlorides with Monovalent Cations on the Cell.

Cells were placed in 0.03 M NaCl solution 2 for 10 minutes, after which they were removed, wiped, and washed in distilled water (pH 5.4) for 5 seconds, then again wiped, and placed in 0.00007 M dye solution 3 at pH 7.7 (M/150 borate buffer solution).