Importance of the Internal Phase Boundary in Penetration of Dye into the Vacuole

Abstract

A cell model 1 was used consisting of chloroform placed between the dye solution and the artificial sap. R_o = the rate of penetration of dye from the dye solution into the chloroform, and R_s = the rate of penetration of dye from the chloroform into the sap. These are obtained by determining the concentrations of dye in the aqueous phases during one hour. The absorption coefficients of the dye are determined by shaking chloroform with the aqueous solutions. These are C_o = cone. of. dye in the chloroform/conc. of dye in the dye solution, and C_s = conc. of dye in the chloroform/conc. of dye in the sap.

(1) The absorption coefficients of crystal violet do not differ very much between pH 5.5 and pH 9, and the rate of penetration of dye into the sap does not vary to any extent in this range. This is because the dye exists chiefly in one form.

(2) The absorption coefficient of methyl violet varies roughly from 4 at pH 5.5 to 20 at pH 9. This is due to the fact that methyl violet is a mixture, (a)When C_o = C_s = 4 the rates R_o and R_s are comparatively rapid, (b) When C_o = 20 and C_s = 4 there is an increase in R_o and R_s, but this is very small compared to the increase in C_o. (c) When C_o = 4 and C_s = 20, the change in R_o may be considered negligible while the decrease in R_s is roughly proportional to the increase in C_s as compared to the results in (a), (d) When C_o = C_s = 20, R_o is slightly higher than in (a), but the increase is very small in comparison with that in C_o, while the decrease in R_s is roughly proportional to the increase in C_s.