Ion Intake in Valonia as Affected by HC1 and CO 2 . ∗

Abstract

Living cells of Valonia ventricosa J. G. Ag. were placed in sea water acidulated to pH 5.2 with CO₂ or HC1. After 3 or 12 hours in these solutions groups of 7-11 cells were removed, and the K, Na, and CI concentrations in the sap extracted from them were determined, and compared with the mean of those in the sap from 3 similar groups of untreated cells. The cells in each sample were selected so as to be of similar approximately uniform size. Excess C02 was removed from the sea water-HCl mixture before using it.

In no case was there any clearly demonstrated change during the first 3 hours, although the low value of K at this time in the HC1 experiments may be significant.

Cells kept 12 hours in sea water-HCl mixture showed a 2.7% increase in K, and a 20% decrease in Na. These correspond to changes of 14 and 10 milli-equivalents per liter, respectively, and are more than double the mean variation between the individual groups of control cells. There was no significant change in CI.

Cells kept 12 hours in sea water~C02 mixtures showed a 1.7% decrease in K and a 64% increase in Na. These corresponded to changes of 9 and 32 milli-equivalents per liter, respectively. The change in K, although too small to be considered significant when evaluated alone, probably represents a real change, since it accompanies an indisputable increase in Na. There was again no change in CI.

Thus HC1 led to an increase in K and a decrease in Na, while CO₂ had the opposite effect. The sea water acidulated with CO₂ differed from that acidulated with HC1 principally in its higher content of CO₂ and HCO'₃: there was no significant difference in pH or in CI' content.