Potentiometric determinations in the protoplasm and cell-sap of Nitella

Summary

A method is described for the construction and use of a non-polarizable microelectrode which is protected within a quartz “electrode chamber”. Thereby the electrode may be saturated with hydrogen or any other gas or liquid.

Using it as a hydrogen electrode, potentiometric measurements were made in the protoplasm and cell-sap ofNitella.

The protoplasm and cell-sap behaved very differently toward the hydrogen electrode.

The protoplasm at once produced a potential of between + ·093 and + ·030 volts with respect to hydrogen zero. These values which obviously cannot represent the concentration of hydrogen ions within the protoplasm, are interpreted as indicating rather its oxidation-reduction potential.

Potentiometric readings for the cell-sap gave pH values of 5·47 to 6·16. The latter value is regarded as more reliable.