The role of water in protoplasmic permeability and in antagonism.

The behavior of the cell depends to a large extent on the permeability of the outer non-aqueous surface layer of the protoplasm. This layer is immiscible with water but may be quite permeable to it. It seems possible that a reversible increase or decrease in permeability may be due to a corresponding increase or decrease in the water content of the non-aqueous surface layer.

Apparent violations of the all-or-none law in relation to potassium in the protoplasm.

The protoplasm of Nitella forms a thin layer surrounding a large central vacuole filled with sap. At the inner surface of the protoplasm is a non-aqueous layer called Y and at the outer surface is a similar layer called X. At each of these layers there is a potential due to the diffusion of KCl in contact with the layer.

Changes in resting potential due to a shift of electrolytes in the cell produced by non-electrolytes.

Experiments on Nitella indicate that the resting potential is due chiefly to the outwardly directed diffusion potential of electrolytes which is set up at the inner, non-aqueous, protoplasmic surface surrounding the vacuole. We might therefore expect that any change in the concentration of these electrolytes would affect the resting potential. The experiments described here indicate that this expectation is justified.

The mechanism of accumulation in living cells.

When a compound enters a living cell until its activity becomes greater inside than outside, it may be said to accumulate. Since it moves from a region where its activity is relatively low to a region where its activity is relatively high, it is evident that work must be done to bring this about. The following explanation is suggested to account for accumulation.