NATURE OF THE ACTION CURRENT IN NITELLA : I. GENERAL CONSIDERATIONS.

The outstanding features of the action curve in Nitella are explained as due to the movement of potassium ions accompanied by increase of permeability. This may be useful as a working hypothesis since it accounts not only for the normal behavior but also for many striking deviations which will be treated in subsequent papers. The views here set forth are in harmony with the local circuit theory of stimulation.