Abstract
1. Electrical currents of varying configurations were applied to single nervefibers of the toad either through a micro-electrode placed directly on one of the nodes of the fiber or through a pair of large electrodes immersed in the poolsof Ringer on both sides of a bridge-insulator.
2. It was shown that the time course of the local excitatory state produced at the node by a brief shock depends markedly upon the mode of application of the shock to the fiber. A brief shock applied at a point far from a node was found to produce, at the node, an excitatory state which attains maximum after a considerable delay. A shock applied directly to a node was shown to induce an excitatory state which grows and decays faster than that caused by a shock applied to the node indirectly.
3. Considering that the action current led through the myelin sheath decays approximately exponentially with time constant of about 100 microseconds, propagation of the potential wave (electrotonic potential) was discussed. It was concluded that the local excitatory state is nothing but the potential difference across the surface membrane at the node of Ranvier, The importance of these results in the whole problem of electric excitation and impulse transmission in the tissues was emphasized.