N. C, and Marine Biological Laboratory,

This paper reviews studies of the effect of ethanol on impulse propagation in single nerve fibers. Voltage clamp experiments on squid giant axons yield the most conclusive results. They show that the sodium conductance increase asso-ciated with excitation is reduced by ethanol. There is also a small but variable simultaneous reduction in the maximum potassium conductance. The action potential and voltage clamp results are self-consistent on the basis of computation with the Hodgkin and Huxley equations. The high ethanol concentration re-quired to block impulse transmission indicates that the axon per se is more resistant to alcohol than other parts of the nervous system. \J p UNTIL 1950 only a few studies had been made on the effect of ethanol on isolated nerve fibers employing classic extracellular techniques.1'2 In general, there was a reduction in the resting and action potentials with ethanol added to the normal Ringer medium in concentra-tions up to 2M. As the resting potential was reduced there was a transient in