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Because of the irreversibility of conduction of spinal reflex arcs, the limitation of Wallerian degeneration to the neurone involved, histological evidence of surfaces of separation in neurone chains of the gray-centered system,1 and the differences between nerve trunk conduction and reflex arc conduction, it is highly probable that intercellular barriers or delicate membranes exist between neurones, especially of the spinal cord. The anatomical relationships between such membranes, or the synapses, seem to have the function of “variable resistence and connection.”2 Because of this faculty they have a very important physiological function in intercellular conduction of the nerve impulse or nerve force, converting the nervous system, as a fixed cellular arrangement, into an instrument of great functional variability. Sherrington has concluded from his studies of the reflex arc and scratch reflex that the synapse varies in its conductivity according to certain qualities of the energy generated in the nerve cell, and that the qualities of this energy vary, besides other causes, always according to the stimuli and receptors stimulated.