GRADED NODAL RESPONSE IN NaCl-DEFICIENT MEDIA, AND THE CRITICAL NaCl-CONCENTRATION FOR “EXCITATION”

Abstract

Employing single myelinated fibres prepared from toad's sciatic-peroneal nerve as material, observations were made on the graded nodal responses elicited in NaCl-deficient media.
When the NaCl-concentration was made gradually smaller than the critical for conduction, first the duration of activity became shorter, and then, in addition, the size became graded. From the relation obtained between the response size and the stimulus intensity, it was supposed that there exists a certain threshold for excitation distinguished from that of conduction, and that this threshold gets higher with smaller NaCl-concentration of the external fluid, to attain practically infinity at about 1/10 of the critical concentratio for conduction. This means that there is a certain critical NaCl-concentration for excitation, distinguished from that for conduction by a mach lower value.