The lateral-line nerve of Japanese eel shows the markedly spontaneous discharges. Those discharges are various in their sizes owing to the fiber-diameters (from 1mv. to 100pv.). The dischargesshow marked seasonal differences according to the temperature of the external environment. Statistical calculations prove that such impulse discharges from a single fiber in situ have some correlation to the heart-beat.
Fibers which elicit small spike discharges and large ones, react differently to many kinds of stimuli, as, pressure, water-flow, mechanical vibration and electrical (D. C. and A. C.) stimulation.
Most fibers show discharges of slow adaptation and only a few fibers of phasic. The weak stimulus excites only a thin fiber, that is, of small spike, and when its strength increases, step by step thickes fibers can be excited and at the same time the dischrge frequencies increase more and more. There can be seen the relation: N=klogS, where N is the average discharge frequencies of the fiber in the initial stage of the stimulation, S the strength and k a constant.
For the vibratory stimuli to a receptor, either of mechanical or electrical, many discharges are elecited in one cycle if its frequency is low and when the frequency of vibration increases gradually, imqulse discharges correspond one to one to those stimuli, such correspondence continues to some frequencies, which is 20-50 per second for thicker fiber and below 10per second for thinner fiber. The more frequent vibration makes the discharge to fall out more and more.
The recepter is easily stimulated by D. C.. Most fibers elicits discharges by the ingoing current and the outgoing current inhibit it. By the A. C. stimulation to the recepter, the fiber discharges only in the negative phase, but for the strong stimulus both in the negative and positive phases. Such mechanism is similar to Weyer and Bray's phenomenon of the cochlea.
The histological construction of the lateral-line shows that many thin and thick fibers innervates the sensory organ. The thinner fiber innervates the more peripheral part of the receptor and the thicker fiber the central part.Both fibers are branching in the sensory cells. Such innervation-modus of thin and thick fibers has been seen already in the receptor of higher order, that is the vestibular organ and the retina.