Fig. 2. L-potentials in nematocytes. Upper trace of each record: membrane voltage; lower trace: stimulatory excursion of the probe. (A,B) L-potentials induced by deflections of the hair bundle of a sensory hair cell at two different time scales (a,b). (A) in Stauridiosarsia hair deflection was 28°; a pre-impulse was used to guarantee synchronous starts of the probe and the hair at the second step. The first response in Aa is superimposed by a T-potential (arrow; see Fig. 4). (B) L-potentials in Coryne induced by hair deflection of +10° (Ba, 1) and –9° (opposite direction, Ba, 2). (C,D) L-potentials induced by deflections of the cnidocil apparatus of a distant nematocyte in Stauridiosarsia; responses from the same pair of cells in C and D; (C) without, (D) with discharge of the cnidocyst of the stimulated cell. The responses in Ca and Da are shown on an enlarged time scale in Cb and Db. Note shortening of latency of L-potential from 15 ms (C) to 2.6 ms (D). T-potentials are superimposed in D (arrows). (E,F) Responses of nematocytes of Stauridiosarsia to transepithelial electrical stimulation at the site of a distant nematocyte. The duration of the voltage step stimuli is indicated by a bar beneath the responses and is reflected in the recorded voltage by distorted rectangles. (E) Four superimposed responses to impulses (Stimulus) of equal duration with positive sign at the cell surface (depolarizing the basolateral membrane); two impulses were of 100 mV, 2 of 120 mV amplitude. One stimulus of each amplitude induced an L-potential; the highest was induced by a 100 mV impulse (latencies 20 and 48 ms). (F) Two superimposed responses to impulses with negative sign at the distant cell surface (depolarizing the apical membrane): the smaller impulse (–40 mV) did not induce a response; the larger (–60 mV) elicited the discharge of the stimulated nematocyte and induced a corresponding large L-potential (latency 10 ms) of long duration, superimposed by two T-potentials. (The small peak-amplitude of the L-potential corresponds to the small membrane voltage of the recorded cell. At the peak the membrane became depolarized to the usual range, about –25 mV, as found in D.)