Fig. 10. Evocation of F events by food juices and their propagation to the manubrium. (A) In a quartered, splayed preparation recording electrodes (R) were placed on two radial strands within the peduncle equidistant from a stimulating electrode (S) on a third radial strand in a flap of body wall. Tentacles (T) were left intact. The dotted lines represent tissues containing one or more radial and circular conduction pathways as described in the text. (B) A control shock was used to establish the characteristic waveforms of E and F events so that they could be recognized in subsequent experiments. Differences in waveform at the two recording sites were attributed to differences in tissue volume and composition drawn into the suction pipette. (C) After application of food juice to the margin on the left flap, trains of F pulses were recorded at both recording electrodes, appearing first on the left electrode.