Fig. 6. External recording of propagated events evoked by radial strand stimulation. (A) A single shock (asterisk) evoked three propagated events: the first, G, (artificially enhanced for improved clarity) corresponds to the overshooting action potential in the motor giant axon; the second, E, corresponds to a propagating impulse in the endodermal epithelial conduction pathway; the third, F, corresponds to propagating impulses in the bundle of small-axons. Inset: experimental arrangement with stimulating (S) and recording (R) electrodes located on an intact radial strand (RS), subumbrella surface upwards. The stimulating electrode is near the velum (v). The dotted lines represent tissues containing one or more radial and circular conduction pathways as described in the text. (B) Recording showing E and F events in a peduncular radial strand close to its junction with the manubrium. Average of three responses evoked by single stimuli (asterisk) delivered to the same strand approximately 5 mm away.

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