ELECTRICAL ACTIVITIES OF THE ANTHOMEDUSAN, SPIROCODON SALTATRIX (TILESIUS)

1. Electrical activities occurring spontaneously and in response to electrical or photic stimulation were recorded from nervous, muscular and non-nervous tissues of Spirocodon saltatrix.2. Two types of quick pulses, nMP's and PSP's, were recorded from the nerve ring. nMP's originated in the outer nerve ring and PSP's, in both the outer and the inner nerve rings. The PSP's appeared to trigger swimming contractions because they always preceded the muscle contraction pulses of the bell (SSP's) and the velum(VSP's).3. Composite pulses with quick and slow phases (QSCP's) and slow monophasic pulses (SMP's) were recorded on the subtentacular region and the tentacles, respectively. The QSCP's had an intimate relationship with nMP's and their quick components appeared to be of nervous origin as were nMP's and PSP's. The SMP's seemed to be myonal or epithelial events and their conduction was restricted to each radial streak.4. Contraction pulses of the velum (VSP's) and the subumbrellar muscle (SSP's) consisted of ...