Direct-current electrical stimulation was used as a means of discharging cnidom components from the marginal tentacles of a species of Cerianthus from Southern Queensland, Australia, in order to facilitate the study of cnidom components by light microscopy. The cnidom consists of b-rhabdoids (3 types), spirocysts, and ptychocysts. Threshold pulses of between 1 and 2 V with a frequency of 1 pulse per second for 2 sec discharge all types of cnidae. However, large numbers of certain cnida types discharge after a longer period of stimulation.