Action potentials elicited in the liverwort Conocephalum conicum (Hepaticae) with different stimuli. - APs were detected on thalli of C. conicum with intra- and extracellular methods of measurement. APs were obtained by electric, heat and cold shock stimuli, as well as with light during the intracellular measurement. The presence of a threshold level and refractory period were observed as typical characteristics of APs. The duration of APs induced by electricity was shorter in all the cases. As a working hypothesis, we suggest the existence of different molecular/physiological mechanisms depending on the kind of stimulus given.