Long-term measurement of endogenous diurnal oscillations of the electrical potential in an individual Acetabularia cell.

In Acetabularia mediterranea the transcellular electrical potential along the cell is subjected to diurnal oscillations which persist under constant conditions. The frequency may significantly differ between individual cells even in simultaneous measurements. The free running period of a distinct cell may be subjected to slow changes during long-term measurements. Such measurements have been performed over about 100 days.