Ionic currents traverse the slime mould physarum

Self generated electric currents were studied in protoplasmic drops and small plasmodia of Physarum polycephalum with the aid of an extracellularly measuring vibrating electrode. Ionic currents up to 15 microamperemetercm-2 density were found to traverse the objects. In protoplasmic drops current always enters the numerous protrusions and leaves areas with a smooth surface. In monopodial plasmodia current enters the strand and leaves both the advancing front and the retracting end. This result points toward large changes in membrane arrangement or properties occurring during development of plasmodia from protoplasmic drops.