Abstract
Action potentials are led off during intermitting illumination of the retina of Calliphora erythrocephala by means of intracellular micro-electrodes. In most electrode positions action potentials are found which in their diphasic timecourse are very similar to the simultaneous recorded mass-response of the eye. It is thought that the retinogramm superimposes on the resting-potential of non-illuminated retinula-cells and pigment-cells by electrotonical spread. In distinct positions of the electrode monophasic action potentials are picked up which depolarize the cell, and have amplitudes up to 30 mV. Action potentials of this type disappear as soon as another part of the eye is illuminated. Those action potentials are assumed to be responses of single retinula-cells to light. Further observation show that depolarization is maintained by some structures outside visual cells, but closely associated with them, e.g. the rhabdomere.