Electrical Connections between Visual Cells in the Ommatidium of Limulus

When microelectrodes are inserted in two cells of the same ommatidium in Limulus, current applied through the membrane of one cell produces a change in potential across the membrane of both cells. The large spikes recorded from one cell and the small spikes recorded from the other always appear synchronously. However, the small spikes are abolished selectively during the hyperpolarizing response. The discrete waves recorded from eyes adapted to darkness occur simultaneously in cells of the same ommatidium.