Intracellular recordings were made from the retinula units of the cricket Nemobius sylvestris. The half width of the angular sensitivity function was estimated at 4,4 degrees. This mean acceptance angle is slightly smaller than the interommatidial angle. In these conditions of light adapted state and for ommatidia of the central eye region, an overlapping between adjacent ommatidia occurs, but only below the 50% sensitivity level. 2. Extracellular positive responses with the waveform of a smoothed retinula receptor potential were recorded and their origin from lamina is postulated. They were strongly influenced by lateral interactions with the neighbouring ommatidia, and it was concluded that a lateral inhibition in the first optic ganglion of the cricket does exist.
