ELECTROPHYSIOLOGICAL INVESTIGATION OF OPTICS OF LOCUST RETINA

Intracellular recordings from single retinula cells of the locust compound eye show that the visual field is about twice as wide in dard-adapted (horizontal [DELTA] [image] = 6.6[degree]) as in light-adapted eyes (horizontal [DELTA] [image] = 3.4[degree]). The time course of this increase in acceptance angle is correlated with the replacement of a dense packing of mitochondria by a fluid-filled palisade around the rhabdom during dark adaptation. This correlation is taken as evidence that the acceptance angle in light-adapted eyes is limited by the internal reflection at the boundary between rhabdomere and cytoplasm. Direct tests of the acuity of single retinula cells to equally spaced black and white stripes of various repeat distances show reasonable agreement with calculation of the contrast caused by such stripes in single receptor cells, with the observed angles of acceptance, and with optomotor and other acuity studies. iNo evidence from the retinula cells supports either optical or electrical interaction between adjacent ommatidia.