Electrophysiology of the retina of Periplaneta americana L. 2. receptor sensitivity and polarized light sensitivity

Abstract

Summary. 1. Retinula cells of Periplaneta in the same state of morphological adaptation differ among themselves in absolute sensitivity by up to 1 log unit (tenfold). 2. Morphologically dark-adapted retinula cells are, on average, ten times as sensitive as light-adapted cells to light on the optical axis. 3. All retinula cells are about 5 times as sensitive to plane polarized light in the plane of its optimum effectiveness as in the orthogonal plane. 4. Retinula cells fall into two groups with optimum plane of polarization 90 ~ apart, corresponding with the 2 planes of rhabdomeric microvilli.