NOTE ON THE EFFECT OF UNILATERAL ILLUMINATION ON THE TRANSVERSE ELECTRICAL POLARITY IN THE AVENA COLEOPTILE

Abstract

Avena coleoptile sheaths, isolated from 30-mm. plants, establish a transverse electrical polarity in the apical region when they are unilaterally illuminated by an intensity of 16 foot candles from an incandescent mazda lamp. The shaded side of the sheath becomes electropositive to the lighted side by an average of about 8 millivolts. The orientation of this electrical polarity with respect to the subsequent curvature is the same as established by gravity and mechanical stimulation, and it is established before photo-tropic bending begins.