FACTORS INFLUENCING TIME COURSE OF S-POTENTIALS RESULTING FROM BRIEF FLASHES

1. Wave forms of the S‐potential (luminosity‐type) from the tench retina were analysed with single or repetitive flashes. 2. In tench the slope of the ‘ ON’ phase was dependent on the relative flash intensity but was independent of flash duration (if it was longer than 15 msec) and the state of adaptation. 3. The slope of the ‘ OFF’ phase was a dual function of flash duration and of the state of adaptation. Light adaptation brought forth a sharp ‘ OFF’ phase, referred to as ‘cut‐off’ in this paper. 4. Temporal or spatial contrast of light and darkness was necessary for the appearance of the cut‐off which was partly responsible for complex wave forms of the L‐type potential. 5. As far as the wave form is concerned the information on the state of adaptation is well processed before it is fed into the S‐space as voltage and does not appear there as a shift in d.c. level. © 1969 The Physiological Society