Fig. 3. Spectral sensitivity S() measurements of an S/LM cell with no background (A) and under blue adaptation (B). All curves are averages of four S() scans, collected alternately from 300 to 700nm and in the opposite direction. The polarisation reversal was detected by a phase change in the response to the flickering stimulus. (A) S() function recorded in the absence of background light (filled circles, hyperpolarizing responses, open circles, depolarising responses). (B) The S() function of the same cell under a bright blue background (Schott DIL 457nm; 1.9x10¹²quantas^-1cm^-2). The solid line is the cone porphyropsin template (Stavenga et al., 1993) with a peak at 372nm.