The double flash ERG during adaptation to the dark.

Electroretinogram (ERG) of albino rabbits and rheusus monkeys were recorded in a dark room applying the double flash stimuli after a sufficient adaptation to light. The stimulus intervals of the flashes were varied. The per cent amplitudes of the ERGs for the first flashes (B1) and those of the second flashes (B2) were plotted against time, as was (B1-B2)/B1 (=K). 1. B1 was independent of the stimulus interval in both species, and increased with lapse of time to reach a plateau. 2. B2 was quite dependent on the stimulus interval, and the ERG dark adaptation curves of the two species were quite different. 3. The time course of (B1-B2)/B1 was specific for the two species. In the rabbit, Ks were almonst equal for three stimulus intervals during states of adaptation to complete darkness, and in the monkey, Ks were different for the three intervals under all conditions.