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Notes: Summary 1. The wave pattern of the normal ERG elicited by flash stimuli, its recovery from a preliminary light adaptation, and a possible interaction between scotopic and photopic activity were studied. 2. a. In the course of dark adaptation photopic and scotopic components greatly overlap in the ERG, so that detail cannot be clearly discerned. Scotopic dark adaptation was, therefore, impeded so that the recovery of the primarily photopic response could be followed while the scotopic response was limited. This was helped by cutting off part of the low-pass filters in the preamplifiers. b. The recovery of the primarily scotopic response was followed during undisturbed dark adaptation in an ERG elicited by weak light stimuli which did not suppress the recovery of the scotopic reponse but were too weak to produce a full photopic response. 3. a. The recovery of photopic electrical activity was characterized by a fast increase in the positive amplitude of the primarily photopic wave within the first minute in the dark which was followed by a decrease in amplitude. b. The scotopic recovery was characterized by a continuous increase in the positive amplitude of the scotopic wave for about 25 minutes which eventually dominated the ERG. 4. When dark adaptation was undisturbed, the amplitude of the photopic wave remained constant after the decrease. It increased again, however, when scotopic recovery was impeded. 5.During undisturbed dark adaptation, the negative photopic and scotopic components exhibited a similar recovery as the respective positive components. 6.The phenomena were explained by assuming an inhibitory influence on photopic recovery by the scotopic activity. 7. As in the light, the primarily photopic ERG is characterized by a number of negative and positive peaks with a fixed latency. They are regularly spaced along the time axis at a frequency of around 140 cps, and are considered to be due to oscillatory potentials, which summate with the negative wave and the positive photopic wave. 8. A slow oscillatory potential at a frequency of 50 cps was observed in light adaptation. It is less clearly visible under conditions of dark adaptation. 9. The appearance of the fast oscillatory potentials and the extent of their superimposition upon the photopic main wave seem to depend on the latency of the latter. Their changes in amplitude are explained by a shortening or lengthening in the latency of the photopic main wave which occur both during the course of dark adaptation and with the change in stimulus intensity.