Abstract
The electrical excitability of the retina was measured in the dark with a light-sensation as an indicator.
1. It was found that any part of the retina, when sensitized with light previously, becomes more sensitive to electrical stimulation. The electrical excitability reaches a maximum about 2 seconds after illumination irrespective of its intensity.
2. For high intensities of sensitizing light the supernormal excitability is maximum at the fovea, and decreases towards the periphery.
3. For sufficiently reduced intensities of light the supernormality is minimum at the fovea, and maximum at 40° from the fovea. This distribution of the electrical excitability agrees with the distribution of the light-sensitivity over the retina.
These experiments suggest that the supernormal electrical excitability is an important measure applicable to researches on the mechanisms of daylight-and twilight vision.
