Table giving Response to varying Intensities of Light
(The intensity of an incandescent gas-burner at a distance of 150 cm.
is taken as unit.)
| Intensity of Light | Response (Light diminishing) | Response (Light increasing) | Mean | Value in volt |
|---|---|---|---|---|
| 7 | 43 | 39 | 41 | 63·0 × 10− volt |
| 5 | 31 | 29 | 30 | 46·1 ×" |
| 3 | 18·5 | 17·5 | 18 | 27·7 ×" |
| 1 | 10 | 9 | 9·5 | 14·6 ×" |
As the zero point was slightly shifted during the course of the experiment, the deflection in each curve was measured from a line joining the beginning of the response to the end of its recovery. A mean deflection, corresponding to each intensity, was obtained by taking the average of the descending and ascending readings. The two sets of readings did not, however, vary to any marked extent.
The deflections corresponding to the intensities 1, 3, 5, 7, are, then, as 9·5 to 18, to 30, to 41. If the deflections had been strictly proportionate to the intensities of light stimulus they would have been as 9·5 to 28·5, to 47·5, to 66·5.
Fig. 104.—Curves giving the Relation between Intensity of Light and Magnitude of Response
In (a) sensitive cell, (b) in frog’s retina.
In another set of records, with a different cell, I obtained the deflections of 6, 10, 13, 15, corresponding to light intensities of 3, 5, 7, and 9.