Abstract
By means of Motokawa's method, the dependence of direct retinal induction on the saturation of inducing colored light was studied in normal and protanomalous subjects.
1. White light was mixed with spectral light of certain brightness in various proportions, and the mixtures were used as inducing light. So long as the amount of white light mixed was below a certain critical value, retinal induction was caused to the same degree, but above the critical value no induction whatever was produced.
2. The minimal saturations for various spectral lights required to produce retinal induction were determined, and the curve for saturation obtained in this way was found to coincide with the curve of colorimetric purity subjectively determined. In the normal, the most unsaturated part of the spectrum was found at 570mμ, the both ends of the spectrum being most saturated. In the protanomalous, however, the curve of saturation showed two minima at 490 and 570mμ; the former was much deeper than the latter.
3. The amount of white light required to check retinal induction was found to be much smaller in the color-defective than in the normal. From these facts it may be concluded that any colored light discriminable from white can cause retinal color induction.
