Abstract
Retinal processes of the toad's retina were analyzed by taking spikes from single retinal elements or a restricted number of element as the index.
1. Curves of spectral distribution of photosensitivity for 71 retinal elements were mapped by Granit's optic method of analysis. 26 elements out of 71 were so-called photopic dominators, 8 scotopic dominators, and the rest so-called modulators.
2. It was shown that the modulators fell into three groups with maxima at three preferential regions of the spectrum. However, the number of elements belonging to the “blue” or B group was found much smaller than those of the other kinds of elements. This is due to the masking effect exerted by scotopic dominators upon the B group.
3. On 25 elements out of 71 Motokawa's electrical analysis succeeded. Three kinds of modulators show supernormal electrical excitability following an illumination by white light for two seconds; the time courses of excitability changes being different according to the kind of modulators.
4. It was shown very clearly by the electric method that photopic dominators are composed of two or three kinds of modulators. All these experiments indicate that the two methods of analysis, optic and electric yield consistent results, if the masking effect stated above is ruled out.
