抄録
Color processes at single retinal elements or at a restricted number of elements of Japanese toads were investigated with the aid of microelectrodes, taking well-isolated spikes as the index. The electrical excitability of a single retinal element as a function of time after cessation of pre-illuminating white light shows a maximum at 1.5, 3 or 5 minutes. These values of crest time correspond respectively to those of the R, G and B elevations which are found on the excitability curve for white light determined with action potentials of the whole optic nerve as the index. From retinal elements responding with isolated spikes to optic and electric stimuli sometimes an excitability curve having two distinct humps was obtained.
A histogram concerning crest times of excitability curves of these isolated elements shows that there are three groups of retinal elements. The number of elements belonging to each group was 23 for the R group, 21 for the G group and 21 for the B group. When red light was used instead of white light for pre-illumination all the 19 elements tested in this series of experiments showed excitability curves of the R type. The retinal elements so far studied are to be identified with Granit's modulators.
