1. Eleven colour-blind subjects diagnosed as red-blind by routine procedure with Prof. Ishihara's charts were subjected to spectroscopic examination as developed by Prof. Hukuda and described in a previous report.
2. Of 11 subjects, all male, one was trichromic, 6 tetrachromic, 2 pentachromic and 2 were hexachromic in the sense of Edridge-Green.
3. All of them had sensation of yellow and blue. Expansion of the yellow zone to both &des, espcially toward the region of shorter wavelength was a most common feature. The green region was often sacrificed for the yellow.
4. Of 22 eyes, 4 had no zone of defective saturation while 7 eyes were characterized with two zones of defective saturation. This trait was not always represented symmetrically in each individual.
5. Two zones, instead of a single zone, of maximum brightness were reported by 14 eyes out of 22.
6. The spectrum was not always shortened at its end of longer wavelength. Some subjeets were suspected of shortening atits end of shorter wavelength.