The Hunterian lectures on colour-vision and colour-blindness : delivered before the Royal College of Surgeons of England on February 1st and 3rd, 1911 / by F. W. Edridge-Green.

  • Fredrick William Edridge-Green
Date:
1911
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Licence: In copyright

Credit: The Hunterian lectures on colour-vision and colour-blindness : delivered before the Royal College of Surgeons of England on February 1st and 3rd, 1911 / by F. W. Edridge-Green. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    every part, though the curve has the same general shape. The three trichromics described in my recent paper ^ on The Relation of Light-Per- ception to Colour-Perception each saw ten consecutive monochromatic patches in the spec- trum instead of the eighteen or nineteen seen by those who see six colours in the spectrum. It is easy to show that the trichromic are dangerously colour-blind. They will mark out with my colour- perception spectrometer a patch containing greenish yellow, yellow, and orange-yellow, and declare that it is absolutely monochromatic. When tested with coloured lights they find great difficulty with yellow and blue. Yellow is con- tinually called red or green. There are several other degrees of colour perception, and it may be well to say a word or two about them, though I class all above the trichromic with the normal-sighted for practical purposes, as they are not dangerously colour-blind, and can always, in ordinary circumstances, dis- tinguish signal lights correctly. In the next stage of evolution four colours are seen in the spectrum, and the fourth colour appears at the fourth point of greatest physiological difference, namely, at the orange-yellow of the hexachromic or six-colour people. These persons I have designated tetra- chromic, because they see four distinct colours in the spectrum, that is, red, yellow, green, and violet. They do not see blue as a definite colour, and are continually classing blues with greens ; they usually prefer to call blue, purplish green. 1 Proceedings of the Royal Society^ vol. B 82, 1910, p. 458.
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