Remarks on colour-blindness and the tests to be adopted for its detection / by F.W. Edridge-Green.

  • Edridge-Green, F. W. (Frederick William), 1863-1953.
Date:
[1900]
Catalogue details

Licence: In copyright

Credit: Remarks on colour-blindness and the tests to be adopted for its detection / by F.W. Edridge-Green. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    by the addition of the complementary to each, as the complementary of yellow is blue, and this mixed with yellow would make white instead of orange yellow. The theory I have formed as to the part played by the retina, which is supported by numerous experi- ments, is that light acting upon the retina liberates the visual purple from the rods and a photograph is formed, the cones conveying the impression of the photograph to the brain. I believe that shortening of the spectrum is due to some defect in this visual substance, as it may be met with in otherwise normal sighted persons and there is light as well as colour loss. When a colour blind person has his spectrum shortened the junctions of his colours are moved towards the unshortened side. In dichromic cases this has led to the division into red and green blindness. When the red end of the spectrum is shortened, the neutral point is proportionately nearer the violet end of the spectrum. I find that the position of the neutral point entirely depends upon the degree of shortening. When the spectrum is shortened in those who see three colours in the spectrum the junctions of the colours are nearer the unshortened side than in those who have a spectrum of normal length. A very strong fact against the Young-Helmholtz theory is that in so-called green blindness I have never found any loss in the perception of light similar to that found when there is shortening of the spectrum. From the experiments that I have made during the last ten years, and from the evidence supplied by others, I feel convinced that not only is there a visual substance but that substance is purple. I will not refer to facts concerning the visual purple which are generally known, or to those which I have already mentioned in my book on colour blindness. Kuhne, who made so many observations on the visual purple, stated that it could not be essential to vision, and