Diagnosis and genetics of defective colour vision / by H. Kalmus.

  • Kalmus, H. (Hans), 1906-1988.
Date:
[1965]
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Diagnosis and genetics of defective colour vision / by H. Kalmus. Source: Wellcome Collection.

    32/134 (page 16)
    18 defective colour vision protanopes, extreme protanomalous and protanomalous men; however, more than three abnormal protan alleles exist w^hich result in a larger number of less different defects. In terms of development protan alleles probably have similar effects—varying only in severity but acting on the same structures; thus the physicist's absolute (p. i6) distinction between dichromatic and anomalously trichromatic protans, i.e. between protanopic and protanomalous men, arbitrary from the point of view of the sense physiologist (pp. 52 ff.), becomes quantitative for developmental genetics. We shall see later that this distinction is in any case often dependent on the method of investigation, for example on desatura- tion of colours in the anomaloscope used or the size of the matching area (p. 45). However, different methods of testing will usually result in a sample of male protan defectives being arranged in the same order of severity. Protanopes lack the normals' red absorbing cone pigment (see pp. 28 if.) which is supposed to be contained in special red sensitive cones, the R cones, and it is at present reasonable to assume that the protanomalous of whatever severity have less of this pigment and perhaps fewer of these cones in their retinae than people of normal colour vision; at least in the more central areas of the retina. The red sensitive cones of the colour-normal person may in protanopes be replaced by the green sensitive G cones (Walls and Mathews, 1952), or they may be missing or non-functional. I II <2^ Ш ó ó IV ÉdaÔ à о ш Deuteranope Щ Extreme protanomaly Ш Cone monochromat Fig. 9. A cone monochromat female in a pedigree of deuteranopia and extreme protanomaly (after Weale, хрзз)-