Heredity of Two Normal Types of Colour Vision

Abstract

I HAVE described¹ two groups of males with normal colour vision (diagnosed using the anomaloscope), but with two different “greenpoints”—that is, two different points on the spectrum at which they see pure green. Moving from the yellow–green side, the subject can tell where the yellow disappears and, moving from the other side, he can tell when the blue in the blue–green disappears. The two different groups of normal males have their green–points at 515 and 525 nm (nanometer = 10⁻⁹ m). I have described a technique which makes it possible to confirm this bimodal greenpoint and have assumed that it depends on two sex-linked normal mutants, which I called P and D. They should now be called G₁ and G₂ (see preceding communication). Three genotypes would be expected in females: G₁/G₁, G₁/G₂ and G₂/G₂; in fact, I found three phenotypes, G₁₁, G₁₂ and G₂₂, a hypothetical G₁₂ group giving intermediate reactions. This hypothesis of inheritance was confirmed in investigations of families (Tables 1 and 2 in ref. 1).