Inheritance of Minor Colour Vision Variations

A CONSIDERABLE amount of attention has been given to the inheritance of major colour vision defects, namely, red-green blindness and anomalous colour vision 1–6 , and the view most favoured at present is that there are two groups of totally sex-linked alleles with three members in each group (together with dominant normal genes) which determine major red and green defects. Walls has recently put forward the view that there might be a third locus, also with three alleles, and totally sex-linked, which determine blue vision defects 6 .