Two genetic types of normal colour vision?

Waaler1,2 reported that normal human colour vision could be divided into two types (bimodally distributed) on the basis of anomaloscope equations (Rayleigh3 matches) and that these two types are determined by hereditary factors in the X chromosome. He also found a perfect correspondence for male subjects between the two types and the loci on the spectrum at which they see “pure” green. Those seeing pure green around 515 nm and requiring relatively less red light in their anomaloscope matches were called G1 while those seeing pure green around 525 nm and requiring relatively more red light in their matches were called G24.