An attempt to analyse colour reception by electrophysiology

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Abstract
The problem of color reception is that the action spectra of the visual pigments involved, the nature of the signals generated nor the interaction between these signals are not known. Only the incident light and the electric results of interaction are known. It is shown that S-potentials from red/green (R/G) units saturated with deep red light show this property added green lights pulls down the ceiling of depolarization, but more added red had no power to raise it again. Thus lights that depress the deep red celling equally stimulate the green pigment equally. From this the action spectrum of the green pigment can be obtained. If assumed that only 2 visual pigments are involved in the R/G unit, and that lights which do not pull down the deep red celling are below the threshold for green cones, then in this range only the red pigment is excited and its action spectrum may be obtained. Its maximum is at 680 nm where no visual pigment so far has been found. In Part 2 the following mathematical problem is considered: "Is it possible that 2 pigments of given action spectra could combine their outputs in such a way that the resultnt would be identical with the output of a 3rd pigment of given action spectrum, for every intensity of every monochromatic light?" The solution shows that this is always mathematically possible, and the necessary interaction function is deduced. It is shown further that if the log action spectra are the "visual parabolas" that resemble Dartnall''s nomogram, then the interaction function is simply a linear transform such as Hartline and Ratliff (1957) have found with lateral inhibition in Limulus and Dormer and Rushton (1959) with silent substitution in the frog. An interaction that matches a single pigment to perfection for all monochromatic lights will not match it for certain mixtures. By this criterion the 680 nm excitability is a pigment and not the resultant of 2 other pigments, i.e. pigments more excitable In other spectral regions. In Part 3 monochromatic lights are matched by red + green mixtures that give identical responses. From this the action spectrum of the red pigment may be obtained without involving nerve organization (except as a null detector).