The Tokoku Journal of Experimental Medicine, Vol . 51, Nos. 3 & 4, 1949.

Physiological Evidence for the Three Components

Theory of Color Vision.

By

Koiti Motokawa.

(本川 弘 一)

(From the Physiological Laboratory of Prof. K. Motokawa,

Tohoku University, Sendai.)

(Received for publication, November 7, 1947)

The theory of Young-Helmholtz is based on the facts of color mixtures.

Young supposed that in the retina there are three types of nerve fibers

which produce a sensation of red, green and blue respectively. The

various color sensations result from the relative strengths with which the

three kinds of fibers are stimulated, and a colorless sensation of white results

if they are all excited equally. Expressed in modern terms, the three

species of nerve fibers assumed by Young may be considered as three

species of cones. Each type of cone contains its own particular photo

sensitive substance, and is concerned with an optic nerve fiber, stimulation

of which produces the color sensation corresponding to it.

Helmholtz1) assumed in each cone three different activities (chemical,

electrical or other processes), because he became aware that the facts of

visual acuity necessitated a smaller unit than three cones. In spite of the

further elaboration of this theory since Helmholtz, there is no physiological

evidence of the existence of three kinds of nerve fibers, cones or activities,

except the experiments of color mixing. The data of color mixing them

selves can be adequately described on the basis of tetrachromatic theories

of Hering2) and others as well, as pointed out by Schrodinger.3) Further

more, these theories are even more natural and simpler from a psychological

point of view; they treat yellow and white as unitary sensations, because

we can perceive no trace of red and green in yellow, and no trace of red,

green and blue in white, although the trichromatic theory claims that

yellow and white are compound sensations.

However, the unitary nature of white as a sensation does not hinder

it from being the result of psychical fusion of two or more separate phy

siological processes. Therefore, it is neither psychological experiments nor

measurements of color mixing that decide the question as to which of these

views is correct. The problem is essentially a physiological one.

The author has shown in a series of papers4)5)6) that the effect of

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