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Show frx-:--g-:-x-:-x-T-x-x-:-x-M-x-z-M-M-xx-x-x-x-:-x-x-x-:-z-x-M-x-x- Many Persons Unable to Distinguish Colors It is a curious fact that color-blind persons are not often aware of their defect of vision. Even scientific men frequently fail to detect this defect In themselves. The following Is a favorite theory to account for the cause of colorblindness. color-blindness. The eye Is capable of four distinct color sensations blue, yellow, yel-low, red and green. These arise, however, how-ever, from only twd sources, each of which has a double action, producing the sensations of two complementary colors. One of the sources of sensation sensa-tion corresponds to blue and yellow, the other to red and green. Mo?t color-blind people are deflcleni In the latter source of sensation and can distinguish, therefore, only blue and yellow, with their compounds, but sometimes the reverse Is the case. The number of persons afflicted Id this way Is much larger than Is commonly com-monly supposed. The average Is said to be one In every 25 men. Women are rarely troubled with colov-blind-ness. |