visual purple defined in 1951 yearvisual purple - visual purple;
visual purple - Compound of a protein with a prosthetic group of which Vitamin A is an essential precursor. Occurs in rods of vertebrate retina. Chemically changed (and bleached) by light, the change being basis of function of rods as light-sensitive receptors. Increases in amount in dark, raising sensitivity of rods to faint light (dark adaptation).
near visual purple in Knolik
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