[Additions to the theory of the dual nature of photoreception].

On the grounds of clinico-physiologic investigations the author revises the existing dual theory of photoreception. The paper describes complex clinical investigations of visual functions in patients with alimentary and essential hemeralopias and shows that rods and cones do not function in conditions of scotopic illumination without the presence of rhodopsin. On the grounds of investigations of the phenomenon of inversion and depression in the short-wave part of the visible spectrum in normal persons after dark adaptation in conditions of scotopic illumination, the author comes to a conclusion that there is a so-called "rhodopsin filter" just the presence of which in the process of dark adaptation creates conditions for appearance of this phenomenon. The author believes that there exist two kinds of photoreception: a direct disc two-component and a mediated rhodopsin one-component, as well as the third, transitory, that corresponds to those conditions of illumination in which the Purkinje's phenomenon appears.