[Optics of the crayfish eye (author's transl)].

Histological and optical observations in the eye of crayfish lead to a new hypothesis of the superposition ray path in this eye. Rays from an object point entering through different facets are superimposed not by refracting systems as in other superposition eyes but by a radial arrangement of orthogonal reflecting planes which are formed by the sides of the crystalline cones and purine layers surrounding them.