Phototaxis

{ ‖Pho′to‐tax″is (?), Pho″to‐tax′y (?) }, n. [NL. phototaxis; photo- + Gr. � an arranging.] (Biol.) The influence of light on the movements of low organisms, as various infusorians, the zoöspores of certain algæ, etc.; also, the tendency to follow definite directions of motion or assume definite positions under such influence. If the migration is toward the source of light, it is termed positive phototaxis; if away from the light, negative phototaxis. — Pho′to‐tac″tic (#), a. — Pho′to‐tac″tic‐al‐ly, adv.