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.
© Webster 1913