Phototactic

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Phototaxis \Pho`to*tax"is\, Phototaxy \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 zoospores of certain alg[ae], 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 Suppl.]