What is "positive chemotaxis"

Chemotaxis \Chem`o*tax"is\, n. Formerly also Chemiotaxis \Chem`i*o*tax"is\ [Chemical + Gr. ? arrangement, fr. ? to arrange.] (Biol.) The sensitiveness exhibited by small free-swimming organisms, as bacteria, zo["o]spores of alg[ae], etc., to chemical substances held in solution. They may be attracted ( positive chemotaxis) or repelled ( negative chemotaxis). -- Chem`o*tac"tic, a. -- Chem`o*tac"tic*al*ly, adv.

n. movement toward a chemical stimulus