Fig. 3. Percentage of newts swimming upstream to the site of amino acid or stream water (control) release. Each compound was tested at 10^–5 mol l^–1; functional groups are illustrated above respective bars. Arg, arginine; Ala, alanine; Gly, glycine; Tau, taurine; Glu, glutamate; Lys, lysine; Cys, cysteine; Leu, leucine; Phe, phenylalanine; Met, methionine; Asp, aspartate; Trp, tryptophan; Val, valine; WF, worm fluids with a corresponding arginine concentration of 10^–5 mol l^–1). Asterisks denote a significant difference between larval responses to test and control (stream water) solutions, using a Fisher exact test (P<0.05).