Analysis of the movement toward an attractant region in single worms. The frequency (A) and duration (B) of forward and backward movements of single worms were analyzed, and forward (filled bar) and backward (open bar) movements were counted. For single presentations: 15°C, n = 10; 0.03 M sodium chloride, n = 7; 0.07 M sodium chloride, n = 7; isoamyl alcohol, n = 11. For simultaneous presentations: 15°C (with 0.03 M), n = 9; 0.03 M, n = 5; 15°C (with 0.07 M), n = 12; 0.07 M, n = 10; 15°C (with isoamyl alcohol), n = 11; isoamyl alcohol, n = 7. Data are the mean ± SEM. The mean for duration was obtained by averaging the means of durations for individual worms. The data showing significant differences (p < 0.01) are linked with a line. (C-H) Distributions of duration of movements. The numbers of movements within a 2ns (n = 1, 2, 3...) interval were summed and expressed as events per hour. The movements of the worms in simultaneous presentation are shown alongside the result from each single presentation.