FIG. 3.

Mean times to lysis of G. catenatum cells in the presence of different bacterial concentrations (top scale). The error bars indicate standard deviations for duplicates of each treatment. The cultures were not monitored between 15 and 25 h after bacteria were added but were checked 48 h after the start of the experiment. All G. catenatum cultures in experimental wells containing bacteria showed mortality after 2 days. Filtrates had no effect on algae at concentrations lower than 0.003 ml of filtrate/ml of algal culture medium (bottom scale). Filtrate which had been microwaved (95°C) caused no mortality.