FIG. 1.

Recovery of competing Naegleria trophozoites from seeded river water by filtration and centrifugation for mixtures of N. fowleri-N. lovaniensis (a) and N. fowleri-N. australiensis (b). Values plotted for each experiment are the number (number of viable amoebae per liter according to control plating) of the two species in the inoculum (I) and the MPN of each species obtained by filtration (F) and centrifugation (C). The theoretical ratio of the two species (in parentheses) and the theoretical total amoebic concentration are shown at the bottom of the figure for each experiment.