Fig. 1. (A) A frequency histogram for the number of cells containing different numbers (1-5) of CVCs obtained for two different populations of Paramecium multimicronucleatum cells. Black columns: cells cultured in a 84 mosmol l^-1 axenic culture medium. White columns: cells adapted to a 4 mosmol l^-1 standard saline solution. Values are means ± S.D. (N=3). (B) SS-1 labeling of the smooth spongiome, visualized by its immunological fluorescence image in cells adapted to a 4 mosmol l^-1 standard saline solution for 24 h. (1) A cell with two CVCs. (2) A cell with three CVCs; an arrowhead indicates branching of a radial arm. (3) A cell with seven (maximum) CVCs. Scale bar, 50 µm.