The locomotion of dissociated sponge cells: A cell‐by‐cell, time‐lapse film analysis

The production of both lamellipodia and peculiar thin protuberances (scleropodia) characterizes the preaggregative motility of cells after dissociation of the sponge Clathrina. The locomotory paths taken by cells before aggregation were recorded by time‐lapse microcinematography. Changes of direction in successive 50‐s time intervals and 50‐s mean velocities of each cell were both taken into account as statistical variables. Their distributions give probability density curves that seem to fit bilateral exponential functions. The analysis of the angles of turn indicates a tendency for the cells to persist in their direction of motion and to make counter‐clockwise turns. Implications of such in vitro cellular behaviors in aggregative and in vivo processes are suggested.