On a collision frequency restricting the growth and population density ofTetrahymena pyriformis

Summary

Tetrahymena multiplies very rapidly up to a certain limit of population density, but growth then ceases and the number of cells becomes stationary. We report here the results of experiments using hollow spherical glass beads with a size and weight similar to those of the cells. Growth inhibition may be a result of cell-to-cell and cell-to-bead collision but not due to production of waste materials nor to exhaustion of nutrients in the medium.