ABSTRACT
The only way an animal cell can recover from an imposed change of its water content is to alter the number of osmotically active particles in its cytoplasm. In the cells of most higher animals this is achieved by moving solute across the membrane in such a direction that the osmotically obligated water flow will correct the volume perturbation. All volume regulatory behavior of cells can be classified either as regulatory volume decrease, in which swollen cells unload excess water, or as regulatory volume increase, in which shrunken cells take on water. 17
