As shown in a previous paper the cells of the liver and of the kidney maintain an osmotic pressure approximately twice that of blood and of erythrocytes, exceeding this slightly in the case of liver and being slightly less in that of kidney. When liver cells are injured by chloroform or by carbon tetrachloride the osmotic pressure they maintain falls to the level of the medium that surrounds them but is promptly restored when recovery from the injury, with some regeneration of liver cells, occurs. When nephrosis is caused by potassium chromate or by chloroform the osmotic pressure maintained by parenchymatous cells of the renal cortex falls to that of the medium about them but returns to its normal level with recovery from the injury.