Artificial modification of the osmotic pressure of the plant cell

Abstract

1. When one end of an internodial cell ofNitella is brought in contact with water, and the other end with the solution of sucrose, transcellular osmosis takes place from water side to the sucrose side. 2. Accompanying transcellular osmosis, the cell sap on the water side is diluted and that on the sucrose side is concentrated. The magnitude of the polar change in sap concentration is dependent on the difference in osmotic pressure between the two external solutions. 3. By tying off an internodial cell ofNitella with strips of silk thread after inducing transcellular osmosis, it is possible to produce cells having arbitrary osmotic pressures within the range of as high as 3 times and as low as 1/4 the normal level. 4. The cells thus produced, which are in fact fragments of the mother internodial cell, can survive indefinitely. 5. The cell, whose osmotic pressure is abnormally high or low, has a marked tendency to be restored to its normal level. 6. The tendency to be restored to the normal osmotic pressure is maintained, if not fully, even when the import or export of solutes to/from the cell is prevented. 7. Turgor pressure of the cell plays no essential role in the osmoregulation.