The shrinkage of protoplasm when a cell is placed in hypertonic solution is called plasmolysis. A cell get plasmolysed due to loss of turgor. When a plasmolysed cell is placed in hypotonic solution it regains its normal shape, this phenomenon is called deplasmolysis. The net force with which, water is drawn into a cell is equal to the difference of OP and TP and known as Diffusion Pressure Deficit (DPD) or Suction Pressure (SP). DPD or SP=OP−TP. The pressure by which the cell sap presses the protoplasm against the cell wall is called turgor pressure. The cell wall being almost rigid and exerts a center pressure known as wall pressure. The hydrostatic pressure developed in a solution when it is separated from pure solvent by semipermeable membrane in a rigid vessel is called osmotic pressure.