Plasmolysis may be defined as the shrinkage of all the protoplasm away from its cellulose wall when placed in a hypertonic solution. Such cell is said to be plasmolyzed cells. If plasmolyzed cells are placed in fresh water before the permanent damage has occurred, water re-enters the cells by osmosis and the cells become turgid once more.
A hypertonic solution has a lesser concentration of water outside the cell compared to inside the cell. Everything in the entire world wants to flow from high concentration to a low concentration, so water rushes out of the plant cells, causing it to wilt. This process is called plasmolysis. The process of plasmolysis occurs when water is drawn out of the cell into fluids outside of the cell through the process of osmosis. Osmosis occurs when a cell has a higher concentration of water than its surroundings.