It depends on how you will use the specimen.
If you will use it for smears, in lieu of a fixative(methanol), you soak it to water. This hemolyzes the cell, releasing hemoglobin and the malarial parasite.
This concept is actually based in diffusion and osmosis. When the cell is soaked in water, it is placed in a hypotonic environment.
The term hypotonic solution is as a solution in which the total molar concentration of all dissolved solute particles is less than that of another solution or less than that of a cell.
That is, solute concentration is greater INSIDE the cell than the OUTSIDE. Now, to achieve equilibrium, water attempts to go inside the cell. Once the maximum capacity of cell size is reached, the cell undergoes ![http://www.wonderwhizkids.com/resources/content/imagesv4/biology/concept/human_phy/Osmosisgif]