Kinetics of water loss from cells at subzero centigrade temperatures.

The cells of which living things are com­ posed and the single-celled microorganisms generally contain very high fractions of water. The high fraction of water in cells introduces a problem when the cells are cooled below 0°C; that is, one has to find out what happens to the water content of the cells when they are cooled to tempera­ tures at which water freezes. There are many factors involved in the process of cooling cells which results in the change of water content in the cells during cooling (9). The scientific work on the cooling of cells has concluded that the biological damage due to cooling was caused by the formation of ice inside the cells. The early workers in this area have suggested that by cooling the cells very rapidly one might produce vitrified water instead of ice inside the cells, and this would prevent biological damage or death. The early workers in this area also showed that some cells and tissues were able to survive at very rapid cooling rates, but they were unable to prove the vitrification process inside the cells. Later, with the discovery of the effect of the cryo­ protective agents, the interest in cooling of cells and organs below 0°C for the purpose of banking was increased ( 10). When the cells are suspended in an aqueous solution ( extracellular fluid) we may distinguish two parts. One part is the