ON THE IMPORTANCE OF MAINTAINING CERTAIN DIFFERENCES BETWEEN CELL SAP AND EXTERNAL MEDIUM.

A striking difference exists between the internal and external solution in the case of Valonia macrophysa. If this difference is abolished by placing cells in their own sap most of them quickly die. There is some ground for believing that the maintenance of differences between the sap and the external medium is of importance for vital processes. The sap of Valonia macrophysa is not a balanced solution in the ordinary sense and the question may be raised whether in general the interior of the cell requires a balanced solution in order to maintain life: or it may be that we must distinguish between internal and external balanced solutions.