Membrane lipid, not polarized water, is responsible for the semipermeable properties of living cells.

It has recently been proposed that the semipermeable surface barrier of living cells is in fact provided by water polarized in multilayers by the cellular protein, and not by the lipids of the cell membrane as had been widely supposed. This review paper summarizes a large and diverse body of recent experimental work, concerned with the structure and function of biological membranes in general and with the passive permeability properties of cell surface membranes in particular, which does not support the polarized water hypothesis. Indeed, there exists a great deal of experimental evidence which supports the concept that the lipid bilayer is a central structural feature of cell surface membranes and that one of the major functions of this lipid bilayer is to provide the selective, semipermeable barrier found at the surface of living cells.