Gravity and intracellular differences in membrane potentials of plant cells.

The electrical potentials across the cell membranes of the lower parts of Zea mays coleoptile cells are about 2 millivolts more negative than across the upper parts. This electrical polarization with respect to gravity occurs when coleoptiles are oriented with their apical ends either up or down and seems independent of the magnitude of the potential when the potential is modified by other treatments.