PROOF OF THE PRINCIPLE OF SUMMATION OF CELL E.M.F.'S

Abstract

The electric polarity of a given region of the root tip (Allium cepa) is increased or decreased when an electrolytic solution (liquid shunt) such as tap water surrounds a segment of that region. The magnitude of change is directly related to the length of the liquid shunt, and the direction of change is detd. by the orientation of the polarity potential in the segment to which the shunt is applied. A liquid shunt around the region of the root which exhibits a positively oriented unidirectional polarity diminishes the electric polarity of the whole; a liquid shunt around the region which exhibits an oppositely oriented unidirectional polarity increases the electric polarity of the whole. This fact furnishes conclusive evidence by a new method that the total observed E.M.F. of the onion root is the algebraic sum of the definitely oriented E.M.F.''s of individual cells. The fact that the E.M.F. between the cut end and the longitudinal surface of the frog sciatic is not altered by following the same procedure used in the expts. on the root, shows that the observed effect produced by adding a liquid shunt to the root, is uniquely characteristic of the system of continuously maintained bioelectric potentials distinctive of the root cells.