The Relations of Bioelectric Phenomena to Ionic Permeability and to Metabolism in Large Plant Cells

Although often treated as separate chapters of physiology, permeability and metabolism are probably as closely related as many other functions of the cell. It is hardly necessary to mention the entrance and exit of oxygen and carbon dioxide, carbohydrates and urea, and all other raw materials or waste products, to illustrate how permeability must influence metabolism. But there is also a converse relation, in that metabolism may in turn influence permeability. As Hoagland has shown in this Symposium, accumulation of mineral elements in the plant cell or root system depends upon oxidative metabolism. This probably operates by setting up and maintaining driving forces or gradients, whether of proteins, organic acids, or merely hydrogen ion gradients, assumed in various theories to attract, hold or pass on potassium and other accumulating elements. But there is also the possibility that metabolism influences the nature and state of the cell surfaces or membranes across...