LINKAGE BETWEEN OUTPUT OF ELECTRIC ENERGY BY POLAR TISSUES AND CELL OXIDATION

Evidence is presented in this report which it is believed establishes the following facts: (a) A quantitative relation exists between cell oxidation and the continuously maintained E.M.F.'s in the root of the onion, Allium cepa. (b) Equal change in oxygen concentration around different regions of the root tip produces an unequal change in E.M.F.; in this way the characteristic distribution of'E.M.F. 's per unit length of root and therefore the pattern of the correlation currents in the root are modified in a characteristic manner by change in oxygen tension. (c) The velocity of oxygen consumption per unit volume of tissue is greatest in the region of active cell division, and the velocity of oxidation in this region is also changed to a greater degree by the same change in oxygen tension than in other regions of the root tip. This fact, which appears to have an important bearing upon the nature of bioelectric currents, was previously discovered in the Obelia stem (17). The experiments supply the connecting link in the evidence for the validity of the theory that the continuously maintained E.M.F. in a polar cell is that of a redox system maintained in state of flux equilibrium as defined elsewhere by one of us (17). There is a correspondence of morphological, functional, and electrical polarity along the root axis of A. cepa. In the unstimulated uninjured condition, the region of active cell division is invariably electropositive in the external circuit to more basal regions; and the distribution of potentials is in general characteristic but in detail specific for each root. For illustrations of the exact distribution of these potentials the reader is referred to the curves in the paper by LUND and KENYON (13). Under constant external conditions, spontaneous fluctuations in electric polarity occur and the distribution of E.M.F. per unit length varies from time to time (20). The first evidence that cell respiration and electric potentials on the root are linked phenomena was furnished by LUND and KENYON (13). They found that the greatest reduction of methylene blue per unit length occurs in the region of high positive potential, where active cell division takes place, and the same region also produces more CO2 per unit length. A corresponding distribution of the concentration of sulphydryl groups per unit length has been demonstrated; the region of active cell division exhibits the most intense color when the nitroprusside test is applied (17). 27