The electric potentials in the coleoptile of Avena sativa

Date

1936

Journal Title

Journal ISSN

Volume Title

Publisher

Abstract

Department

Description

The purpose of this investigation was to determine whether the coleoptile of Avena presented a definite pattern of electric polarity which corresponded with morphological polarity and, if such a pattern existed, would it be possible to use this information in explaining such phenomena as growth, tropistic responses, etc. Does a closed electric circuit exist within the coleoptile which could act as a mechanism for (a) transfer of energy, and (b) transport of ions across cell membranes? The flow of soluble plant materials might then be expressed as a function of the magnitude and direction of the inherent electric potentials. If a definite pattern can be shown to exist then we are in a position to study the possible function of the E.M.F.'s. This can only be done by correlating the electric polarity (direction, magnitude, and duration) with other physiological phenomena as (a) respiration, (b) effect of temperature change, (c) existance of electromotively active substances in different concentrations, (d) effects of anaesthetics, etc. A high degree of correlation has been shown by Lund and collaborators to exist between electric polarity and a large number of physiological phenomena. By passing an electric current of proper magnitude and duration through coleoptiles we should be able to determine, to a certain degree, the role of inherent electric potentials as a mechanism of cell correlation during the development of polarity and growth of the system. A large number of observations by the writer have shown that the apex of the coleoptile of Avena is electronegative to the base, in the external circuit. Differences of electric potential have been shown to exist (a) along the longitudinal axis, (b) diagonally from the apex (internally) to the base (externally), and from the base (internally) to the apex (externally), (c) along the internal longitudinal axis, (d) radially along the longitudinal axis. The distribution of these E.M.F.'s are, in general, characteristic, with each plant exhibiting characteristic differences. Under constant external conditions the E.M.F.'s per unit length may fluctuate spontaneously from time to time. These E.M.F.'s may be permanently suppressed by the action of strong concentrations of anaesthetics and by placing the coleoptiles in boiling water for a few seconds, a fact demonstrated by Rosene (1933) on the Onion root, and by Lund (1931) on sections of Douglas fir. W. G. Clark (1935), has reported an increase in the negativity of the apex of the coleoptile of Avena as a result of illuminating the plant from above

LCSH Subject Headings

Citation