The Electro-osmotic Theory of Phloem Transport in the Light of Recent Measurements onHeracleumPhloem

Abstract

The bearing, on the electro-osmotic theory, of work on the Onsager coefficients for Heracleum phloem, currently reported by Tyree and Fensom (1970), is briefly discussed. As an aid to the discussion the Onsager resistance coefficients are evaluated in terms of Spiegler's frictional model. It is concluded that the experimental evidence, while it does not support the theory, does not invalidate it. Some further suggestions regarding the electro-osmotic theory are put forward.