Observations on the exchange of salt between the xylem and neighbouring cells in Zea mays primary roots

Comparison of two preparations of Zea mays primary roots has shown that the salt concentration in the xylem fluid is altered as it passes through a region of the root where no absorption of salts or water from the external bathing medium can occur. Salts are secreted to the xylem by such a region, presumably from the vacuoles of the cortical cells. It has also been demonstrated that longitudinal water movement through the root cortex is negligibly small during root-pressure exudation.