Abstract
Auxin (indole-3-acetic acid) enhances movement of tritiated water into and out of stem segments of etiolated peas. The time required for water in the tissue to attain one-half equilibrium with water in the surrounding solution is significantly shorter and the initial flux rate is higher in auxin-treated sections. The response is one of the most rapid to auxin, occurring well within 1 min after application of the hormone. This suggests that an action of auxin on the membrane system occurs before or coincident with auxin-induced enhancement of growth and wall elastic extensibility.