Abstract
A very rapid photoreversible attachment of barley root tips to wet glass surfaces is mediated by photochrome. Adhesion of the tips to glass can be seen within 30 sec. in red light. They are released within 30 sec. in far-red light. Both processes are reversible for several light cycles. Indoleacetic acid (IAA) in very low concentrations is necessary for reversibility. Adenosine-5[image]-triphosphate, ascorbic acid, Mn++, Mg++, and K+ are also required in the system. This phenomenon is probably a result of the 1st physiological response to the change in form of photochrome induced by radiation. IAA is essential for this phytochrome action.