Generation of Nutational Movements

Abstract

IN 1953, Arnal¹ described a characteristic of nutation in Triticum coleoptiles which had been hitherto un-reported. His observation was that the movement of the coleoptile consisted of the propagation of a wave of bending, of more or less constant amplitude, from the tip of the growing zone towards the base of the organ. He noted that the increasing displacement of the tip from the mean position is caused by the increasing distance of the bend from the tip rather than by an increasing intensity of curvature of a fixed region of the organ. The organ was sometimes observed to possess two or more curvatures of opposite sense at different points along tho length of the growing zone.