Unlike the petiole or stem, the laminar pulvinus of the primary leaves of Phaseo/us vu/garis L. regenerated after a partial excision. The histological and physiological aspects of these regeneration processes have been studied. On the third day after the excision of the flexor (or extensor) region, the pulvinus was regenerated. When the major part of the extensor was cut away, the period and phase of the circadian leaf movements were unchanged whereas the amplitude was greatly reduced. When the flexor region was excised, period, phase and amplitude were maintained. Some changes could be seen in the ultradian movements after excision of flexor as well extensor regions.