1. Small tumors were formed at stem tips of Red Kidney bean plants decapitated in the second internode and treated with a 2% concentration of 2,3,5-triiodobenzoic acid in lanolin. Proliferation occurred mainly in the endodermis, phloem parenchyma, and cambium. Many derivatives matured as tracheids. Neither vascularization of the tumor nor formation of root primordia took place. 2. Telemorphic responses resulted from treatment with 2,3,5-triiodobenzoic acid in a 2% concentration in lanolin paste applied in a ring around the middle of the second internode of young plants. Similar telemorphic responses followed application of the ammonium salt of this acid in a spray. Three concentrations of the salt (1.0, 0.5, and 0.1%) were used, each in an aqueous and in an emulsion spray. Plants were treated in a young and an old stage. 3 The most significant telemorphic response was the abscission of leaves and buds following the formation of separation layers induced by treatment. Persistence of the effect of the substance was evident in the progressive abscission of the new growth. Epinasty of leaves and dwarfing of growth also occurred. 4. Apart from considerable modification of vegetative growth, treatment with 2,3,5-triiodobenzoic acid appeared to have no independent effect on floral morphology or distribution under conditions of the present experiments. 5. The induction of abscission by this compound is discussed in relation to the role of auxin and the inhibition of abscission by many plant growth-regulating substances.