It has been observed that promotion of cell enlargement by auxin is accompanied by an increase in synthesis of cell wall material (2, 3, 5, 6, 18, 25, 26, 27). Because auxin does not cause an increase in wall synthesis in oat coleoptile segments whose elongation is inhibited with mannitol, the increase in synthesis caused by auxin in uninhibited segments has been regarded as induced by elongati...