Feeding strawberry and poplar leaves with iodoacetate, arsenite, or fluoride decreased the contents of sucrose and ascorbate. The content of hexose increased in high concentrations of iodoacetate but decreased in moderate strengths. Iodo-acetate increased the rate of CO2 output and caused a large decrease in phospholipid with increase of inorganic phosphate. When iodoacetate was fed in nitrogen, CO2 output did not increase. An explanation of the results is that the sucrose and ascorbate of the cell are mainly confined to the vacuole and that the above poisons accelerate the leakage of these compounds from the vacuole so that they are metabolized more rapidly in the cytoplasm. An additional possibility is that iodoacetate ‘uncouples’ oxidative phosphorylation, thereby stimulating respiration and more rapid metabolism of both sucrose and ascorbate.