Studies on the metabolism of the Protozoa. 7. Comparative carbohydrate metabolism of eleven species of trypanosome.

muscle, which is particularly great with DNP. Further experiments on these problems are in progress. SUMMARY 1. The influence of 2:4-dinitrophenol, methylene blue, brilliant cresyl blue, thionine, phenosafranine and Janus Green B on the oxidative phosphoryl-ation of mitochondria isolated from liver, kidney, brain, heart and skeletal muscle of rats has been studied in vitro as well as in vivo. 2. All the substances used produced a high degree of inhibition of oxidative phosphorylation both in vitro and in vivo. In every case, uncoupling of oxidative phosphorylation was accompanied by a change of form of the mitochondria from rod-like to spherical and by swelling. 3. 2:4-Dinitrophenol and brilliant cresyl blue produce activation of adenosinetriphosphatase of liver mitochondria in vitro. 5'-Nucleotidase and both acid and alkaline phosphatases are also stimulated. All the substances used stimulated adenosinetriphosphatase, 5'-nucleotidase and both acid and alkaline phosphatases in vivo. 4. 2:4-Dinitrophenol and brilliant cresyl blue stimulate adenosinetriphosphatase activity of fresh as well as of aged mitochondria. Also soluble adeno-sinetriphosphatase is activated by these substances. 5. Phenosafranine strongly inhibits myokinase of liver mitochondria, both in vitro and in vivo. 6. Prolonged treatment of rats with the substances produces fatty infiltration of the liver. 2:4-Dinitrophenol produces glycogen accumulation instead of fatty infiltration. 7. The significance of the phenomena is discussed. From the numerous papers on the carbohydrate metabolism of trypanosomes which have appeared during the past twenty years, it has become obvious that, with the possible exception of Trypano8oma cruzi (Brand, Tobie, Kissling & Adams, 1949) and the plant trypanosome Strigo-monas oncopelti (Ryley, 1955), cellular motility depends on a supply of extracellular monosac-charide, which is incompletely broken down to a mixture of organic acids; much of this work is admirably summarzed by Brand (1951). Trypano-somes of the brucei-evan8i group [for classification