It is well known that in malignant tumors, their glycolysis are marked both under aerobic and anaerobic conditions, and this is the most important biochemical property common to all malignant tumors. Using the New Yoshida Tumor, the author investigated the quantitative relation in its glycolysis and the effect of thionin on its respiration in order to observe some aspects of its terminal respiration system and besides, the effect of some inhibitors on its glycolysis was studied. The results were as follows: 1) It was found that as reported up to this time, both under aerobic and anaerobic conditions, the glycolysis by this tumor was as marked as by other sorts of tumors and lactic acid was formed in a great quantity. 2) When glucose was added as the substrate, its endogenous respiration was inhibited and the higher the concentration of glucose was, the more marked the inhibitory effect was and yet, in any low concentration of glucose, its respiration was not accelerated. 3) The respiration inhibited by addition of glucose was recovered by addition of thionin: In this case, however, lactic acid formation was decreased. 4) When T.C.A. cycle intermediates were added as substrates, its respiration was little accelerated, but by addition of thionin at the same time as the intermediates, its respiration was accelerated to sme degree. Further, the respiration accelerated by addition of thionin was reduced after a long time reaction and conversely inhibited slightly. 5) KCN inhibited its respiration, but had no effect on glycolysis itself at all, whereas monoiodacetic acid, 2,4-dinitrophenol, aureomycin and NaF inhibibited not only its respiration but its glycolysis at the same time.