Shaking cell suspensions without addition of substrate, O(2)-uptakes were compared in the cases where C source was added as the substrate and in those where amino acids were added as the substrate, after 1, 2.5, 5, and 10 hours respectively; and the following results were obtained: 1. The O(2)-uptake in the case using C source as the substrate is generally diminished in proportion to the length of time the cell suspension was shaken, but the degree of such a diminition varies with substrate. In the case using the C source other than succinate the diminition in O(2)-consumption after the first hour's shaking is marked. In comparing the O(2)-uptake-time curves of shaken cells, on the whole the curve is relatively straight, whereas in the control, cells not shaken, the O(2)-consumption generally decreases by 60 minutes and the curve is a downward curvature. 2. Of amino acids in the case where aspartate or glutamate is used as the substrate, O(2)-uptake rather increases after shaking for 2.5～5 hours. In the case where valine or histidine is used as the substrate, although in the control cells no difference can be seen from endogenous O(2)-utake, shaken cells show differences. 3. The facts mentioned in (1) and (2) seem to indicate that substances existing in cells possiblly playing the role of substrate are consumed by shaking. Shaking after the addition of such a higher C source as glucose and observing cells while a portion of the substrate still remains, the O(2) uptake is greater when the substrate used is such a higher C source or substances closely related to the oxidation pathway. In contrast to this, in the case of cells where the added substance is completely consumed by shaking, the O(2)-uptake is greater when the substances added are such terminal substances of the oxida ion pathway as lactate, pyruvate and acetate. This fact seems to reflect the changes in the arrangement of the enzyme system of cells in the course of oxidation of the subtances added at the time of shaking. In the case of cells shaken after the addition of alanine, aspartate, or glutamate, the O(2)uptake in the cases where substrates are such as aspartate and glutamate besides the substance added at the time of shaking is rather great. This seems to be due to the adaptability of cells to any one of amino acids because of the transamination taking place during the shaking. Moreover, the enzymatic activity of cells is gonerally greater when shaken after the addition of some substances than when shaken without addition of substrate.