An experiment was conducted on the attitude of some strains of B. dysenteriae on citrate and the following results were obtained: 1. Citrate, independently, as substrate, was added to organisms but development of CO(2) and O(2) uptake was not found. Also disappearance of citrate from medium was very little. 2. The disappearance of citrate in medium was accelerated by addition of glucose, pyruvate, succinate, or ATP. From this, it can be concluded that in order for citrate to be analyzed by B. dysenteria, step in which citrate can be activated is required: the energy necessary is believed to be furnished by glucose, other added substrates or ATP. 3. Whether citrate requires energy to pass cell membrane could not be made clear, nor the pathway of metabolism.