Our purpose in this communication is to present experimental data that bear on the nature of the influence of focal infection and the pathology of arthritis. Some phases of the work also throw light on carbohydrate metabolism, and this aspect has been discussed elsewhere.1In order to make plain the significance of the experiments and the reasoning that has led up to them, a brief summary of some previous work will be necessary. This summary, together with new data, will be taken up in the following order: The sugar tolerance in arthritis. The blood gases in arthritis. Absorption from the gastro-intestinal tract in arthritis. The influence of the circulation on the sugar tolerance in arthritis. In view of the interdependence of the several parts of the present studies a certain amount of repetition will be unavoidable. THE SUGAR TOLERANCE IN ARTHRITIS In the course of a study of chronic