Abstract
1. In normal dogs experimental hyperglycemia causes a prompt dilution of the circulating blood. This is evidenced by the increase in the relative volume of serum and the reduction of the erythrocyte counts. If the hyperglycemia is large, the viscosity of the blood is visibly diminished. 2. As the hyperglycemia increases there occurs a reduction of the serum chlorine concentration and an increase in the concentration of corpuscular chlorine. 3. Reduction of an artificial hyperglycemia restores the relative blood volumes to their normal status. The erythrocyte count rises to the normal and the corpuscular chlorine concentration is diminished. If the reduction is a large one, the viscosity of the blood is visibly increased. 4. The same types of conductivity-chloride discrepancy that occur in human blood are found in the blood of dogs. In addition, a third type is described. 5. Hyperglycemia does not cause the same changes in the volume of the average erythrocyte of the dog as it does in the case of human erythrocytes.