1. Brain tissue infected with the virus of Western equine encephalomyelitis shows specific differences in metabolism from brain tissue infected with the virus of poliomyelitis. 2. With added glucose concentration of 121 mg. per cent, oxygen utilization of poliomyelitic brain is significantly below normal and that of encephalitic brain is not. 3. With added glucose concentration of 217 mg. per cent, oxygen utilization of encephalitic brain is significantly below normal and that of poliomyelitic brain is not. 4. With lactate-glucose as the substrate, oxygen utilization of encephalitic brain is significantly below normal and that of poliomyelitic brain is not. 5. With pyruvate-glucose as the substrate, neither encephalitic brain nor poliomyelitic brain differs significantly from normal in oxygen consumption. 6. With succinate-glucose as the substrate, oxygen utilization of poliomyelitic brain is significantly above that of the normal control in the 1st hour. 7. With added glucose concentration of 37.5 mg. per cent, anaerobic metabolism of encephalitic brain is significantly below the normal whereas that of poliomyelitic brain is not. 8. With added glucose concentration of 229.5 mg. per cent, anaerobic metabolism of both encephalitic brain and poliomyelitic brain is significantly below the normal.