THE METABOLISM OF THE BRAIN.

IN a previous paper (Courtice, 1940) observations on the cerebral circulation in unanesthetized subjects suffering from intracranial tumour and in cats anxsthetized with chloralose have been reported. In these experiments the arterio-venous carbon dioxide and oxygen differences have been measured with the subjects and animals lying quietly at rest, so that the respiratory quotients may be calculated, thereby giving an indication of the metabolism of the brain tissue. The methods employed have already been described in detail. The blood sugar estimations given below were made by the method of Hagedorn and Jensen (Peters and van Slyke, 1932), each determination being done in triplicate. In Fig. 1 are plotted the arterio-venous carbon dioxide differences against