For any organ to function properly a constant supply of energy must be available. This energy is obtained from the oxidation of various foodstuffs. The brain oxidizes sugar predominantly. For this reason cerebral disturbances may develop as results either of hypoglycemia or of anoxia. The brain is more sensitive than other organs to lack of oxygen. If the cerebral circulation is interrupted for a few seconds unconsciousness supervenes. Similarly, hypoglycemia may produce impairment of the functions of the brain. The brain is unlike other organs, which seem to oxidize both fat and carbohydrate. For example, the oxygen uptake of muscle remains unchanged during hypoglycemia, as muscle can oxidize fat when carbohydrate is not available.1 The brain, on the other hand, when deprived of its chief foodstuff is no longer able to sustain its functions, so that coma may develop. A cerebral respiratory quotient close to unity, a value which