I Further, even in muscle and liver the inhibition of hexokinase activity by APE is not complete. The relatively normal

" spontaneous" fall of blood-sugar in hepatectomised animals previously injected with APE may well be the expression of carbohydrate utilisation by tissues whose hexokinase is relatively insusceptible to such inhibition and to the residual activity in those tissues which are more susceptible. The corollaries of this view are that insulin’is primarily required for those tissues in which APE readily produces inhibition and, further, that’some degree of such inhibition should be present, even in non-diabetic animals, if insulin is to act. These results are in accord with the views of Russell 60 61 that the anterior pituitary gland acts on carbohydrate metabolism primarily by restricting utilisa-tion in the tissues. Her views are based on the observations that in hypophysectomised animals oxidation is increased, muscle glycogen disappears more rapidly, and, in eviscerated preparations made from such animals, more glucose is required to maintain a normal blood-sugar level.