Previous work( 1 ) has shown that fructose forms glycogen in the liver faster, and to a greater degree, than does glucose when fructose and glucose are injected intraperitoneally into normal fasted rats. These findings suggested that it would be of interest to extend the same method of studying glycogenesis to totally depancreatized rat following administration of these sugars. Treadwell and Roe, Jr., published a procedure for total pancreatectomy of the rat(2). When evaluated by histological studies, determination of amylase content of areas which the pancreas normally occupies, and glucose tolerance tests, it was found that this operation removes essentially all of the pancreas. This operative procedure was used for the studies reported. Since it was desired to study the effect of absence of insulin on glycogenesis in a large number of rats, it was important to establish criteria of the presence of marked diabetes. Only animals conforming to the following criteria were placed in the experiment: (1) Polyuria (20 to 50 cc of urine,/day) in fed rats: ( 2 ) Glucosuria in fed rats, as indicated by a 3 or 4 plus Benedict's qualitative test: ( 3 ) animals receiving fructose were given a glucose tolerance test previous to glycogenesis experiment, and sugar tolerance of animals receiving glucose was tested during the glycogenesis experiment by determining a control and a one-hour post-injection blood sugar value. Only animals were accepted for the experiment which showed a one-hour post-injection blood sugar level above 200 mg% following injection of 2 g of glucose/kg body weight. Fasting blood sugar level could not be used as a criterion of the presence of experimental diabetes. This is indicated by the data of Table I, in which are shown blood sugar levels of depancreatized rats at different intervals during a 30-hour fast. Within 18 hours * Sutpported by a grant from N.I.H., U S . Public s -Health Service.after withholding food, 4 of the 6 animals had a normal blood sugar level. Animal No. 5 on other occasions showed blood sugar levels of 80 and 89 mg"/. after a 24-hour fast. The blood sugar of all animals returned to hyperglycemic levels in 12 hours after food was allowed lagain. It appears that normal blood sugar level of fasted depancreatized rat corresponds to the presence of a low liver glycogen value. In 2 7 depancreatized rats that had a normal blood sugar level after a 24-hour tasting period and were given saline injections, the average liver glycogen was 83 mg per 100 g of liver. Data in Table I1 show a lower glycogen level in depancreatized rats than in normal rats upon a Purina chow diet. In these studies the liver glycogen content was about one-fourth that in normal animals.However, some glycogen was formed in the liver in absence of the pancreas. I t is suggested that these results are probably due to absence from the alimentary tract of pancreatic digestive enzymes that split carbohydrates and proteins.Methods. White rats from the same stock as used in previous studies( 1 ) , weighing 150 to 200 g, were...