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The new method for immunochemical assay of extractable insulin from the pancreas described in this report is based on the change in binding of insulin-I131to insulin antibodies in the presence of varying quantities of unlabeled insulin. The method was used to study changes in extractable pancreatic insulin after administration of tolbutamide to normal mice. Although tolbutamide caused a sharp decline in blood sugar within 2 hours of administration, a consistent decrease of insulin in the pancreas was not observed.

1. Homogenate preparations of liver and kidney from fetal rats failed to synthesize bilirubin glucuronides. The conjugative activity did not reach normal levels until the animal was 5 to 6 weeks old. 2. The levels of uridine diphosphoglucuronic acid were only 10% of those found in adult tissue. 3. Inhibition of beta glucuronidase with potassium saccharate did not stimulate the conjugation of bilirubin. Phenolphthalein glucuronide was not hydrolyzed. 4. No conjugation was observed in homogenates of stomach, intestine or placental tissue. 5. The evidence presented suggests that glucuronyl transferase activity and the production of uridine diphosphoglucuronic acid are impaired in the newborn and the premature animal.

1. Metabolites of Rose Bengal could not be demonstrated in human bile, serum or urine or in extracts from rat liver by a variety of systems involving paper and column chromatography and electrophoresis. 2. Conjugation with cystine-S35or glucuronic acid was not demonstrable. 3. It was concluded that Rose Bengal is not conjugated by the liver in the same form reported for bilirubin (glucuronides) or bromsulfalein (mercapticles).