1) URINARY EXCRETION OF THE PREFORMED GLUCURONIC ACID, AND THE INFLUENCE OF GLUCURONIC ACID UPON THE URINARY EXCRETION OF MEN-THYLGLUCURONIDE IN RABBITS.The preformed glucuronic acid injected to rabbit was excreted into the urine rapidly, and 75 to 90% of the injected dose was excreted within six hours. The excretion was particularly rapid in case of intravenous injection. (Fig. 3). The administration of menthol had no significant influence upon the excretion of the injected preformed glucuronic acid in rabbit. (Tab. 4, Fig. 4).500 mg. of preformed glucuronic acid administered to rabbit orally was hardly excreted into the urine.When the preformed glucuronic acid was administered to menthol treated rabbit, the increase in the excretion of menthylglucuronide was obserbed. (Tab. 2, 3, Fig. 2) However, the dosage and the way of administration of glucuronic acid had little influence upon this effect.Judging from the above results, it appears that the most of the menthylglucuronide excreted in case of the concomitant administration of menthol and preformed glucuronic acid is derived from endogenous source, and that the exogenous glucuronic acid itself is scarecely utilized for the synthesis of menthylglucuronide.100 mg. of glucuronic acid injected together with asorubin-S scarecely influenced the excretion of asorubin-S into the urine. (Tab. 5)2) THE RELATIONSHIP BETWEEN THE SYNTHESIS OF MENTHYLGLUCURONIDE AND THE LIVER GLYCOGEN.The administration of menthol to rabbits resulted in the significant decrease in the liver glycogen contents (Tab. 7, Fig. 6). This procedure, however, hardly produced the histological changes in the liver.No definite correlation was found between the amount of menthylglucuronide excreted into the urine and the pretreatment contents or decrease of the liver glycogen. (Fig. 8, 9, )Intravenous injection of 10 c. c. of 5% glycogen saline solution increased the excretion of menthylglucuronide in rabbit treated by menthol. (Tab. 10)The preformed glucuronic acid, glycogen or glucose could not prevent the decrease of the liver glycogen caused by the administration of menthol. (Tab. 8, Fig. 7) Furthermore, the preformed glucuronic acid and glycogen themselves did not increase the liver glycogen. (Tab. 9)