1. The renal and hepatic excretion of water, cyanol, and azofuchsin I was studied in rabbits under various conditions. It was observed that under the conditions of our experiments the urine rate was independent of the bile rate, and vice versa. The renal excretion of these dyes also was independent of their hepatic excretion except in cases in which the liver was severely damaged. On the other hand, the hepatic excretion of these dyes depended also on their renal elimination.
2. The relationship between the renal and hepatic excretion of cyanol and azofuchsin I could be expressed in the form of hyperbolas.
3. In the use of dyes as a measure of renal function, no noteworthy error is introduced by their hepatic excretion except in cases in which the liver is severely damaged.