1. The output of urobilin is increased in experimental trypanosome anemia presumably as a result of the increased blood destruction.
2. The administration of salvarsan (arsenobenzol) during the anemic period, if it checks the blood destruction, reduces the urobilin elimination, but this result does not follow unless the blood picture improves.
3. Following splenectomy in the normal dog an increase in the urobilin elimination of varying degree occurs, the significance of which is doubtful.
4. Splenectomy during the period of anemia does not cause a decrease in urobilin elimination.
The experiments support the view that the elimination of urobilin may be considered as an index of blood destruction, but they do not explain the decrease in the elimination occurring in man in certain forms of hemolytic anemia following splenectomy.