After extirpation of the spleen there occurs a marked increase in the amount of paired sulphates and glycu-ronates in the urine. There is no relation between these findings and the anemia which develops after splenec-tomy. The fact that this increase follows the introduction of phenol and anthranilic acid favors the idea that the spleen has a destructive action on certain poisons. The formation of urochrome from tryptophan in the animal organism appears to take place in the spleen, or at least this organ plays an important role in the synthesis. Animals that have been made anemic by either phenylhydrazine or by bleeding recover promptly when treated with tryptophan.