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We recently reported' that lignin when fed to a dog or cow causes a substantial increase in the quantity of benzoic acid eliminated in the urine. Since this fact is at variance with results published by others, we undertook to obtain more direct evidence bearing on the metabolism of lignin.The OCH3, or methoxyl group, has been definitely shown to be present in lignin. The Kirpal and Ruhn2 modification of the Zeisel method was employed by us for the quantitative estimation of the methoxyl group.Knowing the methoxyl content of the lignin and also that of the feces before and after the feeding of lignin, it was possible to follow up the demethoxylation in the animal organism. Experiments conducted with a dog showed that over 15 % of the methoxyl initially present in the lignin was liberated and, in the case of the cow, 37% loss of rnethoxyl was observed. We believe that in these experiments we #have direct evidence that lignin is metabolized in the animal organism.We have also conducted experiments in z d r o in which known quantities of lignin and fresh material taken from the 4 compartments of the cow's stomach were incubated at 38" C. for 8 days.It was found that demethoxylation took place in all our experiments, irrespective of whether or not toluene had been added to the medium. Experiments conducted in a similar manner, using fresh material taken from the large and small intestine of a cow gave entirely neg-1 Caonka, F. A., Phillips, M., and Jontbs. D. R., Proc. Am. SOC.