METHAZOLE IN COTTON AND BEANS suggested that five of the minor fecal metabolites were a result of nonmetabolic breakdown of the robenidine which occurred during the extraction process. Chromatography in solvent system I of the radioactivity extracted from the feces with acidified ethanol revealed that all of the radioactivity remained near the origin, while chromatography in solvent system II resolved the radioactivity into ten radioactive spots, none of which was identified. Since more than 60% of the radioactivity found in feces was identified as unmetabolized robenidine, this suggests that robenidine was incompletely absorbed from the digestive tract and does not undergo extensive breakdown in the body of the animal.Tissues. In order to establish the relevance of the urinary metabolites to those occurring in tissues, the radioactivity in selected tissues was isolated by extraction and chromatographed in solvent system I. Benzene extracts of fat and skin, containing 93-95% of the total radioactivity in these tissues, revealed that robenidine was the only compound present. Ethanol extracts of liver, kidney, and muscle containing 87-97% of the total radioactivity in these tissues revealed the presence of p-chlorohippuric acid, p-chlorobenzoic acid, and robenidine as tissue residues. CONCLUSIONSince p-chlorobenzoic acid is excreted as p-chlorohippuric acid in dogs (Novello et al., 1926) and rabbits (Bray et al., 1952) and these compounds have been identified as urinary metabolites of robenidine, this evidence indicates that the scheme shown in Figure 1. represents a major route for the metabolism of robenidine in the rat. No 1amino-3-(p-chlorobenzylidineamino)guanidine, postulated to be a potential metabolite, was found.It is speculated that this aminoguanidine fragment may be a transient metabolite. It could be split by the rat to yield p-chlorobenzoic acid and 1,3-diaminoguanidine, as suggested from the mammalian metabolism of the related aldehyde derivatives of thiosemicarbazide (Williams, 1959). Since there is little literature on the known fate of guanidine in mammalian metabolism, no proposals can be made to suggest the possible fate of the aminoguanidine moiety.ACKNOWLEDGMENT We thank I. J. Morici of the American Cyanamid Company, Princeton, N. J., for conducting the acute toxicology tests. LITERATURE CITED

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