common to both these compounds (Heath & Wildy, 1956a, b). These results indicated that this fungus forms ergothioneine by methylation and sulphuration of histidine. Subsequent work (Wildy & Heath, 1956, 1957) revealed that [2(ring)-14C]histamine would not serve as a precursor of the imidazole nucleus of either histidine or ergothioneine. Various metabolites of histamine, imidazoles possessing m...