Isolation of trans-Aconitic Acid from the Moss Mnium affine.

The water-soluble substance occurring in high concentration (up to 6 percent of the dry weight) in Mnium affine Bland. and forming the main fraction of the plant acids there, has been identified as trans-aconitic acid by nine different criteria. Evidence is presented in favor of the concept that the trans form in this case is the natural isomer and not an artifact derived from cis-aconitic acid. Information is given on the distribution of aconitic acid in other mosses and in liverworts.