THE role of shikimic acid and related compounds in the biosynthesis of the aromatic ring by mutants of E. coli has recently been the subject of extensive study by Davis and his associates1. Their work has indicated that shikimic acid is an important precursor of the aromatic structure in this organism. The reaction sequence by which this compound is aromatized is still not fully understood, but it is believed2 that prephenic acid is one of the intermediates and that the first aromatic compound formed is phenylpyruvic acid. The above findings have raised the question of the existence of a similar biosynthetic pathway in higher plants, and we have now investigated this possibility during current studies on the origin of lignin, one of the principal aromatic plant constituents.