A deseeded Avena test method for small amounts of auxin and auxin precursors

In 1927 Went isolated the growth promoting hormone, auxin, from the tip of the Arena coleoptile, and worked out the now well known Arena test method for its quantitative determination. By the use of this method the chemistry and many phases of the physiological action of auxin have been studied. In physiological work, however, the amounts of hormone involved are frequently so small that quantitative or even qualitative work has often been very difficult or impossible. In this article is presented a supplementary procedure with deseeded Arena seedlings whereby smaller concentrations of the hormone not detectable by the standard method can be quantitatively determined. By the use of this method it has also been possible to demonstrate directly the existence of substances capable of being converted into auxin by the plant. Some data relative to the presence of a precursor of auxin in Arena and synthetic precursors of hereto-auxin are included