[Auxins in coleoptiles of corn].

Aqueous diffusates and ether and ethanol extracts from tips of corn coleoptiles contain two ether soluble auxins. It could be shown by paper chromatography, electrophoresis and staining reactions that one of these (A1) is IAA. The second auxin (A2) is a bound form which was easily converted to IAA under mild conditions. The conversion to the free form already occurred partially during the preparation of the diffusates and the extracts. The bound auxin (A2) is soluble in ether at pH 2.8 and in water at pH 8.0. According to the results of chromatography and electrophoresis A2 has the properties of a weak acid.Besides auxins the coleoptile tips contain large amounts of ether soluble inhibitors of the phenol type. These inhibitors were found mainly in the extracts and they were the reason for the difficulties which have been encountered in previous experiments. Auxins and inhibitors could be separated readily by combination of electrophoresis and paper chromatography.