| Summary: | The products formed during transport in excised plant segments of radioactively labelled indolyl-3-acetic acid and 2,4-dichlorophenoxyacetic acid have been investigated. The techniques employed were extraction of the tissue followed by radiochromatography. It was found that indolyl-3- acetic acid is readily converted to indolyl-3-acetyl aspartate in Coleus tissue but not in Helianthus tissue. 2,4-dichlorophenoxyacetic acid appears to undergo little change. The distribution of radioactive material which results from the transport of labelled auxin in plant segments and small plants was also investigated by means of oxidation and subsequent scintillation counting. It was found that the system has a definite capacity and that much of the transported auxin is immobilised but not necessarily conjugated and that amounts of auxin reaching receiving systems is not a reliable basis for estimating auxin which is transported within tissue. Auxin transport into root primordia, lateral buds, abscission zones and through developmental transition zones is also briefly considered and it is reported that no barrier to the transport is encountered in these regions.
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