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The polar movement of IAA has been examined in 5-mm root segments of Brassica oleracea and Helianthus annuus. The movement was studied partly with IAA-1-14C and partly with IAA-5-³H In both plants a slight acropetal flux of 14C and IAA-³H was found through the segments. The recovered radioactivity in the agar receiver blocks and in the receiver end of the segments increased as a function of time. A large portion of the applied IAA was converted on the cut surfaces and in the tissues of the segments. Chromatographic analysis indicated different destruction products when estimated by scintillation counting and by spraying with indole reagent (DMCA). Chromatograms run in isopropanol : ammonia : water, 8 : 1 : 1, yielded three different substances, one spot near the starting line and one near the front, neither of which has been identified. Finally there was a spot with Rf 0.4-0.6, probably representing IAA.

Gradients of tritiated water, 35S-sulphate and 32P-phosphate, were established in isolated segments of willow stems. Sieve tube exudate was collected as honeydew from the high activity end of the segment. After girdling the stem a few centimeters from the site of sieve tube puncture, the specific activity of 35S and 32P in the honeydew rose, whilst the specific activity of tritium remained constant. These findings indicate that prior to girdling, unlabelled sulphates and phosphates were contributing to the honeydew, whilst there had been no detectable contribution by unlabelled water from the low activity end of the segment. The data support the conclusions drawn from previous experiments by Peel et al. (1969), that water is relatively immobile in sieve tubes of willow when compared to solutes. [ABSTRACT FROM AUTHOR]