Hydrostatic pressures in laticiferous phloem tissues of Hevea brasiliensis trees exhibit a diurnal fluctuation, with minimum values occurring during the day. Pressure decreases with increasing height up the trunk, the gradient becoming greater under conditions of rapid transpiration. Sieve-tube turgor must be controlled independently if pressure-flow is to occur in the expected direction.
1. Twelve aliphatic alcohols of human sebum have been isolated and identified. They belong to three homologous series as follows: saturated normal alcohols (tetradecan-1-ol, hexadecan-1-ol, octadecan-1-ol, eicosan-1-ol, docosan-1-ol, tetracosan-1-ol), saturated i8o alchols (18-methylnonadecan-1-ol, 20-methylheneicosan-l-ol, 22-methyltricosan-l-ol) and unsaturated normal alcohols (eicos-10-en-1-ol, docos-12-en-1-ol, tetracos-14-en-1-ol). 2. The reversed-phase partition chromatographic technique for resolution of fatty acid mixtures (Howard & Martin, 1950) has been extended to include six shorter-chain acids having odd and even numbers of carbon atoms. The author wishes to thank Dr W. S. Rapson for suggesting this work and Dr D. A. Sutton for helpful discussions. Dr D. H. S. Horn helped the author considerably with advice and guidance on many occasions and this is very gratefully acknowledged. The microanalyses were by Mr F. W. G. Sch6ning and Miss J. M. Theron, infrared absorption spectra by Mrs M. A. Raal and X-ray measurements by Dr J. N. van Niekerk. This paper is published by permission of the South African Council for Scientific and Industrial Research.
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