The major functional groups of the various extractive components recovered from Pai wood using organic solvents and hot water have been identified and assigned by means of Fourier transform infrared analyses. The analyses revealed that the components removed by toluene, found mainly in cell lumina and/or lumina surfaces, were predominantly of non-polar, aliphatic compounds such as fatty acids and their monohydric esters. Gummy substances were also evident as well as minor amounts of materials of aromatic nature. The extract fractions recovered using ethanol and hot water, derived principally from within cell walls, consisted of cyclized aromatic components of increased polarity. It has been demonstrated that these components are tannins. FTIR-Charokterisierung der Extroktstoffe von ApoHolz (Afzelio africono Smith)Extraktstoffe von Apa-Holz wurden mit organischen L6-semitteln und Heit~wasser isoliert. Die funktionellen Gruppen der verschiedenen Komponenten wurden mittels FTIR bestimmt. Die Toluol-16slichen Bestandteile, die vor allem aus den Zell-Lumina bzw. v o n d e r Oberfl/iche der Lumina stammen, enthielten vor allem unpolare aliphatische Substanzen wie Fettsfiuren und deren Ester. Gummiartige Substanzen waren ebenso vorhanden wie geringe Mengen aromatischer Komponenten. Die in Ethanol und Heit~wasser 16slichen Fraktionen stammen vorwiegend aus der Zellwand und bestehen aus aromatischen Substanzen h6herer Polarit/it. Es handelt sich dabei fiberwiegend um Tannine.

The microfibril angle of the S 2 layer in wood fibres is an ultra-microscopical feature that influences important properties affecting the utilisation of timber. However, this characteristic is as yet little studied, and this is especially true of the genus Eucalyptus. The microfibril angle of the S 2 layer of the secondary wall was measured in fibres taken from eight-year-old trees of 11 Eucalyptus clones growing in four sites in Brazil. The overall mean microfibril angle measured was 8.88. While the angle seemed to decrease slightly from pith to bark in a non-linear fashion, this decrease was not statistically significant. The microfibril angle showed statistically significant differences between sites and between clones, although the broad sense heritability of the microfibril angel was low (h 2 s0.293). Various theories attempt to explain the microfibril orientation, but we conclude that environmental stresses play an important role in defining the angle in Eucalyptus wood.

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