Untersuchungen über Druckholzbildung—Erste Mitteilung: Die Verteilung des Lignins im Druckholz von Fichte (Picea rubens Sarg.)

Abstract

Normal and compression wood from red spruce (Picea rubens Sarg.) and, to a limited extent, balsam fir (Abies balsamea (L.) Carr.) was subjected to treatment with hydrofluoric acid and decay by the brown rot fungiLenzites trabea Persoon ex Fries andLenzites saepiaria Wulfen ex Fries. The texture and distribution of the lignin remaining after these treatments were studied in transverse and longitudinal sections by electron microscopy. In agreement with previous investigations, the lignin in the secondary wall of normal tracheids was found to form a continuous network. The results obtained with compression wood tracheids showed that there was an isotropic layer with a high lignin concentration located immediately insideS 1, but that this region also contained polysaccharides which were probably oriented in a transverse direction with respect to the fiber axis. The inner part ofS 2, containing the helical cavities, had a uniform distribution of lignin in the form of a continuous network. There was no evidence for a radial distribution of lignin in compression wood tracheids nor for the absence of lignin from the inner portion ofS 2, as had been stated by earlier investigators. The polysaccharides in the cell wall of the compression tracheids, and especially those located in the outer part ofS 2, were partially inaccessible to both acids and fungi. The latter penetrated the wood both through the lumens and through the intercellular spaces.Lenzites saepiaria was by far the more efficient of the two fungi used.