Studies on twisted fibre in trees (I. How varies the angle of twist in Larix Kaempferi, Sarg)

The twisted fibre is a significant defect in Karamatsu (Larix Kaempferi, Sarg. ), which is regarded as one of the most promising trees in this country. This phenomenon of twisted fibre is thoroughly examined by H.G. Champion in India from the silvicultural point of view, whom we are obliged to his kindness sending records of his former works. Our interest was chiefly destinated to observe how varies the angle of twist inward of trunks. The method of P. Misra was not adopted, not because of its technical difficulties but of taking much time to pursue. Disks, 10cm in thickness, were cut down from timbers for test at several portions. (TABLE II) On both end of them, two paralled diameter were drawn. They were split through their centers by a iron blade specially made for this purpose. Spliting just along the diameters of top end, curves were gotten at the base because of the twist of the timber. (FIG. I) Angles of twist 0 were obtained from the arc-length of year rings l and the thicknesss of disks h. 0=tan-1 l/h TABLE II,III-A, B and FIG. III-A, B, C, V, VI seem to tell us as follows: -As for the angle of twist in the trunks of Larix Kaempferi concern, 〔1〕 there is a portion of maximum value corespond to the age of tissue. 〔2〕 The value exists near the tree-axis in infant stage. 〔3〕 As the tree becomes older, it tends to move centrifugally towards the top of the tree. 〔4〕 As the tree grows older, its absolute value becomes more and more larger