A Multilayered Secondary Wall in Fibres of Eucalyptus Obliqua L'hérit.

Abstract

The secondary cell wall structure most commonly found in fibres and tracheids consists of three layers, as first proposed by Bailey and Kerr (1935) and recently reviewed by Wardrop (1964). The thin outermost and innermost layers, the S1 and Sa layers respectively, are characterized by the microfibrils being aligned at a large angle to the fibre axis. Between these two layers there is another, the S2layer, in which the microfibrils are aligned at a small angle to the fibre axis. These layers can be readily distinguished using a polarizing microscope, the S1 and Sa layers appearing bright and the S2 layer dark in transverse sections.