An Electron-Microscopic Investigation of the Cell-wall Organisation of Conifer Tracheids

Abstract

IN the past, considerable controversy has centred upon the interpretation of the observed optical heterogeneity of the secondary-cell walls of conifer tracheids when viewed between crossed Nicol prisms^1–4. More recent optical observations^5,6, however, have shown the walls of these cells to be composed of three coaxial micellar spirals such that the outer and inner spirals are relatively flat and appear bright between crossed Nicols, while the central spiral is steep and appears dark between crossed Nicols.