TIME-COURSE OF THE SECONDARY DEPOSITION OF INCRUSTING MATERIALS ON BORDERED PIT MEMBRANES IN CRYPTOMERIA-JAPONICA

Bordered pit membranes of Cryptomeria japonica were examined successiv ely from the outermost sapwood to the heartwood by scanning electron m icroscopy and by ultraviolet microspectrophotometry in an attempt to e valuate the time course of the secondary deposition of incrusting mate rials and to gain clues to their chemical composition. Scanning electr on microscopy revealed that the bordered pit membranes were covered by incrusting materials from the middle layer of the sapwood to the hear twood. Both the amount and the appearance of the deposited incrusting materials differed among four regions of the wood, namely, the middle to inner layer of the sapwood, the innermost layer of the sapwood, the intermediate wood and the heartwood. From our results it appears that , in C. japonica, incrusting materials are deposited on bordered pit m embranes by stages over several years. Apparent absorption of ultravio let light by the bordered pit membranes was detected in the analysis o f the innermost layer of the sapwood, the intermediate wood and the he artwood. The incrusting materials deposited in these zones were probab ly phenolic compounds. However, differences in the manner and extent o f the absorption of ultraviolet light were found between these three r egions of the wood. The results of microspectrophotometric analysis al so suggested the phased deposition of incrusting materials at the bord ered pit membranes of C. japonica.