Figs. 13 - 15. Transverse sections of peach bark examined with ultraviolet epifluorescence illumination ( bar = 10 microns).  In Figs. 13 - 15, the wound surface is approximately 800 microns above the noted cellular changes. Note the presence of phloem fibers (F) in Figs. 14 and 15. Fig. 13 shows nonwounded control tissue showing ray parenchyma in the region of primary and secondary phloem. Note the lack of autofluorescence. Fig. 14. shows tissue 6 days postwounding. First traces of lignin autofluorescence are in the cell corner-middle lamella region of boundary zone cells (arrows) immediately external to living tissues (LT). Fig. 15 shows tissues 8 days postwounding. Note deposition of suberin linings (arrows) in boundary zone cells and the dedifferentiation of internal tissues in the process of forming new phellogen (LT).