Plate P4. Variable contribution of cell walls to the bulk of vitrinite. 3. T5859; Hole 1118A; 580.69 mbsf. Section of wood where the cell wall material is dominant over the humic corpocollinite cell fillings. In some cases, no cell lumens contain corpocollinite and a much lower reflectance results if all tissues are measured. As far as possible, cell wall materials were excluded from the reflectance data; however, distinction of wall and cell contents is not always as clear as in the fields on this plate (reflected light; field width = 0.22 mm; mean vitrinite reflectance = 0.27%).