Fig. 5.1-7. Longitudinal section of wood of Zygogynum (no common name). This section was made by peeling off the bark of a log, then cutting the wood lengthwise, very close to the surface – a cut known as a tangential section. The long cells, running vertically in the tree are xylary fibers. One on the right has a white lumen – in that fiber, one cut of the microtome knife sliced away the back wall of the cell, the next cut removed the front of the cell, so we see just the two side walls. All that we can see in it is that the walls are thick, lignified secondary walls. For all the other fibers, either the front or the back wall is still present, so we can see their pits in face view – the indistinct white dots (four are indicated by arrows). It is obvious that the pits are narrow and not very abundant. See Fig. 5.1-8 for a different type of pit in face view.