Fig.
7.5-4b. Transverse section of a V-shaped vascular
bundle in a stem of asparagus (Asparagus). As in Fig. 7.5-4a, there are
two large cells here that are differentiating into vessel elements, but which
have not yet begun to deposit secondary wall. These too have been plasmolyzed by
the processes of fixation and dehydration. These cells are very large, but are
filled mostly with a large central vacuole rather than a large amount of
cytoplasm. Such large central vacuoles are very difficult to preserve well, and
they almost always collapse, as they did here.