STONE CELLS
Stone cells, like bast fibres, are branched or non-branched. Each group is then separated into subgroups according to wall structure (whether striated, or pitted and striated, etc.), thickness of wall and of cell cavity, color of wall and of cell contents, absence of color and of cell contents, etc.
BRANCHED STONE CELLS
Branched stone cells occur in a number of drugs. In witch-hazel bark (Plate 31, Fig. 2) the walls are thick, white, and very porous. In some cells the branches are of equal length; in others they are unequal. In the tea-leaf (Plate 31, Fig. 1) the walls are yellowish white and finely porous. When the lower wall is brought in focus, it shows numerous circular pits. These pits represent the pores viewed from the end. The branches frequently branch or fork.
Branched stone cells also occur in coto bark, acer spicatum, star-anise, witch-hazel leaf, hemlock, and wild-cherry barks.
Non-branched stone cells are divided into two main groups, as follows:
1. Porous and striated stone cells, and,
2. Porous and non-striated stone cells.
POROUS AND STRIATED STONE CELLS
Porous and striated walled stone cells occur in ruellia root, winter’s bark, bitter root, allspice, and aconite. These stone cells are shown in Plate 33, Figs. 1, 2, 3, 4, and 5.
The stone cells of ruellia root (Plate 32, Fig. 1) are greatly elongated, rectangular in form, with thick, white, strongly porous walls. The central cavity is narrow and is marked with prominent pores and striations.