1. Soap bark (Quillaja saponaria, Molina).
2. Ceylon cinnamon bark (Cinnamomum zeylanicum, Nees).
3. Sassafras root bark (Sassafras variifolium, [Salisb.] Kuntze).
4. Mezereum bark (Daphne mezereum, L.).
PLATE 27
Groups of Bast Fibres
1. Menispermum rhizome (Menispermum canadensis, L.).
2. Althea root (Althæa officinalis, L.) showing two groups of bast fibres.
The pores, which are absent in many drugs, are, when present, either simple, as in echinacea root (Plate 24, Fig. 4), or they are branched, as in yellow cinchona (Plate 23, Fig. 3).
In each of the above fibres the length and width of the fibre are shown. The fibres also have pores of variable length. Such a variation is common to most fibres with pores. That part of the wall immediately over or below the cell cavity shows the end view or diameter of the pore, as in the fibre of marshmallow root (Plate 24, Fig. 3). As a rule, however, the pores show indistinctly on the upper and lower wall.
OCCURRENCE IN POWDERED DRUGS
In powdered drugs bast fibres occur singly or in groups. The individual fibres may be broken, as in mezereum and elm bark, or they may be entire, as in Ceylon cinnamon and in sassafras bark (Plate 26, Figs. 2 and 3).
The lignified walls of bast fibres are colored red by a solution of phlorogucin and hydrochloric acid, and the walls are stained yellow by aniline chloride.
In fact, few of the fibres found in individual plants occur in a broken condition.