90 PHARMACEUTICAL BOTANY 
5. Micro-crystals (Crystal sand)—Belladonne Radix, Cin- 
chona, Hyoscyamus, Stramonium, Phytolacca, Capsicum. ‘This 
type is frequent in the Solanacez family. 
6. Crystal Fibers—Cascara Sagrada, Prunus Virginiana, Gly- 
cyrrhiza, Aspidosperma, Senna, Viburnum, Unpeeled Calamus. 
7. Membrane Crystals—Aurantii Dulcis Cortex, Limonis 
Cortex, other Citrus peels, Condurango, Wafer Ash bark. 
Solitary crystals, usually in the 
form of rhombohedra, occa- 
sionally in twin crystals, occur 
as sharp angular bodies, each 
one often completely filling up 
B the lumen of a cell. Twin 
Fic. 52.—Cystoliths frorh the leaf of crystals occur in elm bark, hyos- 
the ‘Fig (Ficus carica). A, Cystolith cyamus, etc. They are single 
within cystolith sac; B, cystolith from : : 
which the calcium carbonate has been shee: which have the appear- 
removed for use in other parts of the ance of two prisms united by 
plant. 8B is from leaf that has fallen their flat surfaces. 
off in autumn. (From Stevens after 
Haberlandt.) 
Rosette aggregates or druses 
consist of numerous small prisms 
or pyramids, or hemihedral crystals arranged around a central 
axis, appearing like a rosette or star. They often contain an 
organic center. 
Columnar crystals or styloids are elongated prisms. 
Raphides or acicular or needle-shaped crystals, which fre- 
quently occur in bundles in long, thin-walled cells containing 
mucilage called raphide sacs. They are more frequently found in 
Monocotyledons than in any other plant group. 
Crystal fibers are longitudinal rows of superimposed paren- 
chyma cells each of which contains a single monoclinic prism or 
rosette aggregate. Crystal fibers are found adjacent to scleren- 
chyma fibers such as bast or woody fibers. 
Membrane crystals are monoclinic prisms, each of which is sur- 
rounded by a wall or membrane. In the process of formation, a 
crystal first is formed in the cell sap and then numerous oil 
globules make their appearance in the protoplasm surrounding 
it; later some of the walls of the cell grow around the crystal and 
completely envelop it. (See Fig. 85k.) 
