i88 



A TEXT-BOOK OF BOTANY. 



in the monoclinic system, inasmuch as monoclinic prisms occur in 

 neighboring- cells in the same plant or drug, as in stramonium, 

 quassia, etc. Because they are so small and in many instances 

 not clearly defined they have been termed by the Germans " crystal- 



FIG. 109. Various forms of Silica found in plants. Long rods and spindle-shaped 

 masses (A) and star-shaped fragments (B) found respectively in the thalloid structure 

 made up of roots and shoots and in the leaves of Tristicha hyjnoides, a small, moss-like 

 plant (Podostemaceae) growing on rocks, etc., in running water, especially in waterfalls. 

 C, a longitudinal section of the petiole of Caryota urens, a palm of Eastern Asia, showing 

 grape-like clusters of silica completely filling the cells. D, hat-shaped fragments of silica 

 occurring on the edge of the leaves of Cusparia macrophylla. a rutaceous tree growing near 

 Rio Janeiro; in a, b, c, side views of the masses, whereas in d the surface view shows a struc- 

 ture resembling that of sphero-crystals, E and F, siliceous fragments from the leaves of an 

 orchid, Oncidium leucochilum, growing in Guatemala; in E is shown a base fiber with siliceous 

 masses somewhat resembling the crystal-fibers of calcium oxalate, and in F the isolated 

 siliceous masses are seen. A and B, after Cario; C and D, after Rosanoff; E and F, after 

 Pfitzer. From Dippel in "Das Mikroskop." 



sand" (Kristallsand). The typical tetrahedral form was recog- 

 nized by the French and termed " sable tetraedrique." 



Sphenoidal micro-crystals are found in the following drugs : 

 Belladonnae folia, belladonnse radix, cinchona, dulcamara, phyto- 

 lacca, quassia, Solanum carolinense, and tabacum. 



