POWDERED DRUGS. 
303 
139. Viburnum Prunifolium.— Dark brown ; calcium 
oxalate in rosette-shaped crystals and few monoclinic 
prisms 15 to 35 p in diameter ; crystal fibers with 
rosette -shaped crystals and occasional monoclinic 
prisms of calcium oxalate ; stone cells large, numer- 
ous, irregular, thick-walled and with a few canals ; 
bast fibers comparatively few, lignified. 
0 CALCIUM OXALATE IN MONOCLINIC PRISMS. 
1. NUMEROUS SEEDS. 
140. Vanilla. — Blackish brown ; calcium oxalate in 
monoclinic prisms 7 to 35 p in diameter or in raphides 
about 0'4 mm. long ; unicellular secretion hairs with 
rounded apex and containing oily globules; scleren- 
chymatous fibers more or less thick- walled ; the walls 
strongly lignified and with numerous simple pores ; 
seeds with small thick-walled stone cells. 
The powder of Mexican Vanilla has parenchymatous 
cells with reticulate thickenings. The powder of Tonka 
Bean contains numerous starch grains, which are 
neai’ly spherical, about 7 p in diameter. 
2. SEEDS WANTING. 
141. Viburnum Opulus. — Light brown ; calcium oxa- 
late in monoclinic prisms, or few rosette-shaped crys- 
tals 15 to 30 p in diameter ; crystal fibers with mono- 
clinic prisms of calcium oxalate ; stone cells few, 
relatively thick-walled ; bast fibers numerous, lignified. 
142. Viburnum Prunifolium. — (See 139.) 
143. Xanthoxylum. — Dark brown ; calcium oxalate in 
monoclinic prisms 10 to 25 p in diameter; starch 
grains nearly spherical, 4 to 10 p in diameter ; oil-secre- 
tion cells colorless ; cork cells strongly lignified ; bast 
fibers few, thick- walled, slightly lignified, swelling 
perceptibly in chloral. 
In Southern Prickly Ash occur groups of large, more 
