PARTS OF ROOTS AND STEMS. 
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tions or transverse channels ; fracture uneven, coarsely 
fibrous, surface porous and with groups of white 
sclerenchymatous fibers; odor slight; taste acrid. 
Constituents. — The drug contains two amorphous 
glucosides amounting to about 9 per cent., which are 
closely related to saponin — one soluble in alcohol and 
known as quillajic acid, and another nearly insoluble 
in alcohol and known as sapotoxin ; it also contains 
starch and about 10 per cent, of calcium oxalate. 
QUERCUS ALBA (White Oak). 
The bark of Quercus alba (Fam. Cupuliferee), a tree 
indigenous to the Eastern and Central United States 
and Canada. The bark is collected in spring from the 
branches and trunks of trees from ten to twenty-five 
years of age, and deprived of the periderm and dried. 
Description. — In flat, irregular, more or less oblong 
pieces 5 to 30 cm. long, 10 to 20 mm. in diameter, 2 to 
4 mm. thick ; outer surface light brown, longitudinally 
striate, with occasional patches of dark-brown peri- 
derm ; inner surface yellowish brown, coarsely striate 
and fissured longitudinally, and with detachable bast 
fibers ; fracture uneven, coarsely fibrous, surface 
porous and dotted with groups of white sclerenchy- 
matous cells and fibers; odor slight; taste astringent. 
Constituents. — Tannin about 10 per cent.; starch 
and calcium oxalate. 
Allied Plants. — Quercus rober indigenous to Eu- 
rope is the source of the bark used in England and 
Continental Europe; the bark closely resembles that of 
Quercus alba, but the periderm is not removed ; it con- 
tains from 10 to 16 per cent, of tannin, besides gallic 
and ellagic acids. Quercus velutina, or black oak, yields 
the quercitron bark, which resembles that of Quercus 
alba but is reddish brown, and tinges the saliva yel- 
