CINCHONA 



637 



of powdered Cinchona is heated in a test tube, a tarry distillate is 

 formed having a bright red color. 



Calisaya Bark. Gray or brownish-gray, with numerous patches 

 of foliaceous lichens, having brownish-black and reddish-brown 

 apothecia, and numerous transverse fissures, which give the bark a 

 very characteristic appearance. 



The trunk bark is comparatively thick, while renewed bark is 

 comparatively smooth and uniform in color. 



INNER STRUCTURE. (Fig. 280.) 



POWDER. (Fig. 282.) Reddish-brown; the tissues and cell 

 contents resemble those of red Cinchona; the starch grains are 



FIG. 282. Cinchona: B, bast fibers; Ca, sphenoidal microcrystals of calcium 

 oxalate; P, parenchyma containing few small spheroidal starch grains; E, 

 sieve; K, cork. 



relatively more numerous and larger, occurring in spheroidal, plano- 

 convex and polygonal grains, from 0.003 to 0.015 mm. in diameter, 

 also in 2- to 5-compound grains. 



The following test is distinctive for yellow Cinchona. If 1 gm. 

 of powdered calisaya bark is heated in a test tube, a tarry distillate 

 is formed having a purplish-red color and a somewhat granular 

 appearance. 



A qualitative test having some quantitative value in determining 

 the strength of powdered Cinchona is as follows : 0.500 gm. of pow- 



