POWDERED DRUGS AND FOODS. 



769 



Adulterants. — All chocolate products may be adulterated 

 with any of the cereal starches, those of corn, wheat and rice being 

 usually employed. 



157. GUARANA. — Dark brown; parenchyma thin-walled, 

 containing nearly spherical, more or less altered starch grains 10 /x 

 in diameter ; sclerenchymatous cells nearly isodiametric, non-ligni- 



Fig. 309. Aconite: T, tracheae with scalariform thickenings or bordered pores; 

 ST, stone cells; P, parenchyma with starch grains; S, starch grains; C, E, cork. 



fied ; sclerenchymatous fibers few, narrow ; tracheae few, narrow, 

 annular or scalariform. 



158. PIPER. — Dark brown (Fig. 311) ; stone cells nearly iso- 

 diametric, uniformly thickened or with only three walls thick- 

 ened, the contents consisting of yellowish -brown tannin masses, 

 which give a blue reaction with ferric ammonium sulphate solu- 

 tion ; starch grains spherical, i to 2 /x in diameter ; parenchyiria ■ 

 with remains of chrdmoplastids and reddish-brown tannin masses ; 



49 



