POWDERED DRUGS AND FOODS. 767 



latter may be mentioned the Mogdad Coffee, the seeds of Cassia 

 occidcu talis which are used in various tropical countries. The 

 seeds are free from starch and the cells of the endosperm are 

 thick-walled and contain a brown protein substance. 



Of Coffee adulterants the following may be mentioned: 

 Ground ivory nut (Phytclcphas macrocarpa (Fig. 173), which 

 is distinguished by the thick-walled cells of the endosperm; and 

 the ground kernels of the acorns of several species of Quercus, 

 which are readily identified by the elongated, more or less swollen, 

 distorted starch grains that have a prominent elongated cleft in 

 the middle (Fig. 135). 



155. SASSAFRAS. Light brown (Fig. 236); bast fibers 

 thick-walled, lignified, usually single or not more than two or 

 three together ; starch grains 7 to 20 /a in diameter, single or 2- to 

 3-compound ; parenchymatous cells with irregular masses of 

 tannin ; oil globules numerous. The stem bark contains groups 

 of bast fibers and stone cells, and the parenchymatous cells contain 

 chloroplastids. 



2. Sclerenchymatous Fibers Wanting. 



* Stone Cells Present. 

 t Giving Tannin Reaction with Ferric Salts. 



156. CACAO. -Reddish-brown (Fig. 308) ; consisting chiefly 

 of protein grains, oil and starch (grains 4 to 8 ju, in diameter) ; 

 fragments with brownish or purplish-brown contents (cacao red) ; 

 fat crystals in little prisms or needles ; few fragments of seed-coat 

 consisting of hexagonal epidermal cells, a peculiar mucilage layer 

 of small tabular cells and a layer of nearly isodiametric stone cells 

 10 by 10 jx, the walls of which are 4 n. thick. 



Cacao starch grains show a tendency to cohere and on gently 

 heating a section in water, after removal of part of the oil with 

 ether or chloroform, the compound grains swell into angular, 

 spherical or irregular masses which vary from 15 to several 

 hundred microns in diameter (Fig. 308). The smaller masses 

 thus produced bear a close resemblance to the starch grains of 

 corn and wheat. The central triangular marking of the mass 

 which resembles that of a corn starch grain is formed from the 



