SOPHISTICATION AND SUBSTITUTION 147 



Diagnosis: — Compare with prepared sections of true coffee-bean 

 for seed-coat and endosperm structure. 



Preparation : — Decolorize the fine powder. Centrifuge or other- 

 wise separate. Wash with distilled water. Examine in dilute 

 glycerin (or macerate for a day in ammonia to render the tissues 

 transparent and mount in ammonia). 



Diagnosis: — Compare with coffee-bean tissues. No foreign 

 tissues should be present. The coffee endosperm cells are distinc- 

 tive, and oil globules are detectable in them. Bits of the seed- 

 coat appear in the powdered — very finely ground — preparation as 

 delicate silver-like patches and the sclerenchymatous cells of the 

 seed-coat are readily observed, appearing as peculiarly characteris- 

 tic spindle-shaped, thick-walled cells. These cells should be sought 

 for, as they are always present in genuine coffee. A few small 

 spiral vessels are present. (See Plate 2, Genus Coffea: Fruit 

 Morphology.) The most common adulterant of coffee, namely, 

 ground roasted chicory root, is readily detected by decolorizing 

 the powdered sample with a solution of chlorinated soda; wash, 

 stain with Soudan red, and note the lactiferous vessels which are 

 characteristic of it. Furthermore, the ground sample, digested for 

 fifteen minutes in a solution of potash in a water bath, washed, 

 and mounted in glycerin or chloral hydrate, will show the diag- 

 nostic characters of abundant parenchymatous tissue in wood and 

 cortex, of lactiferous and many small sieve tubes with transverse 

 plates in the cortex, and of vessels with large pits in the wood. 



Note : — If, in examination of ground coffee, starch is ascertained 

 by the chemical tests, thereby indicating cereal or other adultera- 

 tion, the sample should be exhausted with ether to remove the fat 

 and subsequently treated with alcohol to dissolve the coloring mat- 

 ter, before the residue is examined microscopically to determine the 

 adulterant. 



Conclusion : 



Preparation of coffee for commercial purposes results in the removal 

 of the greater portion of the seed-coats so that the bean consists 

 largely of the endosperm. It is necessary to have prepared sections 

 of the various adulterants of coffee for comparative examination 

 as well as to be familiar with the characteristics of genuine coffee- 

 tissue. With this information at hand, the microscopic determina- 



