72 ELEMENTS OF APPLIED MICRUSCOFY. 
3. The Microscopic Structure of Coffee.—The coffee- 
bean is the seed of Coffea arabica, a small tropical tree of 
the family Rubiacee, two of the semi-ellipsoidal beans 
lying base to base in each of its berries. The beans are 
brought into the market generally roasted, either in their 
original form or ground, and although adulteration is 
most easy in the second condition, artificially modelled 
beans of foreign material are not unknown. 
The true coffee-bean is made of thick-walled cells, 
approximately isodiametric, and packed with a finely 
Fic. 29.—Microscopic STRUCTURE OF COFFEE. (After Schimper.) 
240 diameters. 
granular material containing minute oil-drops. The 
cells of the inner part are very characteristic, showing 
knotty thickenings of their walls, as indicated at B in 
Fig. 29. More peripheral cells (C) are smaller and lack 
these swellings, while at the extreme outside of the bean 
is the so-called silverskin, a.thin glistening layer contain- 
ing peculiar fusiform cells with wide walls pierced by 
