LIQUORICE 317 



The student should observe 



(a) The yellow colour of the section, and fibrous bark, 



(b) The minute buds on the unpeeled root, 



(c) The pith in most of the pieces, 



(d) The characteristic sweet taste, free from acridity ; 



and should carefully compare this (the Spanish) variety with the 

 Russian. 



Microscopical Characters. In transverse section the cork- cells are brown 

 and flattened. The cells of the cortex contain small (1-5/u, to 20//<) starch grains 



FIG. 161. Bales of decorticated Liquorice root. 



and prismatic crystals of calcium oxalate. The bast-ring is characterised by 

 the presence of numerous bundles of strongly thickened, striated, yellowish 

 bast fibres accompanied by calcium oxalate cells. The wood contains vessels 

 of varying size (often lOCtyx.) accompanied by wood fibres closely resembling 

 the bast fibres. 



The powder is characterised by the very thick-walled, grouped bast fibres 

 with calcium oxalate cells frequently attached ; by the portions of large, thick- 

 walled vessels with closely packed, bordered pits ; by the small starch grains 

 and by the prevailing yellowish colour which is changed to orange yellow by 

 sulphuric acid. It should be free from polygonal, brownish cork cells (unpeeled 

 root) and from sclerenchymatous cells (olive-stones, almond shells, &c.). 



Constituents. The principal constituent of liquorice root is the 

 sweet principle, glycyrrhizin, which, when quite pure, is a white, 

 crystalline, intensely sweet powder, soluble in water. This has 

 been shown to consist of the potassium and calcium salts of 



