346 



SUBTERRANEAN ORGANS 



Both roots and rhizome have the same distinct and characteristic 

 odour, and a sweetish, afterwards agreeably bitter, taste. 

 The student should observe 



(a) The uniform yellowish brown colour, 



(b) The longitudinal wrinkles of the root, the transverse annula- 



tions and leaf scars on the rhizomes, 



(c) The absence of any evident structure in the transverse section, 



(d) The absence of starch (see below). 



Microscopical Characters. The transverse section exhibits a narrow cork 

 and a largely developed cortex which, like the bast-ring, is free from scleren- 

 chymatous cells or fibres, and from more than an occasional starch grain. The 

 cells have rather thick walls and contain small oil globules, and, frequently 



collected at one end of the cell, groups of 

 very minute acicular crystals of calcium 

 oxalate. The wood consists principally of 

 parenchymatous tissue ; the vessels are 

 isolated or in small groups. In longitudinal 

 section the vessels exhibit porous, annular, 

 or reticulate thickening. 



The powder is characterised by the 

 abundant parenchymatous cells with rather 

 thick walls, inclined to swell in water, and 

 containing oily globules and minute calcium 

 oxalate crystals, by the vessels with charac- 

 teristic thickening, and by the absence of 

 sclerenchymatous cells and fibres and of more 

 than an occasional starch grain. Imported 

 powdered gentian root is frequently much 

 adulterated, particularly with ground almond 

 shells which are readily detected by the 

 sclerenchymatous tissue of which they consist. 



Constituents. Fresh gentian root contains two bitter principles, 

 viz. gentiopicrin and gentiin. During the drying of the root, however, 

 the gentiopicrin disappears and the dry root contains gentiin and 

 gentiamarin, the latter not being present in the fresh root ; this 

 decomposition is induced by the fermentative processes which take 

 place during the drying ; carefully dried root retains its gentiopicrin 

 intact, but still contains enzymes which act upon the gentiopicrin 

 when the tincture is made. 



Gentiopicrin is a pale yellow crystalline bitter substance, and is 

 hydrolysed by emulsin and also by dilute mineral acids to gentiogenin 

 and dextrose ; it is present in G. punctata, G. asclepiadea and certain 

 other species as well as in Chlora perfoliata, Linne. Gentiin is also a 

 crystalline glucoside, but gentiamarin is amorphous. 



Gentian root contains a yellow crystalline acid, gentisic (gentianic) 

 acid, sucrose, and (in the fresh state) a sugar gentianose, together 

 with pectin and oily globules, probably of a cholesterol compound ; 



FIG. 180. Gentian root. Trans- 

 verse section, a, bark ; b, 

 wood. Magnified 2 diam. 

 (Berg.) 



