484 



BOTANY AND PHARMACOGNOSY. 



ible when damp ; internally dark yellow, bark 0.5 to 2 mm. thick, 

 porous, cambium zone distinct ; odor heavy ; taste bitter. 

 Inner Structure. See Fig. 210. 



Fig. 209. Gentiana lutea, growing in the Royal Botanic Society's Gardens (London). 



After Pgrredes. 



Constituents. A bitter glucoside gentiopicrin, about o.i 

 per cent., occurring in yellow needles which are readily soluble 

 in water but less so in alcohol and to which the drug owes its 

 peculiar bitterness and odor; a coloring principle gentisin (gen- 

 tianin or gentisic acid), occurring in yellowish prisms which are 



