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SCIENTIFIC AND APPLIED PHARMACOGNOSY 



occasionally 3; cells of the parenchyma and medullary rays having 

 starch grains about 0.003 mm. in diameter. 



Powder. Yellowish-brown or light pinkish-brown; bast fibers 

 lignified, much thickened, with numerous pores; crystal fibers 

 containing small monoclinic prisms of calcium oxalate; calcium 

 oxalate also in rosette aggregates or monoclinic prisms, from 0.005 

 to 0.025 mm. in diameter; starch grains nearly spheroidal, about 

 0.003 mm. in diameter, not numerous; parenchymatous cells with 

 yellowish- or purplish-brown contents, colored red by solutions of 

 alkalies. 



Fie. 185. Transverse section of inner bark of Rhamnus Frangula: b, bast fibers, 

 surrounded by crystal fibers; m, medullary rays; parenchyma containing 

 rosette aggregates of calcium oxalate. After Vogl. 



Constituents. A glucoside frangulin (rhamnoxanthin), which 

 forms yellow crystals, is insoluble in water and nearly so in alcohol, 

 gives a bright purple color on the addition of solutions of the alkalies, 

 and on hydrolysis yields rhamnose and emodin (see Rhubarb). It 

 also contains the glucoside pseudofrangulin (frangulic acid), which 

 yields pseudoemodin ; rhamnozanthin, a coloring principle; a vola- 

 tile oil; tannin; starch; calcium oxalate; and ash 5 to 6 per cent. 



Allied Plants. The bark of Rhamnus carniolica has been sub- 

 stituted for R. Frangula. It occurs in quills or transversely curved 

 pieces, the bark being from 1 to 3 mm. in thickness; externally cork 



