390 POWDERED VEGETABLE DRUGS 



121. (Fig. 122.) JALAPA. U. S. 



Fine powder. 



The tuberous roots of Exogonium purga Benth., Convolvulaceae. 



Dry feel, resinous on warming. 



Light grayish brown. 



Smoky (faint creosote) odor due to method of drying tubers over 

 open flame. 



Sweetish, pungent. 



Considerable brown suberized tissue. Small-celled outer paren- 

 chyma with numerous aggregate crystals. The inner parenchyma 

 typical, large-celled, filled with starch and resin. Fragments of large 

 and smaller porous ducts and laticiferous ducts. Resin globules and 

 fragments of resin bearing cells. Starch granules simple and com- 

 pound (mostly twos), 14^i to 40/*, and some aggregates, also some 

 pasty starch; hili quite distinct in the larger granules and slightly 

 excentric; cross bands right angled and remarkably distinct, showing 

 complete rotation on turning the analyzer. 



Ash 5 per cent. Impurities should not exceed 5 per cent. 



Among the likely adulterants are starches and flour, roots and 

 rootlets of the same species (excess of fibrous tissue) ; tubers and roots 

 of related species; .sand ancl dirt. 



