NON-POISONOUS DRUGS 



165 



the inner bark of our slippery elm and tlie closely similar 

 English elm (Fig. 159) is due to the large amount of a muci- 

 laginous carbohydrate which it contains. The pith of sassa- 

 fras (Fig. 160) yields to hot water a similar mucilage. 



Fig. 1.57. — Tragacanth Shrub (Astragalus gianmifer, Pulse Family, Lfcrumi- 

 nosa;). yi,- flowering branch. B. leaf from which the leaflets have dis- 

 appeared, leaving onlv the stiff thorn-like "rachis" and the toothed 

 "stipules." C, flower. (Taubert.) — A shrub 30-60 cm. tall; flowers 

 yellow; pod, small, one-seeded. Native home. Southwestern Asia. 



The jelly-like constituent of the lichen called Iceland moss 

 (Fig. 161) is a carbohydrate known as lichenin or lichen- 

 ■starch (Ci^H.^oO,,,). It is insoluble in cold water but be- 

 comes dissolved upon boiling, and forms a jelly when cooled. 

 Lichenin is almost if not quite identical with the gelatinous 

 constituent of carrageen or Irish moss (Fig. 118) which we 

 have alreadv studied. The chief remedial constituent found 



