NON-POISONOUS DRUGS 



165 



the inner l)ark of our slippery elm and the 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. 157. — Tragacanth Shruh (A.-<tragalu.s gummifcr. Pulse Y-dmily, Legurni- 

 nosw). A, fioweriiiK branoh. B, leaf from which the leaflets have dis- 

 appeared, leaving only the stiff thorn-like "raehis" 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 con.stituent of the lichen called Iceland moss 

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

 starch (CiaHooOjo). 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 Iri.sh moss (Fig. 118) which we 

 have alreadv studied. The chief remedial constituent found 



