310 



POPULAR ECONOMIC BOTANY. 



translucent^ and much mixed with seeds^ stalks^ and other 

 foreign substances. It has a fragrant balsamic smelly but 

 is not very agreeable ; its use is principally as a constituent 

 of plaisters. 



Gum Opopanax. — A resinous exudation obtained from 

 incisions in the roots of Opopanax Chironium (Nat. Ord. 

 TJmhellifera). It is a reddish-yellow gum, which occasion- 

 ally^ but rarely, comes from Italy, Sicily, and Greece ; it was 

 known to the ancients, who employed it in pharmacy. 



Gum Ammoniacum^ — The gum-resin of another Umbel- 

 liferous plant — Dorema ammoniacum. 



This gum is the produce of Persia \ it oozes forth from 

 the punctures made in the plant by a species of beetle which 

 infests it. Sometimes it is in yellowish-white tears, but 

 more generally in masses formed by the agglutination of 

 these tears ; the smell is disagreeable. Though produced 

 in Persia, we receive our supply, which is considerable, en- 

 tirely from India. 



Gum Scammony. — A gum-resin procured by making an 

 incision in the upper part of the large perennial roots of 

 the Convolvulus Scammonia (Nat. Ord. Corivolvulacece) , for 

 which purpose the earth is removed from the top of the 

 root. (Plate XVII. fig. 90.) 



