652 BOTANY AND PHARMACOGNOSY. 



Persian or Syrian Tragacanth. — In flattened, lamellated, 

 ribbon-like pieces, 0.5 to 2.5 cm. long, about i cm. wide and from 

 I to 3 mm. thick, irregularly oblong, more or less curved; exter- 

 nally nearly colorless or pale yellowish, with numerous concentric 

 ridges or lamellae; translucent; fracture short, tough, horny, ren- 

 dered more easily pulverizable by a heat of 50° C. ; inodorous ; 

 taste insipid. 



Constituents. — Bassorin (traganthin), 60 to 70 per cent., 

 which gives the mucilage made from this gum its peculiar density, 

 and which serves to distinguish it from acacia, which contains 

 little or no bassorin; a carbohydrate apparently in the nature of 

 an insoluble compound of arabic (gummic) acid, which swells in 

 water but is insoluble in it; arabin, about 10 per cent., soluble 

 in water and probably formed from traganthin ; starch ; ash about 

 3 per cent., of which one-half is calcium carbonate. 



Allied Products. — Smyrna tragacanth, which is collected in 

 Asiatic Turkey and shipped from Smyrna, occurs in pieces that 

 are less ribbon-like, more opaque, of a yellowish-brown color, 

 with numerous prominent concentric ridges, and contains consid- 

 erably more starch than the Syrian or Persian varieties. 



Allied Plants. — Tragacanth is obtained from a number of 

 other species of Astragalus. Gums containing a considerable 

 amount of bassorin are also obtained from Piptadenia rigida, of 

 Brazil, and Acacia micrantha (Caju gum), of Mexico, and also 

 from a number of plants of the Cactaceae (p. 342). 



Sarcocolla is a gummy exudation of Pencea SarcocoUa and 

 P. mucronata (Fam. Penasaceae, one of the Myrtiflorae), small 

 shrubs indigenous to Southern and Central Africa. The gum 

 occurs in small, globular, yellowish-red or brownish-red friable 

 grains, which are often agglutinated into masses and admixed 

 with a few hairs. Sarcocolla has a licorice-like taste. It is soluble 

 in water and alcohol, and contains an uncrystallizable principle 

 sarcocollin, having a taste of glycyrrhizin ; a resin; and a gum. 



The gum yielded by Cochlospermum Gossypium (Fam. Bix- 

 aceae) is sold in India as a substitute for tragacanth, which it 

 resembles. It is free from starch, and has, like the gum of Ster- 

 culia urens, the property of slowly giving off acetic acid when 

 exposed to moist air. 



