TRAGACANTHA. 177 



Vermicelli and Common or Sorts; this sorting is perforraed almost 

 exclusively by Spanish Jews. 



Description— The peculiar conditions under which tragacanth 

 exudes, arising from the pressure of the surrounding tissues and the 

 power of solidifying a large amount of water, will account to some 

 extent for the strange forms in which this exudation occurs. 



The spontaneously exuded gum is mostly in mammiform or 

 botryoidal masses from the size of a pea upwards, of a dull waxy lustre, 

 and brownish or yellowish hue. It also occurs in vermiform pieces 

 more or less contorted and very variable in thickness ; some of them 

 inay have exuded as the result of artificial punctures. It is this form 

 that bears the trade name of Vermicelli. The most valued sort is 

 ho\vever the Flahe Tmgaccmth, which consists of thin flattish pieces or 

 flakes, 1, 2, 3 or more inches in length, by ^ to 1 in width.' They 

 are marked on the surface by wavy lines and bands, or by a series of 

 concentric wave-marks, as if the soft gum had been forced out by 

 successive efforts. The pieces are contorted and altogether very variable 

 in form and size. The gum is valued in proportion to its purity and 

 wmteness. The best, whether vermiform or flaky, is dull-white, 

 translucent, devoid of lustre, somewhat flexible and horny, firm, and 

 not easily broken, inodorous and with scarcely any or only a slight 

 wttensh taste. J J- ^ & 



r S^^^^^^^ of Kurdistan and Persia shipped from Bagdad, which 



nietimes appears in the London drug sales under the incorrect name 



ynan Tragacanth, is in very fine and large pieces which are rather 



more translucent and ribbon-like than the selected tragacanth imported 



pm bmyrna : in fiict, the two varieties when seen in bulk are easily 



dLstmguishable. 



are \ ^^^^"oi" kinds of tragacanth have more or less of colour, and 

 y^^ f*^^*'^™^nated with bark, earth and other foreign substances. They 

 Qj ,. "^^'^^rly to be much imported into Europe, and were frequently 

 ntioned during the past centuries as hIacJc tragacanth. 



tj,^^^'^^^scopic Structure— The transformation of the cells into 

 tissif ^^° • ^** usually not so complete, that every trace of the original 

 of "ce^i^^ ^^f contents has disappeared. In the ordi nary drug, the remains 

 Mice ^^ ^^'^^^ as starch granules may be seen, especially if thin 



Polai -^^^ ^-"^a^^ined under oil or any other liquid not acting on the gum. 

 If ^ ^^^ H'^t will then distinctly show the starch and the cell-walls. 

 Pota.s • section is imbued with a solution of iodine in iodide of 

 celbwTr ^^^ *^^^^ moistened with concentrated sulphuric acid, the 



^ ^ will assume a blue colour as well as the starch. 



^'Smical Composition— When tragacanth is immersed in water 



It., 



^ietv in ?^"^/""^ ^^ *^i® Pharmaceutical and 5 inches in diameter, and bearing tra- 



«»«anth rpt 1 ?', ^^^""^ ^^ some Flake Tra- gacanth. It is probable that the specimen 



^^^ in other ^^ ^°^ ^^^ enormous size, of giim we have described was produced by 



^^^ kind ^?np^*^*^ precisely like the ordi- some species attaining these extraor Juiary 



">«ch aa 2 • K "'J^oii-lihe strips are as dimensions. Among the Kurdistan traga- 



l''''='^.andtl, 1 ^^^^^ ^^^ A of an inch canth, there occur curious cybndncal ver- 



°'>g Weigh, Va^''^'^^* ^^'^"^^^ ^s several inches mi form pieces, about^of an nich in diameter, 



?"^cht ha., : 7 "^^^nces. Professor Hauss- coated with a net-work of woody fibre. \\ e 



{;"ri9tan St " """^^ "s that he has seen in are told by Professor H. that they are 



^is3. et Ha,,'"^ ^^ Astragalus eriostyhts picked out of the centre of cut-off pieces of 



•^issk. more than 6 feet in heiglit stem, split open by rapid drying m the sun. 



M 



