LEGUMINOS&. — 481 
the cells of the pith and medullary rays in process of trans- 
formation into Tragacanth. The transformed cells, if their 
- transformation has net advanced too far, exhibit the angular 
form and close packing of parenchyme-cells, but their walls | 
e much thickened, and evidently consist of numerous very . 
thin strata. A similar mode of gum formation from cellulose 
may be observed in the bark of Kydia calycina (see p. 228), 
and a jess complete transformation of the same kind in the 
exudation from the stem of Bombax malabaricum (see p. 217). 
Description.—Tragacanth consists of different layers, 
either laid one upon another and spirally twisted, or confluent 
into tear-like masses, or extended into curved, narrow, or broad 
nds, varying in width between ¢ inch and 1 inch, and some- 
imes 4 or 5 inches long. These bands are rarely made up of 
single layer, but usually are marked with several parallel . 
dges, indicating the various strata, which are united into — 
broader and thicker laminw. This form of tragacanth is 
known as flake tragacanth or leaf gum, and is the more valuable 
the whiter and more translucent it is. Smyrna tragacanth is 
ostly in rather broad and thick flakes, which are yellowish or 
a brownish tint, and often prominently ridged. Thin, 
tibbon-like, and white flakes are produced in Kurdistan and 
Persia, but are sometimes distinguished in commerce as Syrian 
acanth. Another variety is vermiform tragacanth, also 
ed vermicelli. It consists of very narrow, variously coiled 
contorted string-like pieces, the different coils of which are 
t frequently confluent. Common tragacanth, or sorts, in 
ope known as traganton, is the product obtained by spon- 
neous exudation, formiag. sub-globular, conical, or variously 
ped tear-like pieces, with the surface rounded and more or 
8 irregular, and usually of a brownish or brown colour, and se 
her Waxy in appearance; but it shows the stratification 
scribed above, and, like the white and thin bands, enclose. 
arch, oe 
Tragacanth is hard, tough, ilt to powde 
less, insoluble in alcohol and ether, and 
61: ; é a ee 
43°C Sap LAn 
. - peers | 3 
re ; 
cm with 80 
my 
for 
