340 SUBTERRANEAN ORGANS 



The student should observe 



(a) The small, yellow wood, 



(b) The thick, whitish bark marked with distinct, darker, con- 



centric rings, 



(c) The absence of starch (see below) ; 



and should compare the root with 



(i) Pellitory root, which has oil glands and a large radiate 



wood with conspicuous medullary rays, 

 (ii) Liquorice root, which also has a large radiate wood. 



Constituents. Dandelion root contains a small quantity of a 

 crystalline, bitter substance taraxacin, and also an acrid principle, 

 neither of which, however, has been closely examined. The former, 

 taraxacin, appears to be very susceptible of decomposition, which is 

 probably induced by an enzyme, possibly an oxydase ; the extract 

 prepared from the fresh root is often almost devoid of bitterness. 

 According to recent researches taraxacin is an indefinite mixture. 



The drug also contains choline, resin, the phytosterols, taraxasterol 

 and homotaraxasterol, various fat acids, and in the autumn abundance 

 of inulin. In the fresh root the inulin is dissolved in the cell sap, 

 but in the dry root forms amorphous, transparent lumps not again 

 readily soluble in cold water. The absence of starch, which is so 

 commonly present in roots, especially in the autumn, is a valuable 

 negative character, and is often of service in detecting substitution. 

 The autumn root has been found to contain 25 per cent, of inulin, 

 whereas the spring root contained 18 per cent, of levulin and 17 per 

 cent, of uncrystallisable sugar. Levulin, C 6 H ]0 O 5 , is a soluble carbo- 

 hydrate converted by hydrolysis into dextrose and levulose. 



Uses. Dandelion is a simple, bitter, and mild laxative, and is 

 given in atonic dyspepsia attended by habitual constipation. 



Substitutes. The root of a species of Lactuca which has the vessels 

 arranged in radial rows has been substituted for dandelion root. 



HEMIDESMUS ROOT 



(Indian Sarsaparilla, Radix Hemidesmi) 



Source, &C. Indian sarsaparilla or hemidesmus root is obtained 

 from Hemidesmus indicus, Robert Brown (N.O. Asclepiadece) , a climbing 

 shrub indigenous to India and Ceylon. 



Description. Hemidesmus root usually occurs in long, slender, 

 rigid pieces, often more than 30 cm. in length, but seldom exceeding 

 6 mm. in thickness, which branch occasionally and bear a few fibrous 

 rootlets. Portions of the slender aerial stems with opposite leaf -scars 





