314 SUBTERRANEAN ORGANS 



colour and in the presence of transverse cracks ; they may be dis- 

 tinguished by their agreeable odour and by the difference in the 

 transverse section. 



Constituents. The principal constituent of rhatany root is the 

 tannin (krameria-tannic acid) that it contains. The proportion in 

 which this substance is present has not been satisfactorily deter- 

 mined, but it has been stated to be 84 per cent, in the Peruvian 

 root. The Para variety contains about the same quantity, one assay 

 of the root showing rather more, and another rather less tannin than 

 the Peruvian. These analyses, are, however, of comparatively little 

 value, since the proportion of bark, in which alone the tannin resides, 

 varies in different roots of each variety. The Peruvian root appears 

 to contain a much larger amount of substances soluble in absolute 

 alcohol than the Para root does (23-0 per cent, against 12-6 in the 

 Para Dunwody, 1890), and certainly yields a tincture possessing 

 different properties, that from the Peruvian giving a cloudy and that 

 from the Para a clear mixture with water. Notwithstanding this 

 difference the Pharmacopoeia retains both, since the supply of each 

 is subject to considerable irregularity. 



The root contains in addition a dark red phlobaphene, krameria- 

 red, produced by decomposition of the tannin, as well as starch, and 

 about 2 per cent, of inorganic matter. 



Uses. Rhatany root is employed solely as an astringent. 



Varieties. Several other species of Krameria are known to yield 

 astringent roots, but none are of commercial importance. 



MARSHMALLOW ROOT 



(Radix Althaeas) 



Source, &C. The marshmallow, Althcea officinalis, Linne (N.O. 

 Malvaceae), is not uncommon in moist or marshy places in southern 

 England, and is widely distributed in similar situations in central 

 and southern Europe. Our supplies are derived from plants cultivated 

 in Germany, France, and Belgium. 



The roots are collected in the autumn from plants about two years 

 old, trimmed, deprived of their cork by scraping, and dried. Some- 

 times the root is also split longitudinally, or cut into transverse 

 slices. 



Description. The roots as met with in commerce are generally 

 in straight, tapering, whitish pieces about 15 or 20 cm. in length, and 

 attaining 2 cm. or more in diameter at their upper extremity. They 

 are usually obscurely quadrangular or rounded, with a few broad and 

 deep longitudinal wrinkles. The surface is softly fibrous from the 



