80 POLYGALE^. 



other kinds of rhatany previously unknown : of cliese the more im- 

 portant are noticed at pp. 81, 82. 



Description — The root which attains a considerable size in propor- 

 tion to the aerial part of the shrub, consists of a short thick crown, 

 sometimes much knotted and as large as a man's fist. This ramifies 

 beneath the soil even more than above, throwing out an abundance of 

 branching, woody roots (frequently horizontal) some feet long and | to 

 ^ an inch thick. These long roots used formerly to be found in com- 

 merce; but of late years rhatany has consisted in large proportion 

 of the more woody central part of the root with short stumpy branches, 

 which from their broken and bruised appearance have evidently been 

 extracted with difficulty from a hard soil. 



The bark which is scaly and rugged, and ^^ to oV of an inch in 

 thickness, is of a dark reddish brown. It consists of a loose cracked 

 cork -layer, mostly smooth in the smaller roots, covering a bright brown- 

 red inner bark, which adheres though not very firmly to a brownish 

 yellow wood. The bark is rather tough, breaking with a fibrous 

 fracture. The wood is dense, without pith, but marked with thin 

 vessels arranged in concentric rings, and with still thinner, dark medul- 

 lary rays. The taste of the bark is purely astringent ; the wood is 

 almost tasteless ; neither possesses any distinctive odour. 



Kr. cistoidea Hook, a plant scarcely to be distinguished from Kr. 

 triandra, affords in Chili a rhatany very much like that of Peru. Its 

 root was contributed to the Paris Exhibition of 1867. 



Microscopic Structure — The chief portion of the bark is formed 

 of liber, which in transverse section exhibits numerous bundles of 

 yellow fibres separated by parenchymatous tissue and traversed by 

 narrow brown medullary rays. The small layer of the primary bark is 

 made up of large cells, the surface of the root of large suberous cells 

 imbued with red matter. The latter also occurs in the inner cortical 

 tissue, and ought to be removed by means of ammonia in order to get a 

 clear idea of the structure. Many of the parenchymatous cells ai'o 

 loaded with starch granules ; oxalate of calcium occurs in the neigh- 

 bourhood of the liber bundles. The woody portion exhibits no structure 

 of particular interest. 



Chemical Composition — Wittstein (1854) found in the bark of 

 rhatany (the only part of the drug having active properties) about 

 20 per cent, of a form of tannin called Ratanhia-tannic Acid, closely 

 related to catechu-tannic acid. It is an amorphous powder, the solution 

 of which is not affected by emetic tartar, but yields with ferric chloride 

 a dark greenish precipitate. By distillation Eissfeldt (1854) obtained 

 pyrocatechin as a product of the decomposition of ratanhia-tannic acid. 

 The latter is also decomposed by dilute acids which convert it into 

 crystallizable sugar and Ratanhia-red, a substance nearly insoluble in 

 water, also occurring in abundance ready formed in the bark. 



Grabowski (1867) showed that by fusing ratanhia-red with caustic 

 potash, protocatechuic acid and phloroglucin^ are obtained. Ratanhia- 

 red has the composition C^^H^^O^^ the same, according to Grabowski, as 

 an analogous product of the decomposition of the peculiar tannic acid 

 occurring (as shown by Rochleder in 1866) in the horse-chestnut. 



^ See art. Kino. 



