RHIZOMA ZINGIBERIS. 637 



from which the cortical part has been removed. Much of it indeed is 

 dark, horny and resinous. 



Ginger has an agreeable aromatic odour with a strong pungent 

 taste. 



Varieties — Those at present found in the London market are distin- 

 guished as Jamaica, Cochin, Bengal, and African. The first three are 

 scraped gingers; the last-named is a coated ginger, that is to say, it still 

 retains its epidermis. Jamaica Ginger is the sort most esteemed; and 

 next to it the Cochin. But of each kind there are several qualities, 

 presenting considerable variation infer se. 



Scraped or decorticated ginger is often bleached, either by being 

 subjected to the fumes of burning sulphur, or by immersion for a short 

 time in solution of chlorinated lime. Much of that seen in the grocers' 

 shops looks as if it had been whitewashed, and in fact is slightly 

 coated with calcareous matter, — either sulphate or carbonate of 

 calcium.^ 



Microscopic Structure — A transverse section of coated ginger 

 exhibits a brown, homy external layer, about one millimetre broad, 

 separated by a line line from the whitish mealy interior portion, 

 through the tissue of which numerous vascular bundles and resin-celLs 

 are irregularly scattered. The external tissue consists of a loose outer 

 layer, and an inner composed of tabular cells: these are followed by 

 peculiar short prosenchymatous cells, the walls of which are sinuous on 

 transvei"se section and partially thickened, imparting a horny appear- 

 ance. This delicate felted tissue forms the striated surface of scraped 

 ginger, and is the principal seat of the resin and volatile oil, which here 

 till large spaces. The large -celled parench3-me which succeeds is 

 loaded with starch, and likewise contains numerous masses of resin and 

 drops of oil. The starch granules are irregularly spherical, attaining at 

 the utmost 40 mkm. Certain varieties of ginger, owing to the starch 

 having been rendered gelatinous by scalding, are throughout homy and 

 translucent. The circle of vascular bundles which separates the outer 

 layers and the central portion is narrow, and has the structure of the 

 corresponding circle or nucleus sheath in turmeric. 



Chemical Composition — Ginger contains a volatile oil which is 

 the only constituent of the drug that has hitherto been investigated. 

 By distilling 1121b. of Jamaica ginger with water in the usual wa}^ 

 we obtained 4| ounces of this oil, or about \ per cent. It is a pale 

 yellow liquid of sp. gr, 0878, having the peculiar odour of ginger, but 

 not its pungent taste. It dissolves but sparingly in alcohol (083) ; and 

 deviates the ray of polarized light 21°.6 to the left, when examined in 

 a column 50 mm. long. We learn from kind information given us 

 (1878) by Messi-s. Schimmel &; Co. at Leipzig, that they obtain as much 

 as 22 per cent, of oil from good gingei'. 



The burning taste of ginger is due to a resin which we have not 

 examined, but which well deserves careful analysis. Protocatechuic 

 acid, which is so commonly afforded by resins (see page 243), is also 

 produced by melting the resin of ginger with caustic potash, as shown 

 in 1877 by Stenhouse and Groves. 



* Mr. Garside (Pharm. Journ. Apiil 18, 1874) found both. We have not observed 

 the carbonate to be used. 



