CORTEX CINCHONJ^. 357 



posed by caustic lye, and the alkaloids set at liberty assume the 

 cr3^stallized state. This is in our opinion the origin of the crystals 

 under notice. 



The greater number of the parenchymatous cells are loaded with 

 small starch granules, or in young and fresh barks with chlorophyll 

 In several barks, as in that of C. lancifolia Mutis, numerous cells of 

 the middle cortical layer and even of the medullary rays, are provided 

 with somewhat thick walls, and contain either a soft brown mass 

 or crystalline oxalate of calcium. These cells have therefore been 

 called resin-cells and crystal-cells ; they are mostly isolated, not forming 

 extensive groups or zones, and their walls are not strongly thickened as 

 m true sclerenchymatous tissue. If thin sections of the barks are 

 moistened with dilute alcoholic perchloride of ii'on, the walls of the cells, 

 except the fibres and the cork, assume a blackish-green due to cincho- 

 tannic acid ; this applies even to the starch granules. 



Ckaracters of ijarticular sorts. — The modifications of general struc- 

 ture just described, are sufficient to impart a special character to the 

 lark of many species of Cinchona, provided the bark is examined at 

 its full development, the structural peculiarities being far from well- 

 marked in young barks. 



Thus it is not possible to point out any distinctive features for the 

 Loxa Bark of commerce, because it is mostly taken from young wood. 

 VVe may say of it, that neither resin-cells nor crystal-cells occur in its 

 middle layer, that its laticiferous vessels become soon obliterated, and 

 have indeed disappeared in the older quills ; and that the liber-fibres 

 form interrupted, not very regular, radial rows. 



The quills of (7. Calisaya display large laticiferous ducts, which are 

 wanting in the flat bark. There is a peculiar sort of the latter called 

 Bolivian Calisaya (already mentioned at p. 353), the flat pieces of which 

 still possess very obvious laticiferous vessels. As to the liber-fibres of 

 Calisaya bark, they are, as before stated (p. 356), scattered throughout 

 the parenchymatous tissue or endophheum. In the bark of (7. serobicw- 

 hta, which might at first sight be confounded with Calisaya bark, the 

 liber-fibres form radial, less interrupted rows. The microscope affords 

 therefore the means of distinguishing these tw^o barks. 



The barks of C. succirtihra are particularly rich in laticiferous ducts, 

 iiaostly of considerable diameter, in which the formation of new paren- 

 chyme may not unfrequently be observed. The orange liber-fibres oc- 

 curring in this bark are less numerous, more scattered, and of smaller 

 size than in Calisaya. The fracture of Red Bark, especially the flat sort, 

 IS therefore more finely granular and not so coarse as that of Calisaya. 



Tl 



le 



structural characters of Cinchona barks may lastly be fully ap- 

 d bv ex^mWmcr hnvh^ nf thn allied crcncra Bitena, CascariUaana 



predated by examining barks of the allied gcnci 



nown 



Ginchona Barks. The microscope shows that the liber-hbres of the 

 latter are soft, branched and long, densely packed into large bundles 

 imparting therefore a well-marked fibrous structure. The external 

 appearance of these barks is widely different from that of true cinchona 

 ^arks ; none of them it would appear is now collected for the purpose 

 of adulteration. 



Chemical Composition— The most important and at the same tioie 



