This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
Cascarilla bark is obtained from Croton Eleuteria, J. J. Bennett (N.O. Euphorbiaceoe), a shrub or small tree indigenous to the Bahama Islands, the name cascarilla having its origin probably in the resemblance this bark bears to small quilled cinchona bark, which was formerly called cascarilla (the diminutive of the Spanish cascara, bark).
Fig. 139. - Cascarilla bark. A, large; B, medium; C, small. All natural size.
Cascarilla bark is usually imported in single quills or channelled pieces, commonly varying from 5 to 10 cm. in length and from 4 to 6 mm. in width, rarely exceeding the latter limit. The outer layer of the bark is a white or greyish white cork which owes its characteristic chalky appearance to the presence in the cells of numerous crystals of calcium oxalate. It is longitudinally wrinkled, and often, at more distant intervals, both longitudinally and transversely furrowed, thus assuming a chequered appearance. It frequently bears the minute black apothecia of a small lichen, and easily exfoliates, disclosing a brown or dark grey inner layer (cortex) marked with furrows corresponding to those in the cork. On some portions of the bark the white cork is so thin that the brown cortex shows through and imparts to the outer surface a brown or dark grey colour.
The inner surface of the bark is dark in colour and longitudinally striated. The fracture is short and resinous. The section exhibits under the lens a pale cork layer and a dark brown cortex and bast, the latter being traversed by numerous very thin whitish medullary rays.
A transverse section of cascarilla bark, examined under the microscope, exhibits a cork of varying thickness, the cells of which have thickened outer but thin inner walls; in the latter, numerous minute crystals of calcium oxalate are embedded. Some of the cells of the cortex contain prismatic or cluster-crystals of calcium oxalate, others (secretion cells) droplets of oleo-rcsin. The bast contains in addition small scattered groups of small (not over 26/x wide) bast fibres together with numerous cells filled with a brown amorphous substance, but neither bast nor cortex contains any cells with thickened lignified walls. These characters are useful in distinguishing cascarilla bark from various barks that have been substituted for it.
The bark has a pleasant aromatic colour and an aromatic but rather disagreeably bitter taste. When burned it exhales an agreeable odour, whence its use as an addition to fumigating mixtures, tobacco, etc. It yields about 8 per cent, of ash, but siftings may yield much more, probably because they contain many cork fragments rich in calcium oxalate.
The student should observe
(a) The chalky cork,
(b) The longitudinal wrinkles and longitudinal and transverse fissures,
(c) The short resinous fracture and the appearance of the section under the lens,
(d) The aromatic odour and bitter taste.
Fig. 140. - Cascarilla bark. Transverse section. Magnified. (Berg).
Cascarilla contains about 1 per cent, of volatile oil, a crystalline bitter principle, cascarillin, which is neither alkaloidal nor glucosidal, and at least two alkaloids, viz. betaine and cascarilline, the latter crystallising in prismatic plates; it yields from 7.5 to 10.5 per cent, of ash, sittings commonly affording a higher figure.
Cascarilla is used as an aromatic, bitter stomachic.
Copalchi bark, from Croton niveus, Jacquin (West Indies, Venezuela), occurs in long quills, much larger than those of cascarilla; it has a thin, greyish cork, below which is the cortex marked with minute transverse furrows.
The bark of Croton lucidus, Linne (?): the cork is greyish and firmly adherent; the inner surface is striated and pinkish brown, and the transverse section shows numerous groups of sclerenchymatous cells.
The barks of several other species of Croton have been found in the commercial drug; genuine cascarilla may be identified by the characters given above.