The drug is mentioned by most subsequent writers, some of whom like Pomet probably confounded it with the bark of Cinnamodendron ([p. 19]). It is usually described as produced in Jamaica or Guadaloupe, from which islands no Canella alba is now exported. On the other hand, New Providence, one of the Bahamas whence the Canella alba of the present day is shipped, is not named. Nor do we find any allusion to the drug in the records of the Company (1630-50) which was formed for the colonization of New Providence and the other islands of the group, though their staple productions are frequently enumerated.[314]
Canella alba Murr. was described and figured by Sloane (1707) and still better by Patrick Brown in 1789, and Olaf Swartz in 1791.[315]
Collection—In the Bahamas, where the drug is known as White-Wood Bark or Cinnamon Bark, it is collected thus:—preparatory to being stripped from the wood, the bark is gently beaten with a stick, which removes the suberous layer. By a further beating, the remaining bark is separated, and having been peeled off and dried, is exported without further preparation.[316]
Description—Canella bark occurs in the form of quills, more or less crooked and irregular, or in channelled pieces from 2 or 3 up to 6, 8, or more inches in length, ½ an inch to 1 or 2 inches in width, and a line or two in thickness. The suberous layer which here and there has escaped removal is silvery grey, and dotted with minute lichens. Commonly, the external surface consists of inner cellular layers (mesophlœum) of a bright buff, or light orange-brown tint, often a little wrinkled transversely, and dotted (but not always) with round scars. The inner surface is whitish or cinnamon-coloured, either smooth or with slight longitudinal striæ. Some parcels of canella show the bark much bruised and longitudinally fissured by the above-mentioned process of beating. The bark breaks transversely with a short granular fracture, which distinctly shows the three, or in uncoated specimens the two, cortical layers, that of the liber being the largest, and projecting by undulated rays or bundles into the middle layer, which presents numerous large and unevenly scattered oil-cells of a yellow colour.
Canella has an agreeable cinnamon-like odour, and a bitter, pungent acrid taste.[317] Even the corky coat is somewhat aromatic.
Microscopical Structure—The spongy suberous coat consists of very numerous layers of large cells with thin walls, showing an undulated rather than rectangular outline. The next small zone is constituted of sclerenchymatous cells in a single, double, or triple row, or forming dense but not very extensive groups. This tissue is sometimes (in unpeeled specimens) a continuous envelope, marking the boundary between the corky layer and the middle portion of the cellular layer; but an interruption in this thick-walled tissue often takes place when portions of it are enveloped and separated by the suberous layer.
The proper cellular envelope shows a narrow tissue with numerous very large cells filled with yellow essential oil. The liber forming the chief portion of the whole bark, exhibits thin prosenchymatous cells, which on traverse section form small bands of a peculiar horny or cartilaginous appearance, on which account they have been distinguished as horny liber (Hornbast of German writers).[318] The liber-fibres show reticulated marks due to the peculiar character of the secondary deposits on their cell-walls. The oil-cells in the liber are less numerous and smaller; the medullary rays are not very obvious unless on account of the crystalline tufts of oxalate of calcium deposited in the latter. This crystalline oxalate retains air obstinately, and has a striking dark appearance.
Chemical Composition—The most interesting body in canella is the volatile oil, examined in 1843 under Wöhler’s direction by Meyer and von Reiche, who obtained it in the proportion of 0·94 from 100 parts of bark. They found it to consist of four different oils, the first being identical with the Eugenol or Eugenic Acid of oil of cloves; the second is closely allied to the chief constituent of cajuput oil. The other oils require further examination.[319]
The bark, of which we distilled 20 lb., afforded 0·74 per cent. of oil. This when distilled with caustic potash in excess was found to be composed of 2 parts of the acid portion and 1 part of the neutral hydrocarbon; the latter has an odour suggesting a mixture of peppermint and cajuput.
Meyer and von Reiche evaporated the aqueous decoction of canella, and removed from the bitter extract by alcohol 8 per cent. of mannite, which they ascertained to be the so-called Canellin described in 1822 by Petroz and Robinet.