The Calcutta cassia bark collected in the Khasya mountains and brought to Calcutta is afforded by wild trees of small size. Dr. Hooker who visited the district with Dr. Thomson in 1850, observes that the trade in the bark is of recent introduction.[1963] The bark which varies much in thickness, has been scraped of its outer layer.
Cassia is extensively produced in Sumatra, as may be inferred from the fact that Padang in that island, exported of the bark in 1871, 6127 peculs (817,066 lb.), a large proportion of which was shipped to America.[1964] Regarding the collection of cassia on the Malabar coast, in Java and in the Philippines, no particular account has, so far as we know, been published. Spain imported from the Philippines by way of Cadiz in 1871, 93,000 lb. of cassia.[1965]
Description—Chinese Cassia lignea, otherwise called Chinese Cinnamon, which of all the varieties is that most esteemed, and approaching most nearly to Ceylon cinnamon, arrives in small bundles about a foot in length and a pound in weight, the pieces of bark being held together with bands of bamboo.
The bark has a general resemblance to cinnamon, but is in simple quills, not inserted one within the other. The quills moreover are less straight, even and regular, and are of a darker brown; and though some of the bark is extremely thin, other pieces are much stouter than fine cinnamon,—in fact, it is much less uniform. The outer coat has been removed with less care than that of Ceylon cinnamon, and pieces can easily be found with the corky layer untouched by the knife.
Cassia bark breaks with a short fracture. The thicker bark cut transversely shows a faint white line in the centre running parallel with the surface. Good cassia in taste resembles cinnamon, than which it is not less sweet and aromatic, though it is often described as less fine and delicate in flavour.
An unusual kind of cassia lignea is imported since 1870 from China and offered in the London market as China Cinnamon,[1966] though it is not the bark that bears this name in continental trade. The new drug is in unscraped quills, which are mostly of about the thickness of ordinary Chinese cassia lignea; it has a very saccharine taste and pungent cinnamon flavour.
The less esteemed kinds of cassia bark, which of late years have been poured into the market in vast quantity, are known in commerce as Cassia lignea, Cassia vera or Wild Cassia, and are further distinguished by the names of the localities whence shipped, as Calcutta, Java, Timor, etc.
The barks thus met with vary exceedingly in colour, thickness and aroma, so that it is vain to attempt any general classification. Some have a pale cinnamon hue, but most are of a deep rich brown. They present all variations in thickness, from that of cardboard to more than a quarter of an inch thick. The flavour is more or less that of cinnamon, often with some unpleasant addition suggestive of insects of the genus Cimex. Many, besides being aromatic, are highly mucilaginous, the mucilage being freely imparted to cold water. Finally, we have met with some thick cassia bark of good appearance that was distinguished by astringency and the almost entire absence of aroma.
Microscopic Structure—A transverse section of such pieces of Chinese Cassia lignea as still bear the suberous envelope, exhibits the following characters. The external surface is made up of several rows of the usual cork-cells, loaded with brown colouring matter. In pieces from which the cork-cells have been entirely scraped, the surface is formed of the mesophlœum, yet by far the largest part of the bark belongs to the liber or endophlœum. Isolated liber-fibres and thick-walled cells (stone-cells) are scattered even through the outer layers of a transverse section. In the middle zone they are numerous, but do not form a coherent sclerenchymatous ring as in cinnamon ([p. 526]). The innermost part of the liber shares the structural character of cinnamon with differences due to age, as for instance the greater development of the medullary rays. Oil-cells and gum-ducts are likewise distributed in the parenchyme of the former.
The “China Cinnamon” of 1870 ([p. 530]) comes still nearer to Ceylon cinnamon, except that it is coated. A transverse section of a quill, not thicker than one millimetre, exhibits the three layers described as characterizing that bark. The sclerenchymatous ring is covered by a parenchyme rich in oil-ducts, so that it is obvious that the flavour of this drug could not be improved by scraping. The corky layer is composed of the usual tabular cells. The liber of this drug in fact agrees with that of Ceylon cinnamon.