The Harvesting of Cinchona Bark.
The old idea that for the collection of the bark it was necessary to sacrifice or fell the whole tree, when grown to maturity, had long made way for a better view. In English India, Broughton had begun, in 1866, to pollard the trees, in order to be able to lop the new shoots after four to five years (coppicing system) as is done in Europe with oak and ash coppice. But, besides the trees receiving a serious shock by this treatment, from which they do not so speedily recover, the bark thus obtained is not nearly so good as the stem bark.
It was, therefore, an ingenious idea of Mr. McIvor, in the Neilgherries, to cover the stems with moss, in order to improve the quality of the bark. He was led to this by observing that the best—the so-called crown-cinchona—always occurs covered with moss. He made experiments in this direction and the result was that, not only was the quality of the bark improved, but that in this way it was possible to strip the stem of a part of the bark and to heal the wound thus made by covering it with moss, in other words, to renew the bark by artificial means.
By experiments on a large scale the new discovery was crowned with the best success.
The "mossing system" is almost universally practised in Java since 1879, and numerous chemical analyses have shown that the proportion of quinine in the renewed bark increases, and is even trebled. The "coppicing system" is now only practised when a rapid production of bark is required, or when the sort does not allow of the "mossing system;" the filling, or rather uprooting, of the tree, is still practised exceptionally, when it withers, or when the plantation requires thinning.
Lastly, by way of trial, another method has been followed for a short time, viz., scraping off the outer bark; but though this product offered a precious and valuable material for the quinine manufacturer, the "scraping system" has not been continued on account of culture and commercial considerations. If I do not mistake, the Ledgeriana (in chips) realized at the sales in Amsterdam, in 1879, the enormous price of 10.44 f. per ½ kilogram. The quinine proportion was 13 per cent.
The "Coppicing system" in a modified form, by leaving one shoot on the stem, is now generally and successfully practised in Java with the C. Ledgeriana.
The harvest of cinchona bark deserves a moment's further attention, as so little is known about it. Do not expect a description like "Les Vendanges" in Provence or Languedoc, or a mill-feast in a sugar-works in East Java, or of the padi-cutting in Java described by Multatuli. The reaping of the cinchona bark is unattended by poetical accessories, and the work-people are all quiet. In those elevated regions, sparsely populated, and then only temporarily, no clamor whatever prevails. All nature bears an appearance of monotony and gloominess. In the gardens and woods the sun can hardly penetrate; the trees mostly dripping with rain, or from the clouds floating above, it breaks down in a dreadful thunderstorm. Then the laborers—among whom are not unfrequently mothers with infants at the breast—experience all the miseries of a mountain climate at an elevation of 7,000 feet. Shivering with cold, the women sit, sheltered as much as possible by a screen of plaited dried leaves, peeling the lopped branches, and cutting the wet bark to measure; the small slivers, or so-called refuse, is carefully collected in baskets.
The heavier work is performed by men; they lop the branches, or, if the "mossing system" be followed, they make incisions lengthwise in the stem, at intervals of 3 to 5 or more centimetres, according to the thickness of the tree, and then strip the stem from below upwards to where the branches begin, but in such a manner that strips of bark of equal breadth are left alternately on the stem, by which it assumes somewhat the appearance of a fluted column. The strips of bark are then cut into lengths of 50 centimetres, and the stem, which is partially denuded lengthwise, is entirely enveloped, as is done in Europe to some trees that could not bear exposure to our winters. McIvor at Madras did this first with moss, and hence the name "mossing;" but as this material was soon exhausted in Java, recourse was had to alang-alang, indjoek or dried grass, which occurs in great abundance.
In the course of one year this envelope is removed, then the healing—granulation we should say—the renewing of the bark is begun, and now comes the turn of the strips left on the tree the preceding year to be stripped off. Then the stem. is again bandaged.
The wet bark, after being cut to measure, is dried either in the sun, or artificially, by which the pieces roll up in their breadth and thug form the familiar pipes. The packing is generally in jute-bags. They weigh about 75 kilograms.
From chemical investigation it has been proved that drying in the sun or by artificial beat is the same for the bark, and has no influence on the proportion of quinine.—Phar. Jour. and Trans., Nov. 22, 1884, p. 410.