Source, Etc

The genus Cinchona embraces, according to Baillon, about twenty species, all of which are indigenous to South America and restricted in that country to the chain of the Andes extending from western Venezuela, through New Granada, Ecuador, and Peru, to Bolivia. On the spurs of this mountain range, at an elevation of about 5,000 to 7,000 feet, where the climate is warm and moist, the cinchona trees occur usually singly, not forming forests and seldom groups. They are evergreen shrubs or trees, frequently of handsome appearance and considerable size, attaining upwards of 100 feet in height.

The natives of Peru and Bolivia appear to have been only imperfectly acquainted with the febrifuge properties of the bark of these trees; at least they seldom employed it. After the conquest of Peru the bark found its way into Spain, probably by the aid of the Jesuits, who were frequently instrumental in introducing new drugs into Europe; it was known as Countess bark, Jesuit's bark, or Peruvian bark, and early in the eighteenth century the trade in it at Loxa in Ecuador had assumed considerable proportions.

About this time (1736) the expedition sent by the Paris Academy of Sciences to measure a degree of the earth's surface at the equator, which was accompanied by the botanist Jussieu, found trees, hitherto unknown, that yielded valuable cinchona bark. The botany of these trees was subsequently specially investigated by Mutis (1760), Ruiz and Pavon (1778-1788), Weddell (1845-1848), and others.

The method of collecting the bark - viz. by felling the tree and stripping the bark from it - very soon aroused fears that the trees would eventually be exterminated. Attempts were made by the Jesuits to induce the bark collectors to plant young trees to replace those that they destroyed, and suggestions and attempts to cultivate the trees were not wanting. These eventually culminated in Mark-ham's expedition to Peru and Bolivia (1859), which was successful in introducing Cinchona succirubra, C. officinalis, and other species into

British India, the cultivation being commenced at positions in the Himalayas and Neilgherries that had already been recommended by Royle.

A few years previously the German botanist Hasskarl was commissioned by the Dutch on a similar expedition, and succeeded in bringing plants and seeds to Java.

From small beginnings the cultivation of cinchona trees has rapidly assumed such enormous dimensions that the world is practically independent of South America for its supply of cinchona bark, and consequently of quinine. At present about nine-tenths of the bark required is derived from C. Ledgeriana, cultivated in Java. The cultivation of this species is now being pushed forward in the British Government plantations in India.

The chief species of cinchonas that yield commercially valuable barks are:

1. C. Ledgeriana, Moens (Southern Peru and Bolivia).

2. Cinchona Calisaya, Weddell (Southern Peru and Bolivia).

3. C. officinalis, Linne (Ecuador and Peru).

4. C. succirubra, Pavon (Ecuador).

The first three of these species - viz. C. Ledgeriana, C. Calisaya, and C. officinalis - yield barks rich in quinine, and it is to the cultivation of these three species, especially C. Ledgeriana, that attention is now being directed. C. succirubra has been largely grown in India, but is now being replaced by C. Ledgeriana. C. lancifolia, Mutis, and certain other species yield barks that are poor in quinine; they are therefore not cultivated, but nevertheless these barks are occasionally imported from South America and used to some extent as sources of the cinchona alkaloids.

Collection

The following methods have been adopted in collecting cinchona bark:

1. Felling

Felling. In South America the bark is collected by felling the tree, stripping the bark from it, and drying it either in the sun or over a gentle fire in huts. Large thick pieces from the trunk and large branches are pressed under weights, and often freed from the dead outer portions (bark), and occur therefore in commerce in the form of thick, flat, heavy pieces {flat bark); the bark from the smaller branches curls as it dries into quills (quilled bark). Hence the bark from the same tree may occur in two forms differing very considerably in appearance. Cultivated trees are not allowed to attain the age or size of the South American forest trees, and yield therefore no flat bark.

2. Mossing And Renewing

Mossing And Renewing. Maclvor found in 1863 that, if the bark were removed in longitudinal strips and the trunk were afterwards protected by covering it with moss, the cambium rapidly replaced the bark that had been removed by a fresh growth, and this fresh growth proved to be richer in alkaloid than the natural bark of the tree. This method of collecting the bark was largely adopted in India, and was practised as follows: When the trees had reached a sufficient age longitudinal incisions were made and alternate strips of bark about 4 or 5 cm. wide removed, leaving the intervening strips untouched. The bark thus collected, which had not been subjected to any artificial treatment, was known as ' natural bark.' The trunk was then covered with moss, paper, straw, or other protecting material, and left to replace the bark that had been stripped off. After a sufficient time had elapsed the covering was removed, and the strips that had been left untouched on the first occasion were then collected; these had spent part of their life under a protecting covering of moss, and were called ' mossed ' bark. The tree was then again covered, and having been deprived by the first two strippings of all its original bark, yielded, when visited for the third time, bark that had been entirely developed under the covering of moss to replace that which had been removed; this was ' renewed ' bark.

The process is interesting but laborious and expensive.