The sites have been selected at Neddiwuttum and Dodabetta with reference to the similarity of elevation and climate in those localities to the native mountains of the species which it is intended to cultivate in them, and because they have plenty of deep loamy soil. It has also been determined that the best method of cultivation will be found in planting out the chinchonæ in the open, for reasons already given; and not only will the luxuriant and healthy growth of the plants be provided for by this treatment, but it is also essential for the formation of an abundant supply of alkaloids in their bark. This process depends on the vigorous action of the leaves, and the healthful condition of the leaves is due to a sufficient supply of sunshine. Dr. Lindley says,—"It is to the action of leaves,—to the decomposition of their carbonic acid, and of their water; to the separation of the aqueous particles of the sap from the solid parts that were dissolved in it; to the deposition thus effected of various earthy and other substances, either introduced into plants as silex or metallic salts, or formed there, as the vegetable alkaloids; to the extrication of nitrogen; and, probably, to other causes as yet unknown—that the formation of the peculiar secretions of plants, of whatever kind, is owing. And this is brought about principally, if not exclusively, by the agency of light. Their green colour becomes intense, in proportion to their exposure to light within certain limits."[522]
Under cultivation the chinchona-plants must either be raised in their shrubby form in the open, or as tall trees under the shade of the forest. The latter system, which has been adopted by Dr. Junghuhn in Java, is defended on the ground that, in their natural localities in the Andes, the chinchonæ "grow in damp forests overshadowed by trees." There are two things to be said against this. Firstly, that it is not the case; for though it is true that some species of chinchonæ do grow in damp shady forests, yet they never flourish in such positions, but only when supplied with plenty of light and air; and secondly, even if it was the case, such an argument would be worth nothing. In their wild state, and in localities where they are indigenous, all plants find certain conditions which are favourable to their perfect development; but they have to struggle for existence with a multitude of neighbours. Every condition is not supplied by Providence for the special behoof of one particular genus, and, in virgin forests, all trees suffer more or less from being overcrowded and overshadowed. But under cultivation the case is different. The cultivator endeavours to combine all the conditions best calculated to ensure the perfect development of a particular plant, and does not subject it to the baneful influences of too much shade, merely because it suffered from overshading in its wild state. Mr. McIvor has very aptly illustrated this point, by mentioning that Bruce found wheat growing wild in Upper Egypt, struggling for existence with rushes and other weeds. An English farmer would be surprised if he was told to sow his wheat in the hedges, instead of in the fields, because in its wild state it is found amongst weeds and briars!
The facts that it will be necessary to wait for thirty years before any return can be expected; and that it will have a most injurious effect on the formation of alkaloids in the bark, are sufficient arguments against planting the chinchonæ in the shade of the forest, and waiting for them to run up until the survivors overtop the surrounding trees. It has been necessary to bring these points prominently forward, because attempts have been made to introduce the erroneous system, adopted by the Dutch cultivators, into India.
We now come to the other alternative, that of raising the chinchonæ in their shrubby form, on plantations in open clearings, with plenty of fresh air and sunshine. It is the system of cultivation which I, in common with Mr. Howard and Mr. McIvor, consider to be the most likely to lead to successful results, because it is the only one by which remunerative harvests of bark can be obtained year by year, without injuring the plants.
Two questions require consideration before adopting this method: first, whether the chinchonæ in their shrubby form will yield a sufficient annual supply of febrifugal alkaloids to make the cultivation remunerative; and secondly, whether it will be possible to take the required quantity of bark every year, without checking the growth of the trees.
The trunk or tabla bark naturally yields a much larger per-centage of alkaloids than the canuto or small bark of branches; but as a supply of the former could only be obtained once in forty years, and then at the cost of destroying the plantations, while the latter will yield an annual harvest without any injury to the trees, this point is not of much consequence.[523]
The fact is that very little tabla or trunk-bark comes from South America, and that nearly the entire bark trade is supplied by quill-bark from the branches of shrubs. Some Calisaya bark from Bolivia, some "red bark," and "West-coast Carthagena," from the trunks of C. Palton, arrive in the form of large slabs of tabla-bark; but a great deal of the Calisaya and succirubra bark, the whole of the "crown-bark" from Loxa, and all bark from other quarters, is found only in the form of quills from small branches. I have measured several of the quills which come into the London market, and find that none of them have bark equal in thickness to that already attained by some of the young plants reared by Mr. McIvor at Ootacamund.[524] These quills are evidently taken from small shrubs, and they yield a very good per-centage of quinine. Several samples of quill Calisaya bark, sold in London in March 1862, contained four per cent. of quinine. Their bark was one-eighth of an inch thick, and the quills were just under an inch in circumference. In a cultivated state the yield will of course be much greater, and Mr. Howard, judging from the usual yield of quill-bark, is of opinion that a large produce may be annually realised by growing the chinchonæ as shrubs.[525]
In cultivating the chinchonæ in rows on cleared plantations it will probably be found advisable to grow them to a height of ten or twelve feet, and about twelve feet from each other, so that they may be able to spread out until they are nearly as broad as they are long; and they should be induced to branch as near the ground as possible. A certain number of the branches should be lopped annually for the quinine harvest; shoots would immediately be thrown out below the cuts, from which one or two should be selected to take the place of the lopped branch; and in about six years the new branches, thus formed, would be sufficiently grown to be again removed. In the mean while the same operation would have been going on with other branches, and thus an annual harvest of quill-bark may be obtained for any number of years. Mr. McIvor considers that this treatment will ensure a quick, uniform, and constant supply of bark; and if the lopping and pruning is judiciously conducted, the trees will be benefited rather than injured by the annual removal of a few branches.[526] Chinchona-plants, like oaks and willows, might also be cultivated as pollards.
By cultivating the chinchona-plants on these principles, forming plantations in cleared open ground, giving the plants plenty of light and air, and obtaining annual harvests of quill-bark from the shrubs, quinine-yielding chinchona-bark will become an article of commerce within eight years from the first introduction of the plants into India. After the first harvest the supply will rapidly increase. Extensive Government plantations of the different species at Neddiwuttum and Dodabetta on the Neilgherries, will be in a position to supply any number of chinchonæ for private enterprise, and it is to be hoped that the Government will establish other chinchona nurseries on the Pulney hills, in Coorg, and eventually on the Anamallays.