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tree grows, the larger is the proportion of alkaloids contained in the bark; and that, although the trees growing nearest the plain were generally much larger, yet their bark was by no means so thick in proportion to their diameter as in trees higher up. He adds that, in cutting down trees in the hot plains, he has often been struck with the thinness of the bark compared to that of trees growing in temperate climates.2

There are several other conditions under which the largest amount of alkaloids is formed in chinchona-barks, which are as yet little understood. Dr. Karsten suggests that the content of alkaloids in the same species of chinchona-trees, growing in different ravines, is affected by unceasing mists in one, and constant sunshine resting on the vegetation in the other; the former impeding, and the latter promoting, the formation of quinine. In the Loxa region a great difference has been noticed in the bark of C. Condaminea, according as the tree has grown on the sides of the mountains most exposed to the rays of the morning or of the evening sun: and Mr. Spruce remarks of the "red-bark" trees that the ridges on which they grow all deviate from an easterly and westerly direction, and that the trees are far more abundant on their northern than on their southern slopes. The northern and eastern sides of the trees had also borne most flowers, and scarcely a capsule ripened on their southern and western sides, except on one tree of more open growth than the rest. This phenomenon is due to the fact that the trees receive more sunshine from the north and east, during the summer mornings, the afternoons being usually foggy.

All these points will receive careful attention from Mr. McIvor, in conducting the cultivation; and his observations will soon enable him to decide many points connected

1 Spruce's Report, p. 83.
2 Ibid., p. 27. See also Karsten,

3 Karsten, p. 20.

4 Spruce's Report, p. 23.

p. 20.

with the formation of quinine in the bark, and to ascertain the most advantageous conditions under which the plants should be cultivated.

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."

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

5 Lindley's Theory and Practice of Horticulture, p. 70.

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that, in their natural localities in the Andes, the chinchona 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 chinchona 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 chinchona 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 percentage of alkaloids than the canuto or small bark of the 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.

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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 "Westcoast 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

In quills from large branches there is-more alkaloid than in the smaller branches; in the bark of the trunk the proportion is still further increased,

but this diminishes in quantity and deteriorates in quality in the bark of the roots.- Howard,

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." These quills are evidently taken from small shrubs, and they yield a very good percentage 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.8

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

7 Mr. Me Ivor reports the thickness! 8 The only reason why the value of of the bark of some of the young plants at Ootacamund to be nearly a quarter of an inch. The bark of quills of C. Calisaya given me by Mr. Howard, as samples from a lot on sule, is only one-eighth of an inch in, thickness.

quill-bark is much less than that of tabla-bark is that the former is usually mixed with spurious barks. Otherwise the value of quill-bark would only be about threepence per lb. less than tabla-bark.

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