Travels in Peru and India / While Superintending the Collection of Chinchona Plants and Seeds in South America, and Their Introduction into India.

by Sir Clements R. Markham

Dr. Weddell assures me that he would never recommend that any of the chinchona-trees should be planted in the dense shade of the forest, as in such a situation the greater number would evidently soon be smothered. He is of opinion that the Chinchonæ, in India, should be planted in open ground; but he considers it important that the trunks and soil should be shaded during the first year or two. He proposes to effect this object either by planting the chinchonas at convenient distances in a quincunx, alternately with some more fast-growing trees, which might be cut away when no longer required;[515] or by planting the chinchonas themselves close enough to oblige each other to run up, sufficient space and air being gradually provided by judicious pruning and thinning out. The former method might be a good one if it were not for the faster-growing trees taking up a great proportion of the nourishment from the soil, which would be more profitably reserved for the chinchonas; and probably the efficient shading of the trees, while young and tender, will be more easily and effectually provided for by simple artificial means.

Mr. Howard, the author of 'Nueva Quinologia de Pavon,' whose knowledge on all questions connected with chinchona-plants is not surpassed by that of any botanist in Europe, is clearly of opinion that they should be planted in the open, without shade from other trees, and that they should be cultivated as shrubs; when their branches will yield an ample and remunerative supply of bark.

On the other hand, Dr. Junghuhn, in Java, has planted his chinchonæ under the dense shade of forest-trees, where they must necessarily be watery and unhealthy, where they will not flower or bear fruit, and where he does not expect that they will yield quinine for fifty years, when he contemplates the entire demolition of the plantations by felling all the trees. Now, if such a system as this is to be adopted in India, the chinchona-plants might as well never have been introduced. The plantations would be a wasteful expense to Government, with a remote chance of some profit, forming but a small fraction of the outlay, about twice in a century; and the idea of chinchona cultivation ever being undertaken by private enterprise, on this system, is quite out of the question; for what planter in his senses would commence the cultivation of a product which would yield him no return for forty or fifty years?

When planted in the open chinchonæ grow luxuriantly, yield abundant supplies of seed, and form fine thick bark, which, owing to the free exposure of the leaves to the influence of light and fresh air, contains a large per-centage of alkaloids; while, in the shade of forest-trees, they run up into tall, weak, straggling plants, with little chance of either bearing fruit, or elaborating much quinine in their bark, until, after nearly half a century, some of them at length overtop the other trees, and reach that essential sunshine of which they had been so long deprived.

I not only think, with Mr. Spruce, Dr. Weddell, Mr. Howard, Mr. McIvor, and Mr. Cross, that the chinchona-plants must be planted in the open, and freely exposed to the influence of fresh air and sunshine; but I am most strongly of opinion that, if the opposite system was unfortunately adopted, it would have been far better if the expense and trouble of introducing these precious trees into India had never been incurred.

It is true that, when planted in the forest, the chinchonæ will look well to the casual observer, and that their cultivation can be conducted without skill or care, as all will be left to nature; while, in open ground, it will require great skill and constant attention to get the young trees over the first year or two. The cleared ground will be exposed to the full effects of evaporation and radiation, and much judicious management will be necessary in applying artificial shade, and in adopting other precautions. The open spaces should not, I think, be of very great extent, without being broken up by clumps or irregular lines of trees; and care must be taken that the supplies of moisture and of water are not prejudiced by too much felling. But these details may safely be left to Mr. McIvor, who now has the assistance of two well-instructed English gardeners, named Batcock and Lyall; and he will be able to obtain uniform and constant yearly supplies of bark, without any damage to the trees, which, when once full-grown, will thrive luxuriantly, and yield abundance of seeds.

The most suitable positions for chinchona-plants, as regards elevation and climate, having been pointed out, and the best method of treatment with respect to exposure being decided in favour of planting out in open ground, two other questions remain to be discussed which are intimately connected with the above,—namely, the conditions under which the largest per-centage of febrifugal alkaloids will be formed in the bark,[516] and the method of cultivation which is likely to yield the largest and most remunerative supplies of bark in the shortest time.

One well-established fact, which is proved by universal experience, is that all the species of chinchona-trees produce the thickest bark and the largest per-centage of alkaloids when growing at the highest elevation at which they respectively flourish. Thus, all other circumstances being favourable, the C. Calisaya and C. succirubra species will yield more profitable crops when growing at an elevation of 6000 feet, than at one of 5000 feet. The shrubby varieties of chinchonæ are specially good when their stunted growth is owing to the altitude of the locality.[517] Mr. Spruce ascertained, with regard to the "red bark," that the greater the height at which the tree grows, the larger is the proportion of alkaloids contained in the bark;[518] 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.[519]

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.[520] 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,[521] 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 with the formation of quinine in the bark, and to ascertain the most advantageous conditions under which the plants should be cultivated.