If the thing was not sufficiently evident in itself, the appearance of the barks sent from Java to the Exhibition of 1862 is quite enough to prove that chinchona-plants ought not to be cultivated under the shade of forest-trees. The question of the proper amount of exposure to which each species should be subjected is, however, one which requires very careful consideration; as upon its correct solution depends the most important point of all, namely the method of cultivation which will be most profitable, and most suitable to the operations of private enterprise.
Mr. McIvor commenced experiments in planting out in the spring of 1861. In April he planted out three plants of C. succirubra, two under shade, and one in an open spot surrounded by brushwood and undergrowth. On the 29th of the same month the S.W. monsoon set in, and the plants under dense shade assumed a weak climber-like habit, and were injured from the leaves being cut to pieces by the constant drip from the forest-trees;[510] while the plant shaded by the brushwood continued in the most luxuriant state of health, with its leaves uninjured. In September 1861, six plants of different species were planted out in cleared spots on the highest and most exposed points of the Neddiwuttum site, and all of these have not only borne the cold and drought without injury, but their growth has never even been checked, and at present they are in the finest possible state of health. Their leaves are of the deepest green, some of them measuring 12 inches by 9.
Between May and August fifteen "red-bark" plants were planted out at Ootacamund. The unusual cold of December checked the growth of these plants, but did not injure them in the least, and the leaves still keep their deep-green colour, and measure from 7 to 9 inches.[511]
Early in January 1862, the formation of a nursery was commenced at Neddiwuttum, large enough for 300,000 or 400,000 Chinchonæ; and 2400 were planted out. 150 acres are to be planted, at the Neddiwuttum site, during the year; of which 75 acres will be planted under various degrees of shade from forest-trees, in order to ascertain the results of this method by actual experiment; and 75 quite in the open, the young plants being protected from the direct rays of the sun by artificial shade during the first year or two. The original stock will be retained in the gardens at Ootacamund, for the purpose of propagation, and the propagated plants will be used for stocking the nurseries and plantations.
With regard to the question of whether the chinchonæ should be planted out in dense shade of forest-trees or in the open, it will be well to recapitulate some of the information which has been collected in their native habitat in South America.
In the forests of Caravaya I observed that the plants of C. Calisaya, when in dense shade, were tall and weak, with few branches, and without any sign of ever having flowered or fruited. When very slightly shaded, as on the ridge of rocks above the Yanamayu, or scarcely at all, as on the precipice of Ccasa-sani, they spread more, have a more healthy appearance, and are covered with capsule-bearing panicles; while the most thriving and healthy-looking young plant that I met with, was growing in the open, without any shade whatever. It is quite certain that an abundance of light and air is an absolute necessity for the full development of the alkaloids in the bark of C. Calisaya, and that the trees must either grow at the edge of the forests, or else find their way to the light, by overtopping all other trees: otherwise, as is too often the case, they assume a weakly, straggling habit under the baneful influence of dense shade.
Dr. Weddell is of opinion that, during the first year or two, the soil and trunks of young trees of C. Calisaya should be protected from the direct influence of the scorching sun, as he had observed that plants so exposed generally appeared to have a stunted growth. He refers of course to the Josephiana or shrub variety of C. Calisaya, but their dwarfed habit must be attributed to the less fertile soil of the open grass-land in which they grow, and partly also to the great altitude, and consequently cold climate, rather than to effects of exposure to light and air.
With respect to the "red-bark" species, there cannot be a doubt that they should be planted in the open. On this point Mr. Spruce's observations are quite conclusive. He says—"The trees standing in open ground, pasture, cane-field, &c., are far healthier and more luxuriant than those growing in the forest, where they are hemmed in and partially shaded by other trees; and while many of the former had flowered freely, the latter were, without exception, sterile. This plainly shows that, although the red-bark may need shade whilst young and tender, it really requires (like most trees) plenty of air, light, and room, wherein to develop its proportions."[512]
The "grey-bark" species all bear the marks of exposure to free air, cold, and sunshine; and the overspreading thallus of various Grapideæ on their barks indicates that the trees have grown in open situations, exposed to rain and sunshine.[513]
The C. Condaminea trees, in the neighbourhood of Loxa, grow sometimes in little clumps, and sometimes solitary, but always in dry situations.[514] Dr. Seemann, who visited Loxa when serving on board H.M.S. Herald, informs me that those which he saw, bearing ripe fruit, were on the edge of thickets, entirely exposed to the influence of air and sunshine.