At this elevation we found great scandent trees twisting around the trunks of others, and strangling them: the latter gradually decay, leaving the sheath of climbers as one of the most remarkable vegetable phenomena of these mountains. These climbers belong to several orders, and may be roughly classified in two groups.—(1.) Those whose sterns merely twine, and by constricting certain parts of their support, induce death.—(2.) Those which form a network round the trunk, by the coalescence of their lateral branches and aerial roots, etc.: these wholly envelop and often conceal the tree they enclose, whose branches appear rising far above those of its destroyer. To the first of these groups belong many natural orders, of which the most prominent are—Leguminosæ, ivies, hydrangea, vines, Pothos, etc. The inosculating ones are almost all figs and Wightia: the latter is the most remarkable, and I add a cut of its grasping roots, sketched at our encampment.
Except for the occasional hooting of an owl, the night was profoundly still during several hours after dark—the cicadas at this season not ascending so high on the mountain. A dense mist shrouded every thing, and the rain pattered on the leaves of our hut. At midnight a tree-frog (“Simook,” Lepcha) broke the silence with his curious metallic clack, and others quickly joined the chorus, keeping up their strange music till morning. Like many Batrachians, this has a voice singularly unlike that of any other organised creature. The cries of beasts, birds, and insects are all explicable to our senses, and we can recognise most of them as belonging to such or such an order of animal; but the voices of many frogs are like nothing else, and allied species utter totally dissimilar noises. In some, as this, the sound is like the concussion of metals; in others, of the vibration of wires or cords; anything but the natural effects of lungs, larynx, and muscles.[[56]]
[56] A very common Tasmanian species utters a sound that appears to ring in an underground vaulted chamber, beneath the feet.
May 21.—Early this morning we proceeded upwards, our prospect more gloomy than ever. The path, which still lay up steep ridges, was very slippery, owing to the rain upon the clayey soil, and was only passable from the hold afforded by interlacing roots of trees. At 8000 feet, some enormous detached masses of micaceous gneiss rose abruptly from the ridge, they were covered with mosses and ferns, and from their summit, 7000 feet, a good view of the surrounding vegetation is obtained. The mast of the forest is formed of:—(1) Three species of oak, of which Q. annulata? with immense lamellated acorns, and leaves sixteen inches long, is the tallest and the most abundant.—(2) Chesnut.—(3) Laurineæ of several species, all beautiful forest-trees, straight-holed, and umbrageous above.—(4) Magnolias.[[57]]—(5) Arborescent rhododendrons, which commence here with the R. arboreum. At 8000 and 9000 feet, a considerable change is found in the vegetation; the gigantic purple Magnolia Campbellii replacing the white; chesnut disappears, and several laurels: other kinds of maple are seen, with Rhododendron argenteum, and Stauntonia, a handsome climber, which has beautiful pendent clusters of lilac blossoms.
[57] Other trees were Pyrus, Saurauja (both an erect and climbing species), Olea, cherry, birch, alder, several maples, Hydrangea, one species of fig, holly, and several Araliaceous trees. Many species of Magnoliaceæ (including the genera Magnolia, Michelia, and Talauma) are found in Sikkim: Magnolia Campbellii, of 10,000 feet, is the most superb species known. In books on botanical geography, the magnolias are considered as most abounding in North America, east of the Rocky Mountains; but this is a great mistake, the Indian mountains and islands being the centre of this natural order.
At 9000 feet we arrived on a long flat covered with lofty trees, chiefly purple magnolias, with a few oaks, great Pyri and two rhododendrons, thirty to forty feet high (R. barbatum, and R. arboreum, var. roseum): Skimmia and Symplocos were the common shrubs. A beautiful orchid with purple flowers (Cælogyne Wallichii) grew on the trunks of all the great trees, attaining a higher elevation than most other epiphytical species, for I have seen it at 10,000 feet.
A large tick infests the small bamboo, and a more hateful insect I never encountered. The traveller cannot avoid these insects coming on his person (sometimes in great numbers) as he brushes through the forest; they get inside his dress, and insert the proboscis deeply without pain. Buried head and shoulders, and retained by a barbed lancet, the tick is only to be extracted by force, which is very painful. I have devised many tortures, mechanical and chemical, to induce these disgusting intruders to withdraw the proboscis, but in vain. Leeches[[58]] also swarm below 7000 feet; a small black species above 3000 feet, and a large yellow-brown solitary one below that elevation.
[58] I cannot but think that the extraordinary abundance of these Anelides in Sikkim may cause the death of many animals. Some marked murrains have followed very wet seasons, when the leeches appear in incredible numbers; and the disease in the cattle, described to me by the Lepchas as in the stomach, in no way differs from what leeches would produce. It is a well-known fact, that these creatures have lived for days in the fauces, nares, and stomachs of the human subject, causing dreadful sufferings, and death. I have seen the cattle feeding in places where the leeches so abounded, that fifty or sixty were frequently together on my ankles; and ponies are almost maddened by their biting the fetlocks.