While thus in Sikkim a wonderful variety of vegetation rises in successive zones from the foot of the mountains to heights unparalleled in any other part of the world, animal life abounds only in its lower classes; for the higher orders appear only in few species, and in very scanty numbers. On ascending from the foot of the Himalaya, one is astonished at the silence of the woods, broken at intervals only by the voice of a bird, or the chirping of a cicada. The solitude increases on penetrating into the interior of Sikkim, and is but rarely enlivened by a few monkeys in the valleys, some musk deer on the spare grass of the mountains, in heights of from 8,000 to 13,000 feet, or a few larks, sparrows, finches, pigeons, swallows, falcons, and other birds, some of which ascend to a surprising height. The insects, however, and other invertebrata, make up, by their numbers, for the scarcity of warm-blooded animals, and are often insupportable plagues to the wanderer. Beautiful butterflies sometimes ascend to heights of 10,000 feet, along with the less agreeable mosquitoes and ticks, and in all the streams up to an elevation of 7,000 feet, hill leeches infest the waters in such multitudes that bathing is almost impossible. [Illustration: AFRICAN BUSHMEN.] CHAPTER IX. THE KALAHARI AND THE BUSHMEN. Reasons why Droughts are prevalent in South Africa--Vegetation admirably suited to the Character of the Country--Number of Tuberous Roots--The Caffre Water-Melon--The Mesembryanthemums--The Animal Life of the Kalahari--The Bushmen, a Nomadic Race of Hunters-- Their Skill in Hunting--Their Food--Acuteness of their Sight and Hearing--Their Intelligence and Perseverance--Their Weapons and Marauding Expeditions--Their Voracity--Their Love of Liberty-- The Bakalahari--Their Love for Agriculture--Their Ingenuity in procuring Water--Trade in Skins--Their timidity.