G2 ASPECTS OF TROPICAL NATURE 



rain there keeps a large number of streams perpetually flowiDg, 

 Damara Land, the Namaqua country, and the Kalahari, are 

 almost constantly deprived of moving water. 



From these general remarks it might be imagined that regions 

 so scantily supplied with one of the prime necessaries of life could 

 be nothing but a dead and naked waste ; yet, strange to say, even 

 the great Kalahari, extending from the Orange river in the south, 

 lat 29°, to Lake Ngami in the north, lat. 21°, and from about 

 24° E. long, to near the west coast, has been called a desert, simply 

 because it contains no flowing streams and very little water in 

 wells ; as, far from being destitute of vegetable or animal life, 

 it is covered with grass and a great variety of creeping plants, 

 interspersed with large patches of bushes and even trees. In 

 general, the soil is a light-coloured, soft sand ; but the beds of 

 the ancient rivers contain much alluvial soil, and, as that is 

 baked hard by the burning sun, rain-water stands in pools in 

 some of them for several months in the year. 



The abundance of vegetation on so unpromising a soil may 

 partly be explained by the geological formation of the country ; 

 for as the basin-shape prevails over large tracts, and as the 

 strata on the slopes where most of the rain falls dip in towards 

 the centre, they probably guide water beneath the plains, which 

 are but ill-supplied with moisture from the clouds. 



Another cause, which serves to counteract the want or scarcity 

 of rain, is the admirable foresight of Nature in providing these 

 arid lands with plants suited to their peculiar climate. Thus 

 creepers abound which, having their roots buried far beneath 

 the soil, feel but little the effects of the scorching sun. The 

 number of these which have tuberous roots is very great, — a 

 structure evidently intended to supply nutriment and moisture 

 when, during the long droughts, they can be obtained nowhere 

 else. 



One of these blessings to the inhabitants of the desert is a 

 small. plant named Leroshua, with linear leaves, and a stalk 

 not thicker than a crow's quill; but on digging down a foot 

 or eighteen inches beneath, the root enlarges to a tuber, often 

 as big as the head of a young child, which, on the rind 

 being removed, is found to be a mass of cellular tissue, filUMi 

 with fluid much like that in a young turnip. Owing to 



