372 NATURAL SCIENCE. May, 



the forests of lower Natal, the Perie, and the Knysna have each 

 their own endemic forms. Each is, in fact, a climatic island, and 

 varieties suited to very local conditions have free play. 



Further inland the plateaux of Mashonaland, the Transvaal, and 

 upper Natal are covered with grass, among which are perennials 

 and bulbous plants, and in places isolated shrubs or small trees, 

 chiefly acacias. It is believed that there must be a communication 

 with Abyssinia by ridges or mountain summits, at least 5,000 ft. high, 

 in the tropics, and that the plants have travelled down along these 

 ridges and summits without experiencing any great climatic change 

 on the way, but this is rather theoretical at present. At any rate, 

 they have taken on different specific characters en route in most cases, 

 and they are quite different from those of the coast below 2,000 ft. 

 Following the plants of these grassy plains southwards, we can trace 

 them, often in very modified forms, on isolated mountain summits 

 (such as at Somerset East) as far as the top of Table Mountain at 

 Cape Town ; but within the Cape Colony these grassy mountain tops, 

 which are usually flat and table-like, are also inhabited by a wealth 

 of endemic Cape genera and species, which probably ascended the 

 hills from the lower parts of the peninsula. Every isolated mountain 

 top may be in this way a climatic island, with species of its own. 

 Still these plateaux and tables are generally in a fairly moist climate, 

 and under quite different conditions to either the arid deserts of the 

 Karoo or the western parts of Cape Colony and the lower parts of 

 the peninsula. 



In the Karoo and Namaqualand similar conditions prevail to 

 those of the Sahara, and we find there bulbous plants, succulents, 

 thorny plants, and densely matted perennials, similar in structural 

 type to those of the Sahara, but of utterly different origin. The 

 Cruciferae and Chenopods, which are predominant in the latter, are 

 almost absent here, and their place is taken by Mesembryanthemums, 

 Stapelias, Pelargoniums, and others, which are not found in the 

 north, and make a very different flora. Here, again, we find the 

 landscape the colour of the soil, and scarcely tinted by the vegetation. 



As for the distinctive Cape flora (that is to say, the remainder 

 after the Karoo-Namaqualandand mountain-flora has been subtracted), 

 it is different to any of the others ; the conditions are rather dry, and 

 yet not desert ones ; the rainfall occurs at a different season to that 

 of the eastern slopes and the Transvaal, and the prevailing type of 

 plant is again different. Most are shrubby little perennials like the 

 heaths, and a very large mmiber have heather-like leaves ; there are 

 many bulbs, and scarcely a single annual of any sort or kind. The 

 landscape is not wholly free from the colour of the soil, but it is 

 masked by the grey-green tints of these little shrubs, and sometimes 

 it is bright and rich in colour, as when Erica Plukenetii is in bloom. 

 It is never, however, so beautiful as, for instance, that of the top of 

 Table Mountain in the right month, which simply beggars descrip- 



