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 voute 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 
Cruciferee 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- Namaqualand and 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 number 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 Plukenetit 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- 
