242 Mr Scott Elliot 07i the 



The extreme variety of the Cape flora, which embraces, 

 according to Professor Maccowan, about 10,000 species, is 

 mainly due to these well-marked climatic differences. In 

 fact, the western (or properly south-western) district, the 

 eastern district and Karoo form excellent examples of what 

 Mr Romanes calls physiological islands. They are as 

 thoroughly separated, so far as most of their plants are con- 

 cerned by their different flowering seasons, as is an oceanic 

 island from its neighbouring continent. 



The geology of the country is of interest, too, in connection 

 with the distribution of the plants. It is in the Transvaal 

 that the oldest rocks of the country are to be found, while 

 almost the wliole of the country to the south of these 

 rocks has been covered by a vast series of almost horizontal 

 secondary strata. In the Stormberg these reach a height of 

 some 8000 feet above the sea, while in the mountain ranges 

 nearer the southern corner they are usually about 5000 feet. 

 The whole of the Karoo is a basin of denudation worn out 

 of these secondary strata. This structure of the mountains 

 results in a peculiar and very characteristic scenery. The 

 summit of every mountain in sight from any one point is 

 as flat as a table, and all being at exactly the same level, 

 nothing is more easy than to draw, in imagination, the 

 original plateau, and to note the extraordinary amount of 

 denudation that has taken place. 



It follows, then, that the plants originally coming over 

 this table-land have been divided into at least four main 

 groups. The first party went down the sides of the moun- 

 tains to the west and south-west, and their descendants form 

 the south-western flora of to-day. A second group spread 

 similarly over the eastern districts, mingling towards the 

 north with the tropical coast flora of Africa (very probably 

 they helped to form the tropical flora of the east coast). A 

 third group, when the present dry, arid conditions of the 

 Karoo began to prevail, became correspondingly modified, 

 and form the present remarkable flora of the Karoo, while 

 the fourth group remained on the summits. 



Although the subdivision of Mr Bolus is quite good 

 enough for all j^ractical purposes, still it seemed to me dur- 

 ing my short visit that this vegetation of the tops of the 

 mountains should really be included in the flora of the in- 



