286 .T. W. BEWS. 



tlierefore, that during spring such plants receive full light, 

 and as the grass grows they become more and more shaded. 



My observations were taken when the grass was full-grown. 

 In the commonest of the veld grass-associations, Antlii- 

 stiria imberbis with Andropogon ceresia3f ormis, on 

 an average -^^ of the full sunlight reached the leaves of 

 species of Helichrysum growing prostrate on the ground. 

 Among the still taller grasses, Andropogon nardus and 

 Andropogon f ilipendulus, only J-^j- reached the leaves of 

 Eucomis undulata. 



Again, in a vlei (marsh) with Phrag-mites communis, 

 Cyperus latifolius, and Erianthus capensis, where the 

 last-named was growing to a height of 10 ft., only yJ^ of the 

 total sunlight reached the leaves of Commelina gerrardi, 

 though the latter was straggling up through the grasses. 



(5) MOVEMENTS OF THE AIE. 



As far as winds are concerned the following is the succes- 

 sion of events throughout the year. 



It has been already pointed out that the south-east winds 

 during summer bring the rain-clouds in from the sea. While 

 these rain-bearing south-east winds prevail the anticy clonic area 

 is far out from the coast. The air coming from it has traversed 

 a wide stretch of sea before it reaches the land, and conse- 

 quently it arrives saturated with water vapour. During 

 the whole summei-, while the sun is south of the equator, the 

 land plateau of the interior is being heated, and the hot air 

 rising, the cooler air flows in from the sea to take its place. 

 It deposits its moisture as it passes over Natal in the way 

 already described. 



As winter advances the anticyclone approaches near to the 

 land, and winds coming from the former, having traversed 

 only a short distance of sea, arrive without much moisture. 

 Owing to exceptional cross-currents, however, Port Durnford, 

 in Zululand, as has been shown, gets a good deal of rain during" 



