1 62 SCIENCE IN AFRICA 



in vegetation-covering; in his view the mountain forests may in- 

 duce occult precipitation in the form of dew and mist, not measure- 

 able by the usual methods, up to 25 per cent of the total rainfall, 

 and wherever meteorological conditions tend to instability, forests 

 greatly increase the possibility and quantity of rain. Graham 



(1931) has given notes on the mangrove swamps of the Kenya 

 coast. 



In general, there has been so much interference with vegetation 

 by man in East Africa, that in Uganda, for instance, scarcely any 

 of the original vegetation may be seen below an altitude of 7,000 

 feet, the grasslands, swamps and forests being nearly all secondary 

 growths. Hence plant ecology is peculiarly difficult to interpret. 

 Eggeling (1935) has published a paper on the ecology of swamps, 

 which are so marked a feature of Uganda. 



In Tanganyika the vegetation of Mt. Kilimanjaro has been 

 described in several German books, notably Meyer (1891) and 

 Volkens (1897), and more recently by Cotton (1930). Engler 

 (1894) described the vegetation of Usambara in an early work. 

 J. F. V. Phillips, when botanist in the department of tsetse re- 

 search, was perhaps the first to apply modern principles of ecology. 

 He has described (1930b) the principal vegetation communities 

 and successional relations in the Central Province of Tanganyika 

 and (1931c) has outlined the floral regions. On this P. J. Green- 

 way (1933) and J. D. Scott (1934) have based detailed studies in 

 the more accessible parts of the territory. 



For the Congo Professor de Wildeman has written extensively 

 on vegetation, especially in 191 2, and in his work of 1926 on the 

 Congo forests. He holds that fire has been the principal factor in 

 limiting forest country, a view with which his successor at the 

 Brussels Botanical Gardens, Dr. Robyns, does not entirely agree. 

 Robyns (1930) has published a survey of the vegetation of the 

 Congo with a small map showing distribution. He has also studied 



(1932) the revegetation of the lava fields of the volcano Rumoka 

 (Kivu), and Professor Hauman (1933a) has outlined the alpine and 

 sub-alpine vegetation of Mt. Ruwenzori. In Kivu, extensive re- 

 searches on the relation of the mountain vegetation to the climate, 

 and especially water-supply have been made by H. Scaetta (1933). 

 JFor tlie Katanga G, Pelevoy (1928) has published an ecological 



