Zambezi Basin Research Articles

Flora of the Zambezi Basin

Flora Zambesiaca Mozambique; Federation of Rhodesia and Nyasaland; Bechuanaland Protectorate, Vol. 1, Part 2. Edited by A. W. Exell and H. Wild. Pp. vi + 337–581. (London: Crown Agents for Oversea Governments and Administrations, 1961. Published on behalf of the Governments of Portugal, The Federation of Rhodesia and Nyasaland, and the United Kingdom.) 25s.

The epidemic spread of Rhodesian sleeping sickness 1908–1960

1. 1) The first recognized cases of T. rhodesiense sleeping sickness occurred in Northern Rhodesia, Nyasaland, and Southern Rhodesia between 1908 and 1912. At this time sporadic cases only occurred in the Rhodesias, but there was an epidemic in Nyasaland. 2. 2) The epidemic spread northwards reaching Central Tanganyika in the 1920's, and Uganda and Kenya in the 1940's. With each extension, the disease has become more acute and the strains more rapidly lethal to experimental animals. 3. 3) In Southern Rhodesia the disease remains sporadic and relatively chronic, with the occurrence of “healthy carriers.” 4. 4) In Northern Rhodesia epidemics have occurred, but the disease remains relatively chronic as compared with the epidemic areas of East Africa. 5. 5) In Ngamiland and the Chobe districts of Bechuanaland sporadic cases have occurred since 1934 (possibly since 1909), but since 1957 minor epidemic conditions have appeared. 6. 6) In areas which have been affected by epidemic Rhodesian sleeping sickness, after the disease has been controlled, sporadic cases continue to occur, and these cases in time gradually become less acute. 7. 7) T. brucei was present in Tanganyika before 1914. Epidemic T. rhodesiense was absent, but invaded the Territory during the first World War: it is not surprising, therefore, that there is a wide distinction between these two “species” in terms of infectivity to man. 8. 8) T. brucei in domestic stock and T. rhodesiense in man both occur sporadically in Southern Rhodesia. Since the time of European settlement there has been no recorded epidemic of sleeping sickness: it is unlikely, therefore, that such a marked distinction in human infectivity exists as in Tanganyika; i.e., the theories of Kinghorn and Yorke (1912a) and of Bruce (1915) on the identity of T. brucei and T. rhodesiense still await experimental proof. 9. 9) Several cases of sporadic trypanosomiasis caused by T. rhodesiense (as here defined) have occurred in man in areas outside the normal “rhodesiense area.” 10. 10) In the better authenticated instances the strains from these sporadic cases from outside the “rhodesiense area” might have been derived either from T. brucei or T. gambiense, since both exist in the areas concerned. The original strain, from which the epidemic form of T. rhodesiense has been derived, arose in the Zambezi basin, this is so far removed from any known focus of T. gambiense as to make it unlikely that the strain was derived from anything other than T. brucei.

Catalogue of the Fresh-water Fishes of Africa in the British Museum (Natural History)

THE British Museum has recently published the fourth volume of Mr. G. A. Boulenger's “Catalogue of the Fresh-water Fishes of Africa;” Thus is brought to a conclusion—at any rate, for some years to come—a work of very great value. Mr. Boulenger's research into the ichthyology of the African rivers and lakes has gone far beyond a mere catalogue of species. It began to attract attention nearly twelve years ago by the light that it threw on the past geological history of Africa, the former superficies of this continent at different times in regard to rising and falling levels of land, the connections of the continent with outlying islands, the desiccation or the flooding of great areas of land in, the interior, the increase or the restriction of river basins and of lake limits. Briefly summarised, it went to show that the Nile system in past times has been in direct communication with the now isolated Lake Rudolf, and has come very near to the Chad Basin, which again has communicated intermittently with the Niger, while the Niger or its upper portion may at one. time have had an outlet into the Atlantic in common with the Senegal, and have been separable by only a few miles of land from the upper waters of the Gambia, the Volta, and of all those streams that flow from north to south through the forests of Guinea and the Gold Coast into the great African Bight. On the other hand, it showed a comparative poverty and isolation in fish fauna of the Zambezi Basin and South Africa; and it illustrated, above all, the specialised character and wealth in fish-fauna of the Congo Basin. This region (with which Tanganyika was not always connected) must have approached very closely to the upper waters of the Gaboon and Cameroons rivers to account for the near relationship between their fish-fauna and that of the Congo Basin. Catalogue of the Fresh-water Fishes of Africa in the British Museum (Natural History). Vol. iv. By Dr. G. A. Boulenger. Pp. xxvii + 392. (London: British Museum (Natural History), and Longmans, Green and Co., 1916.) Price 30s.

The Geology of the Zambezi Basin around the Batoka Gorge (Rhodesia)

I. Introduction. At the request of the Council of the British Association, I undertook to examine the country in the neighbourhood of the Victoria Falls of the Zambezi River before the meeting of the Association in South Africa in the summer of 1905. Through the helpful cooperation of the British South Africa Company and the aid afforded to me by its officers in Rhodesia, I was enabled to make good use of the short time available to me for the task; and by rapid traverses of the wild country eastward of the Falls I gleaned much information regarding the geology and physiography of this little-known region. A preliminary account of the exploration was presented at the meeting of the British Association in Johannesburg, and has since been published in the ‘Report’ of that body. In this account the objects of the exploration and the circumstances of the journey are stated, and therefore need not be repeated here; but of the geological results it was only possible at that time to give a bare outline, pending the further examination of the material collected. My present object is to deal more adequately with the geological evidence. The traverses occupied seven weeks in July and August, 1905, during which time a distance of over 600 miles was covered, partly on the northern and partly on the southern side of the Zambezi, as shown on the sketch-map (P1. XVII), the area embraced within these traverses being over 2000 square miles. In exploration of