1 68 SCIENCE IN AFRICA 



report on the mineral content of natural pastures'. Sir John Orr 

 visited South Africa and Kenya on behalf of the committee and, on 

 his recommendation, the Government stock farm at Naivasha in 

 Kenya was selected for exhaustive experiments. An account of 

 Sir John Orr's work in East Africa was published by the Economic 

 Advisory Council (1931). 



In South Africa similar work on the nutritive value of pastures 

 and deficiency diseases of stock has been carried on at Onderste- 

 poort for the last thirty years, and much material has been pub- 

 lished. This work has led directly to the effective control of several 

 diseases, for example, the discovery by Sir Arnold Theiler and 

 his collaborators that Jaagsiekte in horses, etc., are all due to 

 poisonous plants common in natural herbage. Again, Theiler's 

 discovery that Lamsiekte in cattle is caused by bacteria of the 

 Botulinus group, and that infection results from animals chewing 

 bones in order to make good the phosphorus deficiency in natural 

 pastures, is now a classic in veterinary science. Recently work on 

 pasture improvement has been stimulated by the opinion now 

 prevalent that 'breeding must go in at the mouth'. 



The history of pastures and pasture studies in South Africa, with 

 suggestions as to future tendencies, has been written by T. D. 

 Hall (1934), and an up-to-date summary of results has been pub- 

 lished by the Imperial Bureau of Plant Genetics (1937). A num- 

 ber of grasses have been introduced to South Africa from other 

 parts of the continent and elsewhere; notable among these is 

 Teff-grass [Eragrostis teff), which was introduced by Dr. BurttDavy 

 to the Transvaal as early as 1903. Grown as a hay crop it has 

 proved of the greatest value in the drier parts of South Africa, as 

 described by Burtt Davy (191 6). Exotic pasture grasses have not 

 been successfully introduced except for the purposes of winter 

 feed, so research has been directed to the selection of the most 

 suitable of the indigenous species. This has been carried out 

 mainly by the Division of Plant Industry of the Union Department 

 of Agriculture under Dr. Pole Evans, who has published a sum- 

 mary of results (1933). 



The woolly finger grass, consisting of various species of Digitaria, 

 is pre-eminent in carrying capacity, and is richer in minerals, pro- 

 tein and carbohydrates than any other. Possessing stolons and the 



