34 peesidext'.s ajjukkss. 



No one has demonstrated more clearly what can be 

 accomplished by the co-operation of workers in different fields of 

 research than Sir Arnold Theiler, the Director of Veterinary 

 Eesearch, with whom it has been my privilege tO' be associated 

 in several of his investigations dealing with what he once termed 

 " the unsolved stock diseases of South Africa." The cause of 

 such diseases as Jacht-ziekte, Stijfziekte, Geeldikkop, Gouwziekte 

 and Bovine Staggers was only discovered after a close study of 

 the flora and veld conditions of the areas where these diseases 

 occur. So convinced is Sir Arnold of the importance of the study 

 of the veld in connection with obscure plant poisons that he has 

 now speciall,y attached to his staff a botanist whose whole time 

 is devoted to this purpose. 



If the veterinarian can make such progress with the aid of 

 the botanist, there is no reason why similar results should not 

 be attained by the botanist and chemist in the many problems of 

 the veld that await them. To quote a specific case : it is well 

 known that stock fatten more rapidly in the Vaal Kameel Doom 

 Veld in the winter than in any other part O'f South Africa, and 

 that they may remain in good condition for a long time if removed 

 from that region to another part of the country, but no' one can 

 explain the reason. The cause is p?'obably to be found in some 

 close connection between the warm sandy soil of this veld and 

 the physiology' of nutrition, but who^ can say, withovit the most 

 careful enquiry? These problems can only be elucidated by tlie 

 trained botanist working continuously on the spot, and working 

 in co-operation with the chemist. The investigation of such 

 questions is of enormous importance from an economic standpoint, 

 and when such problems are scientifically and systematically 

 attacked the veld will yield a hurd red fold its present resourc^^ 

 and its dangers wilF correspondingly decrease and diminish. 



In conclusion, I wish to acknowledge my indebtedness to 

 INIiss Sydney Stent, of the Division of Botany, who supplied me 

 with notes on the economic plants of the various regions of which 

 she is making a special study. 



