PRESIDENTS ADDRESS. 3 



tions and leading to practical issues. You are aware that the 

 science in which I am particularly engaged deals with the investi- 

 gation into the causes of stock diseases in South Africa, with the 

 object of rinding ways and means to combat them either through 

 the medium of the State or of the farmer himself. This is a 

 branch of applied biology, which during the last fifteen years has 

 been so much in the foreground. It occupies the attention of 

 practically every South African, since, in this sub-continent, 

 stock-raising forms the main occupation of the majority of the 

 population; it has forcibly been brought home through the 

 invasion of the country by some of the most devastating plagues 

 during the last two decades. It is therefore quite natural that I 

 should select my examples amongst those subjects which are 

 most familiar to me, or in which I have personally taken more 

 than a casual interest. Let me tell you first of all that it is a 

 mistake to think that South Africa alone is the country to which 

 the picture of the ten plagues of Egypt applies ; it is a calumny 

 to say that there are more diseases in this sub-continent than 

 anywhere else in the world ; in fact, this country has not one 

 specific disease of its own of any importance. From an epizoo- 

 logical point of view South Africa must only be considered to be 

 a portion of the proverbial dark continent, and although con- 

 siderable light has been thrown on many of the older diseases, 

 there are still some in comparative darkness at the present time. 

 The opening up of this continent, chiefly commencing from the 

 South, brought the white man into touch with the existing 

 diseases ; owing to the geographical situation and ethnographical 

 separation these maladies had hitherto been confined in patches, 

 or. as a result of the survival of the fittest, they had created 

 classes of animals immune against them. The advance of civilisa- 

 tion meant removal of such barriers, and the introduction of 

 animals not immune to these diseases caused recrudescences. 

 The true explanation is that the great majority of these maladies 

 were not previously known to science, and it was only through 

 research work in South Africa that the greater number of them 

 were described. Since those days they have been found in other 

 parts of Africa. For instance, horse-sickness is found all along 

 the East Coast, in Central Africa, and along the shores of the 

 Red Sea. Quite recently, through the kindness of the Bacteri- 

 ologist of the Italian Colony of Erithrea. a sample of virus was 

 sent to me with which I produced the horse-sickness that is so 

 familiar to us all. Red water is known throughout the whole 

 continent. East Coast fever has been described in some of the 

 countries bordering the [Mediterranean. They were there all the 

 time, and it was only since these diseases formed the subjects of 

 thorough investigation in South Africa that attention was drawn 

 to them in the countries so close to Europe. Although in this 

 end of Africa much mystery and even a great amount of super- 

 stition was at one time connected with them a large amount of 

 valuable observations had been collected bv our farmers before 



