12 PRESIDENT S ADDRESS. 



red-water, which, as many of you will remember, was introduced 

 into the Cape Colony many years ago. In those days measures 

 were taken to stop its. spread, but they were of no use, because 

 the cause of the plague was not then known. Only in the 

 beginning of the nineties of the last century it was found in. 

 America that it was due to a parasite which lived in the red 

 corpuscles ; the parasite developed in the body of a tick, and was 

 transmitted by these to new cattle. This was as much an epoch- 

 making discovery as Bruce's, that the trypanosoma disease was 

 carried by winged insects. The statements of the American 

 scientists were subsequently verified in this Colony, and when 

 the attention of South African workers was drawn to the pre- 

 sence of similar parasites in the blood of South African stock 

 suffering from various other ailments, then it was only natural 

 to conclude that in their propagation ticks also must be responsi- 

 ble. The conclusion proved to be correct. It was further 

 proved that there also existed the theoretical reservoir ; it was 

 found that it was the recovered animal itself which remained 

 infected. This fact, so paradoxical as' it appears for healthy 

 animals to spread a disease, explains the permanency of infec- 

 tion on our pasture; although they are immune, they maintain 

 the contamination. The investigations by Lounsbury into 

 heart-water, a disease caused by an invisible organism which at 

 one time rendered the rearing of cattle and small stock almost 

 an impossibility, more particularly in this neighbourhood, proved 

 definitely that also here ticks were responsible. Once these 

 facts were well established, it was a natural conclusion to expect 

 that the destruction of the ticks would mean the eradication of 

 the disease, just as the destruction of mosquitoes meant the 

 disappearance of malaria. This conclusion at one time had only 

 appealed to a limited number of farmers, and it is even at the 

 present time not sufficiently appreciated. Perhaps it is not 

 scientific enough, or there is not enough mystery about it. When 

 the terrible disease. East Coast fever, was introduced into 

 Smith Africa, the presence of a parasite found in the blood 

 corpuscles was soon recognised, and the conclusions had to be 

 drawn that here again ticks were responsible. This also proved 

 correct. After the species of tick which transmitted the disease 

 had been traced, and their life-history was fully understood, 

 and once it had been realised that in this disease, unlike the 

 others caused by intracellular parasite, the immune animal did 

 not represent the reservoir for the virus, it became possible to 

 successfully combat it. In the course of time the most powerful 

 remedy proved to be the dipping tank, which was deciedly the 

 salvation of the Xatal farmer, all other methods of stopping 

 the spread in that Colony having failed. For the destruction 

 of the ticks as the root of many evils in stock, the dipping tank 

 must be considered to be the best and most practical means, 

 and its introduction into South Africa is a great scientific 

 attainment The first man to make continuous use of it was the 



