EXPERIMENTS WITH BLOOD FROM BIG GAME. 279 



state most emphatically that Where there is no game there is no 

 Nagana, and example after example could be cited of the state- 

 ment that the game having been driven out, the disease dis- 

 appeared, and on the reappearance of the game that the cattle 

 again became sickly. Those who hold the Tsetse-fly theory 

 explain this by affirming that where the big game is there also is 

 the Fly. Others, as mentioned above, are of opinion that the 

 game contaminate the grass and drinking-water and so infect 

 the cattle. 



" That the presence of the wild animals in the vicinity of 

 horses and oxen is not the only factor in the problem is shown 

 by the fact that in the old days when the big game was numerous 

 and roamed over the whole country, hunters and travellers never 

 complained of the Fly until they encountered the disease in low- 

 lying tracts of country, or along the large river valleys ; and at 

 the present day it is stated, on the authority of Mr. L. Peringuey, 

 that in the Hermansdorp District of Cape Colony, where herds of 

 buffalo are still found, the Fly Disease is unknoAvn, nor has the 

 Tsetse-fly itself been ascertained to occur there. Now we know 

 the disease to be caused by a blood parasite, and that the disease 

 can be carried by the Tsetse from affected to healthy animals, we 

 can see how such theories may have some foundation in fact. 



" At first I thought that by a careful microscopical examination 

 of the blood of the big game some light could be thrown on the 

 subject, and to this end I submitted the blood of buffalo, wilde- 

 beeste, koodoo, impala, bush-buck, reed-buck, and the smaller 

 varieties shot in the heart of the Fly Country to a lengthened 

 microscopical examination, but with no result. 



" Thinking, however, that the parasite might exist in too 

 small numbers, as we have seen is frequently the case in cattle, 

 to be readily discovered by direct examination, I next instituted 

 a series of experunents by injecting a moderately large quantity 

 of blood, taken immediately after death, into dogs, as it has been 

 proved by experiment that in cases in which the parasite could 

 not be demonstrated by the microscope, an inoculation experi- 

 ment of this kind readily discovered them. 



" Of course, it was necessary that the dogs used for experi- 

 ment should be kept at the top of the Ubombo, as the results 

 would have been useless if they had been exposed to infection in 

 any other way than by the injection of the blood. 



" This meant a delay of several hours between the procuring 

 of the blood and the injection of it into the dog, as the vi^ild 

 animal might be shot five or ten miles from the foot of the hills, 

 and the Ubombo itself is some 2,000 feet high. 



" Again, it would evidently facilitate matters if the blood 

 could be kept liquid, as the blood coagulum might entangle in 

 itself all the parasites contained in the blood. 



"I therefore made a preliminary experiment to find out if 



