1904.] on Sleeping Sickness in Uganda. 516 



auy manifest symptoms of the disease. This seems to be an 

 imjjortant point, because if this trypanosome is in reality the cause 

 of sleeping sickness, a certain proportion of the natives inhabiting 

 the sleeping sickness area ought to harbour these parasites in their 

 blood. On the other hand, if this parasite is the true cause of 

 this disease, then no native living in a non-sleeping sickness area 

 ought to harbour a single trypanosome in his blood. It will, there- 

 fore, be interesting to examine the blood of natives in the sleeping 

 sickness area and the non-sleeping sickness area of Uganda. 

 Further, it will act as a check if we examine natives living in a 

 non-sleeping area, say in Nairobi, in British East Africa, which is 

 some hundreds of miles away from any infected place. 



Eighty natives from tlie sleeping sickness area were examined, with 

 the result that twenty-three were found to have trypanosomes in 

 their blood, giving a percentage of 28*7. One hundred and seven- 

 teen were examined from non-sleeping sickness areas, but not a single 

 trypanosome was found. 



You will all agree with me that these results make it very highly 

 probable that the trypanosome under discussion is the real cause of 

 this disease ; but there are other methods of adding to this proof, fur 

 example, by experiments on animals. If this trypanosome gives rise 

 to symptoms of sleeping sickness in one of the lower animals, this 

 will be a great addition to the proof that this parasite is the cause of 

 sleeping sickness. 



The best animals procurable in Entebbe for the purpose of animal 

 experimentation are monkeys. The infective material is injected 

 under the skin, into the spinal canal, and also into the cavity of the 

 brain. The animals show no symptoms for a long time ; their tem- 

 perature remains absolutely normal, and they appear to be in perfect 

 health, but after some months fever of an irregular type sets in and 

 the animals begin to show symptoms of lethargy, sitting about all 

 day, and taking very little interest in their surroundings. Towards 

 the end they sit all day long with their heads bent on their chests, 

 apparently asleep, and show a strong resemblance to the later 

 symptoms of the disease in man. 



During this time the monkeys show, constantly, trypanosomes in 

 their blood, sometimes in fairly large numbers. 



Therefore it is shown that the trypanosomes derived from cases 

 of sleeping sickness give rise to a long chronic disease in the monkey 

 with symptoms closely resembling those seen in man. From these 

 animal experiments, taken in connection with the other observations, 

 we may now assert that these trypanosomes are the cause of sleeping 

 sickness. 



I now pass on to the " distribution of sleeping sickness in 

 Uganda." 



This has been investigated by Dr. Hodges, one of the Uganua 

 Colonial Surgeons, and he has prepared this map (Pig. 5), which dis- 

 closes a remarkable fact. Sleeping sickness is found to have a very 



