SLEEPING-SICKNESS 169 



the disease has spread. In their bodies the harmful 

 effect of the parasite has through countless genera- 

 tions become attenuated, but it leaps into full activity 

 again as soon as the Trypanosoma wins its way into 

 the body of any introduced cattle, horse, or domesti- 

 cated animal. Whether the Trypanosoma does any 

 harm to the fly, or whether it passes through any 

 stages of its life-history in the body of the fly, is 

 still a debatable point. Possibly it does not, and the 

 proboscis of the fly acts then simply as an inoculating 

 needle. 



The Report of Colonel Bruce, which was issued 

 three years ago, shows that the sleeping-sickness 

 which devastates Central Africa, from the West Coast 

 to the East, is also conveyed by a species of tsetse 

 fly. Writing over a hundred years ago of Sierra 

 Leone, Winterbottom mentions the disease. ' The 

 Africans,' he says, ' are very subject to a species of 

 lethargy which they are very much afraid of, as it 

 proves fatal in every instance.' Early last century it 

 was recorded in Brazil and the West Indies ; and in 

 all probability the deaths which our slave-owning 

 ancestors used to attribute to a severe form of home- 

 sickness, or even to a broken heart, were in reality 

 caused by sleeping-sickness. The severity of the 

 disease, which always terminates fatally, is shown by 

 the fact that in a single island — Buvuma — the popula- 

 tion has recently been reduced by it from 22,000 to 

 8,000, whilst whole districts have been almost depopu- 

 lated. In one year the deaths in the region of Busoga 

 reached a total of 20,000; and it is calculated that 

 although the disease was only noticed in Uganda for 

 the first time in 1901, that by the middle of 1904 100,000 

 people have been killed by it. The disease is caused 

 by the presence of a second species of Trypanosoma 

 in the blood and in the cerebro-spinal fluid. The 

 existence of this parasite has now been proved in all 



