AGENTS OF DISEASE 283 



in horses, donkeys, mules, camels, monkeys, 

 and other animals, and are known to be present 

 in the blood of many birds, reptiles, and fishes. 

 The unfortunate human being attacked by this 

 practically fatal disease at first becomes dull, 

 feverish, and apathetic. This is followed by 

 difficulty in speech and locomotion, with tremors 

 of the tongue and outstretched hand, accom- 

 panied by an ever-increasing drowsiness, until 

 at last complete somnolence sets in and the 

 unhappy victim dies in a state of coma. 



Originally peculiar to tropical West Africa, 

 sleeping sickness has spread along the trade 

 routes as they have been opened up, wherever 

 the biting Tsetse-fly, Glossina palpalis, which is 

 the principal if not the only transmitting agent, 

 is present, and has swept onwards in its devas- 

 tating march past the shores of Lake Victoria 

 Nyanza to the confines of the Soudan. Since 

 the disease was first noticed in the west of 

 Uganda in 1901, more than 200,000 people have 

 perished from it. Of 300,000 natives living on 

 the shores and islands of the great and beautiful 

 Lake Victoria Nyanza, less than 100,000 remain, 

 the rest having died from sleeping sickness 

 within the last five or six years. And mark this 

 fact, in every case the disease has been trans- 

 mitted from one victim to another by the blood- 

 sucking fly Glossina palpalis. 



Man is not the only sufferer from serious 

 diseases produced by the presence of these 

 flagellate organisms called trypanosomes, in the 

 blood. Thus the fatal disease called Ngana, 

 which is so widely spread throughout Africa, 



