A CHAPTER ON INSECTS 139 



is a strange mysterious disease characterized, as the 

 disease progresses, by lethargy and a somnolescence 

 which terminates fatally. 



It had long been known on the western coast of 

 Africa, but, in 1901 a virulent outbreak occurred in 

 central Africa, in the Uganda district and along the 

 shores of Lake Victoria Nyanza. The disease killed 

 so many that the British government undertook to 

 investigate the causes of the disease and to seek a 

 remedy. The wide-spread nature of this epidemic in 

 which 200,000 died in one year compelled notice. 

 Colonel Bruce of the British navy, who was expe- 

 rienced in the investigation of infectious diseases, 

 was sent there in 1903 to investigate the conditions 

 and the characteristics of the disease. 



As in the case of malaria and yellow fever it took 

 the highest qualities of scientific observation to 

 discover the particular organism of the disease and 

 to find out the way in which it is transmitted. 

 Colonel Bruce had the problem to work out, of the 

 nature and the mode of infection of sleeping sickness. 

 He determined that as to its nature, it is produced by 

 the presence in the blood and the cerebro-spinal 

 fluid of a cork-screw shaped parasite a minute 

 animal organism somewhat longer than the diameter 



