210 ANIMAL LIFE AND HUMAN PEOGRESS 



siderably less than the mortality from such diseases as, say, 

 rinderpest and East Coast fever. And the human mortality, 

 so far as one can ascertain from official statistics, has averaged 

 about 1 in 30,000 during the five years preceding the war. 

 Clearly, therefore, it would be possible to show a higher 

 mortality from other tropical diseases both among natives 

 and among Europeans. 



In 1908 and the two succeeding years cases of sleeping 

 sickness were detected in Rhodesia and Nyasaland. " These 

 cases occurred where the incriminated tsetse-fly of Uganda 

 (Glossina palpalis) could not be the carrier of the disease, and 

 attention was therefore directed to another tsetse-fly [G. morsi- 

 ians), which was abundant in many parts of those countries, 

 which was not limited to the neighbourhood of water, and 

 which might be found wherever there was suitable shade. 

 This discovery led to great apprehension among missionaries 

 and other Europeans in those countries, and in 1911 appeals 

 were made to the Secretary of State for energetic measures 

 to be taken to combat the spread of the disease. As a re.sult 

 the Royal Society, at the request of the Colonial Office, sent 

 out a Commission under Sir David Bruce." ^ 



In 1913 Dr. W. Yorke and Dr. Kinghorn, of the Liverpool 

 School of Tropical Medicine, discovered that the tsetse-fly 

 {Glossina morsitans) of Rhodesia transmitted a trypanosome 

 which produced a very virulent strain of sleeping sickness 

 in man, and held that certain wild animals were in nature 

 infected with the same parasite. These discoveries led to a 

 general revival of the great interest which had previously been 

 taken in tsetse-flies by colonists, zoologists and the members 

 of the medical profession. These, I take it, are the considera- 

 tions which induced the authorities of this University to 

 include the subject of my lecture under the general heading 

 of " Animal Life and Human Progress." 



I will now proceed to define the general characters of a 

 tsetse-fly, and endeavour to show as far as possible how to 

 distinguish it from other members of its class. 



The range of colour and pattern in tsetse-flies is not very 



» Rep. Inter-Depart. Committee on Sleeping Sickness, p. 3 (1914). 



