344 TSETSE FLIES 



of the terrible malady in a country where no 

 trace of the Glossina palpalis, the sole known 

 medium of the disease's transmission, could be 

 found. The attention of these experts was first 

 attracted to the fact that although the last- 

 named insect was apparently wholly absent, 

 the other commoner member of the family, the 

 transmitter of "fly disease " in cattle, existed in 

 extensive belts. Investigation into the latter 

 insect's habits, peculiarities, and mode of life 

 were then pushed forward, with the somewhat 

 startling result that his responsibility for the 

 conveyance of the newly discovered sleeping 

 sickness parasite was placed beyond doubt. 



Here then was the whole secret ; but with its 

 discovery science found itself confronted by 

 difficulties compared with which those attending 

 the elimination of the disease in Uganda paled 

 into utter insignificance. Here is the reason. 

 Glossina palpalis, the first discovered spreading 

 agency of the parasite of the disease, is an insect 

 to whose existence water in fairly large volumes 

 appears to be necessary. They dwell and pro- 

 pagate upon the shores of lakes, rivers, and 

 fairly large streams. By the removal of human 

 habitations from the vicinity of water, therefore, 

 the destructive activity of this fly is at once 

 checked, and the cases of infection greatly 

 reduced in number. But what preventive 

 measures could be adopted to prevent the spread 

 of sleeping sickness disseminated by the newly 

 discovered medium ? Glossina morsitans appar- 

 ently cares nothing for water. Its myriads 



