THE SITUTUNGA AND SLEEPING SICKNESS 29 



from infection, for as many as 5,765 failed to cause infec- 

 tion in a monkey. In 1914, however, I frequently saw 

 footprints of Enjobe on the island, which had presumably 

 swum across the narrow channel between Nsadzi and the 

 large isle Kome to the east where Enjobe abound. The 

 flies were again tested and found to be infected, for after 

 2,076 had fed upon a monkey it showed the Trypanosome 

 in its blood. ^ Less than half the number of flies that 

 did not produce an infection in 1911 produced an infec- 

 tion in 1914, and this is associated with the arrival of 

 the buck in the continued absence of the population. 



It seems hardly possible to entertain the idea of de- 

 stroying the Enjobe, since when hard pressed it takes 

 refuge in dense papyrus swamps, and even if it could once 

 be eliminated from the islands would soon find its way 

 back by swimming from the mainland, and would resume 

 its former relations with the native. Is it, then, possible 

 to eliminate the fly ? 



On this question I shall have something to say in 

 the chapter devoted to the natural history of Glossina 

 palpalis. 



^ Reports of the Sleeping Sickness Commission, No. xvii, 1919, p. 71-74. 



