i6 4 'INFINITE TORMENT OF FLIES' 



presence of the parasite of yellow fever. By its works 

 alone can it be judged. It seems that, like the germ 

 of rinderpest and of foot-and-mouth disease, it is ultra- 

 microscopic, and our highest lenses fail to resolve it. 

 From the course of the disease and the nature of its 

 host, it will probably prove to be something like the 

 organism which causes malaria. The means of 

 warring against Anopheles and Culex are equally 

 applicable in the case of Stegomyia, but, since the 

 last-named flies by day, they are more difficult to 

 carry out, and more irksome to endure. By the in- 

 telligent application of these preventive measures the 

 Americans have freed Havana for the first time from 

 yellow fever, and have materially reduced the amount 

 of malaria, and they have been equally successful at 

 Panama. 



King Solomon sent to Tarshish for gold and silver, 

 ivory, and apes and peacocks, and at the present day 

 people mostly go to Africa for gold, diamonds, ivory, 

 and game. These are the baits that draw them in. 

 Of the great obstacles, however, which have for 

 generations succeeded in keeping that great continent, 

 except at the fringes, comparatively free from immi- 

 grants, three and these by no means the least im- 

 portant are insignificant members of the order 

 Diptera. We have considered the case of Culex and 

 Anopheles; the third fly we have now to do with is 

 the tsetse fly (Glossina), which communicates fatal 

 diseases to man and to cattle and domesticated animals 

 of all kinds. 



There are at least seven species of the genus which 

 received its name as long ago as 1830, when Wiede- 

 mann first described it. Perhaps the best known 

 species is Glossina morsitans, which was named by 

 Westwood. 



The members of the genus Glossina are unattractive 

 insects, a little larger than our common house-fly, 



