94 THE UNIVERSE. 



in the midst of thick smoke. For this purpose they set up 

 regular roosts formed of branches, and suspended above 

 masses of wood which burn perpetually beneath them. 

 Squatted on these they receive their friends during the 

 day, and at night, heated from below and smoked on all 

 sides, they stretch themselves on them in order to sleep. In 

 the Southern United States it is also a common practice to 

 resort to a smoke as a protection against the attacks of 

 gnats and mosquitoes, both in-doors and in the field. 



Some savage races only free themselves from the on- 

 slaughts of this accursed brood by smearing their bodies 

 with a filthy coating of grease; and it is to protect himself 

 against them that the miserable Laplander condemns him- 

 self to be smoked all day long in his dark hut. The com- 

 panions of the astronomer Maupertuis were so tormented by 

 the stings of the mosquitoes during their travels in Lapland 

 that, to free themselves from them, they had recourse to the 

 extreme measure of covering their faces with tar. 



An ordinary -looking fly infesting Africa is still more for- 

 midable : it disputes the soil with us foot by foot ; there is 

 a struggle between man and it as to which shall have pos- 

 session. Where it lives it prevents him from carrying on 

 agriculture, and limits his explorations ; he can only become 

 master of the soil when he has exterminated it. This fly, 

 generally called tsetse by the natives, is shaped like our 

 common species, and seems to all appearance equally in- 

 offensive, but its mouth secretes a venom the activity of 

 which by far surpasses that of the most poisonous serpents. 

 A few stings of the tsetse are enough to kill the strongest 

 ox in a short time ; and yet if we attempted to ascertain 



