106 



THE UNIVERSE. 



only requires a few of its stings to overwhelm the strong- 

 est ox; and yet if we attempted to ascertain the weight 

 of its deadly agent by means of the most delicate balance, 

 it is so small that we should perhaps find the calculation 

 impossible. 



It is an inexplicable anomaly that this fly, which inevi- 

 tably kills certain animals, does not injure others. It 

 selects all its victims from our cattle; the goat and the 

 ass alone defy its sting. Nor do its attacks i:»roduce any 



54. The Tsetse Fly, natural size and magnified. 



effect upon man and wild animals. But what is still more 

 singular, this dipterous insect kills the adult animal, but 

 sucks the blood of its offspring without doing any mischief 

 The tsetse quickly poisons cattle, but produces no effect 

 upon the calf Livingstone says that during his wander- 

 ings his children were frequently stung by it, Avithout ever 

 suffering in the least degree; in fact, they paid no atten- 

 tion to it; whilst the deadly fly killed forty-three oxen 

 in spite of the strictest Avatch. 



The tsetse infests both banks of the Zambesi, and moves 



