NATURAL HISTORY OF SOUTH AFRICA 



for this clrcaria worm. Should the eggs enter the 

 water from the urine or faeces of an infected person 

 or animal, they quickly hatch, and the larvae attack 

 and enter the bodies of these hosts. Here they 

 complete their cycle of development, and when mature 

 leave their lowly host and emerge into the water. 

 Unless able to enter the body of a human being or 

 some other warm-blooded animal, they perish in about 

 thirty-seven hours. So here, once again, we have a 

 valuable ally in the bird. To reduce or eradicate the 

 disease, the intermediary hosts of the worm must be 

 attacked and destroyed. Large numbers of species 

 of birds feed greedily upon fresh water molluscs and 

 other forms of aquatic life. Others devour the winged 

 insects which pass the larval period of their lives in 

 water. In our struggle against this terrible scourge 

 which is prematurely killing off or making physical 

 wrecks of thousands of people, the water-frequenting 

 birds are our greatest allies. 



The microscope reveals the alarming fact that the 

 germs of that terrible disease, sleeping sickness, breed 

 in practically all the larger wild animals. They are 

 immune to sleeping sickness ; but a blood-sucking 

 fly carries the germs from these to both natives and 

 Europeans. The disease has swept off the human 

 populations of entire districts, and it is threatening 

 to make tropical Africa unfit for human habitation. 

 It may be necessary to kill the wild animals, but they 

 are not really guilty. True, they unconsciously carry 

 the germs in their blood, but the arch-criminals are 

 the women who wear the plumes of wild birds in their 



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