•INFINITE TORMENT OF FLIES' 



Where the wafer is stopped in a stagnant pond, 

 Danced over by the midge. 



R. Browning : ' By the Fireside.' 



The last few years of the nineteenth and the first few 

 years of the present century are marked in the annals 

 of medicine by a great increase in our knowledge of 

 certain parasitic diseases, and, above all, in our know- 

 ledge of the agency by which the parasites causing 

 the diseases are conveyed from host to host. 



Chief among these agencies in carrying the disease- 

 causing organisms from infected to uninfected animals 

 are the insects, and, amongst the insects, above all 

 the flies. Flies — e.g., the common house-fly {Musca 

 domestica) — can carry about with them the bacillus of 

 anthrax, and, if brought into contact with a wounded 

 surface, may thus set up an outbreak of woolsorter's 

 disease. Flies, ants, and other even more objection- 

 able insects, are not only capable of disseminating 

 the plague bacillus from man to man, and from 

 rat to man, but they themselves fall victims to the 

 disease, and perish in great numbers. They are active 

 agents in the spread of cholera, and the histories of the 

 South African and Cuban wars definitely show that 

 flies play a large part in carrying the bacilli of enteric 

 fever from sources of infection to the food of man, 

 thus spreading the disease. They are also accused 

 of conveying the inflammatory matter of Egyptian 



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