344 CARRIERS OF DISEASE 



called " contagious." The numerous animals which sur- 

 round and are associated with man act very largely as 

 casual carriers and distributors of disease microbes. Thus 

 dogs and even the cleanly cat are frequently carriers of 

 disease. But more especially those creatures which visit 

 man's food stores and food ready for consumption (such 

 as bread, fruits, cold meat, etc.) are active carriers. Rats 

 and mice run over such stores and pollute them. But 

 the most widely active in this way is the common 

 house-fly. 



Whilst white men have developed an almost automatic 

 resistance and objection to the visits of flies to their lips, 

 eyelids, and any wound or scratch of the skin a resistance 

 which is not shown by many savage races they yet allow 

 house-flies to swarm in their dwellings, to run about and 

 sample their food, with an indifference which is, when the 

 truth is known, truly horrible in its fatuity and foolhardi- 

 ness. For the fact is that the feet and proboscis of the 

 common house-fly are covered with microbes of all sorts, 

 picked up by his explorations upon every kind of filth. 

 At every step which he takes he plants a few dozen 

 microbes, which include those of infantile diarrhoea, typhoid, 

 and other prevalent diseases. This is easily shown by 

 allowing him to walk over a smooth plate of sterilised 

 nutritive gelatine and preserving it afterwards free from 

 the access of microbes from the air. In twenty-four hours 

 every footstep of the fly on the gelatine is marked by an 

 abundant and varied crop of microbes, which have multi- 

 plied from the individuals let drop by the little pedestrian. 

 There is no doubt whatever that the house-fly is a main 

 source of the dissemination of the microbe of infantile 

 diarrhoea, and the cause annually of hundreds of thousands 

 of deaths of children in the great cities of Europe and 

 America, Also in camps and infected districts he is 

 largely responsible for the introduction of the microbe of 



