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Photo by N. A. Cobb Copyright, 1910, by the National Geographic Magazine 



FEMALE HOUSE-FLY RESTING ON GLASS AND SEEN FROM ABOVE 



The house-fly swallows many kinds of germs and spores, and deposits them all day long 

 at mtervals of a few mmutes in its excreta, the "fly specks." Thc^se germs and spores pass 

 through the fly m less than an hour, and come out in the fly specks alive and uninjured, 

 lilies spread more germs in this way than in any other. The house-fly sticks close to man 

 and IS a dangerous agent m the spread of human diseases. Diseases of animals and plants 

 are spread m the same way. The hairs on the back of a fly are not a haphazard arrangement, 

 but correspond m number and location on all house-flies. 



