4OO 



ELEMENTARY BIOLOGY 



exposed in groceries, meat shops, kitchens, restaurants, dining 

 rooms, or picnic grounds. Flies will visit open wounds or sores 

 on the bodies of animals, and they will visit the excrements of 

 man and other animals. We may thus see what excellent 

 opportunities this animal has not only to collect a varied 

 assortment of bacteria but also to distribute them widely. 



FIG. 206. A breeding place for house flies 



The community that saves itself money or trouble by permitting back yards of this kind 

 usually pays for its economy and indifference with disease and death. With the econo- 

 mies of motor cars and traction engines must be reckoned the reduction in typhoid 

 fever and other fly-borne diseases 



From a report made by an army commission as to the causes of 

 epidemic fevers in the army camps during the Spanish-American War, 

 we learn that " flies swarmed over infected fecal matter in the pits 

 and fed upon the food prepared for the soldiers in the mess tents. 

 In some instances where lime had recently been sprinkled over the 

 contents of the pits, flies with their feet whitened with lime were 

 seen walking over the food." We can readily understand why it 

 was that more soldiers were killed by intestinal diseases than by 

 Spanish bullets. 



