104 THE HOUSE FLY DISEASE CARRIER 



fects of contaminating with non-pathogenic and putre- 

 factive bacteria have as yet not been studied, and the 

 effects of season, temperature, atmospheric conditions, 

 different diets, irregular and scanty feeding, and other 

 disturbing factors have not received sufficient attention. 



"Consequently it would be premature to conclude 

 that the experiments and observations described in this 

 paper do more than indicate that, under exceptionally 

 favorable conditions, certain bacteria can be recovered 

 from the contents of the alimentary canal and fecal 

 deposits of infected flies for several days after infec- 

 tion; and that these flies are capable of infecting cer- 

 tain materials on which they feed for several days. The 

 experiments with tubercular sputum and anthracic 

 blood alone afford evidence as to the duration of life 

 in the contents of the alimentary canal of pathogenic 

 bacteria taken up under natural conditions. 



'That flies sometimes do become grossly infected 

 under natural conditions is shown by the fact that in 

 a few instances pathogenic bacteria have been isolated 

 from naturally infected flies. Simmons (1892) iso- 

 lated cholera vibrios from flies which were captured 

 in a post-mortem room in which the bodies of persons 

 dead of cholera were lying. Tsuzuki (1904) was able 

 to cultivate the same organism from flies captured in 

 a cholera house, and Tizzoni and Cattani (1886) ob- 

 tained cultures from flies caught in cholera wards. 

 Hamilton (n. 1903) and Picker (1902) isolated B. 

 typhosus from flies caught in houses in which persons 

 were lying ill of typhoid fever, and Faichnie (1909) 



