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 (11. 1903) and Ficker (1902) isolated B. 
typhosus from flies caught in houses in which persons 
were lying ill of typhoid fever, and Faichnie (1909) 
