CARRIAGE OF DISEASE 
105 
obtained B. typhosus from a number of flies caught in 
various places where typhoid fever prevailed. He 
further showed that B. typhosus or B. paratyphosus 
(A) could be cultivated for several days from the in¬ 
testines of perfect insects which emerged from larvae 
fed on feces containing these organisms. 
“Several observers [Celli (1888), Hayward (1904), 
Lord (1904) and Buchanan (1907)] have shown that 
the feces of flies which have fed on tubercular sputa 
contain virulent tubercle bacilli. Buchanan (1907) 
demonstrated that flies which had walked over nat¬ 
urally infected anthracic meat were capable of infect¬ 
ing agar plates. Yersin (1894) in Hong-Kong ob¬ 
served many dead flies lying about in his laboratory 
where he made autopsies on plague animals. He dem¬ 
onstrated by inoculation into animals that a dead fly 
contained virulent plague bacilli. 
“Finally the experiments of Macrae (1894) at the 
Gaja jail show that exposed milk may become infected 
by the agency of flies. 
“Even these observations only prove that cultures 
of pathogenic organisms may occasionally be obtained 
from naturally infected flies, and they do not afford 
conclusive evidence that such flies are a frequent source 
of disease in man by infecting food materials. Though 
many of the observations cited by Nuttall and Jepson 
seem to indicate that flies have frequently acted as car¬ 
riers of disease, it has only once (Macrae) been dem¬ 
onstrated that food has actually been grossly contam¬ 
inated by them.” 
