The House-fly as a Carrier of Disease 
i53 
standard of cleanliness in that locality. Flies caught in a street of 
modem, fairly high class, workmen’s dwellings forming a sanitary 
oasis in the midst of a slum area, carried far less bacteria than those 
caught in the adjacent neighborhood. 
Thus, as the amount of dirt carried by flies in any particular 
locality, measured in the terms of bacteria, bears a definite relation 
to the habits of the people and to the state of the streets, it demon¬ 
strates the necessity of efficient municipal and domestic cleanliness, 
if the food of the inhabitants is to escape pollution, not only with 
harmless but also with occasional pathogenic bacteria. 
The above cited w T ork is of a general nature, but, especially in 
recent years, many attempts have been made to determine more 
specifically the ability of flies to transmit pathogenic organisms. 
The critical reviews of Nuttall and Jepson (1909), Howard (1911), 
and Graham-Smith (1913) should be consulted by the student of 
the subject. We can only cite here a few of the more striking experi¬ 
ments. 
Celli (1888) fed flies on pure cultures of Bacillus typhosus and de¬ 
clared that he was able to recover these organisms from the intestinal 
contents and excrement. 
Firth and Horrocks (1902), cited by Nuttall and Jepson, “kept 
Musca domestica (also bluebottles) in a large box measuring 4x3x3 
feet, with one side made of glass. They were fed on material 
contaminated u r ith cultures of B. typhosus. Agar plates, litmus, 
glucose broth and a sheet of clean paper were at the same time 
exposed in the box. After a few days the plates and broth were 
removed and incubated with a positive result.” Graham-Smith 
(1910) “carried out experiments with large numbers of flies kept 
in gauze cages and fed for eight hours on emulsions of B. typhosus 
in syrup. After that time the infested syrup was removed and the 
flies were fed on plain syrup. B. typhosus was isolated up to 48 
horns (but not later) from emulsions of their feces and from plates 
over w r hich they walked.” 
Several other w r orkers, notably Hamilton (1903), Ficker (1903), 
Bertarelli (1910) Faichnie (1909), and Cochrane (1912), have iso¬ 
lated B. typhosus from “wild” flies, naturally infected. The papers 
of Faichnie and of Cochrane we have not seen, but they are quoted 
in extenso by Graham-Smith (1913). 
On the whole, the evidence is conclusive that typhoid germs not 
only may be accidentally carried on the bodies of house-flies but 
