Experiment No. 1. Typhoid Fever and Fly.—The fly was placed under 
the bell-jar with filter paper saturated with fresh boullion culture of B. 
typhi abdom., twenty-four hours old. The fly was closely watched, and 
after he had been observed to walk over the filter paper several times, the 
bell-jar was carefully moved from the filter paper. After twenty minutes 
had passed, a Petri plate containing a thin film of sterile agar was placed 
under the jar, and the fly again watched. He did not seem to be attracted 
to the agar, and after waiting perhaps half an hour, it was decided to 
force the fly to walk over the agar film. So he was carefully caught be- 
tween the agar film and the Petri dish cover, and he then walked over the 
agar beautifully. The agar plate was incubated for twenty-four hours 
and the result was very significant. It is shown on plate No. 1, on which 
the clearly defined fly path, marked by bacteria colonies, is clearly shown. 
A further examination determined the presence in these colonies of the 
typhoid bacilli. 
Experiment No. 2.—A similar experiment with some filter paper, sat- 
urated with typhoid fever, using another fly, somewhat less time elapsing 
between his inoculation, and being made to walk over the agar. This fly 
did not enjoy walking on the agar and jumped around over the plate con- 
siderably, as shown by the large number of colonies; plate II. Once or 
twice he made a fairly straight track, however, as may be seen. These 
colonies were also proved to contain typhoid fever. 
Experiment No. 3. Prodigiosus.—Large fly. After one-half hour 
walked over gelatine; too lively to make tracks; infected whole plate; 
plate III. 
Experiment No. 4. Prodigiosus.—Ily’s wings removed, and then he 
was allowed to walk over infected paper and agar plate; plate IV. 
Experiment No. 5. Prodigiosus.—After eighteen hours fly, that had 
been infected with prodigiosus, was allowed to walk over plate; plate V. 
CONCLUSIONS. 
It is evident that the fly can become infected with bacterial filth and 
hold on to it for sufficient time to inoculate food materials or other ma- 
terials surrounding human lives. They must always be regarded as a 
menace to health as long as they have access to filth in the neighborhood 
