J 30 TYPHOID FEVER 



flies were seen through the glass pane to settle on the infected matter and also on the 

 agar plates, the broth and the paper. After a few days the agar plates and tlie broth 

 were removed, incubated at 37° C. for 20 hours and respectively examined and 

 subcultured for the presence of the enteric bacillus. No difhculty was experienced in 

 finding colonies of the Bacillus typhosus on the agar plates and also in recovering it 

 from the exposed broth, in which the flies were seen to walk." 



The paper was covered with fl}--specks, but B. typhosus was 

 not obtained from them. Several somewhat similar experiments 

 were carried out and the writers came to the conclusion that the 

 bacilli adhered to the external parts and did not pass through 

 the alimentary canal. This is probably due to the fact that the 

 'specks' were left for several days before examination, and in 

 consequence the bacilli in them died owing to drying. 



Ficker (1903) carried out a more elaborate series of 

 experiments, keeping various numbers of flies in 10 litre flasks, 

 and allowing them to feed on pure cultures of B. typhosus. 

 After 18 to 24 hours the flies were transferred to clean flasks, 

 and were subsequently transferred to clean flasks every two or 

 three days. Cultures were made from crushed flies at frequent 

 intervals. In his series of experiments B. typhosus was recovered 

 from flies 5 to 23 days after they had been infected. Agglutina- 

 tion tests were made use of to prove the identity of the bacilli 

 isolated. Graham-Smith (1910) carried out experiments with 

 large numbers of flies kept in gauze cages and fed for eight 

 hours on emulsions of i). typhosus in syrup. After that time the 

 infected syrup was removed and the flies were fed on plain 

 syrup. B. typhosus was isolated up to 48 hours (but not later) 

 from emulsions of their fseces and from plates over which they 

 walked. In the latter case infection was largely due to inocula- 

 tion by the flies' proboscides. The bacillus was isolated up to 

 the sixth day from intestinal contents. 



The iso/atiou of B. typhosus from 'zvikV flies. 



Hamilton (1903) seems to have been the first to isolate 

 B. typhosus from five out of eighteen ' wild ' flies in Chicago, 

 caught in two undrained privies, on the walls of houses and in 

 the room of a typhoid patient. She thought that the outbreak, 



