EXPERIMENTS WITH BACILLUS TYPHOSUS 249 



on the fences of two yards, on the walls of two houses, and in the 

 room of an enteric fever patient. 



Ficker (1903) found that when flies were fed upon typh(jid 

 cultures they could contaminate objects upon which they rested. 

 The typhoid bacilli were present in the head and on the wings and 

 legs of the fly five days after feeding. He also recovered B. ty- 

 jjIiosuh from the flies 23 days after they had been infected. The 

 bacillus was isolated from flies caught in a house in Leipzig, where 

 eight cases of typhoid had occurred. He calls attention to the 

 fact that the value of Celli's conclusions is diminished owing to 

 the fact that at the time the experiments were carried out the 

 differentiation between B. typhosus and organisms of a similar 

 character was hardly possible. 



Buchanan (1907) was unable to recover the bacilli from flies 

 taken from the enteric ward of the Glasgow Fever Hospital. 

 Flies were allowed to walk over a film of typhoid stool and then 

 transferred to the medium (Griinbaum and Hume's modification of 

 MacConkey's medium), and subsequently allowed to walk over 

 a second and a third film of medium. Few typhoid bacilli were 

 recovered and none from the second and third films. 



Sangree (1899) performed somewhat similar experiments to 

 those of Buchanan and recovered various bacilli in the tracks of 

 the flies. This method of transferring the flies immediately from 

 the infected material to the culture plate is not very satisfactory, 

 as I have already pointed out (1908), as it would be necessary for 

 the flies to be very peculiarly constructed not to carry the bacilli. 

 The fly should be allowed some freedom before it has access to the 

 medium to simulate natural conditions. Experiments of this kind 

 were carried out in the summer of 1907 by Dr M. B. Arnold 

 (Superintendent of the Manchester Fever Hospital) and myself 

 Flies were allowed to walk over a film of typhoid stool and 

 then were transferred to a wire cage, where they remained for 

 twenty-four hours with the opportunity of cleaning them- 

 selves, after which they were allowed to walk over the films of 

 media. Although we were unable to recover B. typhosus the 

 presence of B. coli was demonstrated. B. coli was also obtained 

 from flies caught on a public tip upon which the contents of 

 pail-closets had been emptied ; the presence of B. coli, however, 



