248 



THE CARRIAGE OF TYPHOID FEVER BY FLIES 



broth. The agar plates and broth were removed after a few days, 

 and after incubation at 37° C. for twenty-four hours colonies of 

 Bacillus typhosus were found on the agar plates, and the bacillus 

 was recovered from the broth. In a further experiment the in- 

 fected material was dusted over with fine earth to represent 

 superficially buried dejecta, and the bacillus was isolated from agar 



Fig. 98. Agar plate culture of tracks ot .1/. ilumestica caught in a room and allowed 

 to walk across and around the medium. Natural size. (Prepared by H. T. 

 Giissow.) 



plates upon which the flies had subsequently walked, as in the 

 former experiment. They also found the bacillus on the heads, 

 wings, legs and bodies of flies which had been allowed to have 

 access to infected material. 



Hamilton (1903) recovered Bacillus typhosus five times in 

 eighteen experiments from flies caught in two imdrained privies. 



