126 THE HOUSE FLY— DISEASE CARRIER 



third experiment the infected flies were captured and 

 killed. By means of sterile' forceps their heads, wings, 

 legs, and bodies were separated and respectively placed 

 in sterile broth. Sub-cultures of the broth all gave a 

 positive result. The authors conclude that M. domes- 

 tica can convey B. typhosus from infected sources to 

 objects upon which they walk, rest, or feed, and that 

 bacilli adhere to the external parts of flies. Tt has not 

 been proved that the enteric bacillus passes through the 

 digestive tract of the fly.' 



"Hamilton (II. 1903) in Chicago, caught eighteen 

 flies in and about houses and rooms occupied by ty- 

 phoid cases, and states that she found B. typhosus in 

 five of them. 



"Ficker (1903) caught flies in a house in Leipzig 

 where eight cases of typhoid had occurred. He isolated 

 B. typhosus from the flies. He carried out experiments 

 with M. domestica kept in ten-liter flasks into which he 

 introduced some sugar, strips of filter paper, and cul- 

 ture of typhoid bacilli in bouillon. This was spread 

 on the glass and partly absorbed by the filter paper. 

 After eighteen to twenty-four hours the flies were trans- 

 ferred to clean flasks. He found the flies to survive 

 over four weeks in captivity if protected from the cold 

 and fed on sugar, bread and water, or milk. He notes 

 that flies may all die during a cold night, irrespective 

 of typhoid bacilli being present in their food. The 

 flies were transferred to clean flasks every two or three 

 days. The flies to be examined were etherized and 

 rubbed up in a mortar — the crushed material being 



