DISTRIBUTION OF BACTERIA IO9 



Sujtimary of experiments with B. prodigiosus. 



The experiments which have been carried out in relation to 

 the period during which B. prodigiosus remains ahve on the legs 

 and wings and in the crops and intestinal contents of infected 

 flies, on the infection of sugar and agar plates by living flies, and 

 on the time during which infected material may be deposited, 

 are sufficiently numerous and conclusive to allow of definite 

 statements being made on these points. 



B. prodigiosus may be cultivated from the legs and wings of 

 infected flies for 18 hours (and occasionally longer) after infection. 

 It can be cultivated from the contents of the crop and intestine 

 in large numbers up to 4 or 5 days, and has been found surviving 

 in the intestine up to 18 days. There is no evidence to show 

 that B. prodigiosus multiplies in the crop. Flies allowed to walk 

 over agar plates are capable of infecting them (probably by 

 means of material regurgitated through their proboscides) for at 

 least 7 days. They are capable of infecting sugar for at least 

 2 days. Contaminated faeces may be deposited during several 

 days after infection, the periods varying with the kind of food. 

 Flies fed on milk deposited infected freces during 7 days, those 

 fed on syrup during 4 days, and those fed on sputum for 2 days. 

 Clean flies may infect themselves by feeding on the deposits left 

 by infected flies, especially if the latter have been freshly passed 

 shortly after infection. Milk seems to be frequently contamin- 

 ated by infected flies whether they merely drink it or fall into 

 it. In the single experiment which was tried, flies which walked 

 and fed on meat did not infect it. Fossihly B. prodigiosus is not 

 a suitable organism for the last experiment. 



