DISTRIBUTION OF BACTERIA IO3 



cultures made from them at intervals. It was found that B. pro- 

 digiosits could no longer be recovered from the dried watery 

 emulsions after 18 hours. They were still present in small 

 numbers in the milk and syrup drops after 28 hours. In the 

 sputum emulsions similarly treated they were present after 

 3 days in considerable numbers. 



{g) The infection of fresh flies from the deposits of 

 infected flies. 



Several experiments were made to ascertain whether clean 

 flies became infected if placed in cages lately occupied by 

 infected flies. For example flies were fed on syrup infected 

 with B. prodigiosHs. One hour after feeding they were trans- 

 ferred to a fresh cage, and allowed to remain there for two hours, 

 and then transferred to a third fresh cage. In the second cage 

 numerous deposits of faeces and vomit were left. Eight clean 

 hungry flies were then put into the second cage, and immediately 

 sucked at the deposits left by the infected flies. After being 

 allowed to remain in the cage for various times these eight flies 

 were dissected and cultures made from their organs, with the 

 following results. 



TABLE 13. Showing the itifection of clean flies from the 

 deposits of infected flies. 



Cultures from 



In infected No. of 



caare for flv 



Legs Wings 



I'S hours 



3"5 



Several experiments of this type were carried out which 

 seem to indicate that clean flies may sometimes infect themselves 

 from the vomit and faeces deposited by infected flies even up to 

 several days after infection. 



