98 



DISTRIBUTION OF BACTERIA 



TABLE 8 {continued). 



Time after Flies 

 infection used 



4 days 



f(l) 

 1(2) 



(2) 



i(3) 



((0 



(2) 



1(3) 



12 

 I^ 



i6 



Legs 



+ (13) 



+ indicates a few colonies of B. prodigiosits, + + several colonies, and +4-4- 

 numerous colonies. The numbers in brackets after the later results indicate the 

 number of colonies found. o = no colonies appeared, - =no cultures made, ...=one 

 fly used. 



It is evident from the above table that B. prodigiosits may 

 remain alive on the legs and wings for at least 18 hours after 

 feeding. Exceptionally it may remain alive longer. It is 

 present, in large numbers, in the contents of the crop and intestine 

 and on the proboscis for four or five days. After this time its 

 numbers gradually diminish, cultures after 17 days yielding 

 negative results. 



(b) Experiments to determine whether B. prodigiosits mitltiplies 



in the crop. 



A fine capillary was drawn out of thermometer tubing and 

 marks scratched on it with a file, one about half an inch and the 

 other about two inches from the end. Flies were fed on a dilute 

 emulsion of B. prodigios/ts. Some of this emulsion was drawn 

 up to the first mark, and water to the second mark to dilute it. 

 The fluids were mixed and the mixture sown on an agar plate. 



