DISTRIBUTION OF BACTERIA IO5 



TABLE 14. S/ioii'ing the results of cultures made froui fluid 

 and partially dried milk on zuhicli flies infected ivith B. pro- 

 digiosus had been allcnved to feed. 



In other series of experiments with large numbers of flies 

 infection of the milk was obtained in the case of B. prodigiosus 

 and the spores oi B. anthracis up to the i ith day. 



All the experiments done show that artificially infected flies 

 {M. domestical, kept in captivity, may contaminate milk on which 

 they feed for several days. 



Experiments zuitJi blowflies {C. erythrocephala). 



Several experiments were also carried out with blow-flies 

 {^C. erythrocephala)., of which one is quoted. 



About 20 blow-flies were confined in each of four cages, the 

 flies in two of the cages being infected by feeding on an emulsion 

 of B . prodigiosus in syrup, and those in the other two cages being 

 similarly infected by feeding on an emulsion oi B. pyocyaneus. 



In each instance the emulsion was placed in a watch-glass, 

 and a short distance above it was fixed a piece of zinc pierced 

 with round perforations about three-sixteenths of an inch in dia- 

 meter. Through these perforations the flies put their proboscides 

 and drank the fluid, and occasionally, though rarely, soiled their 

 legs by putting them through. It was, however, impossible for 

 them to fall into the fluid. It was noticed that, after feeding, 

 they not infrequently deposited vomit on the zinc, and no doubt 

 sometimes infected their feet and wings by walking and falling 

 into it. They also infected their limbs by contact with their pro- 

 boscides by cleaning them (p. 107). The two sets of flies infected 

 with /). prodigiosus and the two sets infected with B. pyoeyaneus 

 were fed daily through sterilized perforated zinc trays on syrup 

 and sterilized milk respectivel}', and cultures were made from 

 the remains of these fluids. The results of these experiments 

 are given in Table 15. 



