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XX. On the Persistence of Bacilli in the Gut of an Insect 
during Metamorphosis, By A. Bacort, F.ES. 
[Read March 1st, 1911.] 
In the course of some research work I am conducting, the 
possibility of a Bacillary infection of the larval gut of an 
insect persisting through the period of metamorphosis and 
continuing in the adult after emergence from the pupae is 
of considerable importance. I therefore infected the food 
of some newly hatched larvae of Musca domestica with a 
culture of Bacillus pyocyaneus. Puparia from this brood 
were sterilised outwardly by placing them in 5 per cent. to 
10 per cent. solutions of lysol for five or ten minutes, then 
washing them in sterilised distilled water and transferring 
to tubes of sterile broth. They were allowed to remain in 
the tubes of broth for varying periods, and were then 
removed to a second tube of sterile broth and torn open 
with sterile needles. The first tube formed the control, 
the second the culture tube. Other puparia were passed 
five or six times through the flame of a Bunsen burner, 
and then treated in the same manner as the first batch. 
Growths of pyocyaneus were obtained in all the culture 
tubes and in some instances from the controls as well; 
these latter being cases in which the puparia had been 
allowed to remain in the control tubes for periods of eight 
or twelve hours. Adult flies that had been reared from 
infected puparia which had been sterilised as _ before 
mentioned, were again sterilised after their emergence, 
and when experimented with also gave positive results 
A specimen that emerged from its puparia whilst under 
observation was used after sterilisation with the same 
result, only that it gave much quicker and _ stronger 
growth, presumably because it had not been able to void 
the contents of the gut, which is the usual habit shortly 
after emergence. 
These results, which have since been confirmed by 
Dr. Ledingham of the Lister Institute, seem to prove 
TRANS. ENT, SOC. LOND. 1911.—Part 11. (octT.) 
