Il6 FATE OF ORGANISMS EATEN BY LARVA 



from larvse infected with B. pyocyaneus under conditions which 

 exclude the chance of re-infection in the pupal or imaginal period 

 undoubtedly remain infected with the bacillus ; (2) in the imago 

 the infection is maximal at emergence and then diminishes 

 suddenly ; (3) the possibility of a dangerously pathogenic 

 organism being taken up by the larva and subsequently dis- 

 tributed by the fly is one which deserves serious consideration." 

 Ledingham (ill. 191 1) made some experiments with pupee 

 sent to him by Bacot, employing another method of disinfection. 



"After washing the pupa; in successive tubes of broth and saline solution, they were 

 transferred to a Petri dish containing a small quantity of absolute alcohol, where they 

 remained for three or four minutes. The alcohol was then ignited and allowed to 

 burn out almost completely. Some of the pupte, as the result of the process, seemed 

 to be slightly desiccated externally. They were then placed in 10 "/o formalin for 

 four to five minutes. Thereafter they were removed one by one to a tube of sterile 

 broth and shaken up. From this tube they were removed to a second broth tube and 

 shaken. Finally from this second tube each pupa was removed to an agar slope and 

 mashed up with a strong platinum loop. The two broth tubes and the series of agar 

 slopes were incubated at 37° C. Next day both the broth tubes were sterile but all 

 the agar slopes showed abundant groivth in ivhich B. pyocyaneus 7L>as present.'' 



Graham-Smith (V, 1911) carried out several series of experi- 

 ments with blow-fly larvae. 



In one series the larvse when seven days old were placed in several tin boxes 

 containing moist earth and allowed to feed on meat infected with {a) a spore-bearing 

 culture oi B. anthracis, (b) B. typhosus, (r) B. enteritidis (Gaertner), {d) B. prodigiosus 

 and [c) V. cholercE derived from cultures respectively. After seven days the remains 

 of the meat were removed, and the larvre fed on fresh meat. At intervals specimens 

 of the larvffi were placed in alcohol for 15 minutes and then passed through the flame 

 and dissected. Cultures from their organs yielded B. anthrads, but none of the 

 other organisms. The flies emerged from the 18th to the 25th days after infection. 

 Each morning the cages in which the pupse had been placed were examined, and the 

 flies which had emerged removed. Some were killed and dissected within a few 

 hours, and others were placed in glass cages and kept alive for various periods of 

 time on syrup. 



" Altogether about 70 flies emerged from larvze fed on meat infected with 

 B. anthracis. Of these, 17 were dissected and cultures made from their organs within 

 a few hours of emerging. From four specimens B. anthracis was not cultivated, but 

 from the other 13 cultures were obtained. It was present in the intestinal contents 

 of 10 ; on one or both wings of 8 ; on one or more legs of 12 ; and on the heads 

 of 8." 



Three specimens were dissected after living two days in a cage. From the legs, 

 wings and intestinal contents of all B. anthracis was obtained. One or more 

 colonies were obtained from the organs of some of the flies up to the 19th day, but 

 not after that time though some of the flies survived up to the 33rd day. Several 

 of the cultures obtained were proved to be virulent. 



