Il8 FATE OF ORGANISMS EATEN BY LARVA 



" F'rom the practical point of view the main conclusions to 

 be drawn from the experiments detailed in this communication 

 is that the typhoid bacillus can lead only a very precarious 

 existence in the interior of larvae or pupae which possess, at least 

 in so far as these investigations warrant, a well-defined bacterial 

 flora of their own." 



Nicholls (191 2), working with the larvae of Sarcophagula and 

 Sarcophaga, came to the conclusion that "during development the 

 fly possesses very great powers of destroying micro-organisms" 

 and that " a freshly hatched fly may be considered probably 

 sterile." When breeding larva; of Sarcophagula in faeces infected 

 with B. typhosus he found that these bacilli rapidly disappeared 

 from the larvae if they were removed from their infected 

 surroundings. 



Graham-Smith (1912) carried out a further series of experi- 

 ments, using blow-flies, green-bottles and house-flies. In his 

 previous paper it was pointed out that " possibly they (the 

 bacteria) might be found in flies which emerge from larvae which 

 had fed on the flesh of infected animals." 



Series I. 



" In one series therefore half-grown larvae of C. erythrocephala and L. Ciesar were 

 allowed to feed on the bodies of guinea-pigs which had died from infection with 

 B. enteritidis and B. anthrads. The larvse pupated in lo — 15 days and the flies 

 began to emerge in 20 days. In order to avoid the possibility of the flies re-infecting 

 themselves after emerging the pupie were removed to clean cages and placed on clean 

 sand. In some cases before the preparation of cultures the flies were sterilized in 

 various ways, while in other cases no sterilization of the exterior was attempted. 

 Sometimes the flies were killed shortly after emerging, while on other occasions they 

 were kept for some hours or days. In the latter case they were fed on^yrup. 



" ^. anthracis. — Cultures on agar were prepared in the way previously described 

 (1910) from the intestinal contents of 51 1 flies, 170 C. fiythrocep/iala and 341 L. casar, 

 which emerged from larvae which fed on the body of a guinea-pig dead of anthrax. 

 Only three colonies were met with which resembled in any way those produced by 

 B. anthracis. By subcultures they were proved not to be those of B. anthracis. 



" B. enteritidis. — Cultures on MacConkey's lactose neutral-red agar were made 

 from the intestinal contents of 27 flies, all C. erythrocephala, which emerged from larv£e 

 which had fed on the body of a guinea-pig dead of infection with B. enteritidis. A 

 large number of colonies of non-lactose fermenting organisms developed on the 

 plates ; but although subcultures were made from many no example of B. enteritidis 

 was isolated." 



