114 FATE OF ORGANISMS EATEN BY LARVA 



CHAPTER XI 



THE SURVIV^AL IN THE ADULT FLY OF MICRO-ORGANISMS 

 INGESTED BY THE LARVA 



Faichnie (1909, p. 580) seems to have been the first to 

 suggest that bacteria ingested by the larva might survive the 

 pupal stage and be present in the intestine of the adult. He 

 put forward this hypothesis because, during the investigation 

 of a small outbreak of typhoid at Kamptee, India, he realized 

 that " infection by the excrement of flies bred in an infected 

 material " might explain " many conclusions previously difficult 

 to accept." Shortly afterwards he carried out the following 

 interesting experiments (p, 672). 



"On August i2th, 1909, three ounces of feces, containing B. typJiostis, were 

 thrown into a box of earth and covered with a wire cage, and about 30 flies were let 

 loose inside. These flies all died in a day or two, but on August 26th, 14 days later, 

 one fly hatched ; on August 27th, 12 flies were hatched ; on this same day, after the 

 flies were hatched, the box of earth was replaced by an earthenware plate which had 

 been previously washed in a solution of i in 500 perchloride of mercury ; sugar and 

 water as food in separate porcelain saucers were also introduced, and the wire cover 

 was changed for a bell-shaped mosquito net. On August 26th, one fly, one day old, 

 was transfixed with a red hot needle after chloroforming it, flamed and put into a bottle 

 of sterile salt solution. It was shaken up and i c.c. of the solution put into McConkey 

 broth, which remained unchanged for 48 hours. After this the fly was crushed with 

 a sterile glass rod and a drop plated ; B. typhosus was found." Four other flies one 

 day old gave the same results, and two flies 6 days old and two flies 9 days old also gave 

 the same results. " On September loth two flies 13 days old were put into a dry 

 sterile bottle and left for 24 hours; they were then removed, and some salt solution was 

 poured into the bottle, and from this solution of excrement B. typhosus was obtained." 

 The two flies were treated as the previous ones hatl been and B. typhosus was obtained. 

 From one fly 16 days old and from its excrement B. typhosus was also obtained, but 

 not from another. 



From the foregoing experiment it will be seen that out of 

 the 13 flies bred from a typhoid stool at least 6 contained 

 B. typhosus in their intestines ; and the bacillus was recovered 

 from the intestines and excrement of a fly 16 days old. 



" A second series of experiments was carried out with the 

 faeces of a man suffering from paratyphoid fever (/>. para- 

 typhosus A) the diagnosis having been made b\' a blood culture. 



