122 FATE OF ORGANISMS EATEN BY LARVA 



which develop from larvae infected with the spores of B. antJiracis 

 are infected. 



(3) " Of non-spore producing organisms only those which 

 are adapted to the conditions prevailing in the intestine of the 

 larva, such as Morgan's bacillus and certain non-lactose fermenting 

 bacilli, survive through the metamorphosis and are present in 

 the flies. Organisms such as B. typhosus, B. enteritidis, and 

 B. prodigiosiis rarely survive." 



Tebbutt (191 3) carried out experiments in the following way. 



" Ova of M. domestica were placed upon agar slopes to which a little fresh human 

 blood was added together with the organisms with which the young larvae were to be 

 infected. Sometimes the ova were sterilized by washing in 3 % lysol for two or three 

 minutes. Larvae when full-grown were placed on sterile sand to pupate and the 

 pupae were stored in sterile test-tubes till they were examined or till imagines 

 emerged. The method of examining the pupae was that described by Ledingham 

 (191 1), the blunt end being seared with a hot iron, a capillary pipette inserted and 

 the contents sucked out and plated on MacConkey's neutral red lactose agar. 



" The imagines were examined either as soon as they were first noticed or after 

 feeding on sterile sugar-cane solution. The method used was to wash them separately 

 in 2 "/„ lysol for seven to ten minutes, then in two or three successive tubes of broth, 

 after which each was crushed in a small amount of broth and the latter plated out on 

 several MacConkey lactose plates, so that the whole of each imago was bacteriologically 

 examined. The broths used to wash the fly were also incubated in order to detect 

 bacteria on the external surface, and subcultures were made from the last broth in 

 which the fly was washed before being crushed and plated. 



" The ova, larvK, pupae and imagines were kept throughout at a temperature 

 of 25° C." 



With regard to the bacteria met with and employeci in this 

 research a few comments are necessary. The principal patho- 

 genic organism on which larvae were fed was one of the mannite 

 types of the dysentery bacillus, viz. Bac. ' Y ' of Hiss and 

 Russell. 



Tebbutt (p. 525) came to the following conclusions : 

 (i) " Pathogenic organisms such as B. dysenteri<£ (type 'Y') 

 cannot be recovered from pupae or imagines reared from larvae 

 to which these organisms have been administered. 



(2) " When the larvae have been bred from disinfected ova 

 and are subsequently fed on B. dyseiiteri(E (type ' Y '), this 

 organism may be successfully recovered from the pupae and 

 imagines in a small number of cases. 



(3) " Under similar conditions B. typhosus was not recovered 

 in a single case from pupa: or imagines. 



