FATE OF ORGANISMS EATEN BY LARVA II7 



"A few other experiments were carried out with these flies. Four flies were 

 allowed to walk over agar plates a few hours after emerging. Numerous colonies 

 of B. anthracis developed on these plates. 



" Twelve flies a few hours old were kept in a glass cage and fed on syrup. Shortly 

 after their first meal some of the remains of the syrup on which they had been feeding 

 was smear-ed on the surface of agar plates. Numerous colonies of B. anthracis 

 developed on these plates. Nearly every fly very shortly after emerging deposited a 

 large quantity of whitish, semi-fluid material. Cultures made from this material were 

 negative. The faeces deposited by flies two days old contained B. anth-acis in 

 considerable numbers, as also did the remains of syrup on which they had fed. 



"j9. anthracis was not found in cultures made from the fneces of flies 22 and 

 23 days old, nor in those made from the remains of syrup on which they had been 

 feeding, but a single colony of B. atithracis was obtained from the remains of syrup 

 on which flies 21 days old had fed." 



The experiments with the flies bred from larvae fed on B. typhosus (45 flies), 

 B. enteritidis (14 flies), B. prodigiosus (25 flies) and V. choleric (20 flies) were entirely 

 negative. 



Two other series of experiments with these organisms were 

 also negative, and the writer came to the conclusion that " these 

 experiments seem to indicate that, under the conditions described, 

 none of the non-spore-bearing organisms mentioned commonly 

 survive sufficiently long to be found in the blow-flies which 

 emerge from infected larvae." 



Ledingham (x. 191 1) in several series of experiments found 

 that " although typhoid bacilli were liberally supplied to larvje 

 of MiLsca doniestica, all attempts to demonstrate B. typhosus in 

 the pupae or imagines were unsuccessful until recourse was had 

 to disinfection of the ova." 



In one of his experiments the eggs were thoroughly disinfected by a short sojourn 

 in lysol. The young larvae were placed on a sterile agar slope, which remained 

 sterile. "Human blood mixed with typhoid bacilli was spread on the agar and this 

 process was repeated, the larvre being transferred to a fresh agar slope with blood 

 every day." Under these highly artificial conditions B. typhosus was isolated from 

 the larvce and from one pupa. No imago was obtained. 



" In the experiments with unsterilized ova great difficulty 

 was experienced in determining whether B. typhosus was present 

 in MacConkey plates owing to the almost invariable occurrence 

 of the colourless typhoid-like colonies of Bacillus ' A^ ' which 

 was evidently an organism thoroughly adapted to the conditions 

 prevailing in the interior of the larvae, pupae and imagines." 



1 This organism appears to be identical with one, Ca. 8, commonly found in adult 

 flies (see Chap. xiv). 



