FATE OF ORGANISMS EATEN BY LARVA II9 



These experiments confirm the results previously obtained 

 and indicate that non-spore-bearing organisms, not accustomed 

 to the conditions prevailing in the intestine of the larva, do not 

 commonly survive even when the larvai feed on the bodies of 

 animals which have died as the result of infection from such 

 organisms. The results obtained from the spore-free forms of 

 B. antJivacis are in remarkable contrast with the previous 

 experiments with spore-bearing forms (see p. 116). 



In two other series of experiments the larvee of M. doviestica 

 were used. 



Series II. 



" In this series house-flies, M. domestica, were allowed to deposit eggs on food 

 consisting of a mixture of boiled meat, potato, and rice. The larvne which emerged 

 were kept in clean card cream boxes containing clean sterile sand. About three days 

 after hatching, batches of the larva; were transferred to six fresh boxes and fed on 

 similar food infected with pure cultures of vaiuous organisms. The food in one box 

 was not infected. That in the second box was infected with B. prodigiosus, that in 

 the third with a coccus producing pink colonies, that in the fourth with Morgan's 

 bacillus, that in the fifth with B. enteritidis and that in the sixth with B. anthracis. 



" After a day or two the surface of the food became dry, but the larvre lived and 

 fed on the moist part below, as they do under natural conditions. The boxes were 

 inspected daily and as pups; developed they were transferred to fresh boxes, so that 

 the flies on emerging should not become contaminated by crawling over the infected 

 materials. Some of the pupffi were examined by cultures. The end of the pupa was 

 sterilized by the application of a cautery, and the contents were removed by means 

 of a fine pipette through the sterilized surface. After emulsification in salt solution, 

 agar and MacConkey plates were sown. The former usually showed large numbers 

 of colonies of cocci and other organisms, and the latter colonies of lactose fermenting 

 and non-fermenting bacilli. Nineteen pupae from the non-infected box were examined. 

 In four non-lactose fermenting bacilli were met with. Of these a large number were 

 isolated and examined and one turned out to be an example of Morgan's bacillus. 

 In cultures made from fifteen pupae which had developed from larvae infected with 

 the coccus one colony of the coccus occurred. Cultures made from eleven pupae which 

 developed from larvae infected with B. prodigiosus yielded no colonies of that 

 organism. 



" From each box a large number of flies emerged. Cultures were made from the 

 intestinal contents of these, usually within a few hours after hatching. In some cases 

 the exterior of the fly was sterilized, and in others no sterilization of the exterior was 

 attempted. Cultures from 40 flies which emerged from the control box yielded no 

 organisms of special interest, though on the MacConkey plates a number of non-lactose 

 fermenting organisms developed whose characters will be discussed later. Cultures 

 from 194 flies which emerged from larvK infected with the coccus producing pink 

 colonies, and from 117 flies which emerged from larvae infected with B. prodigiosus, 

 yielded negative results. Cultures from 21 flies which emerged from B. enteritidis 

 infected larvae also yielded negative results. 



