ANTHRAX 183 



{b) Experiments zvith anthrax spores. 



" An emulsion of an old anthrax culture was made and heated to 70° C. for 

 15 minutes, and subsequently a number of flies were allowed to feed on it. These 

 flies were transferred to fresh cages daily and fed on syrup. Specimens were caught 

 and dissected at intervals. Cultures were made, on agar, from their legs, wings, 

 heads, crop and intestinal contents and fcecal deposits. Although numerous smears 

 were made from crop and intestinal contents at various times, no anthrax bacilli were 

 seen microscopically, showing that the spores do not develope into bacilli in the fly." 



" This experiment shows that flies infected with anthrax spores 

 may carry the spores on their legs and wings for at least 10 days, 

 and that the spores are present in considerable numbers in the 

 crop and intestinal contents for at least 7 days. The vomit and 

 fsecal deposits contain living spores for 6 days or longer. In 

 another experiment, which was intended to confirm and prolong 

 the one just described, a number of flies were allowed to feed on 

 syrup infected with anthrax spores. Unfortunately an epidemic 

 of Empusa vinsccB killed off these flies after 20 days." 



This experiment, however, confirmed the previous one and 

 showed that anthrax spores may remain alive on the legs and 

 wings and in the intestinal contents for at least 20 days. Faeces 

 passed 14 days after infection contained living spores. 



The experiment differed slightly from the last since the flies 

 were kept in one cage all the time and were not transferred to 

 fresh cages daily. 



" In order to ascertain how long spores will retain their vitality 

 in dried faeces and vomit the following experiment was made. 



" After feeding on infected material the flies were placed for 24 hours in a fresh cage 

 (A), and then removed to another. At intervals (i, 3, 4, 5, 7, 8, 12, 13 and 20 days) 

 cultures were made both from the vomit and ffeces deposited on cage A and, in every 

 case, numerous colonies of B. anthracis grew. At the end of 20 days the cage was 

 sterilized by mistake. Probably the spores would have remained alive for a much 

 longer period." 



In order to ascertain how long anthrax spores may remain 

 alive in dead infected flies some infected flies, dead of empusa 

 disease, have been kept in a bottle. From time to time cultures 

 have been made from them. At the time of writing, nearly 

 three years later, the spores are alive and virulent. 



