118 INFECTIONS OF THE DIGESTIVE TRACT 



identity. There is a considerable group of strict anaer- 

 obes whose members are able to induce in guinea-pigs 

 (when subcutaneously injected) certain characteristic 

 lesions, including hsemorrhagic oedema, necrosis of cells 

 due to proteoclastic enzymes, and in certain cases evolu- 

 tion of gas. Finally, the introduction of cultures of 

 putrefactive anaerobes into the circulation of a living 

 rabbit which is killed in the course of a few minutes and 

 then incubated is sometimes a method very helpful for 

 the establishment of the identity of an anaerobic micro- 

 organism. This method, which was first employed by 

 Welch and Nuttall, 1 must be regarded as an extremely 

 important means of revealing not only the gas-forming 

 properties of a pure culture of anaerobes, but also of 

 showing those of a suspension of the mixed fa3cal flora. 

 Here the blood and tissues of the rabbit act as a pecul- 

 iarly favorable culture medium for the growth of the gas- 

 bacillus (B. aerogenes capsulatus) , the bacteria having 

 been thoroughly spread by the blood through the body 

 and the conditions of growth being highly anaerobic. 

 Welch and Nuttall made use of their procedure to isolate 

 the gas-bacillus and to demonstrate its ability to make gas 

 on a proteid medium containing little sugar. The bacil- 

 lus of rauschbrand (symptomatic anthrax) also induces 

 the conditions obtained by the gas-bacillus, but unlike 

 the gas-bacillus, sporulates under these conditions. 

 The bacilli of botulism and of malignant oedema do not 



1 "A Gas-producing Bacillus (B. aerogenes capsulatus, nov. spec.) 

 Capable of Rapid Development in the Blood Vessels after Death," 

 Butt, of the Johns Hopkins Hosp., iii, p. 81, 1892. 



