INFECTIONS OF THE DIGESTIVE TRACT 119 



form gas in the incubated rabbit, but induce other evi- 

 dences of putrefaction. 



It seems singular that almost no use has been made by 

 subsequent investigators of this ingenious and extremely 

 valuable method of studying the gas-bacillus. Acting 

 on the suggestions carried by the paper of Welch and 

 Nuttall, we have used the method not merely as an aid 

 in the identification of B. aerogenes capsulatus, but also 

 (with somewhat unexpected success) as a means of deter- 

 mining whether the gas-bacillus is present in considerable 

 numbers in the faeces. 



The conditions found at autopsy after twenty-four 

 hours' incubation of a rabbit previously injected intra- 

 venously with a pure culture of B. aerogenes capsu- 

 latus have been so fully described by Professor Welch 

 that it is unnecessary to add anything to his description 

 aside from emphasizing the fact that the almost intoler- 

 able odor of putrefaction which is developed during the 

 incubation experiment is dependent in part on the pro- 

 duction of butyric or a closely allied acid. 1 It should 

 also be added that an odor very similar to that charac- 

 teristic of the incubation experiment can be observed in 

 the faeces of some persons with chronic disturbances of 

 digestion, and frequently in persons with advanced anae- 

 mias associated with irregular diarrhoeal conditions. 



The incubation method of Welch and Nuttall has 

 apparently never been employed in connection with the 



1 1 do not know of another equally impressive example of the 

 ability of microorganisms to induce rapid putrefactive decompo- 

 sition. 



