INFECTIONS OF THE DIGESTIVE TRACT 203 



ducing a more strict condition of anaerobiosis by the 

 reducing activity of the cells. 



If we cultivate B. aerogenes capsulatus on sugar 

 bouillon we find that it is a large producer of gas (mainly 

 hydrogen and carbon dioxide) and that it makes butyric 

 and closely related acids in abundance, while the forma- 

 tion of lactic acid is small. On media which contain 

 very little sugar but much proteid, the organism is 

 still able to make gas in considerable amounts, though 

 less freely than on a sugar medium, in which the libera- 

 tion of gas is remarkably rapid. In nearly sugar-free 

 media the gas bacillus produces butyric acid, and the 

 quantity of this hi old cultures may be surprisingly 

 great. Ammonia is formed at the same time and serves 

 to neutralize at least in part the acid which is simul- 

 taneously made. Most varieties of the organism are not 

 indol producers when grown alone in blood bouillon. 

 There are strains which make indol. 



More important for the pathologist than any of these 

 substances is the formation of a moderately hsemolytic 

 substance (or substances) by the gas-bacillus. Evidence 

 of such substances was obtained in a five-day culture 

 of capsulatus in blood bouillon. One-half of one cubic 

 centimeter of the filtrate from this culture induced 

 haemolysis in a suspension of rabbit's red cells prepared 

 by Ehrlich's method, the filtrate having been carefully 

 neutralized to the litmus point. The same result was 

 obtained in the case of red cells from a large Rhesus 

 monkey. Treatment of this filtrate in an exhaustion 

 apparatus very slightly reduced the hsemolytic action; 



