306 EDEMA 



is questionable if the ordinary pathogenic organisms can cause 

 a pneumothorax, since they are for the most part not capable of 

 producing gas. The colon bacillus produces gas in sugar-con- 

 taining media, but the amount of sugar in the pathological 

 exudates is too small to yield any considerable amount of gas ; 

 an exception is the pleural effusion in diabetes, and pneumo- 

 thorax from infection of the pleural effusion in a diabetic by 

 I>. coli has been reported. Complete quantitative analyses of 

 the gas in this form of pneumothorax seem not to have been 

 made, but May found about 20 per cent, of CO 2 . The com- 

 bustibility of the gas has frequently been noted, and is prob- 

 ably due to hydrogen and methane. 



