366 EDEMA 



present are the same as the organisms produce in similar culture-media, modified 

 somewhat by absorption. The anaerobic gas-producing organisms have been 

 found as the cause of such gaseous accumulations; it 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-containing 

 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 

 pneumothorax from infection of the pleural effusion in a diabetic by B. coli has 

 been reported. Complete quantitative analyses of the gas in this form of pneu- 

 mothorax seem not to have been made, but May found about 20 per cent, of CO2. 

 The combustibility of the gas has i^frequently been noted, and is probably dueto 

 hydrogen and methane. 



