336 Gaseous Edema 



days the bacilli sediment and the bouillon again becomes clear. The 

 reaction of the bouillon becomes strongly acid. 



Milk. — In milk the growth is rapid and luxuriant under anaerobic 

 conditions, but does not take place in cultures exposed to the air. 

 The milk is coagulated in from twenty-four to forty-eight hours, 

 the coagulum being either uniform or firm, retracted, and furrowed 

 by gas bubbles. When litmus has been added to the milk, it be- 

 comes decolorized when the culture is kept without oxygen, but turns 

 pink when it is exposed to the air. 



Potato. — The bacillus will also grow upon potato when the tubes 

 are inclosed in an anaerobic apparatus. There is a copious gas- 

 development in the fluid at the bottom and sides of the tube, so 

 that the potato becomes surrounded by a froth. After complete 

 absorption of the oxygen a thin, moist, grayish-white growth takes 

 place upon the surface of the medium. 



Vital Resistance. — The vital resistance of the organism is not great. 

 Its thermal death-point was found to be s8°C. after ten minutes' 

 exposure. Cultures made by displacing the air with hydrogen are 

 less vigorous than those in which the oxygen is absorbed from the 

 air by pyrogallic acid. It was found that in the former class of 

 cultures the bacillus died in three days, while in the absorption ex- 

 periments it was kept alive at the body temperature for one hundred 

 and twenty-three days. It is said to live longer in plain agar than 

 in sugar-agar. To keep the' cultures alive it has been recommended 

 to seal the agar-agar tube after two or three days' growth. 



Metabolic Products. — The bacillus is unable to make use of the 

 uncombined oxygen of the atmosphere, and derives its oxygen sup- 

 ply entirely from carbohydrates in the medium in which it grows. 

 It causes fermentation of most carbohydrates with the evolution of 

 much gas and some acid. It coagulates milk. 



Simonds''' divides the organisms known as B. aerogenes capsulatus 

 or B. welchii into four groups according to their metabolic activities 

 as follows: 



1. Organisms that ferment inulin and glycerin with production 

 of gas and increase of acidity. Do not form spores in media con- 

 taining either substance. Produce strong hemolysins, and are 

 pathogenic for guinea-pigs, even after many months cultivation 

 upon artificial media. 



2. Organisms that produce acid and gas from glycerin but not 

 from inulin. Form spores in inulin but not in glycerin broth. 

 Hemolytic and pathogenic powers variable. 



3. Organisms that produce acid and gas from inulin but not from 

 glycerin. Form spores in glycerin but not in inulin broth. Hem- 

 olysis and pathogenicity variable. 



4. Organisms that do not produce acid or gas from either inulin 

 or glycerin and from spores in both inulin and glycerin broths. 



* Jour. Infectious Diseases, igis, XVI, 32. 



