346 Gaseous Edema 



becoming clouded in two to three hours. After a few days the ba- 

 cilli 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 mUk 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. Butyric acid is formed in 

 the milk. 



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 hy- 

 drogen 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 absorp- 

 tion experiments 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 to 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 dextrose, saccharose and lactose with the 

 evolution of carbon-dioxide and hydrogen gases in the approximate 

 proportion H: CO2 :: i : 2 J'2, and the production of lactic and 

 butyric acids. It coagulates milk and softens gelatin. 



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. 



* Jour. Infectious Diseases, 1915, xvi, 32. 



