BACILLUS AEROGENES CAPSULATUS 491 



drying, particularly in the absence of sunlight. Viable spores have 

 been obtained from dust in a vault which had not been opened for 

 fifteen years. Sporulation does not take place, as a rule, in the tissues; 

 spores are frequently found in the intestinal tract. They do not form 

 readily in media containing utilizable carbohydrates, but are found 

 on the surface of slanted blood serum 1 and in protein media. Simonds 2 

 finds that an acidity greater than 1 per cent, to phenolphthalein 

 inhibits spore formation. 



Products of Growth. B. aerogenes capsulatus forms a gelatinase 

 in the absence of utilizable sugars. In dextrose, lactose and saccharose 

 media it produces an energetic fermentation, the products being 



FIG. 68. Bacillus aerogenes capsulatus, smear from liver of rabbit. X 1000. 



butyric and lactic acids, carbon dioxide and hydrogen in the pro- 

 portions H:CO2 = i approximately; 3 comparatively little acid is 

 formed. Welch and Nuttall state that the organism decomposes 

 protein with the formation of carbon dioxide and hydrogen and nitro- 

 gen gas; but it is probable that little or no gas is formed from protein. 

 According to Brown, 4 the organism forms a toxin in sugar-free broth, 

 which is pathogenic for guinea-pigs. The toxin is not formed in broth 

 containing utilizable carbohydrates. 



Simonds 5 has distinguished four distinct types or subgroups of 

 Bacillus aerogenes capsulatus, which differ essentially in their fer- 

 mentation of certain sugars and in their sporulation as follows : 



1 Dunham, loc. cit. 



2 Loc. cit., p. 31. 



3 Smith, Brown, and Walker, Jour. Med. Research, 1905-1906, xiv, 193. 



4 Annual Report, Massachusetts State Board of Health, 1909. 



5 Loc. cit., p. 13. 



