182 INFECTIONS OF THE DIGESTIVE TRACT 



to refer briefly to certain Gram-negative facultative 

 anaerobes which liquefy gelatin and which are regarded 

 as having the ability to induce putrefaction in proteid 

 material. The most important member of this group 

 is the organism called B. vulgaris, or proteus vulgaris, 

 which is known to make a tryptic ferment and 

 to peptonize casein and attack carbohydrates. It is 

 said by A. E. Taylor to produce indol, skatol, and diam- 

 ino-acids when grown on casein. The organism is one 

 which is sometimes found in moderate numbers in the 

 fseces of healthy individuals where, as a rule, liquefying 

 aerobic organisms are not numerous. B. proteus vulgaris 

 was formerly regarded as a very important agent in the 

 production of putrefactive decompositions outside the 

 body and it has been suspected of inducing active putre- 

 faction within the human intestine. Recent investiga- 

 tions indicate clearly that other types of microorganisms 

 belonging to the class of strict anaerobes are much more 

 important factors in putrefaction generally than is the 

 B. proteus vulgaris, which is sometimes, however, asso- 

 ciated with these anaerobes. It appears that the ability 

 of B. proteus vulgaris to attack native proteids has been 

 overestimated. I have gamed the impression from the 

 study of the action of this organism on milk in fermenta- 

 tion tubes that its peptonizing action on casein is ordi- 

 narily not considerable during a period of four to five 

 days' sojourn in the incubator at body temperature. 

 That B. proteus vulgaris is capable of inducing acute dis- 

 ease of the human gastro-enteric tract appears to be well 

 established. There are instances on record of severe 



