164 PATHOGENIC BACTERIA. 



The bacillus appears to be rather common as a sapro- 

 phyte, and, as it has been found in the perspiration, 

 probably is not uncommon upon the skin. 



The unpleasant odors that sometimes accompany sup- 

 puration are probably, in most cases, due to the Bacil- 

 lu s pyogenes fcetidus of Passet (Fig. 52). This organism 

 measures about 1.5 p. in length and 0.5 // in breadth. It 

 is motile ; it probably does not form spores. The colonies 

 are small white disks without distinctive features. In 

 gelatin punctures a thin grayish-white growth occurs 

 upon the surface, and surmounts a collection of spherical 

 confluent colonies in the puncture. It does not cause 

 any liquefaction. 



Upon potato an abundant brownish growth takes place. 



The cultures all give off an unpleasant putrefactive 

 odor. The organism is only pathogenic for mice and 

 guinea-pigs. 



Occasionally other organisms of minor importance are 

 found in pus. Most of these, like the Bacillus pyocyaneus 

 and Bacillus pyogenes fcetidus, are probably harmless 

 saprophytes accidentally present, so that it will hardly 

 be proper to devote space to their consideration. 



Before leaving the subject of suppuration, however, 

 attention must be called to several rather common bac- 

 teria which may at times be the cause of troublesome 

 suppuration. Among these are the pneumococcus of 

 Frankel and Weichselbaum, the Bacillus coli communis, 

 and the typhoid bacillus. 



The pneumococcus has not infrequently been discov- 

 ered most unexpectedly in abscesses of the brain and 

 other deep-seated organs, and seems to have powerful 

 chemotactic powers. For a careful consideration of it 

 the reader must be referred to the chapter upon Pneumo- 

 nia, where it is considered in full. 



The Bacillus coli communis, which is always present in 

 the intestine, seems at times to enter the blood- or lymph- 

 channels and stimulate suppuration, and numerous cases 

 are on record showing this. The points most frequently 



