PATHOGENIC BACTERIA. 237 



Specimens of pus will nearly always be found to contain 

 bacteria, which can be demonstrated by cultivation, and, 

 as a rule, also in smears made and stained upon cover- 

 glasses. The bacteria are generally found outside the pus- 

 cells. In the case of the gonococcus and the diplococcus 

 intracellularis meningitidis they are characteristically found 

 in pairs, inside. of, or at least attached to the pus-cells. 

 The character of the suppuration differs somewhat with the 

 different species of pyogenic bacteria. The kind of abscess 

 above described localized and having a central slough, 

 usually rather slow in progress is typical for the staphylo- 

 coccus pyogenes aureus, which is prone to produce circum- 

 scribed areas of suppuration. The streptococcus pyogenes, 

 on the other hand, oftener leads to suppuration of a more 

 diffused character, such as we see in cellulitis and erysipelas; 

 but either organism may, at times, produce the effects 

 usually characteristic of the other. Pus having a blue or 

 green tinge generally owes the color to the presence of the 

 bacillus pyocyaneus. The commonest pus-producing organ- 

 ism is then the Staphylococcus pyogenes aurcus, and next to 

 that the streptococcus pyogenes. Among the other pyogenic 

 bacteria the following may be named : 



Staphylococcus pyogenes albus, including staphylococ- 

 cus epidermidis albus; streptococcus of erysipelas (prob- 

 ably identical with streptococcus pyogenes); gonococcus; 

 diplococcus intracellularis meningitidis ; Staphylococcus 

 pyogenes ciireus; micrococcus tetragenus ; micrococcus 

 pyogenes tennis, which may be the same as the micrococcus 

 lanceolatus; Staphylococcus cereus albus and flavus. 



Pus-formation may also be due to micrococcus lanceola- 

 tus, bacillus pyocyaneus, bacillus proteus, bacillus coli 

 communis, bacillus pyogenes fetidus, bacillus pneumonias 

 (of Friedlander), bacillus aerogenes capsulatus, the ray 

 fungus of actinomycosis, and possibly the bacillus of bu- 



