256 BACTERIOLOGY. 



sess a marked tenacity to vitality, for it is not rare to 

 observe recurrences of inflammatory conditions due to 

 this organism, often at a relatively long time after the 

 primary site of infection is healed. 



When introduced into the tissues of lower animals its 

 effects are uncertain. Rosenbach and Passet claimed 

 that protracted, progressive, erysipelatoid inflammations 

 were produced, and Fehleisen, who described a strep- 

 tococcus in erysipelas that is in all probability identical 

 with the streptococcus pyogenes now under considera- 

 tion, stated that it produced in the tissues of rabbits 

 (the base of the ear) a sharply defined, migratory red- 

 dening without pus-formation. The writer has encoun- 

 tered a culture of this organism that possessed the prop- 

 erty of inducing erysipelas when introduced into the 

 skin of the ear, and disseminated abscess-formation 

 when injected into the circulation of rabbits. This 

 observation has an important bearing upon the ques- 

 tion concerning the identity of streptococci found in 

 inflammatory conditions. As a rule, it is difficult to 

 obtain any definite pathological alterations in the tis- 

 sues of animals through the introduction into them of 

 cultures of this organism by any of the methods of 

 inoculation ordinarily practised. Occasionally, how- 

 ever, cultures are encountered that are conspicuous for 

 their pathogenic powers. 



This is the streptococcus pyogenes, and is the organism 

 most commonly found in rapidly spreading suppura- 

 tion in contradistinction to the staphylococcus pyogenes 

 aureus, which is most frequently found in circumscribed 

 abscess-formations; they may be found together. 



If the opportunity presents, obtain cultures from a 

 case of erysipelas. Compare the organism thus obtained 



