STREPTOCOCCUS PYOGENES. 483 



rabbit, as has been proved by experiment, provided 

 they possess sufficient virulence (Knorr, Petruschky). 

 If the culture does not have the required virulence to 

 produce this effect the virulence can usually be acquired 

 by passage through animals. Streptococci obtained from 

 the same disease and from the same individual usually 

 show very much the same degree of virulence. 



Occurrence in Man. Streptococci have been found 

 in man as the primary cause of infection in the follow- 

 ing diseases : Erysipelas, acute abscesses, small and 

 large, cellulitis, circumscribed as well as diffused, sep- 

 sis, puerperal infection, lymphatic abscesses, angina, 

 pneumonia, periostitis, otitis media, mastoiditis, men- 

 ingitis, empyema, and endocarditis. Associated with 

 other bacteria in diseases of which they were the specific 

 cause, they have also been found as the secondary or 

 mixed infection in many diseases, such as in pulmonary 

 tuberculosis, bronchopneumonia, septic diphtheria, and 

 diphtheritic scarlatina. In diphtheritic false membranes 

 this micrococcus is very commonly present, and is fre- 

 quently the source of deeper infection, such as abscesses 

 and septicaemia; and in certain cases attended with a 

 diphtheritic exudation, in which the Loffler bacillus 

 has not been found by competent bacteriologists, it 

 seems probable that the streptococcus pyogenes, alone 

 or with other pyogenic cocci, is responsible for the local 

 inflammation and its results. These forms of so-called 

 diphtheria, as first pointed out by Prudden, are most 

 commonly associated with scarlatina and measles, ery- 

 sipelas, and phlegrnonous inflammation, or occur in in- 

 dividuals exposed to these or other infectious diseases. 

 So uniformly are streptococci present in the pseudo- 

 membranous inflammations of patients sick with scarlet 



