360 APPLICATION OF METHODS OF BACTERIOLOGY 



for instance, as the spreading erysipelatoid manifestations 

 on the one hand, and the circumscribed abscess formations 

 on the other. 



The results that follow upon the inoculation of animals 

 with cultures of streptococci obtained from various inflam- 

 matory lesions are, as a rule, inconstant. At times cultures 

 will be encountered that are apparently without virulence, 

 no matter how tested; while again cultures from other 

 sources exhibit the most marked pathogenic properties, 

 even when employed in almost infinitesimal quantities. 

 Between these extremes every gradation may be expected. 

 The virulence of a culture as exhibited upon animals under 

 experiment is not necessarily proportional to the intensity 

 of the pathological process from which it was derived. 



In general it may be said that the virulence of strepto- 

 coccus is directly proportionate to its power to hemolyze 

 blood. That is to say: a culture that actively and con- 

 spicuously brings about the laking of blood with complete 

 decolorization of the hemoglobin is more apt to be virulent 

 than one devoid of that property. With fluctuations in 

 such hemolytic function there are corresponding fluctuations 

 in virulence. 



There is never any certainty of faithfully reproducing, by 

 inoculation into susceptible animals, the pathological lesion 

 from which a culture of the organism may have been ob- 

 tained. The introduction into a susceptible animal of a 

 culture derived from either a spreading phlegmon or an 

 erysipelatous inflammation may result in erysipelas, general 

 septicemia, local abscess-formation, or, as said, may have 

 no effect at all. Cultures may be encountered that are 

 pathogenic for one susceptible species of animals and not 

 for another. 



