242 BACTERIOLOGY. 



which accompany the formation of larger abscesses in 

 the tissues of human beings. 



From these small abscesses in the tissues of the rabbit 

 the staphylococcus pyogenes aureus may again be ob- 

 tained in pure culture, and will present identically the 

 same characteristics that were possessed by the culture 

 with which the animal was inoculated. 



THE LESS COMMON PYOGENIC ORGANISMS. The 

 pus of an acute abscess in the human being may some- 

 times contain other organisms beside the staphylococcus 

 pyogenes aureus. The staphylococcus pyogenes albus 

 and citreus may be found. The colonies of the former 

 are white, those of the latter are lemon-color. With 

 these exceptions they are in all essential cultural pecu- 

 liarities similar to the staphylococcus aureus. As a rule 

 they are not virulent for animals, and when they do 

 possess pathogenic properties, it is in a much lower de- 

 gree than is commonly the case with the golden staphy- 

 lococcus. The streptococcus pyogenes is also sometimes 

 present. The commonest of the pyogenic organisms, 

 however, is that just described, viz. : the staphylococcus 

 pyogenes aureus. 



THE STREPTOCOCCUS PYOGENES. From a spread- 

 ing phlegmonous inflammation prepare cover-slips and 

 cultures. What is the predominating organism ? Does 

 it appear in the form of irregular clusters like those of 

 grapes, or have its individuals a definite regular arrange- 

 ment? Are its colonies like those of the staphylococcus 

 pyogenes aureus f 



Isolate this organism in pure cultures. In these cul- 

 tures it will be found on microsopic examination to 

 present an arrangement somewhat like a chain of beads. 

 (Fig. 51.) 



