226 BACTERIOLOGY. 



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 

 sometimes contain other organisms beside the staphylo- 

 coccus pyogenes aureus. The staphylococcus pyogenes 

 alb-US 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 

 peculiarities 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 

 degree than is commonly the case with the golden 

 staphylococcus. The streptococcus pyogenes is also 

 sometimes present. The commonest of the pyogenic 

 organisms however is that just described — the staphylo- 

 coccus pyogenes aureus. 



The Stkbptococcus Pyogenes. — From a spread- 

 ing phlegmonous inflammation prepare cover-slips and 

 cultures. What is the predominating organism ? Does 

 it appear as irregular clusters of grapes, or has its in- 

 dividuals a definite regular arrangement? Are its 

 colonies like those of the staphylococcus pyogenes 

 aureus ? 



Isolate this organism in pure cultures. In these cul- 

 tures it will be found on microscopic examination to 

 present an arrangement somewhat like a chain of beads. 

 (Fig. 47.) 



Determine its peculiarities and describe them accu- 

 rately. They should be as follows : 



Upon microscopic examination a micrococcus should 

 be found, but differing in its arrangement from the 

 staphylococci just described. The single cells are not 



