LOCALIZED INFECTIONS OF PUS NATURE 79 



effects in the production of infection. In increasing 

 severity there are the following grades: 



FIG. 24 



Secondary infection of a glomerulus of kidney by the Staphylococcus aureus, 

 in a case of ulcerative endocarditis. The cocci (stained doubly) are seen 

 plugging the capillaries and also lying free. X 300. (Muir and Ritchie.) 



Abscess. A local collection of pus in which the 

 resistance put up by the tissue prevents the inflamma- 

 tion from going on to the next grade, or diffuse, not 

 limited, spreading cellulitis or phlegmon, or to multiple 

 abscesses. The next grade of severity would be 

 septicemia or pyemia, defined before. They arise 

 chiefly when the active inflammation enters and 

 involves the bloodvessels. The softening of tissue 



