WOUND INFECTIONS 265 



from risk was often excessive. These facts are well 

 known to the public and it is also generally known 

 that when a wound made by the surgeon, or the 

 result of accident, suppurates or gives rise to fever, it 

 is because it has become infected. The germs which 

 usually give rise to wound infection have been care- 

 fully studied by bacteriologists and are now well 

 known. The two most common species, which are 

 responsible to a large extent for the suppuration of 

 wounds, for erysipelatous inflammation, and for "blood- 

 poisoning," are widely distributed and are commonly 

 found upon the surface of the body and of mucous 

 membranes in healthy persons. One of these is a 

 micrococcus which, when cultivated in artificial media, 

 is recognised by the fact that it forms masses of 

 a golden-yellow colour. These masses are made up 

 of minute spherical cells which adhere to each other 

 in irregular grape-like bunches hence the technical 

 name Staphylococcus pyogenes aureus. The other is 

 also a micrococcus in which the spherical cells are 

 united in chains, like strings of pearls. This is called 

 Streptococcus pyogenes. This latter is also called the 

 streptococcus of erysipelas because it has been demon- 

 strated to be the cause of erysipelatous inflammations. 

 These two species of pathogenic bacteria give rise 

 to a great variety of infectious processes. Both are 

 found, either separately or associated, in the pus of 



