286 MANUAL OF BACTERIOLOGY. 



in most cases suppuration nevertheless does not occur. The 

 local conditions have an important influence in determining 

 infection. Regions of hyperemia, edema, anemia or necrosis 

 are especially liable to suppuration, as are tissues which have 

 been bruised, lacerated, strangulated or otherwise damaged. 

 Furthermore, the general condidon of the patient is of great im- 

 portance. Chronic diseases and conditions of exhaustion or 

 depression dispose to suppuration, and the depraved condi- 

 tion of the tissues in diabetes renders the sufferei from this 

 disease especially liable to it. These facts have already been 

 enumerated in a previous chapter (page 178). In the lower 

 animals we find that it is often very difficult to produce sup- 

 puration artificially with the ordinary pyogenic bacteria. In 

 rabbits the subcutaneous introduction of Staphylococcus pyo- 

 genes aureus frequently fails to produce an abscess. Suppura- 

 cion is likely to result, however, if an irritant body like a piece 

 of sterilized potato or sterilized glass be introduced along with 

 the bacteria. 



There are probably a number of other specific predisposing 

 causes in the animal body about which we are only beginning 

 to obtain an understanding. The weakening of the alexins, 

 the absence of opsonins and other intricate conditions are 

 probably subject to great variability, and may serve to explain 

 the tendency to infection at certain times. 



Pyogenic bacteria are most frequently introduced into the 

 body through the agency of injuries and wounds of various 

 sorts. They are very widely disseminated in nature and have 

 been found clinging to various objects, especially in city houses. 

 The infection of a wound with pyrogenic cocci, when the sup- 

 puration is of a spreading character, such as is most character- 

 istic of streptococcus infection, is known in everyday language 

 as "blood-poisoning." It is possible for infection to take place 

 around hair-follicles through the unbroken skin. In such in- 

 stances the suppurative inflammation first shows istelf in a 



