268 INFLAMMATION 



and tissue elements. Many leucocytes may be present in a tissue 

 without suppuration; e. g., erysipelas. Necrosis of cells with their 

 gradual liquefaction and absorption may also occur without suppura- 

 tion; e. g., infarcts, aseptic liquefaction necrosis, etc. Hence for sup- 

 puration to occur there must be produced substances with positive 

 chemotaxis, to cause accumulation of leucocytes, for if a necrotic area 

 is devoid of leucocytes, it does not suppurate; e. g., caseous tubercles. 

 Secondly, necrosis must occur, for digestion and liquefaction of living 

 cells and tissues does not take place. Only substances meeting these 

 requirements — -i. e., causing positive chemotaxis and cell necrosis — 

 will cause suppuration. Therefore, although bacterial infection is 

 the usual cause of suppuration,*^ it may be produced by many other 

 substances, among which the following are the best known: Bacterial 

 proteins, even from non-pathogenic bacteria; oil of turpentine, mer- 

 cury, croton oil, silver nitrate solutions (5 to 10 per cent.), and certain 

 vegetable proteins (vegetable "caseins"). 



An excellent example of the importance of leucocytes for suppura- 

 tive softening is the caseous tubercle, which is usually free from 

 leucocytes and does not undergo suppuration. If for any cause leuco- 

 cytes are attracted into the caseous area, softening and pus formation 

 promptly occur. Hence Heile*'^ found that while pus from a "cold" 

 tuberculous abscess will not digest fibrin and does not give the biuret 

 reaction, both reactions appear after a leucocytosis has been brought 

 about by injection of iodoform. It was formerly considered that the 

 softening was due to the digestive action of the enzymes of the in- 

 fecting bacteria, many of which were known to produce digestive 

 enzymes dissolving protein culture-media; e. g., Staphylococcus pyo- 

 genes. Although to some extent these enzymes may be a factor in 

 causing the softening of the fixed tissues and of the killed leucocytes, 

 their effect is probably insignificant as compared with the enzymes 

 liberated by the leucocytes, as shown by the production of active 

 experimental suppuration under aseptic conditions with turpentine, 

 croton oil, etc.** Suppuration is, therefore, the result of three proc- 

 esses: (1) Necrosis of cells; (2) local accumulation of leucocytes; 

 (3) digestion of the necrotic cells, fibrin, and tissue elements by en- 

 zymes which are derived from three sources, as follows: (a) the 

 leucocytes; (6) the infecting bacteria (if such arc present); (c) the 

 fixed tissue-cells. Possibly small quantities of enzymes are also intro- 

 duced in the blood plasma, but these are probably very inconsiderable. 



*" Buchner considers that bacteria will not produce suppuration unless they 

 are broken down so that their -pyogenic proteins are released; e. g., anthrax bacilli 

 cause suppuration when acting locally, as in malignant pustule, but not when 

 they are causing septicemia, because only in the former case are their pyogenic 

 proteins liberated 



8^ Zeit. klin. Med., 1904 (55), 508. 



** Apparently suppuration may occur in herpes zoster vesicles in the absence 

 of bacteria, according to the findings of Kreibich (Wien. klin. Woch., 1901 (14) 

 683). 



