SUPPUEATION 229 



metaphysical theory which would endow a single cell, without 

 organs or nervous system, with the reasoning powers of highly 

 developed animals, a position incompatible with the entire 

 evidence of experience. 



SUPPURATION 



For the formation of pus two conditions are necessary : (1) 

 the accumulation of leucocytes, and (2) necrosis and liquefaction 

 of cells 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 suppuration ; 6. (/., infarcts, aseptic liquefaction, 

 necrosis, etc. Hence for suppuration to occur there must be 

 produced substances with positive chemotaxis, to cause accumu- 

 lation 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 substance meeting these 

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

 will cause suppuration. Therefore, although bacterial infection 

 is the usual cause of suppuration, 1 it may be produced by 

 many other substances, among which the following are best 

 known : Bacterial proteins, even from non-pathogenic bacteria ; 

 oil of turpentine, mercury, croton oil, silver nitrate solutions 

 (5 to 10 per cent.), and certain vegetable proteids (vegetable 

 " caseins "). 



An excellent example of the importance of leucocytes for sup- 

 purative softening is the caseous tubercle, which is usually free 

 from leucocytes and does not undergo suppuration. If for any 

 cause leucocytes are attracted into the caseous area, softening and 

 pus formation promptly occur. Hence Heile 2 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 infecting bacteria, many 

 of which were known to produce digestive enzymes dissolving 

 proteid culture-media ; e. g., Staphyloeoccus pyogenes. Although 

 to some extent these enzymes may be a factor in causing the 



1 Buchner considers that bacteria will not produce suppuration unless they 

 are broken down so that their pyogenic proteids 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 proteids liberated. 



2 Zeit. klin. Med., 1904 (55), 508. 



