230 INFLAMMATION 



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 turpen- 

 tine, croton oil, etc. 1 Suppuration is, therefore, the result of 

 three processes: (1) Necrosis of cells; (2) local accumulation 

 of leucocytes ; (3) digestion of the necrotic cells, fibrin, and 

 tissue elements by enzymes which are derived from three sources, 

 as follows : (a) the leucocytes ; (6) the infecting bacteria (if such 

 are present); (c) the fixed tissue-cells. Possibly small quanti- 

 ties of enzymes are also introduced in the blood plasma, but 

 these are probably very inconsiderable. Normal serum, and 

 probably also normal cells, contain antibodies for the proteo- 

 lytic enzymes of the leucocytes, and hence neutralization or 

 destruction of these antibodies may be an important factor in 

 determining the rate and amount of suppuration. 2 



The proteolytic enzymes of the leucocytes and tissue-cells 

 have been previously considered in connection with the subject 

 of autolysis (Chap, iii), and it is necessary here only to call 

 attention to the fact that these enzymes are of at least two varie- 

 ties : (1) Proteolytic enzymes of the polymorphonuclear 

 leucocytes, which act best in alkaline medium (Opie 3 ); (2) auto- 

 lytic enzymes of the tissue-cells, which act best in an acid 

 medium (Hedin, et aL). Possibly the mononuclear leucocytes 

 contain, like the tissue-cells, enzymes acting in an acid medium. 

 The antienzymatic action of pus serum is favored by an alka- 

 line reation, but is altogether lost in an acid medium (Opie). 



COMPOSITION OF PUS 



Because of its method of production, pus consists of the follow^- 

 iug substances : (1) The constituents of the exuded blood plasma ; 

 (2) the constituents of the leucocytes (and tissue-cells) that 

 exist free in the pus ; (3) the products of digestion of the pro- 

 teids of the leucocytes and necrosed tissues. All analyses of 

 pus that are recorded in the literature are in harmony with the 

 above statements. In general the analyses consider pus as com- 

 posed of two chief portions, the pus-corpuscles and the pus 

 serum. As is to be expected, the composition of pus-corpuscles 

 is simply that of a large mass of leucocytes, which contain 

 minute quantities of substances taken up from the pus serum 



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

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



2 See Opie, Jour. Exper. Med., 1905 (7), 316). 



3 Jour. Exper. Med., 1906 (8), 410. 



