306 INFECTION AND RESISTANCE 



after standing on the clot points to a probability of this, no direct 

 evidence has so far been satisfactorily produced. In the hope that 

 the leukocytes would give up alexin possibly as a secretion as sug- 

 gested by Denys the writer, with Cary, some years ago kept 

 washed leukocytes at 37.5 C. in Locke's solution, but was unable 

 to find any evidence of alexin production within 48 hours. 



The apparent extraction of hemolysin from macrophages by 

 Tarassewith, moreover, has met with a similar refutation. Korschun 

 and Morgenroth 36 have shown that these hemolytic extracts are ex- 

 tremely heat resistant, are alcohol and ether soluble, and do not act 

 as antigens. They are quite different from the serum hemolysins, 

 therefore, and probably closely related to the hemolytic lipoidal 

 substances described by Noguchi and others. 



Further strong arguments against the assumption of the pres- 

 ence of hemolytic alexin in the body of the macrophages have been 

 advanced by Gruber 37 and by Neufeld. 38 Gruber showed that no 

 extracellular hemolysis takes place when leukocytes are brought 

 together with sensitized red blood cells, and Neufeld showed that 

 even after the phagocytosis of such sensitized cells the hemolysis is 

 very much slower, and of a different character from extracellular 

 serum hemolysis. In the intracellular digestion there are no mere 

 solution of the hemoglobin and formation of a shadow form 

 (stroma), but there occur a gradual degeneration with the forma- 

 tion of a granular detritus of hemoglobin. 



It is probable, then, that the digestion of bacteria and cells 

 within the phagocytes is carried out by substances not identical with 

 those taking part in serum lysis. It is not unlikely that the intra- 

 cellular process is a quite complicated one, not depending on a single 

 enzyme. 



In addition to the bactericidal substances extracted from leuko- 

 cytes a number of true enzymes have indeed been obtained by various 

 investigators. We have mentioned in another place that one of the 

 earliest observations in this respect was that of Leber, 39 who noticed 

 that sterile pus could liquefy gelatin. It may be commonly observed 

 in paraffin or celloidin sections of staphylococcus abscesses that a 

 ring of apparently digested or degenerating tissue is formed about 

 an accumulation of leukocytes in foci in which the bacteria may 

 be too sparse to be held accountable for the changes. These leuko- 

 proteases have subsequently been carefully studied by Opie, 40 Joch- 

 mann and Miiller, 41 and a number of others. 



36 Korschun and Morgenroth. Berl klin. Woch., 1902. 



37 Gruber. Quoted from Sachs, in "Kraus u. Levadiii Handbuch," Vol. 2, 

 p. 991. 



38 Neufeld. . Arb. a. d. kais. Gesundh. Ami., Vol. 28, 1908. 



39 Leber. "Die Entstehung der Entziindung," Leipzig, 1891. 



40 Opie. Jour. Exp. Med., Vol. 7, 1905; Vol. 8, 1906; Vol. 9, 1907. 



41 Midler and Jochmann. Munch, med. Woch., Nos. 29 and 3~L, 1906. 



