BACTERICIDAL PROPERTIES OF BLOOD SERUM 145 



Muir, 21 who studied the conditions thoroughly , comes to the con- 

 clusion that the complement is in truth used up in hemolysis, but 

 that it does not always disappear completely, this depending upon 

 the relative amount of sensitizer or amboceptor present. (He con- 

 firms the quantitative ratios between the two substances found by 

 Morgenroth and Sachs in hemolytic reactions, a subject discussed 

 by us in another place.) 



Liefmann and Cohn, 22 in a more recent publication, have come 

 to different conclusions. They believe that the disappearance of free 

 complement from hemolytic complexes is not due to its chemical 

 union with the sensitized cells in the process of hemolysis, but is due 

 rather 



(1) to a fixation by the products of hemolysis (stromata, etc.) 

 after the reaction is accomplished, 



(2) to dilution, and 



(3) to weakening because of prolonged preservation in dilute 

 solution at 37 C. 23 



Theoretically this is of considerable importance if confirmed, 

 since it would bear out strongly the conception of complement as a 

 true enzyme or ferment. From the point of view of the practical 

 utilization of complement fixation for various purposes it makes 

 little difference, since here the disappearance of complement is the 

 essential thing, irrespective of whether this occurs in the course of 

 its activity or because of fixation by the products of its own action. 



We now have the basic principle of hemolysis ; facts which can 

 easily *be shown to hold good for bacteriolysis and for the bacteri- 

 cidal processes even when no actual solution takes place. Briefly 

 reviewed, these facts are as follows: The antigen (blood cells, bac- 

 terial cells, etc.) undergoes hemolysis or bacteriolysis when acted 

 upon by two factors, one a thermostable substance, specific and in- 

 creased during immunization, the other a thermosensitive substance 

 present in fresh serum, not increased 24 by immunization of the ani- 

 mal with the antigen and not specific. The specific thermostable 

 substance becomes united with or fixed to the antigen regardless of 

 the presence or absence of the thermosensitive alexin or comple- 

 ment, and with such avidity that the union takes place even at C. 

 The alexin or complement, however, cannot enter into relation with 

 the antigen unless this has been rendered susceptible to it by attach- 

 ment to the thermostable specific substance. When this has taken 



21 Muir. Lancet, Vol. 2, 1903, p. 446. 



22 Liefmann and Cohn. Zeitsch. f. Immunitatsforsch. Or., Vol. 8, p. 58, 

 1911. 



23 In tlie ordinary dilution used in Wassermann tests, the unit of comple- 

 ment employed may deteriorate entirely within several hours at 40 C. 



24 Bordet. Ann. de I'Inst. Past., Vol. 12, 1898. Confirmed by v. Dun- 

 gern, Munch, med. Woch., No. 20, 1900. 



