PROPERTIES OF ANTIBACTERIAL SERUM 571 



Properties of Antibacterial Serum. We have here to 

 consider the three main actions mentioned above, namely, 

 (a) bactericidal and lysogenic action, (b) opeonic action, and 

 (c) agglutinative and the closely allied precipitating action. Of 

 these the two first are concerned with the protective property of 

 an anti-bacterial serum. 



(a) Bactericidal and Lysogenic Action. Pfeiffer found that 

 if certain organisms, e.g., the cholera spirillum, were injected 

 into the peritoneal cavity of a guinea-pig highly immunised 

 against these organisms, they lost their motility almost immedi- 

 ately, gradually became granular, swollen, and then disappeared 

 in the fluid these changes constitute " Pfeiffer's phenomenon." 

 Further, he showed that the same phenomenon was witnessed 

 if a minute quantity of the anti-serum was added to a certain 

 quantity of the corresponding organisms, and the mixture injected 

 into the peritoneal cavity of a non-treated animal. Pfeiffer 

 found that the serum of convalescent cholera patients gave the 

 same reaction as that of immunised animals. He obtained the 

 same reaction also in the case of the typhoid bacillus and other 

 organisms. From his observations he concluded that the reaction 

 was specific, and could be used as a means of distinguishing 

 organisms which resemble one another. He accordingly con- 

 sidered that a specific substance was developed in the process of 

 immunisation, and that this was rendered actively bactericidal 

 by the aid of the living cells of the body. It was subsequently 

 shown, however, by Metchnikoff and by Bordet that bacteriolysis 

 might occur outside the body by the addition of fresh peritoneal 

 fluid or normal serum to the heated immune-serum. Pfeiffer 

 also found that an anti-serum heated to 70 C. for an hour 

 produced the reaction when injected with the corresponding 

 organisms into the peritoneum of a fresh animal. The outcome 

 of these and subsequent researches is to show that when an 

 animal is immunised against a bacterium, there appears in its 

 serum an anti-substance, which is generally known as immune- 

 body, amboceptor (Ehrlich), or substance sensibilisatrice (Bordet), 

 is comparatively stable, resisting usually a temperature of 70 C., 

 for an hour. It cannot produce the destructive effect alone, but 

 requires the addition of a substance normally present in the serum, 

 which is spoken of under various names complement (Ehrlich), 

 alexin or cytase (French writers). The complement is relatively 

 unstable, being rapidly destroyed by a temperature of 60 C., 

 and it is not increased in amount during the process of 

 immunisation. Though ferment-like in its instability, it differs 

 from a ferment in being fixed or used up in definite quantities. 



