40 IMMUNE SERA 



nate somewhat related organisms, though not, 

 usually, to so high a degree. In other words, while 

 agglutinins may be nearly, if not quite, specific in 

 their action, a serum which produces agglutination 

 may be far from being so. 



The following examples will illustrate the point. 

 In a case of infection with paratyphoid bacilli, 

 type B, the bacilli of the infecting type B were 

 agglutinated 1:5700; typhoid bacilli, however, only 

 1:120, while paratyphoid bacilli type A were not 

 agglutinated at all. In a case of typhoid infection 

 an agglutination with a dilution of i : 40 was obtained 

 for paratyphoid type B, while typhoid bacilli were 

 agglutinated in a dilution of i : 300 and over. As a 

 rule the agglutination with the infecting agent is by 

 far the strongest, i.e. it proceeds even in high dilu- 

 tions, whereas other bacteria require a stronger 

 concentration. 



In all this we are dealing with the same phenom- 

 enon which undoubtedly plays a role in the agglu- 

 tination with blood of icteric patients, the so-called 

 group agglutination, as it was first termed by Mein- 

 hard Pfaundler. 1 The bacteria which are aggluti- 

 nated by one and the same serum need not at all 

 be related in their morphological or other biolog- 

 ical characteristics, as Pfaundler at first assumed. 

 Conversely, micro-organisms which, because of the 



1 tiber Gruppenagglutination und das Verhalten des Bacte- 

 rium coli bei Typhus, Muench. mcd. Wochenschrift, 1899, No. 15. 



