AGGLUTININS 63 



ism, the serum will lose its agglutinating power no 



mly for that organism, but also for all other varietiei 



:hat it formerly acted on. Saturated with the others 



tts action upon the first is reduced little or none at all 



The serum of an animal immunized against two 



microorganisms A and B. loses its agglutination 



when saturated with A , only for A . Saturated with 



A and B it loses agglutinating power for both. 



The absorption test is extensively used in the 

 identification of bacteria, but it must be used with 

 caution, as its interpretation is open to error. Refer- 

 ring to the figure illustrating specific and group 

 agglutinins, let us assume we have obtained a 

 specific typhoid serum by immunization with typhoid 

 bacilli. By virtue of the common agglutinin, this 

 serum will act also on colon bacilli. On extracting 

 such a serum with typhoid bacilli, all the aggluti- 

 nating power would be lost, that for typhoid bacilli 

 as well as that for colon. On extracting the serum 

 with colon bacilli, we would remove the aggluti- 

 nating power for these bacilli, but leave the specific 

 agglutinating power for typhoid bacilli. If we 

 extracted the serum with a culture suspected to be 

 typhoid bacilli, and found after extraction that 

 the serum no longer agglutinated known typhoid 

 bacilli, we could conclude that the suspected culture 

 was also one of typhoid bacilli. 



Formation of the Agglutinins According to the 

 Side-Chain Theory Receptors of First, Second and 



