88 



THE PRINCIPLES OF IMMUNOLOGY 



colon titer. The primary colon titer of 1000 would have a very low 

 content of minor agglutinin for typhosus, the removal of which 

 would leave the primary titer for typhosus practically unchanged 

 after absorption with colon bacilli. 



The differences of absorption of major and minor agglutinins may be 

 illustrated by the use of a typhosus immune serum. We may use, for illustra- 

 tion, as closely related organisms bacillus typhosus and bacillus paratyphosus B. 

 Preliminary titration of the serum is carried out as usual against bacillus 

 typhosus and bacillus paratyphosus B. Let us suppose that the serum shows 

 a titer of 1-4096 for typhosus and 1-512 for paratyphosus B. Thick emulsions 

 of typhosus and para B are made as described in the previous experiment, 

 killed by 56 C. for one hour and mixed in equal volume with 1.5 c.c. serum, 

 incubated for one hour and refrigerated for twelve hours, then centrifuged 

 and the fluid pipetted off. The experiment with the results may be illus- 

 trated in the following protocol: 



Tube 



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3 

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I 



8 



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IS 



16 



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Result 



Result 



Result 



