76 LABORATORY COURSE IN SERUM STUDY 



them, and subsequently removing the agglutinated bacteria by 

 centrifugation. The agglutinins for this species having been ab- 

 sorbed by the bacteria will be removed by this procedure, leaving 

 the agglutinins for the species not used in the absorption unin- 

 fluenced. For the complete removal of agglutinins it is necessary 

 to leave the serum in contact with the bacteria for a long period 

 and often to repeat the treatment of the serum with bacterial 

 suspension several times. These facts are illustrated in Experi- 

 ment 1. 



The experiment illustrates the general principle that an animal 

 may produce specific and distinct antibodies simultaneously 

 against a number of different antigens. 



Experiment 1 



ABSORPTION OF AGGLUTININS FROM THE SERUM OF AN ANIMAL IM- 

 MUNIZED AGAINST Two SPECIES OF BACTERIA 



Reagents : 



1. Serum of an animal simultaneously immunized against Bacillus 

 typhosus and Bacillus coli. The students who have immunized this 

 animal should bleed it from the carotid at a preceding lesson and 

 should distribute the serum to other members of the class, diluted 1-10 

 with salt solution. Each student requires 5 c.c. of this dilution. 



2. Thick suspension of typhoid bacilli killed by heating one hour at 

 55 C. 



3. Thick suspension of colon bacilli killed by heating one hour at 

 60 C. 



Both these suspensions should be used undiluted for the absorption, 

 and in a dilution of 1-10 for titrating the agglutination. 



4. Salt solution. 



A. PRELIMINARY TITRATION OF AGGLUTINATIVE POWER OF IMMUNE 



SERUM 



The dilutions of serum required for this test should be prepared 

 in f-inch test tubes according to a protocol to be made out by the indi- 

 vidual student. Before making any such series of dilutions it is highly 

 important to write out plainly the amount of serum and salt solution 

 to be placed in each tube in order to avoid errors. 



