82 LABORATORY COURSE IN SERUM STUDY 



and the supernatant fluid obtained after centrifugation has lost 

 its agglutinative power both for the homologous strains and for 

 allied species. If, on the other hand, the serum is treated with a 

 suspension of the one allied species, the minor agglutinins only 

 are absorbed. The supernatant fluid then shows undiminished 

 agglutinative power for the homologous strain, but does not ag- 

 glutinate the allied strain used in absorption. These facts are 

 brought out in Experiment 2. 



Experiment 2 



ABSORPTION OF MAJOR AND MINOR AGGLUTININS FROM SERUM OF 

 AN ANIMAL IMMUNIZED AGAINST A SINGLE SPECIES 



Reagents : 



1. Serum of an animal immunized to Bacillus typhosus. The 

 serum must be known to contain group agglutinins for Bacillus coli. 1 



2. Two specimens of the same serum in 1-20 dilution which have 

 stood in contact over night with typhoid and with colon bacilli re- 

 spectively. These may be prepared on the previous day by the in- 

 structor. Heavy suspensions of typhoid and colon bacilli are first 

 prepared by washing off the growth of a number of agar bottles and 

 heating for one hour at 56 and 60 respectively. To each of these sus- 

 pensions is added an equal volume of a 1-10 dilution of agglutinating 

 serum. The tubes are incubated for one hour at 37, shaken thoroughly 

 and placed in the ice box over night. They should be shaken once or 

 twice during the period of 24 hours. They are then centrifugalized and 

 the supernatant fluids removed and used in the second part of the 

 experiment. 



3. Suspension of killed typhoid bacilli as in Experiment 1. 



4. Suspension of killed colon bacilli as in Experiment 1. 



5. Salt solution. 



(1) Titrate the original antityphoid serum against both typhoid 

 and colon emulsions according to the following protocol. This gives a 

 basis for comparison with a similar test on the same serum after it has 

 been in contact with the bacteria. 



1 To insure successful class work this must be previously ascertained in 

 each case, since individual animals may vary considerably in regard to the pro- 

 duction of minor agglutinins. 



