DEMONSTRATION OF AGGLUTINATION TEST 311 



solution. Only a sufficient quantity of the growth to give 

 a slight cloudiness to the salt solution in a small test tube 

 should be used. 



Note on Antigen. Where a series of agglutination tests are to 

 be made at intervals, the antigen should be standardized so that 

 the same concentration will be used for each test. Great care should 

 be used in preparing the antigen to avoid clumps in suspension. 

 In some cases thoroughly shaking in a shaking machine will afford a 

 satisfactory antigen, in others it must be filtered through a filter paper, 



FIG. 69. Macroscopic Agglutination of B. cholerce suis by Dorset- 

 McBryde-Niles Serum. From left to right tubes show, first, 

 complete agglutination, heavy sediment, clear supernatant 

 liquid; in each succeeding tube the sediment becomes less, the 

 turbidity greater, the tube at the right showing uniform cloudi- 

 ness and no sediment, no agglutination. (Orig. Giltner.) 



2. The antiserum may consist of immune serum a 

 rabbit immunized to the typhoid bacillus may be used to 

 furnish the serum , or hog cholera serum or virus may be 

 used with B. typhosus and B. cholerce suis respectively. 



3. The following table shows the various combinations 

 of serum, antigen and salt solution to give definite dilu- 

 tions. Physiological salt solution should be used in dilut- 

 ing the serum. 



