164 VETERINARY BACTERIOLOGY 



lysis would indicate that the organism had bound the amboceptor 

 and complement, and, therefore, was Bacillus typhosus in fact, 

 while hemolysis would indicate the reverse. The accompanying 

 figure will make this clearer. In carrying out a test of this 

 kind it is necessary to arrange a very complete series of checks. 

 When properly managed, the method is very accurate and has 

 yielded results of value in many cases. 



C. 



Fig. 77. Fixation or absorption of complement: A, Diagrammatic rep- 

 resentation of 1, Bacterial cell, a (B. typhosus in text), with antigen b; 2, 

 amboceptor for the antigen of (1) (the antityphoid serum); 3, normal com- 

 plement of the guinea-pig's blood with the haptophore c and the zymophore 6. 

 4, red blood-cell (sheep) with the antigenic receptors 6; 5, amboceptor from the 

 blood of the rabbit immunized against 4. B, 1, Bacterial cell -f amboceptor 

 + complement makes a complete lytic series; bacteriolysis occurs, and the 

 complement is removed from solution; 2, the red blood-cell + its amboceptor; 

 no hemolysis, as the complement has been used by the other series. C, 1, 

 Bacterial cell not B. typhosus, to which amboceptor (2) cannot unite, hence the 

 complement is not removed from the serum, and when the red blood-cells 

 and their specific amboceptor are added, a complete hemolytic system (3) is 

 formed and hemolysis occurs. 



This test has been most used in the diagnosis of syphilis, the 

 antigen being secured from a macerated syphilitic fetus and the 

 amboceptor from the blood of the suspect. This is known as the 

 Wassermann syphilis test. A similar test may be used for diag- 

 nosis in other diseases. The same method may be used also in 

 the differentiation of proteins. In this case the antigen used is the 

 protein, and the first amboceptor is in the serum of an animal 

 immunized against this protein. The method is even more reliable 

 than the precipitation tests already discussed, but is more difficult 



