SERUM DIAGNOSIS 12 1 



If this hemolytic serum he heated, it loses its hemolytic 

 power, but it may be restored by the addition of a small 

 amount of normal serum from some animal of the same 

 species. Therefore, if red blood-cells be mixed with 

 their inactivated hemolytic serum (i. e., their hemolytic 

 serum which has been heated), and normal serum from 

 some animal of the same species as that from which the 

 hemolytic serum came be added, hemolysis of the red 

 cells will take place. Should there be immune bodies 

 for a certain germ in the added serum, the hemolysis 

 will occur just the same. If, however, there be immune 

 bodies for a certain germ present, and a pure culture of 

 that germ be added to it before it is mixed with the red 

 cells and their inactivated hemolytic serum, the germs 

 become attached to the immune bodies, so fixing the 

 constituents of the serum as to prevent its acting upon 

 the inactivated hemolytic serum to restore its hemolytic 

 power. Hemolysis, therefore, does not occur. 



In the Wassermann test for syphilis, red blood-cells 

 of the sheep are mixed with human serum which has 

 been rendered hemolytic for them and inactivated by 

 heat. The addition, now, of human serum from what- 

 ever source would, of course, activate the inactivated 

 serum, and hemolysis of the red cells would occur. The 

 serum which is to be tested for syphilis is mixed with 

 an extract of syphilitic fetal liver, pure cultures of the 

 syphilitic germ being unavailable, and then added to the 

 mixture of inactivated hemolytic serum and red cells. 



