no IMMUNE SERA 



ceptors and then exposed them to the action of a 

 freshly drawn normal serum. After several min- 

 utes the red cells were, of course, completely haem- 

 olyzed by the complement. They now prepared 

 an anti-cholera serum and with it sensitized some 

 cholera bacilli. If now, there was any complement 

 remaining in the tube which contained the haemo- 

 lyzed cells, then the sensitized cholera bacilli should 

 dissolve if placed in the same tube and the existence 

 of at least two separate complements would be 

 proven. If, on the other hand, the red cells had 

 taken up all the complement, the cholera bacilli 

 would not dissolve, and therefore tend to prove that 

 but one complement existed in that normal serum. 



Their experiments seemed to prove that there 

 was but one complement present, inasmuch as 

 it made no difference which combination was 

 allowed to act on the complement first; in either 

 case the combination first added absorbed all of 

 the complement and therefore the second found no 

 complement remaining upon which to act. 



Realizing that complement is absorbed only when 

 an antigen (page 88) combines with its specific anti- 

 substance, the absorption of complement by an 

 antigen and an unknown serum indicates that the 

 serum contained antibodies for the particular antigen 

 used. This reaction may therefore be employed as 

 a test for various antibodies by using the necessary 

 antigens. 



