MODIFICATIONS OF THE WASSERMANN REACTION 477 



broken up with difficulty and that interfere greatly with hemolysis. 

 With serums having a titer of 1 : 1000 or over, the agglutinins are not 

 so much in evidence; a satisfactory reaction is best observed, therefore, 

 with a potent amboceptor (1 : 1000) serum. 



The hemolytic serum may be preserved in 1 c.c. ampules after 

 adding an equal part of glycerin, and a stock dilution prepared and 

 titrated in the usual manner. The serum is also well preserved dried 

 on filter-paper, as described on p. 80. A trial titration should always 

 be made to determine the potency of the serum before the paper slips 

 are prepared. 



// paper amboceptor is used, the uniform rule of titrating it with the 

 complement and corpuscles on hand should be observed before the actual 

 tests are made. This is done chiefly because, where one guinea-pig 

 serum is used for complement, it may occasionally happen that the 

 serum is less active than usual, so that if fixed doses of complement and 

 amboceptor are used, the reactions may at times prove to be incomplete 

 and inaccurate. The process of titration is so simple that any one may 

 readily conduct it, and thus fulfil the most important requirement of any 

 complement-fixation test, namely, adjustment of the complement, 

 amboceptor, and corpuscles to one another. 



Titration of Serum Hemolysin. Prepare a 1 : 100 dilution by mixing 

 0.1 c.c. of immune serum (inactivated) with 9.9 c.c. of saline solution. 

 To a series of six small test-tubes add increasing amounts of this diluted 

 serum as follows: 



Tube 1: 0.1 c.c. amboceptor serum (1 : 100) +0.1 c.c. complement 



(40 per cent.) + l c.c. corpuscle suspension (1 per cent.). 

 Tube 2: 0.2 c.c. amboceptor serum (1 : 100) +0.1 c.c. complement 



(40 per cent.) + l c.c. corpuscle suspension (1 per cent.). 

 Tube 3: 0.4 c.c. amboceptor serum (1 : 100) +0.1 c.c. complement 



(40 per cent.) + l c.c. corpuscle suspension (1 per cent.). 

 Tube 4: 0.5 c.c. amboceptor serum (1 : 100) +0.1 c.c. complement 



(40 per cent.) + l c.c. corpuscle suspension (1 per cent.). 

 Tube 5: 0.8 c.c. amboceptor serum (1 : 100) +0.1 c.c. complement 



(40 per cent.) + l c.c. corpuscle suspension (1 per cent.). 

 Tube 6: 1 c.c. amboceptor serum (1 : 100) +0.1 c.c. complement 



(40 per cent.) + l c.c. corpuscle suspension (1 per cent.). 



Sufficient saline solution is added to the first tubes of the series to 

 bring the total volume up to 2 c.c. The tubes are then shaken gently 

 and placed in the incubator at 37 C. for two hours (or one hour in 

 water-bath at the same temperature), during which time they should be 

 inspected and shaken gently several times. At the end of the period of 

 incubation that tube which shows just complete hemolysis contains one 



