452 THE TECHNIC OF COMPLEMENT-FIXATION REACTIONS 



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 tne period of 

 incubation that tube which shows just complete hemolysis contains one 

 amboceptor unit, and double this amount is used in making the main 

 tests. If the serum has a titer of less than 1 : 500, it should not be used 

 either in preparing the amboceptor slips or in- conducting the reaction. 



Titration of Dried Amboceptor Paper. After the paper (S. & S. No. 

 597) has been evenly saturated with immune serum and dried, the sheets 

 are cut into 5 mm. strips and standardized by placing increasing lengths 

 of paper into a series of tubes as follows : 



Tube 1: 1 mm. paper +0.1 c.c. complement (40 per cent.) (5 drops) 



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

 Tube 2: 2 mm. paper+0.1 c.c. complement (40 per cent.) (5 drops) 



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

 Tube 3: 3 mm. paper+0.1 c.c. complement (40 per cent.) (5 drops) 



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

 Tube 4: 4 mm. paper+0.1 c.c. complement (40 per cent.) (5 drops) 



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

 Tube 5: 5 mm. paper+0.1 c.c. complement (40 per cent.) (5 drops) 



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

 Tube 6: 6 mm. paper+0.1 c.c. complement (40 per cent.) (5 drops) 



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



One cubic centimeter of saline solution is added to each tube, and 

 the mixture shaken gently and incubated at 37 C. for two hours or 

 one hour in a water-bath. At the end of this time the tube just completely 



