478 THE TECHNIC OF COMPLEMEMT-FIXATION REACTIONS 



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 cento) (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 

 hemolyzed contains one amboceptor unit, and in performing the test double 

 this amount is used. (See Fig. 118). 



This titration should always be conducted before the actual tests 

 are set up, as is the rule in conducting the Wassermann reaction. When 

 the titer of the paper is known, it may not be necessary to set up all the 

 tubes of the foregoing series, as a few only are necessary to determine 

 if the same amount of paper as was used in the previous tests will suffice 

 with the new complement and corpuscle suspension at hand. 



All titrations and the main tests may be conducted in a water-bath 

 (37 C.). With the aid of a good thermometer a satisfactory bath is 

 easily improvised. In fact, I believe that better results are secured 

 in the water-bath than in the incubator. It is possible, therefore, to 

 conduct these reactions in a perfectly satisfactory manner without the 

 aid of an expensive incubator. 



4. Antigen. Acetone-insoluble lipoids (Noguchi) are to be used 

 exclusively if the tests are conducted with active serums. When heated 

 serums are used, any extract may be employed, as in making the Wasser- 

 mann reaction, but the same antigen gives excellent results, and I use it 

 exclusively in conducting the Noguchi reaction with both active and 

 inactivated serums. 



