286 Wassermann Reaction for Diagnosis of Syphilis 



Five per cent, suspen- Normal guinea-pig Hemolytic rabbit Result (final readings 



After the reagents are added, enough 0.85 per cent, salt solution 

 is added to each tube to bring the total bulk of the mixture up to 



5 CC. 



From the results shown in the tubes it is evident that the hemolyz- 

 ing quantity of the rabbit serum lies between 0.0005 ^^d 0.0003 

 CC, and is probably 0.0004 cc. To be as accurate as possible, a 

 second series of experiments should be made with 0.0005, 0'0004S) 

 and 0.0004 CC, so that the proportion of amboceptor serum neces- 

 sary to effect hemolysis be known within small limits. This least 

 quantity, that will certainly cause hemolysis in two hours at 37° 

 C., is known as the unit. The combination of the unit of corpuscular 

 suspension (i cc), the unit of complement (o.i cc), and the unit 

 of hemolytic amboceptor is known as the hemolytic system. 



As soon as this unit is known accurately, we are in position to 

 reverse the conditions of the test. Thus, if we should desire to know 

 how much variation there may be in the complements from different 

 animals under different conditions of age, feeding, health, etc, we 

 can now do so by determining whether, when i cc. of the corpuscles, 

 I unit of amboceptor and varying quantities of complementary 

 serums are combined, any variation in the final results will obtain. 



Or, if we desire to know to what extent the sheep corpuscles may 

 change through prolonged keeping or other manipulation, it can 

 be done by maintaining the unit of amboceptor and the unit of 

 complement and adding larger or smaller quantities of the corpuscles. 



The conditions under which the unit of amboceptor is titrated 

 constitute the standard conditions of the Wassermann reaction. 

 In it are always employed i unit of sheep corpuscle suspension, i 

 unit of complement, and i unit of amboceptor. Here, however, a 

 slight difference of opinion is reached, it being argued by many experi- 

 menters that such exact proportions may make the test uncertain, 

 because, should there be the slightest tendency on the part of the 

 remaining reagents to inhibit hemolysis by means other than comple- 

 ment fixation, it would result in positive readings where the final 

 result should be negative. To overcome this possibility, they dif- 

 ferentiate between the amboceptor unit and the amboceptor dose, 

 the latter being commonly twice and sometimes four times the 

 unit. 



Now, though the amboceptor unit is determined by the method 

 given, it by no means follows that those proportions are the only 



