SYPHILIS 



103 



and you will have a pipette which will enable you to measure 

 I or 4 units of any fluid quickly and accurately. 



The Process. — Take i unit of the serum to be tested and 4 units 

 of normal saline solution and mix them in a small test-tube. 

 This is the control, to see whether there is sufficient complement 

 for the test, as is practically always the case with fresh serum. 



Take i unit of the serum and 4 units of the antigen, diluted 

 I in 10, and mix. This is the actual test. 



Incubate five minutes or more in the water-bath at 37° C, or 

 fifteen minutes or more in the ordinary incubator. Whilst this 

 incubation is going on, prepare the mixture of sensitized cor- 



FiG. 24. — Opsonic Incdeator modified to serve for the Wassermann 

 Reaction also. 



puscles by taking 4 parts of the amboceptor serum and i part 

 of the deposit of washed red corpuscles and mix. 



Now add i volume of this latter mixture to each tube. After 

 a few minutes, stir by sucking the mixture into the pipette and 

 expelling it again once or twice. If the corpuscles in any tube 

 are not practically completely dissolved, repeat this process after 

 a few minutes more. Allow to settle, and read off the result. 



In a negative test there will be complete, or almost complete, 

 haemolysis in both tubes. 



In a positive test there will be complete, or almost complete, 

 hemolysis in the first tube, and no haemolysis in the second. 



One of the advantages of this method is that there is very 

 little likelihood of technical error, the process being so simple ; 



