154 APPENDIX. 



pig serum is added, and the mixtures allowed to 

 remain in contact at 37 C. for one hour in order to 

 bind the complement. 



In this mixture we have antigen; w r e may or may 

 not have antibody; we have complement. 



If the antibody is present, the complement will 

 be anchored by the combination, and so be unavail- 

 able for the hasmolytic test next in order. If no 

 antibody is present, the complement will still be 

 free to act in the hasmolytic test. 



At the end of the hour, we add to the above 

 mixtures: one cc. of a 5% suspension of sheep 

 blood cells, and one cc. of the amboceptor dilution 

 containing double the solvent dose for that amount 

 of sheep blood cells. Thus, if the titer of the 

 haemolytic serum is 1/1800, we take one cc. of a 

 dilution 1/900. 



All the tubes are made up to the same volume 

 with normal salt solution, namely, to 5 cc.,and are 

 then placed in the incubator at 37 C. and kept 

 there for two hours. Then they are placed on ice 

 until the next day, when the results are noted 1 

 The whole procedure is clearly shown by the pro- 

 tocol from Wassermann and Plaut reproduced 0:1 

 page 155. 



Few experiments in immunity require such care- 

 ful technique, or are open to so many sources of 

 error as this serum test for syphilis. In view, 

 too, of the enormous responsibility assumed in 

 making a positive diagnosis of syphilis, it is appa- 

 rent that the test should only be undertaken by 



