THE WASSERMANN TEST. 81 



Suppose that at this time all the tubes except No. 6 show complete 

 hemolysis. This one shows only partial hemolysis. This means 

 that one-twelfth of a drop of the inactivated blood serum of the rabbit 

 will be sufficient for complete hemolysis with the quantities used in 

 the test. It is customary to use in the final determining tests about 

 three times the minimum amount of rabbit's serum which will bring 

 about complete hemolysis. Hence, if the final determining tests are 

 arranged in the same proportion as the tests made to ascertain the 

 titre (or strength) of the rabbit's serum, one-quarter of a drop of 

 this serum would be used. 



5. It is now necessary to make another test by adding to ten 

 drops of a 5 per cent, washed sheep's corpuscles emulsion, diluted 

 with forty more drops of salt solution, one drop of rabbit's serum and 

 placing this tube into the incubator for several hours. At the end of 

 this time there must not be any hemolysis at all. This will show 

 that the rabbit's serum has been inactivated properly, and that it 

 contains no more complement, the latter has been entirely destroyed 

 and cannot interfere in the final test. The inactivated rabbit's serum 

 must be kept in the refrigerater, where it will keep for several months. 



6. Another necessary reagent is an extract which will contain 

 the antigen of the suspected syphilitic antibodies (or syphilitic ambo- 

 ceptor) the presence or absence of which in the blood serum to be exam- 

 ined is to be determined by the test. This antigen cannot be prepared 

 from a pure culture of the organism causing syphilis, because so far 

 it has been impossible to obtain it in pure culture. It can be pre- 

 pared, however, from the liver of a newborn child dead from con- 

 genital syphilis. This liver is cut up into small pieces and one part 

 by weight of liver is rubbed up very thoroughly with five parts of 

 absolute alcohol. The mixture is then shaken in a shake machine 

 for twelve to twenty-four hours, allowed to stand, then filtered and 

 the clear filtrate known as the alcoholic antigen extract is ready for 

 use. 



7. Complement deviation in the case of syphilis is not an abso- 

 lutely strictly specific reaction, which means that the syphilitic antigen 

 extract can be replaced by some other preparations which will do the 

 same work, and unite with the syphilitic antibodies and deviate the 

 complement. The substitute most commonly used in place of the 

 luetic antigen is an alcoholic extract of guinea-pig's heart, which is 

 prepared as follows: After the animal is dead the heart is removed, 

 washed in physiologic salt solution, dried between filter papers, and 

 weighed. The heart is then cut up, and the parts dropped into a 

 mortar which contains washed sterile quartz sand; add fifty times the 

 weight of the heart of 95 per cent, alcohol and triturate with the alcohol 

 and sand until the heart has been very finely divided. The entire mix- 

 ture is next removed from the mortar to a flask or other suitable glass 

 vessel and heated on a water bath for three to four hours at 60 C. 

 After cooling, the evaporated alcohol must be made up to the original 



