164 MODERN BIOLOGIC THERAPEUSIS 



consists of a saline extract of liver from a 

 syphilitic fetus. The exact nature of the anti- 

 gen that produces the antibodies taking part in 

 the Wassermann reaction is unknown. Al- 

 though a pure lipoid cannot stimulate the pro- 

 duction of antibodies when used to inoculate an 

 experimental animal, it reacts outside the body 

 with the antibodies in the blood of the syphili- 

 tic. The Wassermann reaction is a lipotropic 

 reaction and is not due to the interaction of 

 specific antigen and antibody. An extract of 

 heart, liver or kidney in alcohol may be used as 

 antigen, and some serologists recommend the 

 addition of cholesterin to the alcoholic extract. 

 A safe and stable antigen is Noguchi's acetone 

 insoluble fraction of beef -heart, liver or kidney. 

 Practical Value Though biologically non- 

 specific, the Wassermann reaction is clinically 

 specific, except perhaps in cases of leprosy, 

 yaws, sleeping sickness and scarlet fever. A 

 positive reaction may be obtained in any stage 

 of syphilis but is most apt to occur in the sec- 

 ondary stage. A negative reaction at any stage 

 of the disease does not exclude the possibility 

 of syphilis. Antiluetic treatment, especially 

 mercury, frequently results in the reaction be- 



