APPENDIX. !57 



the resulting precipitate and clear fluid separately. 

 It was found that the substance concerned in the 

 reaction was soluble in alcohol,- and the authors 

 thereupon made alcoholic extracts of the syphilitic 

 organs. These worked satisfactorily in making the 

 test. It was natural to think that the substance 

 which effected the reaction might be related to the 

 lipoids, and so the authors next studied the be- 

 havior of alcoholic extracts of normal human and 

 animal organs. While these extracts also sufficed 

 to produce the reaction, it was evident that they 

 were not as active as extracts from syphilitic 

 organs. After it had been found that alcoholic ex- 

 tracts could be used for the test, a number of 

 authors almost simultaneously published favorable 

 results with chemically defined substances. Forges 

 and Meier used lecithin, Levaditi glycocholate of 

 soda, Sachs and Altmann oleate of soda, and 

 Fleischmann even used vaseline. The last-named 

 also used cholesterin with favorable results, but 

 Forges and Meier obtained only negative results 

 with this substance. On the whole, however, it 

 seems that the extracts, especially of syphilitic 

 organs, give the most uniform results. 



At the present time, therefore, Wassermann be- 

 lieves that the really active principle in the antigen 

 may be a combination of lipoids with certain protein- 

 like substances, and that the latter component, 

 when it is derived from syphilitic material, has 

 something of a specific character. In this connec- 

 tion Wassermann refers to the researches of 



