PRACTICAL APPLICATIONS OF METHOD 199 



adding a small amount of fresh guinea pig complement. After these 

 materials had been together for a certain time, sensitized red blood 

 cells were added. If the complement was bound during the first 

 exposure no hemolysis resulted and the reaction was regarded as 

 positive. From their results they drew the following conclusions : 



1. Immune serum from monkeys, produced by treatment with 

 syphilitic material, will sensitize syphilitic material from human 

 beings or monkeys, so that an alexin-fixing complex is formed. 



2. Complement fixation results only when the syphilitic immune 

 serum of monkeys is added to similar material from men or mon- 

 keys, but not when added to organ extracts of normal men or mon- 

 keys. 



3. Normal monkey serum has no such action. 



They concluded that their results justified them in assuming a 

 specific fixation due to specific antisyphilitic immune bodies in the 

 blood of the treated monkeys. They excluded experimentally the 

 possibility of fixation by a precipitin reaction resulting from the 

 treatment of the monkeys with human material. It might well have 

 happened that precipitins against human protein appearing in the 

 serum of the treated monkeys might subsequently react with the 

 human protein material used as antigen, a complement-fixing com- 

 plex resulting. This, however, was excluded by the fact that they 

 obtained positive reactions only when the human material was ob- 

 tained from luetic lesions. 



The same authors, with Schucht, 6 very soon after this, extended 

 their method to the diagnosis of syphilis in human beings. The 

 same thing had been done shortly before their publication appeared 

 by Detre 7 on a smaller material. By these and many other investi- 

 gations it was very soon shown that syphilis may be reliably diag- 

 nosed by complement fixation when extracts of the syphilitic organs, 

 employed as antigen, are mixed with the inactivated serum of syphi- 

 litic individuals. It was incidentally shown by Wassermann and 

 Plaut 8 that the reaction could be obtained not only with blood serum 

 but also with spinal fluid in paralytic cases. 



It was generally assumed, at this time, that the reaction in syph- 

 ilis depended, as in the case of other infections, upon the presence in 

 the syphilitic serum of specific antibodies. For it seemed reasonable 

 to suppose that the specific antigen obtained in the extracts was de- 

 rived from the extraction of large numbers of spirochetes demonstra- 

 ble in the extracted organs. 



This, of course, is the most logical and simple theoretical concep- 

 tion of the reaction, and is justified on the basis of analogy. Un- 



6 Wassermann, Neisser, Bruck, and Schucht. Zeitschr. f. Hyg., Vol. 55, 

 1906. 



7 Detre. Wien. kl WocU., Vol. 19, No. 21, 1906. 



8 Wassermann and Plaut. Deut. med. Woch. } No. 44, 1906. 



