APPENDIX. 151 



complement), had used up all the complement, and 

 left none for the blood combination. 



If we were to repeat the whole experiment, but 

 leave out, in the first part of the test, say the spe- 

 cific typhoid serum, we should find that the blood 

 cells would be dissolved. This is readily under- 

 stood when it is remembered that then we would 

 have only typhoid bacilli and complement, two 

 factors which cannot ccmbine directly. The com- 

 plement would therefore be left free to act in the 

 blood combination. 



If hasmolysis occurs we may therefore conclude 

 that one of the factors in the first combination was 

 absent, and conversely, if haemolysis does not occur, 

 we know that the first combination must have 

 been perfect, i.e. all three factors must have been 

 present. 



It is at once apparent that in adapting this test 

 to the detection of syphilis antibodies, pure cultures 

 of the causative organism, i.e. of the " antigen," 

 were not available. Wassermann therefore made 

 use of extracts of syphilitic organs rich in spiro- 

 chaetes in place of the typhoid bacilli, and used 

 either the serum or the cerebrospinal fluid of the 

 suspected case in place of the typhoid antiserum. 

 The rest of the test was similar to that described 

 above. When hasmolysis of the sheep cells occured, 

 Wassermann said it showed that the first combina- 

 tion was incomplete; when haemolysis was com- 

 pletely inhibited, it showed, he said, that the first 

 combination was perfect ; i.e. that the serum or 



