E. A. Watson 
183 
pure syphilitic antigen, the extract of a syphilitic liver was first used 
in Wassermann’s original method. But, later on, it was found that 
non-specific extract of normal liver and other organs answered equally 
well, and such are now commonly used. The reaction in syphilis is not 
accordingly a true and specific antigen-antibody combination and is 
dependent upon more or less gross changes in the serum of syphilitic 
patients. It is not to be compared, therefore, and is greatly inferior 
to our test method for dourine either in delicacy, specificity or 
trustworthiness. 
In conclusion, I venture to express absolute confidence in the 
complement fixation test for dourine as it is now presented, and to 
claim that apparent failures or discrepancies are due, not to the method 
itself, but to faulty technique on the part of the operators or of the 
collectors of the test serum. 
12—2 
