SPIROCHuETA PALLID A. 209 



immunity against a second has been a long known clinical 

 doctrine. 



Diagnosis. Wassermann Reaction. The finding of the tre- 

 ponenia in the lesions constitutes the best means of diagnosis 

 at our command. In the absence of this proof recourse has 

 been had of late years to a reaction based on the principles 

 enunciated by Bordet and Gengou, elaborated by Wassermann, 

 and altered and simplified by Noguchi and others. We have 

 learned that when infection has taken place or when certain 

 substances are injected, that antibodies or amboceptors specific 

 for the cause of the infection or for these substances are pro- 

 duced in excess. We have also learned that in the presence 

 of complement or alexin union will take place between ambo- 

 ceptors and their specific poison or antigen. The complement 

 is necessary in the union and is utilized in its consummation. 



Given then a known antigen (made of syphilitic material) 

 and a known definite complement, we can tell, by the addition 

 of an unknown serum and proper incubation, whether the un- 

 known serum contains the specific syphilitic amboceptors. If 

 it does, the union will take place between the amboceptors 

 and the antigen, and the complement will be consumed in 

 bringing this union about. The complement will, therefore, 

 not be available for future use. If the specific amboceptors 

 are not present in the unknown serum, no union is possible 

 between the complement and antigen. Complement, there- 

 fore, will still be free and available for further use. The 

 positiveness or negativeness of the above reaction is demon- 

 strated by making use of a hsemolytic reaction in which com- 

 plement, of course, is needed. If the reaction has been pos- 

 itive, no complement will be available and no haBmolysis will 

 take place. If negative, the complement will enter the 

 hsemolytic combination of complement hsemolysin corpuscles, 

 and haBmolysis will take place. The technique, as given by 

 Noguchi, is briefly as follows : Seven small test-tubes are 

 used, and contain the following: 



Tube 1. 1 drop patient's serum + complement 4- antigen. 



Tube 2. 1 drop patient's serum + complement (no anti- 

 gen). 



14 M. B. 



