METHODS FOR CONDUCTING THE SYPHILIS REACTION 433 



with alcoholic instead of aqueous extracts of syphilitic liver as antigen. 

 It is true that this method is not an exact quantitative reaction, and 

 that it is probably less delicate than some of the modified methods, 

 but its advantages are that it is easy of manipulation, is readily 

 learned, and is especially recommended for persons who perform these 

 tests at irregular intervals, as false positive reactions are less likely 

 to occur than when the more delicate methods are used. 



Second Method. In this method the technic is essentially the 

 same as in the first method, except that three different antigens are 

 used instead of one, namely, cholesterinized extract of normal heart, 

 alcoholic extract of syphilitic liver, and acetone-insoluble lipoids. 

 This method has three advantages: (1) It permits the use of a choles- 

 terinized extract under conditions where any tendency to non-specific 

 fixation is to be controlled; (2) an antigen may at any time suddenly 

 become anticomplementary and yield false results, whereas by this 

 method the source of error is detected and may be avoided, since it is 

 not dependent upon any one extract; (3) an extensive study of the 

 comparative values of antigens has led to the distinct impression that 

 the lipodophilic antibody in different syphilitic serums frequently 

 shows a special affinity for the lipoids in a certain plain antigen more 

 than it does for those in another antigen; in fact, I have not infre- 

 quently found that, with weakly positive serums, if one antigen had 

 been employed, a false negative report would have been rendered, the 

 true reaction being given by the other two antigens. These results 

 could not be ascribed to faulty antigen, for with other weakly positive 

 serums the extract would be found to react satisfactorily. 



As previously mentioned, cholesterinized alcoholic extracts are 

 very sensitive, so that from this standpoint additional antigens would 

 appear to be superfluous. This very property, however, in my 

 opinion, renders it advisable to control them with less sensitive ex- 

 tracts. In this way all the advantages of a very sensitive antigen 

 may be secured, and the disadvantages avoided until more extended 

 use demonstrates whether or not it is entirely safe to use these extracts 

 alone. 



With strongly reacting serums all antigens possess equal antigenic 

 power. With the serums of long-standing or treated cases of syphilis 

 the cholesterinized extracts may react strongly positive, whereas with 

 the aqueous and the alcoholic extracts the reactions are weakly 

 positive, or negative with one and positive with the other. In cases 

 of syphilis that have received considerable treatment the reaction 

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