224 The Philippine Journal of Science 1923 



performed and the minimal fixing dose of serum established a 

 second time, shortly after clinical cure, and again some months 

 later when several of them had become negative. Table 2 gives 

 a summary of these cases and the clinical results of treatment. 



In Table 3 are tabulated the results of the test before treat- 

 ment on these twelve cases and the effect of treatment on the 

 complement-binding strength at intervals afterward. 



It is evident from Table 3 that, during the first month 

 after treatment, there is a rapid fall in complement-binding 

 strength with lipoidal antigen, then a more-gradual weakening 

 over a period of several months until in the majority of cases 

 the reaction becomes negative with 0.1 cubic centimeter, or 

 the standard dose of serum. Several of these cases received 

 a second injection of neosalvarsan but always in about two 

 weeks after the first, so that the initial rapid diminution 

 in strength of the serum in the first month may have been due 

 to the repeated treatment. Nevertheless, the Wassermann re- 

 action with 0.1 cubic centimeter of serum was still strongly 

 positive a month or more after the first injection, and two or three 

 weeks after clinical cure in several instances, and in seven of the 

 twelve cases was still positive five months after the first injec- 

 tion. The fact is established that clinical cure is not coincident 

 with disappearance of positive reaction ; but, in our studies, the 

 serum gradually, within a period of several months, became 

 negative in seven of the twelve cases and much weaker in the 

 others, following clinical cure and without further treatment. 



The rapidity with which a positive serum becomes negative 

 in a general way seems to depend on the degree of complement- 

 fixing strength with lipoidal antigens present in a particular se- 

 rum before treatment, although there are exceptions to this even 

 in our small series. If we compare the six weakest sera with the 

 six strongest we find an average minimal fixing dose for the 

 former of 0.0071 cubic centimeter, and for the latter 0.0026. 

 One month after treatment the corresponding figures are 0.053 

 and 0.023. In five months we find in the first group three 

 negative sera and three weakly fixing sera, and in the second 

 group two negative, two strongly positive, and two weakly 

 fixing. 



We judge from this behavior of the Wassermann reaction that 

 a positive test following clinical cure does not necessarily in- 

 dicate persistence of the infection, but may rather be due to a 

 gradual process of elimination by the body of substances upon 

 which a positive reaction depends; and, since the majority of 



