Salvarsan treatment was attended by the rapid disappearance of headaches and gastric symptoms and by a rapid gain in weight and feeling of well-being. Salvarsan was continued twice a week for two months, whereupon Lepère returned to work. He has been successfully at work now for seven months without return of symptoms. Four months after beginning of treatment, the spinal fluid was examined and found entirely negative. Nevertheless, the serum W. R. has remained positive despite eight months of salvarsan treatment. 1. What is the meaning of the titrations in the spinal fluid Wassermann reaction? When Plaut originally applied the Wassermann reaction to spinal fluids, he used 0.2 of a cc. of spinal fluid. With this amount of fluid he found that cases of general paresis gave a positive reaction in about 100% of the cases while this positive reaction was only given by 40 to 60% of the cases of cerebrospinal syphilis and tabes dorsalis, hence he promulgated a differential point that a negative reaction in spinal fluid indicated that the case was not general paresis. Hauptmann later showed that if 1 cc. of spinal fluid were used, a positive reaction would occur in practically 100% of the cases of general paresis, cerebrospinal syphilis and tabes. Therefore, at present, we use the different titers of spinal fluid from which we draw the following conclusions: If the reaction in the untreated case is negative with 0.1 and 0.3 of a cc. and positive with the 0.5, 0.7 and 1 cc. dilutions as in the case of Lepère, we are probably dealing with non-paretic neurosyphilis. With this method of titration we are also better able to watch the progress of treatment as the dilutions of 0.1 and 0.3 cc. become negative first. 2. How soon can one expect improvement after commencement of salvarsan therapy in cases of diffuse neurosyphilis? The time relation of results in treatment varies with each individual case. In the case of Lepère gastric symptoms that had been present for a number of months disappeared as if by magic after the first injection of salvarsan. As a rule, it is true that the more acute the symptoms the quicker their disappearance but this does not hold for all cases, as in this particular instance the long-standing symptoms disappeared very rapidly. The symptoms often disappear very much more rapidly than the laboratory, tests change.