We made a diagnosis of CEREBROSPINAL SYPHILIS rather than general paresis on account of, first, the slow course of the disease; second, the vascular type of the cerebral insult, hardly typical of paresis; and third, the mild spinal fluid reaction. Treatment will hardly cure the hemiplegia, at least so far as restoration of cerebral tissues lost in the insult is concerned. We were perhaps entitled to consider that, as in the cases of Petrofski (17), O’Neil (19), Robinson (45), the meningitic process could be arrested. Unfortunately, our treatment of 20 injections of salvarsan over a period of 10 weeks, followed by a number of months of bi-weekly injections of mercury salicylate, proved incapable of making any change in the mental and physical picture or in the laboratory findings. 1. Can we explain the apparently poor reaction to treatment of the cerebrospinal syphilis in the case of Jackson by supposing a more deep-seated involvement than the meningovascular involvement indicated by the hemiplegia and the signs in the fluid? Autopsied cases in our experience show focal parenchymatous involvements that have not caused obvious clinical symptoms at any time during the course of the disease. These symptomatically silent lesions may have been present. 2. What is the comparative prognostic value of seizures in paretic neurosyphilis and in such a meningovascular case as that of Jackson? Paretic seizures are often and indeed characteristically recovered from. Moreover, autopsies in paretic neurosyphilis characteristically show no gross focal destructive lesions to correspond with the seizures. The paretic seizures are apparently more irritative than paralytic. However, the seizures of the meningovascular group of neurosyphilis are also, though less commonly, recovered from, so that the differential diagnosis on the basis of the outcome of seizures is not safe. Rarely paretic neurosyphilis itself also develops seizures from which no recovery is made.