Characteristic and constant in paretic neurosyphilis is the =Plasmocytosis and Lymphocytosis, Perivascular= in distribution about small cortical vessels. There is also a characteristic (though characteristically less prominent) =Plasmocytosis and Lymphocytosis, Meningeal= in distribution. The pleocytosis of the spinal fluid, almost constant though variable in amount in life, is an indicator of the meningeal picture and less directly of the parenchymatous picture. =Granular Ependymitis= (“sanding” of ventricle floors) is characteristic and may be regarded as part of the parenchymatous picture. This ependymitis is an indicator how chemical changes could be readily produced at least in the ventricular fluids, since the limiting membranes of the nerve tissue are here subject to multiple breaks. The “sanding” is a neuroglia reaction to these multiple small breaks (Weigert’s explanation). Parenchymatous losses have led to =Atrophy and Sclerosis=, of very varying extent in different parts of the encephalon. The atrophy is characteristic in paretic neurosyphilis, but by no means constant. Numerous cases have come to autopsy without clearly defined gross atrophy. Sclerosis is also characteristic and even more frequent than atrophy, doubtless because sclerosis represents an earlier phase of a process eventuating in gross atrophy. A =Tabetiform Picture= characterizes the spinal cord, but in this case the tabetic clinical picture did _not_ precede the paretic clinical picture. We are consequently to regard the tabetic spinal process as incidental and on all fours with the =Cerebellar and Pontine Atrophy=. =VASCULAR NEUROSYPHILIS (“syphilitic cerebral thrombosis”). Autopsy.= =Case 4.= James Pierce was an almshouse transfer to the Danvers Hospital in his fiftieth year. He died three years later. The accompanying brain pictures demonstrate so extensive a lesion of the left hemisphere that it is of great interest to determine if possible the genesis and course of his disease. It appears that syphilis had been acquired somewhere about the age of 38 or 40, so that the total duration of the process was between 13 and 15 years. In Pierce’s forty-third or forty-fourth year, he had a shock while walking in the streets of his native city, whereupon he was subsequently transferred to the Danvers Hospital, whose data have been summed up as follows (we are obliged to Dr. Charles T. Ryder for these data): =Neurological examination:= Neuromuscular condition: Barely able to walk or stand without assistance; hemiplegia of right side; swings foot out and drags toe out and around in attempting to walk. Right hand held by side, flexed at right angle; fingers contracted and thumb thrown across palm. Can lift arm from side; practically no movements of forearms or fingers; atrophy of deltoid, arm, forearm, and hand. Muscular movements of left upper extremities fairly well performed; good strength.