I. The results obtained by the French method appear to show a fairly consistent increase in cells throughout this study.2. Seventy-six cases of dementia paralytica out of seventy-seven showed a lymphocytosis. Differential counts did not aid materially towards diagnosis. One case of clinical paresis was cytologically negative. Three cases of tabes dorsalis were cytologically positive. Two cases of cerebral syphilis showed a slight increase in cells.Ninty-three per cent of the cases of dementia paralytica gave a positive increase in globulin. One case of tabes dorsalis and one of cerebral syphilis gave a negative globulin reaction.3. Korsakoff’s psychoses show practically no increase in lymphocytes of albumin.4. Eighty-nine per cent of the epileptics showed abnormal increase in lymphocytes, at the same time no case of epilepsy gave an increase in globulin.5. The diagnostic value of lymphocytosis in spinal fluids in cases of manic depressive insanity and dementia præcox still remains unexplained although there is no reason why those individuals may not become infected with the syphilitic virus. The five cases which showed a positive cell count and a positive increase in globulin also gave a positive history of acquired syphilis.6. Two of three cases of traumatic psychoses gave a lymphocytosis but a negative globulin reaction.7. Four out of five cases of senile symmetrical atrophy gave negative results throughout.8. Two out of four cases of cerebral arteriosclerosis of nonsyphilitic genesis gave a mild lymphocytosis but a negative butryic acid reaction.9. Morphinism and acetanilidism gave a lymphocytosis without increase in the globulin content, except in one case where there was a question of paresis.I am indebted to the kindness of Dr. William Mabon, superintendent of Manhattan State Hospital, for the opportunity of making this study, and to Dr. George H. Kirby for his most valuable assistance and encouragement in the division of the work.