1. In the secondary and tertiary stages of
syphilis without direct involvement of the nervous system the cerebro-spinal fluid yielded the
butyric acid reaction of feeble intensity. The fluid under these conditions gave neither a positive cytodiagnosis nor the Wassermann test for
syphilis. 2. The cerebro-spinal fluid of cases of hereditary
syphilis showed a positive butyric reaction in about 90 per cent. and a positive Wassermann test in about 80 per cent. of the cases examined. 3. The cerebro-spinal fluid of cases of cerebral and spinal
syphilis yielded the
butyric acid reaction and the cytodiagnosis in every instance (100 per cent.) and gave the Wassermann reaction in from 50 to 75 per cent. of those examined. 4. The cerebro-spinal fluid from cases of
general paralysis gave positive
butyric acid reactions in 90 per cent., positive cell counts in 91 per cent., and positive Wassermann test in 73 per cent. of those examined. 5. The cerebro-spinal fluid from cases of
tabes dorsalis gave positive
butyric acid reactions and cell counts in 100 per cent. and positive Wassermann test in 53 per cent. of those examined. 6. The cerebro-spinal fluid from other forms of
psychosis in which a syphilitic history was not obtained gave positive
butyric acid reactions and cell count in 2.8 per cent. and Wassermann test in 13 per cent. of those examined. 7. The cerebro-spinal fluid from cases of acute inflammatory diseases of the meninges always gave a flocculent precipitate with the
butyric acid reaction but never gave the Wassermann test. 8. The cerebro-spinal fluid from persons suffering from
typhoid fever,
pneumonia,
pulmonary tuberculosis, etc., in which the meninges are not inflamed, gave neither the
butyric acid nor the Wassermann test. 9. We think it justifiable to conclude that the
butyric acid reaction affords a ready means of distinguishing normal from pathological cerebro-spinal fluid and will prove to be useful in routine clinical practice, especially in detecting syphilitic disease and in confirming or setting aside certain doubtful diagnoses of syphilitic or metasyphilitic lesions of the central nervous system. The reaction should commend itself as a valuable addition to the Wassermann test, the results of which it is capable of confirming and extending.