Compared with the extensiveness of our knowledge of the clinical and pathologic involvement of brain, cord and coverings in syphilis, the facts relating to the contagiousness of spinal fluid, or, in other words, its spirochetal contents, are disappointingly meager. The earliest investigations are probably those of Uhlenhuth and Mulzer,1 who in 1913 reported negative results from the inoculation of rabbits with the spinal fluid from both early and late forms of cerebrospinal syphilis. A later observation by the same authors reported a positive inoculation from early cerebrospinal syphilis. Hoffmann2 produced experimental syphilis in a monkey with spinal fluid obtained from a case of early papular syphilis, and Nichols and Hough3 were successful in inoculating a rabbit from a case of acute cerebrospinal syphilis by intratesticular injection of spinal fluid. From this case they were able to grow successfully the organism. In nineteen cases of paresis, tabes and