Several years ago, while making many routine examinations of spinal fluid it was occasionally disconcerting to find one which had a normal cell count, negative globulin reaction and yet which gave a positive Wassermann test. In checking them up, it was found that the individual making the cell counts had, at times, introduced a small amount of acetic acid into the specimen of spinal fluid. The technic employed was that of drawing glacial acetic acid into a white blood pipette and then blowing the excess of acid from the pipette. The spinal fluid was then drawn into the pipette, the small amount of acid which remained in the pipette being sufficient to differentiate the white cells for counting. When a small amount of fluid was withdrawn from the main bulk and used only for the Wassermann test the difficulty cited above was no longer encountered.