The following is a report of a series of investigations made to determine whether the patient's blood could be collected on filter paper, dried, and used in the complement-fixation test for syphilis. This procedure was attempted for the following reasons: less blood is necessary, which is especially important with children; the outfit for the collection of blood is simple and inexpensive; the risk of the specimen being spoiled by bacterial contamination or by the things which usually produce hemolysis might be eliminated, and in addition the specimens might be preserved for a long period of time with little deterioration. Noguchi,1 in his modification of the Wassermann test, made use of the hemolytic amboceptor on such paper, with practical success. Can the substance present in the blood of persons with active syphilis dried on paper be preserved in a like manner? If so, can such a test be standardized so that