“…A slide agglutination test has been used (34). Different products of the tubercle bacillus have been used (1, 5, 15,20,23,29,33,35,36) in attempts to make the test more specific, and modifications of the method of adsorbing antigens on the erythrocytes have included the use of tannic acid (37)(38)(39), inulin or trypsin (38), and treatment of the cells with Forssman antibody (30). In an effort to explain false negative reactions, "incomplete" or "blocking" antibodies have been looked for by the use of such diluents as pooled serum, 5 per cent bovine albumin, glycine solution, or polyvinyl pyrrolidone (30), and by the use of the Coombs antiglobulin technique (26,40).…”