1. Friedberger, E., Z. Immunitaetsf., 2, 208 (1909).
2. Keysser, F., and Wassermann, M., Z. Hyg., 68, 535 (1911).
3. Bordet, P., C.R. Soc. Biol., 74, 877 (1913).
4. Nathan, E., Z. Immunitaetsf., 17, 478 (1913).
5. Dale, H. H., J. Pharm. Exp. Ther., 4, 167 (1913).