1. Allison, A. C., and Davies, P., in Mononuclear Phagocytes in Immunity, Infection and Pathology (edit. by van Furth, R.), 487–506 (Blackwell, Oxford, 1975).
2. Davies, P., and Allison, A. C., in The Immunobiology of the Macrophage (edit. by Nelson, D. S.) (Academic, London and New York, in the press).
3. Lay, W. H., and Nuzzenzweig, V., J. exp. Med., 128, 991–1009 (1968).
4. Huber, H., Polley, M. J., Luiscott, W. D., Fudenberg, H. H., and Müller-Eberhard, H. J., Science, 162, 1281–1283 (1968).
5. Da Silva, W. D., Eisele, J. W., and Lepow, I. H., J. exp. Med., 126, 1027–1048 (1967).