1. Ardlie, N. G., G. Glew, and C. J. Schwartz: Nature (Lond.) 212, 415 (1966).
2. Born, G. V. R.: Ann. roy. Coll. Surg. Engl. 36, 200 (1965).
3. -- D. C. B. Mills, and G. C. K. Roberts: J. Physiol. (Lond.) (in the press) (1967).
4. Haslam, R. J.: In: Symposium on Physiology of Haemostasis and Thrombosis (Detroit 1966). (Ed. Johnson, S. A., and W. Seegers). Springfield, Ill.: Ch. C. Thomas (in press) (1966).
5. O'Brien, J. F.: J. clin. Path. 17, 275 (1964).