SEVERAL discoveries over the past 15 years have progressively led to the recent suggestion that metals of low work function (high in the electromotive series) would not thrombose on implantation into the aorta or vena cava when used as a prosthetic vessel replacement. A series of experiments based on the above hypothesis has recently been completed. The results appear to confirm the postulate which may now, perhaps, be dignified by the term "theory." Historically, several of the more important experiments which led to the hypothesis were: 1. Abramson's classical experiments in 1927 to 1942 in which he quantitated the electrophoretic characteristics of blood cells of several mammalia and showed that these all had a negatively charged surface and moved toward the positive pole in an electrophoresis apparatus.1,2 2. The discovery that with onset of thrombosis the normal polarity of an electrode pair, placed across blood vessel wall, reversed. Normally,