Summary
A comparative survey of the blood coagulation mechanism has been carried out in man, non-human primates and carnivores. In man, the average rate of conversion of fibrinogen to fibrin by thrombin is slightly faster and the ability of plasma to neutralise thrombin is less than in the animal species. Otherwise, in general, the activity of the clotting mechanism in monkeys and carnivores is equal to or greater than that of man. These results do not explain the increased susceptibility to spontaneous cardiovascular disease seen in the human species.