The activators of blood clotting present’ in mammalian tissue, i.e. the agents responsible for the conversion of prothrombin to thrombm, have been shown to be lipoproteins of a very high particle weight (l-3). These substances readily form sediments in a strong centrifugal field (31,OOOg), but remain in solution when subjected to weaker centrifugal forces (5000g). The consideration of the manne...
