SummaryNormal whole blood was allowed to stand in glass tubes at 37° C, and the clotting process stopped at various intervals by the addition of sodium oxalate. During the first 15 minutes a marked acceleration of clotting activity was found. Study of the individual coagulation factors showed the following changes: a sustained and rapid fall in platelet count, a sustained and rapid rise in PTC (factor IX), a steady fall in fibrinogen, a more gradual fall in AHF (factor VIII), a rapid rise and subsequent fall in proaccelerin (factor V) activity, a somewhat lesser and slower rise and fall in proconvertin (factor VII) activity, and a slow fall in prothrombin concentration. No changes were noted in Hageman factor or PTA activities.
