Summary
Early fibrin digests were analyzed in the ultracentrifuge and were found to contain compounds with molecular weights up to 3 x 106; these compounds are considered to be soluble fibrin complexes. Their similarity with intermediate polymers in inhibited clotting systems has been stressed. Their viscosity at low shear rates is extremely high; therefore, a rapid method to establish their presence in plasma would be the measurement of plasma and serum viscosity at low shear rates. Moreover, they shorten the clotting time (thrombin time) of fibrinogen considerably.