The principles relating the lysis times of fibrin clots to their contents of fibrin, plasminogen and plasminogen-activator were investigated. Mathematical considerations suggested that the square of the lysis time should correlate linearly with the fibrin content, and inversely with the activator and the plasminogen contents of the system. Experimental studies, during which these parameters were independently varied, showed that the predicted relationships were valid for concentrations that gave clot-lysis times in the range normally used for studies of fibrinolysis.
