ALLINGTON1 described a method in which a fibrin gel is ultimately formed by dilution of a urea solution of fibrin monomer. Some investigators may prefer to have the original gel structure formed consequent to the action of thrombin on fibrinogen, so it should be noted that a simple charcoal adsorption procedure is highly effective in the removal of plasminogen from a variety of human and animal fibrinogens, including commercially available ones2–6.

Fibrin clots exposed to mixtures of plasmin with appropriate levels of ϵ-amino-n-caproic acid, lima beam trypsin inhibitor, or soybean trypsin inhibitor underwent greater lysis, after washing and further incubation with buffer only, than did clots exposed to plasmin alone. The destruction of plasmin by antiplasmin was antagonized by the bean inhibitors, but was potentiated by ϵ-amino-n-caproic acid.