There is no evidence for the change from transverse to longitudinal orientation hypothesized to explain X-ray and electron microscope structures. Dissolution of the clot through fibrinolysis to produce soluble products is difficult to reconcile with transverse cross-linking. There are flaws in the interpretation supporting transverse cross-linking of experiments with fibrin as a template and stretching. In summary, the strongest evidence from X-ray crystallography, fibrinolysis, and electron microscopy experiments favors the presence of longitudinal cross-links in fibrin.