Many theories have been advanced to explain the origin and mode of growth of pterygium. Arlt ascribes it to an erosion of the cornea at the scierai margin, which in healing pulls the conjunctiva into the cicatrix. Poncet found micrococci in some of his pathologic preparations, and regarded them in the light of etiologic factors. Theobald concluded that the long-continued action of the recti muscles, usually the interni, was the responsible cause. Mannhardt regardedepiscleritis as the promoting element.
None of the explanations, however, are entirely satisfactory. A thorough and critical examination of this subject has recently been made by Fuchs of Vienna, who after long-continued clinical and microscopic investigation concluded that a pterygium results from a pinguecula; that the hyaline degeneration which occurs in this pathologic product is continued on the adjoining corneal tissue over which the conjunctiva is pulled.
As many methods of operation have been introduced for the