Resultant upon operations performed for fistula in ano, I have had under my observation two cases presenting localized pyogenic cysts. I say cysts, because of the fact that, for a certain length of time, the secretion was not apparent, and when the cystic calibre was exhausted, there would be a flow of pus for several days, until it became encysted again. Since both of these cases were operated upon by incision, I have been constrained to express a preference for the ligature in the destruction, curatively, of fistulous canals.
The incised canal, with its continuity severed, is prone to heal too quickly to perfect the destruction of the pyogenic surface of the canal. On the other hand, the ligature, being drawn taut, approximates the internal and external orifices at once, strangulates, and apparently makes a deep fistulous canal seem to be a superficial one. Granulations supply the underlying pyogenic membrane