The lacrimal sac is subject to acute and to chronic inflammation. The primary lesion in either condition is usually not in the sac but in the nasolacrimal duct in the form of an obstruction. On account of the obstruction of the duct there is interference with the normal flow of tears through the sac. The tears, with their bacterial content, are retained, and inflammation follows in the sac. The contents of the sac are augmented by a mucopurulent secretion from the inflamed mucosa; then the sac becomes dilated and the walls thickened. The distention is known as a mucocele. The enlarged sac forms a visible and palpable tumor below the inner end of the lower eyelid. Pressure on this will usually cause regurgitation into the conjunctival sac or, less often, into the nose. Irrigation of the sac through the punctum and the canaliculus causes the contents to be washed into