_Operation is contra-indicated in cases of bony atresia._ Although attempts have been made to make an artificial canal in order to restore the hearing power, a successful result has not yet been obtained. Apart from the difficulty of retaining the patency of any canal so made, the accompanying malformation of the middle ear renders a successful result impossible (Paper by author, _Journal of Laryngology, &c._, March, 1901). Although the tympanic membrane is said to have been exposed by operation in a few cases, experience has shown that the supposed tympanic membrane was really the capsule of the temporo-maxillary joint. (ii) _In acquired cases_ operation is indicated if the other ear is deaf; if the site of the occlusion of the auditory canal is in its outer part and is due to membranous or fibrous tissue, and if there is no previous history of middle-ear disease, and if the labyrinth is still intact. Operation is not advised if the other ear is normal, unless the patient particularly desires it. _Operation is contra-indicated_ if there is internal-ear deafness on the affected side and if the other ear is normal; or if there is a definite history of the closure of the auditory canal having been the result of a previous middle-ear suppuration. In the latter case the destructive changes within the tympanic cavity will be so marked that the chances of improving the hearing will be very slight in spite of the most successful operation. =Operation.= If the obstruction be due to a fibrous band, an attempt may be made to remove it by excising it by the intrameatal method. In other cases the post-auricular method is necessary. The chief point to remember is to make a large opening. For this reason the post-auricular method is to be preferred, as a considerable portion of the upper posterior wall can be removed and a large meatal flap fashioned (see p. 401). =Results.= If the stricture or point of occlusion of the auditory canal is limited and composed of membranous and fibrous tissues, a good result can be usually obtained, and there is no reason why complete recovery of hearing should not take place if the labyrinth and tympanic cavity are normal. Unfortunately, as in all cases of stricture, there is a tendency for it to recur. OPERATIONS FOR AURAL POLYPUS In this section only the aural polypi which project from the tympanic cavity into the external auditory meatus will be considered; whereas the treatment of granulations, and with them the minute polypi which are still limited to the tympanic cavity, will be discussed in the chapter on operations within the middle ear. =Indications.= An aural polypus should _always_ be removed because, apart from the fact that it is a symptom of underlying disease, it may obstruct free drainage of the purulent discharge, and therefore become a source of danger. =Operation.= The simplest and the best method is _removal by the snare_.