The instrument usually relied upon for this purpose is known as Bellocq's canula (Fig. 20). This little instrument consists of a hollow curved tube of metal fashioned somewhat like a Eustachian catheter, and bearing within it a flexible and adjustable metallic band which carries at its extremity an eyelet. Any one who has used the Eustachian catheter will recall the number of instances in which it could not be passed, or if passed the frequency in which great distress followed. If this be true of the Eustachian catheter, it is also true of the Bellocq canula, the difficulty in the case of the catheter, indeed, being the lesser of the two, inasmuch as the physician has a number of sizes to select from. Conceding, however, that the instrument (with a long stout thread passed through the eyelet of the stylet) has been placed in position in the nasal chamber, one end of the thread is seized within the mouth and brought out between the lips, while the other, carried by the instrument, is withdrawn through the nose and is allowed to hang from the nostril. The two ends of the thread are now tied firmly together, and a pledget of lint or cotton, fashioned somewhat after the shape of the posterior naris, is tied to the thread. Traction is now made upon the nasal portion of the thread until the plug is firmly lodged against and within the posterior naris. The remaining portion of the oral thread is now cut off close to the velum, and the free end of the nasal thread secured by adhesive plaster to the integument. The nostril should next be stopped from in front by pledgets of lint or absorbent cotton. The size of the nasal chamber and naso-pharyngeal varies so markedly that a rhinoscopic examination is of use in fixing upon the size of the plug. If it be too small, it will be drawn entirely within the nose, and possibly beyond the bleeding spot. If it be too large, it will partially or entirely occlude the posterior naris of the opposite side, and thus by interfering with nasal respiration greatly increase the distress, or by pressure against the Eustachian fossa and velum interfere with the hearing and with deglutition. The plug should be retained in position until a purulent mucus appears within the nose: this is usually about the third day. The plug now usually becomes a little loose, and can readily be withdrawn by pushing it back into the pharynx, where it is seized with forceps. Too long retention of the plug in position is followed by great fetor and the free formation of muco-pus--conditions which tend to debilitate the patient.