If a patient be doomed to wear a tube constantly in his trachea, the instrument described above can be removed at a suitable interval after the operation and its place supplied by a single tube of the same size and form as has been found adapted in the case. In the convexity of this permanent tube an ovoid opening should be made to allow of the passage to the larynx of the respiratory current, in part at least, and to its mouth a pea-valve may be fitted which shall admit air on inspiration, and not allow it to escape on expiration, thus doing away with the necessity of the patient's closing the opening of his tube with his finger each time that he requires to speak. Several forms of these valves have been devised, but practically they are of little use, are annoying to the patients, and, as a rule, not tolerated by them. How shall the operation of tracheotomy be performed? An answer to this question necessitates a short description of the operative steps of the different procedures that is given in the order in which, I believe, the operations are, as a matter of experience, found to occur in practice--viz. 1st, superior {153} tracheotomy, combined or not with cricotomy; 2d, thyro-cricotomy and, 3d, inferior tracheotomy. Certain preliminaries are common to all. The patient should be extended upon a table covered with one or two thicknesses of blanket and of suitable height, which has been placed sideways in front of a window if the operation is done by daylight. (At night several candles tied together afford a better and safer light than a kerosene or oil lamp.) The surgeon stands at the right side of his patient and facing the window. Of his two assistants--and the value of trained assistance in this operation is inestimable--one faces him, without obscuring the light, and is prepared to use the sponges, hand the instruments, manipulate the retractors, and render such direct assistance as may be required. The second sits at the head of the table and holds the head of the patient steadily, the neck being well extended and thrown backward over a small round pillow (or, better, a wine-bottle wrapped in a towel) which has been placed beneath it. The head must be held directly in the median line of the patient's body, and even in that of the operating-table. The assistant's attention must never waver from this important duty. In certain cases too great inclination of the head backward serves to increase the urgent dyspnoea, or even to check respiratory efforts. This effect he must watch for, and be prepared to relieve instantly by raising the head. His duties also include the preliminary administration of an anæsthetic, and its use during the operation if required. That such use is safe in this class of operations is now generally admitted, but it is not always necessary. The operation is not an exceedingly painful one, and I have often performed it, with the adult patient's consent,