Inferior tracheotomy is comparatively difficult to perform, and during its performance dangers may have to be encountered greater and more numerous {149} than those met with in either of the other operations. This is true certainly of children. As regards young children, Holmes states that after the age of five or thereabouts the surgeon can, if he prefer it, open the trachea below the isthmus of the thyroid gland. He himself does not recommend the operation before puberty. In the case, however, of a foreign body loose in the windpipe of a child, where a large opening is required, it can hardly be obtained above the thyroid body and below the cricoid. To cut through the isthmus of the thyroid (median tracheotomy) is, in early life at least, a doubtful proceeding when it is of large size, on account of its vascularity, and the incision must be made below it--in other words, an inferior tracheotomy. When the operation of tracheotomy shall be performed is a question which the experience and individual views of the surgeon, based on experience, must decide in each case. The doubt always arises in the mind of the inexperienced operator whether the symptoms are sufficiently urgent to render the operation necessary. To him these general rules may be given: The immediate indication for the operation is to be looked for in the thorax. It is the recession of the lower part of the sternum and contiguous ribs and the retraction of the intercostal spaces and clavicular fossæ at each act of inspiration. He must not wait until lividity of the lips and blueness of the fingernails prove that the blood is being imperfectly oxygenated (Mackenzie). Let him remember also that, aside from the immediate and imminent danger of sudden suffocation, a remote one exists and increases the longer he postpones his operation and allows the struggle for air to continue--viz. vascular engorgement and oedema of the lungs, especially in young children; the production of all those conditions which allow, and even predispose, the lung after the operation to fall an easy prey to the inflammatory processes. The instruments necessary for the performance of the operation of tracheotomy are few and simple, and are such as may ordinarily be found in any small operating-case. A scalpel, a probe and sharp-pointed bistoury, dissecting and artery forceps, a tenaculum, a grooved director, two small retractors, scissors, and a dilator for the tracheal wound, are necessary. To these may be added the needles and thread, waxed ligatures, sponges, and tape. The tracheal tube is elsewhere described. A faradic battery, good suction syringe, and a large flexible catheter may render good and timely service if at hand.