The trocar, inserted in the cannula, should be plunged quickly into the cavity at the site selected. Considerable resistance will be offered by the skin. If the trocar be small it is enough to anesthetize the skin; if large, a small incision will permit of its better use. The instrument makers have provided cannulas of various descriptions, to which tubing may be attached, so that the fluid may be conducted into a suitable receptacle, and wetting the patient avoided. It is well to draw the skin aside and not to make the instrument pass directly into the cavity to be tapped unless it contain pus and it be desired to keep it open. If this precaution is taken the skin will cover the deep opening after it slips back into its position, and will act as a valve to prevent leakage. In this way infection may be avoided. When fluid has ceased to be serous and has become purulent, as in empyema, it is often so thick that it will not flow through any hollow instrument. In such an event free incision should be made. When the thorax is involved incision is made between the ribs, and in order to maintain drainage a good-sized drainage tube should be inserted. This at times may be so compressed between the ribs that an inch or more of one rib should be exsected to provide against this possibility. TRANSFUSION AND INFUSION. Though much has been said concerning the indications for these procedures no explicit directions have been given. While they are often emergency measures they are, nevertheless, frequently practised. In well-regulated institutions the conveniences are always at hand for instant resort when needed; but it would be well for every general practitioner to have ready at all times the few things that are required, for at least hypodermoclysis. In country practice, however, a clean fountain syringe, a suitable aspirator needle (both carefully sterilized), some boiled water, table salt (when nothing else is at hand), and soap and water for sterilization of the operator’s hands and the patient’s skin are all that are necessary. In every outfit there should be a needle which may be used for this purpose. It may be carried in a glass tube, always sterilized, and ready for use. No fountain syringe should be used which has not been freshly boiled, except in an emergency. Tablets containing common salt in definite amount, so that a solution of given strength can be made by adding them to a definite amount of water, can be procured. With such a needle, a few tablets, and a fountain syringe the surgeon is prepared for any emergency. For intravenous infusion for which no pressure is required, an ordinary funnel, with rubber tubing attached, will be sufficient without the use of a rubber bag.