Failing the syringe described, a 10 c.c. Record syringe will be found to be quite efficient, if suitable needles can be obtained. The syringe, needles, and glass measure for the solution should be boiled in plain water or normal saline, as soda interferes with the action of the drug. TECHNIQUE OF INJECTION.--The needle is introduced into the subcutaneous tissue, and pushed on slowly to its full length, the fluid being injected as the needle advances. The needle is then partly withdrawn, and pushed in in a different direction so as to infiltrate a fresh area. This procedure is repeated, and as wide an area as possible infiltrated from the one puncture. The needle can then be completely withdrawn and introduced at a fresh point which has already been rendered analgesic. The deeper tissues can nearly always be infiltrated from the surface, but if large blood-vessels traverse the region to be infiltrated, it may be necessary to defer the deeper injection until these have been exposed. It is wise to infiltrate wide of the intended line of the incision, since it is not possible to anticipate with certainty the extent of an operation until it has been commenced. The secret of successful anæsthesia is to employ plenty of the solution, and make the injection thorough. The skin over the area becomes blanched within a few minutes of the injection owing to the action of the adrenalin. Anæsthesia is not usually complete until ten minutes have elapsed, and the operation should not be commenced until it has been made certain by suitable tests that the anæsthesia is complete. The duration of the anæsthesia is usually at least an hour and a half. It will be seen that the injection in the manner described above is entirely subcutaneous, the pain-conducting nerves from the skin being caught up by the drug as they traverse the superficial fascia in the area infiltrated. This method usually gives complete satisfaction, but some surgeons advise that the infiltration should be commenced with an _intra-dermal_ injection so as to reduce the pain of the needle punctures to a minimum. A fine needle is employed, the prick of which is practically painless. If the skin at the selected point is pinched up between the finger and thumb, and held firmly, this lessens its sensibility. The needle is advanced beneath the epidermis with a quick but light thrust. The injection into the substance of the skin causes a distinct wheal, which stands out from its surroundings like an urticarial wheal. From this starting-point a long needle can be introduced into the deeper tissues without pain. The intra-dermal injection may be carried along the whole length of the area to be infiltrated, each fresh puncture being made in the margin of the wheal-like area already anæsthetised.