For _hypodermoclysis_ from 500 to 1000 Cc. may be employed; the anterior abdominal wall, the flank, the thigh, and the retromammary tissues are the best regions in which to inject the solution. Absorption will be assisted by gentle massage. Local anesthesia by the freezing spray, or by cocaine, will rob the procedure of its discomfort. Adrenalin may be added to the solution, whose formula is given above, in emergency cases where it seems to be especially needed. In instances where infusion is practised for the purpose of washing out the blood, _i. e._, in the acute toxemia of uremia, alcoholism, etc., nothing of the kind will be required; but in conditions of lowered blood pressure, _i. e._, shock, it will prove of great value, as already indicated. CATHETERIZATION. Catheters, as such, are intended for the withdrawal of urine from the urinary bladder, or for the introduction and withdrawal of cleansing fluids. They are made of metal, glass, gum, and silk, or other similar material, in various sizes, while some are specially formed or bent in order to pass more easily over the obstruction offered by a median prostatic enlargement. Various forms are sold in the surgical depots, from which the purchaser may make a choice. Next to the simple tubular forms the elbowed or Coudé catheters are of the greatest value. Catheters should be sterilized before use. Those used occasionally should be cleaned after use and dried, while those in daily use may be kept in an antiseptic solution after cleansing. The cleansing of a catheter should include not only attention to the exterior, but also removal from its bore of all clots, debris, etc. Some pressure behind the fluid used for this purpose is advisable. A clean metal or glass catheter may be sterilized in a flame just before use. All flexible catheters should be boiled just prior to their insertion, or they should be taken out of an air-tight receptacle in which they have been kept in contact with some antiseptic, or in an antiseptic vapor. For the latter purpose _paraform_ offers an excellent material, as there is given off from it formaldehyde vapor, which is a powerful bactericide. It comes in crystals and in tablets. Rubber catheters should be boiled in a 5 to 10 per cent. solution of ammonium sulphate. The urethra should also be cleansed, especially the meatus, in either sex. Cases of cystitis may be directly traced to infection introduced by a catheter, the result being the same whether the germs be not removed from the instrument or are carried in by it from the anterior urethra. This is particularly true in paralytics who have no power of expelling the urine, and in prostatics who need regular catheterization.