contract when pinched, nor does it bleed when cut. If this type of tissue is evident, do not close the wound.  If the wound is deep, consider the support of the surrounding tissue; if there is not enough support to bring the deep fascia together, do not suture because dead (hollow) spaces will be created. In this generally gaping type of wound, muscles, tendons, and nerves are usually involved. Only a surgeon should attempt to close this type of wound. NOTE: To a certain extent, firm pressure dressings and immobilization can obliterate hollow spaces. If tendons and nerves do not seem to be involved, absorbable sutures may be placed in the muscle. Be careful to suture muscle fibers end-to-end and to correctly appose them. Close the wound in layers. This is extremely delicate surgery, and the Corpsman should weigh carefully the advisability of attempting it–and then only if he has observed and assisted in numerous surgical operations. If the wound is small, clean, and free from foreign bodies and signs of infection, steps should be taken to close it. All instruments should be checked, cleaned, and thoroughly sterilized. Use a good light and position the patient on the table so that access to the wound will be unhampered. The area around the wound should be cleansed and then prepared with an antiseptic. The wound area should be draped, whenever possible, to maintain a sterile field in which the Corpsman will work. The Corpsman should wear a cap and mask, scrub his hands and forearms, and wear sterile gloves. Suture Materials In modern surgery, many kinds of ligature and suture materials are used. All can be grouped into two classes: nonabsorbable sutures and absorbable sutures. NONABSORBABLE SUTURES.—These are sutures that cannot be absorbed by the body cells and fluids in which they are embedded during the healing process. When used as buried sutures, these sutures become surrounded or encapsulated in fibrous tissue and remain as innocuous foreign bodies. When used as skin sutures, they are removed after the skin has healed. The most commonly used sutures of this type and the characteristics associated with each are listed below.  Silkfrequently reacts with tissue and can be “spit” from the wound.  Cotton ¾loses tensile strength with each autoclaving.  Linen ¾is better than silk or cotton but is more expensive and not as readily available.  Synthetic materials (e.g., nylon, dermalon) are excellent, particularly for surface use. They cause very little tissue reaction. Their only problem seems to be the tendency for the knots to come untied. (Because of this tendency, most surgeons tie 3 to 4 square knots in each such suture.) Nylon is preferred over silk for face and lip areas because silk too often causes tissue reactions.  Rust-proof metal (usually stainless steel wire) has the least tissue reaction of all suture materials and is by far the strongest. The primary problems associated with it are that it is more difficult to use because it kinks and that it must be cut with wire cutters. ABSORBABLE SUTURES.—These are sutures that are absorbed or digested during and after the healing processes by the body cells and tissue fluids in which they are embedded. It is this characteristic that enhances their use beneath the skin surfaces and on mucous membranes. Surgical gut fulfills the requirements for the perfect sutureease of manufacture, tensile strength, and variety availablemore often than any other material.  Manufacture of catgut: Though it is referred to as “catgut,” surgical gut is derived from the submucosal connective tissue of the first one-third (about 8 yards) of the small intestine of healthy government-inspected sheep. The intestine of the sheep has certain characteristics that make it especially adaptable for surgical use. Among these characteristics is its uniformly fine-grained tissue structure and its great tensile strength and elasticity.  Tensile strength of catgut: This suture material is available in sizes of 6-0 to 0 and 1 to 4, with 6-0 being the smallest diameter and 4 being the largest. The tensile strength increases with the diameter of the suture. 4-42