tourniquet (tight enough to impede the venous return of blood to the trunk, yet loose enough to allow arterial supply to the extremity) will further delay systematic absorption of the poison. Place a tourniquet between the bite and the heart, about 2 inches above the bite. A tourniquet should only be used if competent medical help is reasonably expected to take over management of a snakebite victim. 2. Clean a knife or razor blade and the fang marks by daubing with antiseptic, if available. 3. Make a small cut over each fang mark (deep enough, one-fourth of an inch or more, to penetrate the skin). Orient each cut parallel to vital structures (generally parallel to the long axis of the limb). 4. Apply suction. Suction can best be applied by mouth, but not if there are open oral lesions present. In this case, some other means of applying suction must be found. After 30 minutes, suction is of little benefit. CARE OF WOUNDS.— Open wounds are a serious hazard in a survival situation, not only because of the tissue damage and blood loss, but also because of the increased possibility of infection. Little can be done to prevent wound contamination at the time of the injury. Proper wound care can minimize further contamination and promote healing and preservation of function in the injured part. . Clothing should be cut or torn away from a wound; drawing clothes over the wound may introduce bacteria into the wound. l Whenever possible, avoid touching the wound with fingers or any unsterile object. All water and instruments used in wound care should be sterilized by boiling. Washing your hands before you treat any wound is very important in keeping down infection. . Clean all wounds as soon after occurrence as possible. Only antiseptics especially designed to use in open wounds should be used directly in the wound. NOTE: Common antiseptics such as Mer- thiolate, iodine, and Mercurochrome should never be applied directly to a wound. These solutions destroy only part of the bacteria and actually damage the exposed tissues. . When cleansing solutions for wounds are not available, a suitable substitute may be a poultice made of fern root. To prepare a poultice, you boil finely chopped roots in water until syrupy. Allow the poultice to cool and apply directly to the wound. . The “open treatment” method is the safest way to manage wounds in a survival situation. No attempt should be made to close a wound by stitching. The wound should be left open to permit drainage of pus from infection. As long as a wound can drain, it generally will not become life threatening. If a wound is gaping, the edges can be brought together with adhesive tape cut in the form of a butterfly or dumbbell. When a butterfly bandage is applied properly, only a small portion of the adhesive is in contact with the wound; but a large surface of the tape is in contact with the skin on either side of the wound, providing traction that pulls the edges of the wound together. The narrow center permits some free drainage from the wound, and the strips can be removed easily if the wound has to be opened should infection develop. Exposure In certain climates, you will be exposed to excessive heat or cold and must safeguard yourself from its effects. Proper procedure is the key to prevention of all cases of heat or cold exposure. HEAT.— Increased sweating requires more fluid intake. The duration of physical activity should be less during the first days of heat exposure and increased gradually as you become acclimatized. Alternate work and rest periods should be established. Avoid working in direct sun or on extremely hot days. Wear lighter clothing in hot environments. C O L D . —  The most important aspect of prevention of cold-related injury is awareness of existing weather conditions and the likelihood of weather change. Adequate clothing to protect as much exposed skin as possible must be worn. Rain gear should be donned before you become wet; wool clothes and wind-protective garments should be donned before you start to shiver. Improvised clothing may be made from parachute material. Obtain shelter that provides protection from the wind, precipitation, and surface water as well as insulation from ground, snow, or ice. Impro- vised shelters, described in Survival Training 5-41