The direct cause of bed sores then is pressure, and pressure is aggravated by moisture, wrinkles in the bed clothes, crumbs or other hard particles, lack of cleanliness, friction of any kind, or by rough, careless handling. Bed sores occur most often over bony prominences, such as the end of the spine, elbows, heels, shoulders, hips, ankles, and knees, but they may form anywhere, even on the ears or back of the head. They are more likely to appear on thin, aged, or depleted patients. These painful and serious sores can be prevented almost always by faithful care. When they occur, they result in the great majority of cases purely from negligence, and a person who knows the danger and yet through carelessness allows one to develop upon a patient may justly feel herself disgraced. Prevention of bed sores depends upon keeping the skin dry and clean and upon relieving pressure by special devices and by turning the patient frequently. The parts where pressure comes should be washed at least twice daily with warm water and soap, rubbed frequently with alcohol to improve the circulation and to keep up the tone of the skin, and powdered with a little good toilet powder. Much powder is likely to do harm by collecting in hard, irritating particles. The bed should be kept constantly dry and smooth, and free from crumbs, lumps, wrinkles, or other inequalities. Prolonged pressure should be relieved by turning the patient often,--once every waking hour is not too often if the body is emaciated,--and by pillows, pads, and rings. Small pillows or thick pads of cotton should be placed under the patient's back and shoulders, between the knees and ankles when he lies on his side, and in other places where sores are likely to develop. Rubber rings are useful, but few patients like them for a long time. They should not be inflated more than necessary to raise the affected part from the bed; if much inflated, they are uncomfortable and may do harm. The ring may be covered with a muslin pillow case, or it may be wound smoothly with long strips of bandage or old muslin. Ordinary cotton batting wound with strips of muslin may be made into rings and used to remove pressure from heels, elbows, or other parts. These cotton rings are less heating than pads, and give better support. The first sign of a bed sore is either redness of the skin or a dark discoloration like a bruise. Every point where a bed sore may form should be inspected daily. If the slightest symptom of a sore appears, the patient must not lie on the affected part, and every effort should be made to keep the skin from breaking; vigorous rubbing at this stage is dangerous, and will by no means make up for previous neglect. The condition should be reported to the doctor at once. If in spite of all efforts the skin does break, a peculiarly difficult kind of open wound results which must be treated and dressed according to the doctor's directions.