The scalp should be well cleansed with soap and warm water every three or four weeks. The hair should be dried quickly with a soft towel and by sitting in the sun or near a stove. One is likely to catch cold by going out of doors when the hair is wet. Hair oils and dandruff cures should not be used unless advised by a physician. Pinching and wrinkling the scalp twice weekly with the fingers makes the blood tubes grow larger and bring more food to the hair. It will also in many persons stop the hair from falling out and prevent dandruff and itching. [Illustration: FIG. 48.--Photographs showing how keeping the hair tidy improves the appearance.] Do not use the hair brush of another person or exchange hats with your companions. Unclean persons and those living or playing much with them often have among their hairs little creatures called _head lice_. They suck blood and cause constant itching. The doctor will tell any one how to get rid of them easily. =Keeping the Skin Clean.=--The amount of dead matter carried out by the sweat on to the skin every day is equal to a mass as large as your thumb. Dust also works through the clothing and sticks fast to the moist skin. For this reason every one should wash the whole body once or twice each week. The feet should be washed oftener as they become more soiled. Many persons take a bath every day. A cold bath taken just after rising in the morning wakes up the nerves, makes the heart work better, and gives health and strength to the whole body. Afterward, the body should be well rubbed with a coarse towel. The bath may be taken by lying in a tub of water or by rubbing the body over quickly with a wet sponge. A hot bath is best for cleansing the skin. A warm bath makes one sleepy and should, therefore, be taken only at bedtime. _The hands should always be well washed before handling food._ Persons neglecting to do this have caused much sickness because of the disease germs on their hands. One hundred and fifty persons were given typhoid fever in one city in Massachusetts by a man who handled milk without washing his hands. Dirt and disease are companions. You must be clean if you would be healthy. =The Kidneys.=--The sweat glands do not take out of the blood one quarter as much waste matter as the kidneys. These are two bodies longer than the finger and more than twice as wide, and having the shape of a bean. One lies on either side of the backbone below the liver. The blood coming to the kidneys is full of waste and dead matter picked up from all parts of the body. This is passed out through the thin walls of the thousands of little blood tubes into the many tiny tubes of the kidneys. [Illustration: FIG. 49.--The blood tubes in a piece of skin as large as the head of a pin.]