A well-developed man can drag a little less than his own weight over a level surface, while a draught-horse can draw only two-thirds. The horse, therefore, is relatively weaker than man. There are some insects, however, which are able to move nearly fifty times their own weight. From what you have learned about the importance of exercise, you will understand how necessary it is that every muscle should be trained. In no other way can you preserve sound, rugged health. HYGIENE OF THE MUSCLES. When the muscles are properly used, they become large, firm, and dark red in color. Such use of them causes the skin to act freely, while the brain is made vigorous and the digestion improved. It is the best medicine in the world. You must be careful not to strain or overwork your muscles, as it is very hurtful. Your strength must be built up by moderate, careful, and regular exercise. The muscles need not only exercise to make them strong, but a constant supply of good, pure blood. You must eat wholesome food, in proper quantities, at regular intervals. You must take plenty of exercise in the sunlight. The blood and the muscles demand the light and the heat of the sun to make them strong. EFFECTS OF EXERCISE. The effect of exercise upon the muscles may be clearly seen in the arm of the blacksmith; in the foot and leg of the walker; in the fingers of the pianist; and in the hand and fore-arm of the skillful penman. * * * * * How many muscles have you? How are the bones moved? How are the muscles generally found? In what manner do they work? What is a voluntary muscle? An involuntary one? Illustrate the difference. Compare the strength of a well-developed man with that of a horse. What is said of some insects? Why should the muscles he trained? What is the result? What kind of medicine is such exercise? How must your strength be built up? What do the muscles need beside exercise? Where should the exercise be taken? Show some of the effects. CHAPTER XII. REST AND POSTURE. “Early to bed and early to rise” should be your motto. Children need abundant sleep, and ought to retire early and rise as soon as they awake in the morning. Their bodies and brains require regular rest. Never lie on your back when sleeping, but on the left or right side. Place your limbs in the easiest position possible; otherwise you will be troubled by bad dreams, which will awake you from slumber. Try to keep your mouth closed, so as to breathe through your nostrils. You will thus escape the unpleasant habit of snoring. TIME FOR SLEEP. Infants and old people need more sleep than boys and girls. Night is made for rest, and the day for work. Do not take naps through the day nor sit up late at night. Never lie down to sleep directly after a meal.