278. In the latter instance, how does the contraction take place? Are the striated muscle fibers voluntary or involuntary? Name an exception to this rule. Give other peculiarities of the muscle fibers of the heart. What causes the contraction of smooth muscle fibers? Of striated muscle fibers? Why do little children seldom injure themselves by overexertion? How is the danger increased in youth?
279. What class of people are in most peril from violent or excessive exercise? Why? At what age should one cease from haste of all kinds? Give instances of valuable lives lost from personal imprudence.
280. What are the effects of insufficient exercise upon the young? How does it predispose to disease? What makes the children of the laboring classes so hardy? Is a regulation step desirable in walking? Why not? Why is it more fatiguing to walk uphill than on level ground?
281. How does the management of the breath affect this fatigue? How should a belt be worn, if used during exercise? Can other forms of exercise be successfully substituted for walking? Why not? What is the difference in movement between walking and skating? Which is the better exercise? What are the dangers from skating? What precaution should be used by those who have weak ankles?
282. Name the different action of the muscles in the forward and backward movements in rowing. What is the comparative value of rowing as an exercise? Why is it especially desirable for women? How should women dress when rowing, horseback riding, tennis playing, etc.? What rules should be observed by rowers? Why should the breath be allowed to escape while the oar is in the water?
283. What sanitary measures should be observed after a row? What effect has too frequent and too prolonged immersion on young swimmers? Does swimming require much muscular exertion? Why? Why does an occasional swimmer become exhausted sooner than an experienced one? On what do ease and speed in swimming depend? Is the habit of diving desirable? Should diving ever be practiced in shallow water?
284. Why is lawn tennis the most desirable of outdoor games? Ans. Not only because nearly every muscle of the body is brought into exercise, but because it is one of the few field sports in which women can gracefully join. In this it shares the honor with croquet. What are the dangers attendant on lawn tennis? From what do many of them arise? Why should tennis shoes have heels? To what class of people is horseback riding particularly suited? What class of invalids should not indulge in bicycling and tricycling? To what class is it peculiarly beneficial?
285. What are the dangers attendant on baseball games? Football? When may light and heavy gymnastics be profitably employed? Name a sufficient apparatus. What are the objections to gymnasium exercise? Its advantages?
THE SKIN.
49. What are the uses of the skin? Describe its adaptation to its place. What is its function as an organ? Describe the structure of the skin. The sensitiveness of the cutis. The insensitiveness of the cuticle.