THE MUSCLES 55 



4. What is the difference between the motion called flexion and that 



called extension ? 35 



5. Describe their action, and state which are the more powerful 36 



6. What is the difference between voluntary and involuntary muscles? 36 



7. Illustrate the difference between the two 36 



8. State all you can of the tendons or sinews 36, 37 



9. What is meant by contraction of the muscles ? 37 



10. In how many and what ways may contraction be effected 38 



11. What is stated of after-death contraction ? 38 



12. Why cannot a muscle in life continue contracted a long time? 38 



13. How then can the constant beating of the heart be explained ? 39 



14. How does the strength of a man compare with that of a horse? 40 



15. What can you state in regard to the relative strength of animals ? . . 40 



16. What, in relation to physical strength ? 40 



17. What, in relation to physical degeneracy ? 40, 41 



18. What, in relation to the importance of exercise ? 41 



19. What is the effect of exercise upon the heart, skin, and appetite ? . . 41, 42 



20. How does exercise affect the current of the body's circulation ? . . . . 42 



21. How does judicious exercise affect the muscles ? 42 



22. What is stated of violent and spasmodic exercise ? 42 



23. Of the exercise of walking ? 43 



24. Of running, leaping, and other modes of exercise ? 43, 44 



25. Of physical culture, in connection with out-door exercises ? 44 



26. What are the results of excessive exercise ? 45 



27. Of the importance of gymnastics in our schools and colleges ? 45, 46 



28. Of the importance of rest from labor or exercise ? 49 



29. What processes take place during sleep ? 49 



30. What about the amount of sleep required ? 50 



31. What effects follow insufficient sleep ? 50 



32. Illustrate nature's demand for sleep 50 



