Wise doctors have said that the boy who uses tobacco while he is growing, makes every part of his body less strong than it otherwise would be. Even his bones will not grow so well. Boys who smoke can not become such large, fine-looking men as they would if they did not smoke. Cigarettes are small, but they are very poisonous. Chewing tobacco is a worse and more filthy habit even than smoking. The frequent spitting it causes is disgusting to others and hurts the health of the chewer. Tobacco in any form is a great enemy to youth. It stunts the growth, hurts the mind, and cripples in every way the boy or girl who uses it. Not that it does all this to every youth who smokes, but it is always true that no boy of seven to fourteen can begin to smoke or chew and have so fine a body and mind when he is twenty-one years old as he would have had if he had never used tobacco. If you want to be strong and well men and women, do not use tobacco in any form. REVIEW QUESTIONS. 1. What two kinds of joints have you? 2. Describe each kind. 3. Find as many of each kind as you can. 4. How are the joints kept moist? 5. How many bones are there in your whole body? 6. Count the bones in your hand. 7. Of how many bones is your spine made? 8. Why could you not use it so well if it were all in one piece? 9. What is the use of the little cushions between the bones of the spine? 10. How many ribs have you? 11. Where are they? 12. Where are the shoulder-blades? 13. Where are the collar-bones? 14. What are bones made of? 15. How can we show this? 16. What is the difference between the bones of children and the bones of old people? 17. Why do children's bones bend easily? 18. Tell the story of the lame lady. 19. What does this story teach you? 20. What happens if you lean over your desk or work? 21. How will this position injure your lungs? 22. What other bones may be injured by wrong positions? 23. Why do old people's bones break easily? 24. How should the feet be cared for? 25. How does tobacco affect the bones? 26. What do doctors say of its use? 27. What is said about cigarettes? 28. What about chewing tobacco? 29. To whom is tobacco a great enemy? Why? 30. What is always true of its use by youth? CHAPTER II. MUSCLES. [Illustration: W]HAT makes the limbs move? You have to take hold of the door to move it back and forth; but you need not take hold of your arm to move that. What makes it move? Sometimes a door or gate is made to shut itself, if you leave it open.