8. Twelve pairs of nerves pass from the base of the brain: the first pair, called the nerves of smell, to my nose; the fourth pair, called the nerves of sight, to my eyes; the fifth pair, called the nerves of taste, to my mouth, tongue, and teeth. One pair pass to my face; another to my ears. The ninth, tenth, eleventh, and twelfth pairs to my tongue and parts of my throat and neck.[3] 9. The spinal cord is a bundle of nerves extending from the base of my brain, down through the whole length of my spine, or backbone. It is the largest nerve in my body. 10. From the spine, thirty-one pairs of nerves, called _spinal nerves_, pass to different parts of my body; some to the lungs, some to the heart, some to the stomach, some to the bones, and some to the muscles and skin. 11. If a nerve be destroyed it cannot carry messages to and from the brain. Before filling a tooth, the dentist sometimes destroys its nerve. 12. If a nerve be pressed upon too long it cannot perform its duty. If I press upon the nerve passing to my foot, I stop it from communicating with the brain; the foot loses its feeling, or, as I say, "is asleep." 13. If I drink alcoholic liquors, or snuff, smoke, or chew tobacco, my brain and nerves cannot do their work well; because alcohol and nicotine are very poisonous to the brain and nerves. 14. The brain must be supplied with good blood; The brain must be used; The brain must be rested; I must drink wholesome drink, eat wholesome food, take enough exercise, and breathe pure air, that my brain may be supplied with pure blood; I must study and think, that my brain may grow and be strong for work; I must rest my brain when it is tired, either by changing my employment, or by going to sleep; I must not poison my brain with alcohol or tobacco. [3] NOTE.--_A fuller description of the Nerves of the Brain_: Twelve pairs of nerves pass from the base of the brain; the first pair, called the nerves of smell, to my nose; the second pair, called the nerves of sight, to my eyes; the third, fourth, and sixth pairs to the muscles of my eyes; the fifth pair to my forehead, eyes, nose, ears, tongue, teeth, and different parts of my face; the seventh pair to different parts of my face; the eighth pair, called the nerves of hearing, to the inner part of my ear; the ninth pair to my mouth, tongue, and throat; the twelfth pair to my tongue; the eleventh pair to my neck; the tenth pair to my neck, throat, lungs, stomach, and different parts of my body. * * * * * QUESTIONS ON THE FORMULA. 1. Describe the brain. 2. Where is the brain placed? 3. Describe the outer membrane of the brain. 4. Describe the middle membrane of the brain. 5. Describe the inner membrane of the brain. 6. Tell about the nerves. 7. Tell about the use of the two kinds of nerves. 8. Tell about the nerves which pass from the brain. 9. Tell about the spinal cord. 10. Tell about the nerves which pass from the spinal cord.