6. The whole body is covered by the skin. 7. The two sides of the body are alike. CHAPTER III. THE INSIDE OF THE BODY. ~1.~ Thus far we have taken only a brief look at the outside of the body, just as if we had looked at the case of a watch, and of course we have found out very little about its many wonderful parts. Very likely you want to ask a great many questions, such as, How does the inside of the body look? What is in the skull? What is in the chest? What is in the abdomen? Why do we eat and drink? Why do we become hungry and thirsty? What makes us tired and sleepy? How do we keep warm? Why do we breathe? How do we grow? How do we move about? How do we talk, laugh, and sing? How do we see, hear, feel, taste, and smell? How do we remember, think, and reason? All these, and a great many more interesting questions, you will find answered in the following lessons, if you study each one well. ~2.~ When we study the inside of the body, we begin to understand how wonderfully we are made. We cannot all see the inside of the body, and it is not necessary that we should do so. Many learned men have spent their whole lives in seeking to find out all about our bodies and the bodies of various animals. ~3. The Bones.~--If you take hold of your arm, it seems soft on the outside; and if you press upon it, you will feel something hard inside. The soft part is called _flesh_. The hard part is called _bone_. If you wish, you can easily get one of the bones of an animal at the butcher's shop, or you may find one in the fields. ~4. The Skeleton.~--All the bones of an animal, when placed properly together, have nearly the shape of the body, and are called the _skeleton_ (skel'-e-ton). The skeleton forms the framework of the body, just as the heavy timbers of a house form its framework. It supports all the parts. ~5. The Skull.~--The bony part of the head is called the _skull_. In the skull is a hollow place or chamber. You know that a rich man often has a strong room or box in his fine house, in which to keep his gold and other valuable things. The chamber in the skull is the strong-room of the body. It has strong, tough walls of bone, and contains the _brain_. The brain is the most important, and also the most tender and delicate organ in the whole body. This is why it is so carefully guarded from injury. ~6. The Backbone.~--The framework of the back is called the _backbone_. This is not a single bone, but a row of bones arranged one above another. Each bone has a hole through it, about as large as one of your fingers. A large branch from the brain, called the _spinal cord_, runs down through the middle of the backbone, so that the separate bones look as if they were strung on the spinal cord, like beads on a string.