~1.~ Did you ever see a Venus's fly-trap? This curious plant grows in North Carolina. It is called a fly-trap because it has on each of its leaves something like a steel-trap, by means of which it catches flies. You can see one of these traps in the picture. When a fly touches the leaf, the trap shuts up at once, and the poor fly is caught and cannot get away. The harder it tries to escape, the more tightly the trap closes upon it, until after a time it is crushed to death. [Illustration: VENUS'S FLY-TRAP.] ~2.~ But we have yet to learn the most curious thing about this strange plant, which seems to act so much like an animal. If we open the leaf after a few days, it will be found that the fly has almost entirely disappeared. The fly has not escaped, but it has been dissolved by a fluid formed inside of the trap, and the plant has absorbed a portion of the fly. In fact, it has really eaten it. The process by which food is dissolved and changed so that it can be absorbed and may nourish the body, is called _digestion_ (di-ges'-tion). ~3.~ The Venus's fly-trap has a very simple way of digesting its food. Its remarkable little trap serves it as a mouth to catch and hold its food, and as a stomach to digest it. The arrangement by which our food is digested is much less simple than this. Let us study the different parts by which this wonderful work is done. [Illustration: THE DIGESTIVE TUBE.] ~4. The Digestive Tube.~--The most important part of the work of digesting our food is done in a long tube within the body, called the _digestive tube_ or _canal_. ~5.~ This tube is twenty-five or thirty feet long in a full-grown man; but it is so coiled up and folded away that it occupies but little space. It begins at the mouth, and ends at the lower part of the trunk. The greater part of it is coiled up in the abdomen. ~6. The Mouth.~--The space between the upper and the lower jaw is called the _mouth_. The lips form the front part and the cheeks the sides. At the back part are three openings. One, the upper, leads into the nose. There are two lower openings. One of these leads into the stomach, and the other leads to the lungs. The back part of the mouth joins the two tubes which lead from the mouth to the lungs and the stomach, and is called the _throat_. The mouth contains the _tongue_ and the _teeth_. [Illustration: THE TEETH.] ~7. The Teeth.~--The first teeth, those which come when we are small children, are called _temporary_ or _milk teeth_. We lose these teeth as the jaws get larger and the second or _permanent_ teeth take their place. There are twenty teeth in the first set, and thirty-two in the second. Very old persons sometimes have a third set of teeth. [Illustration: SALIVARY GLANDS.]