“The other twelve will come some day, my boy; at present you have the right number of teeth for a child of your age. They do not all come at one time, but one after another. We begin with twenty, and no more. They are called milk teeth, or first teeth. When we are about seven years old they begin to fall out and are replaced by others stronger and set in more firmly. In addition to this second score of teeth there appear later twelve others, bringing the total number up to thirty-two. Those farthest back, in the inmost cavity of the mouth, come late, when we are eighteen or twenty years old, or even older, for which reason they are called wisdom teeth to signify that they appear at an age when the reason is well developed. These thirty-two last teeth constitute the second cutting. I call them last because they are never replaced by any others; if we lose them, that is the end of our teeth; no more will come.” “I have two now that are loose,” said Emile. “They must come out soon to leave room for the new teeth that are to take their place. The others will get loose, too, and the twenty that you have now will be succeeded by twenty others, to which, sooner or later, will be added twelve more which come only once. These last occupy the back part of the jaws, three on each side, top and bottom. Thus the final number will be thirty-two. “These thirty-two teeth are divided into three classes according to their shape and the work they must do. The same names being repeated top and bottom and right and left, I show you merely the eight teeth of half a jaw. In every tooth there are two parts to be distinguished, the crown and the root. The root is the part that is embedded in the jaw-bone like a nail hammered into wood; the crown is the part that comes into view, and it may be likened to the head of a nail. The root holds the tooth in place, fixes it firmly; the crown cuts, tears, and grinds the food. “In the two front teeth in each half-jaw the crown grows thinner toward the top. The edge is straight and sharp, fitted for cutting food, dividing it into small mouthfuls. Therefore these teeth are called incisors, from the Latin incidere, meaning to cut. Their root is a simple pivot. The next tooth is called canine. Its root is a little longer than those of the preceding teeth, and its crown is slightly pointed. The dog, the cat, the wolf, and carnivorous animals in general have this tooth shaped like a powerful fang, which serves to catch and hold prey, but above all acts as a weapon in attack and defense. It is the canine teeth that you see crossing one another, long and pointed, two on each side, when you raise the upper lip of a cat or a dog. Because of these remarkable fangs of carnivorous animals, especially the dog, which in Latin is canis, the name canine has been given to the teeth that in man are like them, if not in form and use, at least in the position they occupy.