Both jaws are armed with teeth for biting and chewing our food. Wehave during our lives two sets of teeth. The first, called the milk teeth, are twenty in number, and are shed while we are young. The others, known as the permanent teeth, last through the rest of our life. There are thirty-two permanent teeth in the complete set.
The trunk is that part of the body which would be left if the head and limbs were lopped off. The main pillar of the body is the backbone, which extends from the neck to the bottom of the trunk. It is not actually a single bone, but a string of separate bones called vertebra, and is called the vertebral column. The vertebrae are joined together by thick smooth pads of gristle, which form springy, yielding cushions between each bone and theone above it. The seven smallest and topmost vertebras form the neck; they support the head. Next to these come twelve vertebras, each of which supports a pair of ribs-one on either side. The ribsform a kind of hollow bony cage,
