Читать книгу The House We Live In; or, The Making of the Body онлайн

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Helen: About fifty.

Percy: I guess one hundred.

Mother: Not quite right, for there are over two hundred. All the bones together are called the skeleton. The frame of a house divides it into rooms, and on it are fastened the boards, laths, and shingles. In the house in which we live the flesh is fastened to the bones, and the whole is covered with skin. This framework also protects the curious rooms inside the trunk of the body. The largest bone in our frame is the leg bone, which reaches from the hip to the knee. It is called the femur, or thigh bone.

Elmer: Are the bones solid, mother?

The thigh bone.

Mother: No; I have brought some pictures to show you how they look, for we can not see our own bones. One of them shows a bone that is sawed through lengthwise. You see the larger part at the end is full of little holes, like a sponge. This makes it light and strong. There is a hollow place in long bones filled with marrow. It also fills the spongy parts. Marrow is made of fat and cells.