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

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Percy: The flesh moves.

Muscles of the hand.

Mother: That is because the muscles of your arm pull back when you shut your fingers, and stretch out when you open them. They are some like this piece of India rubber. If you pull it out, it gets thinner, and if you let go, it snaps back and becomes short and thick. Perhaps you have seen the leg of a fowl cut off at the joint, and know if you take hold of the strong cords you can move the toes up or down. So the muscles and tendons move in our feet and hands in the same way. Every step we take, one muscle lifts the toes in front, and another pulls up the heel behind.

If a person sits still much of the time, he will have weak, small muscles, because he does not use them. That is one reason why people are so very weak after being ill. When we use our muscles, they grow large and strong. You have seen the blacksmith’s arm and noticed how large and strong it is. To use our muscles does not wear them out, but does them good.

Elmer: I should think the muscles were our servants, to do whatever we wish done.