Did you ever see the swallows flying about the eaves of a barn?
Do they have very stout legs? No! They have very small legs and feet, because they do not need to walk. They need to fly.
The muscles that move the wings are fastened to the breast. These breast muscles of the swallow must be large and strong.
EXERCISE OF THE MUSCLES.
People who work hard with any part of the body make the muscles of that part very strong.
The blacksmith has big, strong muscles in his arms because he uses them so much.
You are using your muscles every day, and this helps them to grow.
Once I saw a little girl who had been very sick. She had to lie in bed for many weeks. Before her sickness she had plenty of stout muscles in her arms and legs and was running about the house from morning till night, carrying her big doll in her arms.
After her sickness, she could hardly walk ten steps, and would rather sit and look at her playthings than try to lift them. S