Mother: And how many joints has the leg?
Helen: Three joints.
Mother: That is right. The one at the hip, as I have said, is a ball-and-socket joint; the one at the knee is a hinge joint, and the ankle is quite like the wrist. Then we have the foot, with a number of small joints, like the hand.
Percy: But we have toes on our feet instead of fingers; still there is the same number.
Mother: Yes, and some people can use their toes to draw pictures, write, and do many other things. Now we have found what our body-house is like on the outside, and we see how well each part is made for the work given it to do.
SUBSTANCES IN THE BODY
SUBSTANCES IN THE BODY
OTHER: Percy, do you remember what men use in building houses?