His mouth has two lips. The upper lip is larger than the under. He has no teeth. In the back of his head, not far from his mouth, is his brain, or nerve-centre.
The worm is the only jointed animal that has red blood. Mr. Worm is dark-colored because his body is full of the earth which he swallows.
If you keep him out of the earth for a while, his skin will get pale and clear. Then you can see his red blood run in two long veins. He needs fresh air to keep this red blood pure. He dies very soon if he is shut up in a close box or case.
LESSON XII.
MR. EARTH-WORM AT HOME.
I told you the earth-worm has two veins. One runs down his back, the other runs along the under side of his body.
There are tiny holes, like pin pricks, in his body. These are for the air to reach his blood, to keep it red and pure.
In his body poor Mr. Worm has something that no other creature has. He has two bags or sacks for lime. This is in some way to help him with his food.
Mr. Worm has no teeth with which to grind his food. He has inside his body small bits of stone. These are as small as grains of sand. They are instead of teeth to grind his food.
When you study birds you will find that, like Mr. Worm, they have no teeth. They, too, carry little millstones inside their bodies.