The Digestive Tube.~--The most important part of the work of digesting our food is done in a long tube within the body, called the _digestive tube_ or _canal_.
~5.~ This tube is twenty-five or thirty feet long in a full-grown man; but it is so coiled up and folded away that it occupies but little space.

It begins at the mouth, and ends at the lower part of the trunk.
The greater part of it is coiled up in the abdomen.
~6.

The Mouth.~--The space between the upper and the lower jaw is called the _mouth_.

The lips form the front part and the cheeks the sides.

At the back part are three openings.