This box is divided across the middle by a strong muscle, so that we may say it is two stories high.
The upper room is called the chest; the lower one, the abdomen (ăb dō´mĕn).
In the chest, are the heart and the lungs.
In the abdomen, are the stomach, the liver, and some other organs.
THE STOMACH.
The stomach is a strong bag, as wonderful a bag as could be made, you will say, when I tell you what it can do.
The outside is made of muscles; the lining prepares a juice called gastric (găs´trĭk) juice, and keeps it always ready for use.
Now, what would you think if a man could put into a bag, beef, and apples, and potatoes, and bread and milk, and sugar, and salt, tie up the bag and lay it away on a shelf for a few hours, and then show you that the beef had disappeared, so had the apples, so had the potatoes, the bread and milk, sugar, and salt, and the bag was filled only with a thin, grayish fluid? Would you not call it a magical bag?
Now, your stomach and mine are just such magical bags.
We put in our breakfasts, dinners, and suppers; and, after a few hours, they are changed. The gastric juice has been mixed with them. The strong muscles that form the outside of the stomach have been squeezing the food, rolling it about, and mixing it together, until it has all been changed to a thin, grayish fluid.