Food is turned into blood by being digested. Men have digesting bags, more commonly known under the name of stomachs, inside of them, into which portions of digestible substances are placed from time to time. These inside digesting bags are particularly convenient, because when a fair quantity of food is once packed away there, men may move about in pursuit of their business without having to give any further heed to the digesting work that is going on in their behoof. Before, however, food is passed down into the digesting bag, it is first ground in a powerful mill, and mixed up with liquid into a sort of paste. The mill has many pairs of very hard stones set in rows over against each other. It is called the _mouth_, and the stones are termed _teeth_. The liquid, which makes the ground food into paste, is poured out from little taps laid on in the mill or mouth, and is called _the saliva_. When the ground and moistened food has been deposited in the stomach, more liquid is poured out upon it there. This liquid is termed the “gastric” or _stomach juice_. Next it is shaken, and churned up, and turned over by the movements of the stomach-bag. After a few hours’ churning, it has become so soft and pulpy from the soaking, that it is ready to advance another stage. Then a sort of sluice-gate at the end of the stomach is opened, and down the pulp goes into the bowel, there to be mixed with another liquid called _bile_, or _liver juice_, and the soaking or digestion is completed. The pulp then consists of two things—a white milk-like liquid; that is the rich and nourishing part of the food, ground and soaked down to the utmost fineness, and mingled with some of the water which has been drunk. And a coarse solid substance, still undigested; that is the waste part of the food which has resisted the dissolving power of the stomach, and is on its way to be rejected as good for nothing. The white milk-like essence of the food gets sucked up, by a quantity of little holes or mouths that lie all over the lining of the bowel, as the pulp moves down this canal. Then it is carried by tubes provided for the purpose into one main channel. This channel runs upwards until it ends in the great forcing pump. Poured into the heart, it reinforces the blood which it finds there, and is sent onwards with it through the supply-pipes. This is how food becomes blood.