In a little book of this character I think it important that those persons who may read it should have some idea of the processes of digestion in human beings, and for this reason I propose to give a short space for a resume of the subject.

The process of digestion is both physical and chemical. The food passes into the alimentary canal, where it is liquefied and its nutritive principles are changed by the digestive fluids into new substances, which are in proper form to be absorbed by the blood. The digestive system includes the alimentary canal and appendages, - viz., the teeth, the salivary glands, the gastric glands, the intestinal glands, the liver, and the pancreas. There are seven stages of digestion, - prehension, mastication, insalivation, deglutition, gastric digestion, intestinal digestion, and defecation. The hands, lips, and teeth together are involved in prehension. Mastication triturates the food, and this act is brought about by the teeth - in the upper and lower jaws, the lower jaw moving and the upper jaw stationary - and the muscles. Mastication should be thorough and is a most important part of digestion. In the adult there are thirty-two teeth, sixteen in each jaw, - viz., four incisors, two canines, four bicuspids, and six molars, or grinders. The lower jaw makes a downward, an upward, a lateral, and an anteroposterior movement Insalivation comes next. The saliva is secreted by the submaxillary, parotid, and sublingual glands. The parotid saliva is thin and watery. The submaxillary and sublingual saliva is viscid. The saliva moistens and agglutinates the food and helps the swallowing of it. The ptyalin of the saliva converts starch into sugar and dextrin is formed. This completes the first stage of digestion.

Deglutition comes next and carries the food from the mouth to the stomach. The bolus of food passes from the mouth into the pharynx, from the pharynx into the oesophagus, and from the oesophagus into the stomach.