The process begins in the mouth; here the food is chewed and moistened with saliva before being swallowed; both the chewing and the moistening are important to insure good digestion later on. The enzymes have no particular ability to penetrate a mass of food material; what they do is to attack it from the outside and work in as it decomposes. Since enzyme action is thus a surface action, it is evident that the larger the surface the more efficient will be the action. Chewing is nothing in the world but a mechanical breaking up of the food to get the largest possible surface. We have sufficient proof of its importance in the digestive disturbances that arise as the direct consequence of improper chewing. Of recent years it has been realized that undernutrition, particularly in children, is often a result of the failure to chew the food properly; it has been found, furthermore, that bad teeth or improperly shaped mouths are very frequently responsible. For this reason in most of our large cities dental clinics are being established for the purpose of inspecting and, if necessary, caring for the mouths of school children. The result of this work is to improve the general average of health among children simply by increasing the extent to which the food is chewed. This fact, together with that described in Chapter XIII as to pus pockets, should impress upon both parents and teachers the fundamental importance of proper care of the teeth. This includes not only the prevention of decay by daily thorough cleaning and the securing at intervals of not more than six months of dental inspection with treatment where necessary, but also in the case of children with deformed jaws the special treatment necessary to bring the teeth into position for effective chewing. Too much stress can scarcely be laid on the importance of these precautions.