_Mastication promotes the flow of saliva and the insalivation of the food._--The more efficiently food is masticated the greater is the salivary flow, and the more intimately is it mixed with the saliva, or, as we say, insalivated. The saliva has apparently no effect on fats; whether it acts on proteids seems more doubtful, though by some authorities the penetration of these by the alkali of this fluid is said to aid in their subsequent digestion; on starch, however, the saliva acts very potently, and hence mastication plays a special part in promoting the digestion of starchy foods. Indeed, if only mastication be persisted in long enough, starch may be wholly converted into maltose within the mouth, and it need scarcely be said that it is better for the individual himself to manufacture his maltose in this way than that he should take it ready made for him in the form of one of the many “malt extracts” on the market. Patients are often forbidden starchy food, while they are allowed the maltose which they can quite well manufacture in their own mouths. Provided they be sufficiently insalivated, there are few starchy foods which are indigestible, not even excepting the proverbially indigestible new potato. These remarks are especially applicable to children, as will be more particularly insisted on later. _Mastication increases the amount of alkaline saliva passing into the stomach_, and this not only prolongs the period of starch digestion within this organ but, by its influence upon the reaction of the gastric contents, influences all the digestive processes taking place there. I shall have occasion to point out later that a deficient supply of alkaline saliva in the stomach predisposes to certain forms of indigestion. _Mastication acts reflexly upon the stomach._--It is now known that the act of mastication influences the stomach reflexly, promoting the flow of gastric juice and thus preparing the stomach for the entrance of food into it. If the œsophagus of a dog is cut so as to allow the swallowed food to escape instead of passing into the stomach, it is found that the mastication of food causes a considerable flow of gastric juice. Food introduced into the stomach unaccompanied by mastication is less effective in promoting the gastric flow. It is probable that the influence of mastication on the flow of gastric juice is largely produced through the medium of psychic influences, for the more efficient the mastication the more is the sense of taste affected.