_I._ I think the improvements you mention would only cause a temporary suspension of the evil. They might indeed make it the _fashion_ to wear natural waists; but like all other fashions, it must unavoidably give way to new modes. They might lop off a few of the branches; but science, a knowledge of physiology alone, is capable of laying the axe at the root of the tree.--What is digestion, Ellinora? _E._ It is the dissolving, pulverizing, or some other _ing_, of our food, isn't it? _I._ Hayward says that "it is an important part of that process by which aliment taken into the body is made to nourish it." He divides the digestive apparatus into "the mouth and its appendages, the stomach and the intestines." The teeth, tongue, jaws, and saliva, perform their respective offices in mastication. Then the food passes over the epiglottis, you recollect, down the gullet to the stomach. The saliva is an important agent in digestion. It is secreted in glands, which pour it into the mouth by a tube about the size of a wheat straw. _Alice._ I heard our physician say that food should be so thoroughly masticated before deglutition (you see I have caught your technicals, Isabel,) that every particle would be moistened with the saliva. Then digestion would be easy and perfect. He says that dyspepsia is often incurred and perpetuated by eating too rapidly. _I._ Doubtless this is the case. As soon as the food reaches the stomach, the work of digestion commences; and the food is converted to a mass, neither fluid or solid, called chyme. With regard to this process, there have been many speculative theories. It has been imputed to animal heat, to putrefaction, to a mechanical operation (something like that carried on in the gizzard of a fowl,) to fermentation, and maceration. It is now a generally adopted theory, that the food is _dissolved_ by the gastric juices. _Ann._ If these juices are such powerful solvents, why do they not act on the stomach, when they are no longer supplied with _subjects_ in the shape of food? _I._ According to many authorities, they do. Comstock says that "hunger is produced by the action of the gastric juices on the stomach." This theory does not prevail, however; for it has been proved by experiment, that these juices do not act on anything that has life. _Alice._ How long does it take the food to digest? _I._ Food of a proper kind will digest in a healthy stomach, in four or five hours. It then passes to the intestines. _Ann._ But why does it never leave the stomach until thoroughly digested? _I._ At the orifice of the stomach, there is a sort of a valve, called pylorus, or door-keeper. Some have supposed that this valve has the power of ascertaining when the food is sufficiently digested, and so allows chyme to pass, while it contracts at the touch of undigested substances. _A._ How wonderful! _I._ And "how passing wonder He who made us such!" _Alice._ No wonder that a poet said--