It is best to avoid mixing acid fruits and cereals. Even healthy people find that a breakfast of oranges and bread does not agree as well as one of milk and bread. The saliva, which contains ptyalin, is secreted in the mouth. The ptyalin starts starch digestion, but it does not work in the presence of acid. Eating acid fruits makes the mouth acid temporarily, and consequently the starch does not receive the benefit it should from mouth digestion. The result is an increased liability to fermentation in the alimentary tract. To get the best results it is absolutely necessary to masticate all starchy foods well. If this is not done it is merely a question of time until there is indigestion, generally accompanied by much acidity and gas production. This condition is a builder of many ills. Recipes for pies and cakes are not given in this book. The less these compounds are used the better. They are very popular and can be made according to directions in conventional cook books. Pies should be made with thin crusts, which should be baked crisp both on bottom and top. The best cakes are the plain ones. When desserts are eaten, less should be taken of other foods. Most people make the mistake of eating more than enough of staple foods and then they add insult to injury by partaking of dessert. CHAPTER XV. TUBERS. ==================================================================== Pro- Carbohy- Calories Water tein Fat drates Ash per lb. -------------------------------------------------------------------- Potato............ 78.3 2.2 0.1 18.0 1.0 375 Sweet potato...... 51.9 3.0 2.1 42.1 .9 925 Jerusalem artichoke. 78.7 2.5 0.2 17.5 1.1 The two tubers that are of chief interest are the Irish potato and the sweet potato. The former is easily and cheaply grown on vast areas of land and therefore forms a large part of the food of many people. Properly prepared it is easily digested and very nourishing. The sweet potato is a richer food than the Irish potato, but on account of its high sugar contents people soon weary of it. The southern negroes are very fond of this food. Like all other starches, potatoes must be thoroughly masticated, or they will disagree in time. Potatoes are of such consistency that they are easily bolted without proper mouth preparation. In time the digestive organs object. A new tuber is receiving considerable attention. It is the dasheen. It is said to be of very agreeable flavor, mealy after cooking, and produces tops that can be used in the same manner as asparagus. The dasheen requires a rather warm climate for its growth. PREPARATION.