Elements of the theory and practice of cookery

"The Staff of Life," "More about Bread," "A Machine Baker," and " Crackers " are the titles of short articles about bread in Food and Beverages, pp. 39-50. Farmers' Bulletin No. 112, sent free on application to the U. S. Department of Agriculture, Washington, D. C, gives many interesting facts about Bread and Bread-making not included in this little text-book. Boys and Girls in Biology, by Sarali Hackett Stevenson, contains in its first chapter an excellent description of the life of yeast. Books published several years ago, however, before the processes of fermentation and bread-making were as well understood as they are now, may contain incorrect statements ; new facts are discovered daily, so, as a rule, use the most recent books you can find. CHAPTER V FOOD IN ITS RELATION TO LIFE Section 1. Body stuffs and Foodstuffs It is essential that the body should be perfect in order that the brain may have a chance to do its work. — G. Stanley Hall. 240. Body, organs, tissues, cells. — The body of a human being, like those of most all animals and plants, consists of parts called organs. The special work of each organ is called its function. What is the function of the eye ? Of the lungs ? Of the stomach ? Of a root ? Of a leaf ? Organs differ from one another, not in function only, but also in make-up, or structure. The various kinds of material composing the organs of the body are called tissue, bony tissue being found in bones, nervous tissue in nerves, muscular tissue not in muscles only, but in other organs. The tissues of the body are made up of cells, as the walls of a house are constructed of bricks. Instead, however, of being laid together, as bricks are, these cells grow together, each kind of tissue being built of similar cells of a particular kind. 241. Cells in the body not all alike. — One yeast-cell is much like another, but how about the cells in a grain of wheat? Starch-cells differ from bran-cells in struc- ture because they differ in function. Each yeast-cell is 136 FOOD IN ITS RELATION TO LIFE 137 independent, doing all its own work ; but in higher forms of life, both plant and animal, where many cells are joined together in one individual, some have one function, some another. We may compare a yeast-plant to a man living alone, preparing his own food and mak- ing everything he needs ; while a tree or a horse or the body of a human being is like a nation, in which some men are farmers, some manufacturers, some merchants, and so on. And just as the merchant does not under- stand farming, nor the man that raises wheat know how to make it into flour, so a cell of one kind cannot do the work of another. Cells in lung tissue, for example, are adapted for absorbing oxygen, and cells in the retina of the eye for receiving rays of light ; but neither of them are able to take in food until it has been prepared for them by stomach-cells. 242. Bodystuffs. — In the cells of the body many com- pounds are found, most of them being combinations of some or all of the following elements : carbon, hydro- gen, oxygen, nitrogen. Calcium is found in bones, phosphorus in nerves, iron in blood, coloring it red ; and these and other elements in small quantities in various tissues.