FOOD. All organized bodies are nourished 7 the introduction into their internal sir-m ores of materials from without, which form lie numerous kinds of food so familiar to us. <hough man derives his food from both the vegetable and animal kingdoms, it is found that the animals which are consumed by man lerive their nourishment from the vegetable kingdom alone, so that plants are the true source of all the food both of man and the lower animals. The principal constituents of the human body, as well as all other animal bodies, are the organic elements, carbon, hy drogen, oxygen, and nitrogen ; and it is the waste of these substances which is constantly going on that it is the object of food to sup.. ply. Plants, however, do not supply the animal with carbon, hydrogen, oxygen, and nitrogen, in a simple form, but as secretions of the vegetable tissues known to chemists under the names of gluten, fibrin, albumen, casein, Etc.
The plant itself does not derive its food from the organic elements in a pure form, but com bined with each other : thus, carbonic acid gas, consisting of carbon and oxygen; water, composed of oxygen and hydrogen; and am monia, of hydrogen and nitrogen, are the great sources of vegetable nutrition, and conse quently of the various secretions used as the food of man and animals. Not only do these secretions serve to build up the fabric of the human body, and to supply the daily waste of tissue which is going on, but they also sup ply materials for keeping up animal beat within the system.
The reader will find a familiar exposition I of this subject, and of the relative value of albumen, fibrin, casein, starch, sugar, fat, oils, acids, spicei, condiments, &c., in Dr. Lankester's ' Food of Man.'