It is evident that a variety of food is necessary for health. Animals fed exclusively upon one class, or upon a single article of diet, droop and die; and in the human family we know that the constant use of one kind of diet causes disgust, even when not very long continued. Consequently, we infer that the welfare of man demands that his food be of sufficient variety to supply his body with all of its component parts. If this is not done the appetite is deranged, and often craves the very article which is necessary to supply the deficiency. After the component parts of the organism have assimilated the nutritious elements of particular kinds of food for a certain length of time, they lose the power of effecting the necessary changes for proper nutrition, and a supply of other material is imperatively demanded. When the diet has been long restricted to proteids, consisting largely of salt meats, fresh vegetables and fruits containing the organic acids, become indispensable; otherwise, the scorbutic condition, or scurvy, is almost sure to be developed. Fresh vegetables and fruits should be eaten in considerable quantities at the proper seasons. VALUE OF ANIMAL FOOD. The principal animal food used in this country consists of _Pork, Mutton, Beef_, and _Fish_. Beef and mutton are rich in muscle-producing material. Although pork is extensively produced in some portions of this country, and enters largely into the diet of some classes, yet its use, except in winter, is not to be encouraged. The same amount of beef would give far greater returns in muscular power. In addition to the meats mentioned, _Wild Game_ furnishes palatable, nutritious, and easily-digested food. _Domestic Fowls_, when young, are excellent, and with the exception of geese and ducks, are easily digested. _Wild Birds_ are considered much healthier food than those which are domesticated. All of these contain more or less of the elements which enter into the composition of the four classes of foods. VEGETABLE FOODS. _Wheat_ is rich in all the elements which compose the four classes, and, when the flour is unbolted, it is one of the best articles for supplying all the elements. _Barley_ stands next to wheat in nourishing qualities, but is not so palatable. _Oats_ are rich in all the elements necessary for nutrition. Oatmeal is a favorite article of diet among the Scotch, and, judging from their hardy constitutions, their choice is well founded. In consequence of the large proportion of phosphorus which they contain, they are capable of furnishing a large amount of nourishment for the brain. _Rye_ is nutritious, but it is not so rich in tissue-forming material. _Indian Corn_ is an article well known and extensively used throughout the United States, and is a truly valuable one, capable of being prepared in a great variety of ways for food. It contains more carbon than wheat, and less nitrogen and phosphorus, though enough of both to be extremely valuable.