tain it can efficiently produce flesh or repair wasted tissue. So important is this distinction, in fact, that one of the divisions of food most generally recognized by physiologists is into nitrogenous and non-nitrogenous, or, as Liebig termed them, the flesh-forming and the heat-producing. Both kinds are essential to the maintenance of life, and it is because vegetables as a whole are deficient in nitrogen that the highest degree of bodily vigor cannot be kept up by them alone. sustains such action. It is essential to the idea of a food that it support or increase vital actions; whilst medicines usually may lessen, increase, or otherwise modify some of them. "Foods are derived," says Dr. Edward Smith, "from all the great divisions of nature and natural products, as earth, water, and air, solids, liquids, and gases; and from substances which are living and organic, or inanimate and inorganic. The popular notion of food as a solid substance derived from animals and vegetables, whilst comprehensive is too exclusive, It is understood that the structures of the since the water which we drink, the air which body are in a state of continual change, we breathe, and certain minerals found in the so that atoms which are present at one hour substance of the earth, are, adopting the defi- may be gone the next, and when gone the nition given, of no less importance as foods. structures will be so far wasted, unless the procIt is, however, of great interest to note how fre- ess of waste be accompanied by renewal. But quently all these are combined in one food, and the renewing substance must be of the same how closely united are substances which seem nature as that wasted, so that bone shall be reto be widely separated. Thus water and min-newed by the constituent elements of bone, erals are found in both flesh and vegetables, and flesh by those of flesh. This is the duty whilst one or both of the components parts of assigned to food,- to supply to each part of the air, viz., oxygen and nitrogen, are distributed through every kind of food which is alone capable of sustaining life. Hence, not only may we add food to food to supply the waste of the body, but we may within certain limits substitute one for another as our appetites or wants demand. . . Further, there seems to be an indissoluble bond existing between all the sources of food. There are the same classes of elements in flesh as in flour, and the same in animals as in vegetables. the body the very same kind of material that it lost by waste. As foods must have the same composition as the body, or supply some such other materials as can be transformed into the substances of the body, it is desirable to gain a general idea of what these substances are. The following is a summary of the principal materials of which the body is composed: Flesh, in its fresh state, contains water, fat, fibrin, albumen, besides compounds of lime, phosphorus, soda, potash, magnesia, silica, and iron, and certain extractives, whose nature is unknown. Blood has a composition similar in elements to that of flesh. Bone is composed of cartilage, fat, and salts of lime, magnesia, soda, and potash, combined with phosphoric and other acids. Cartilage consists of chondrin, from which gelatine is formed, with salts of soda, potash, lime, phosphorus, magnesia, sulphur, and iron. The brain is composed of water, albumen, fat (so-called), phosphoric acid, osmazome, and salts. "The vegetable draws water and minerals from the soil, whilst it absorbs and incorporates the air in its own growth, and is then eaten to sustain the life of animals, so that animals gain the substances which vegetables first acquired. But in completing the circle the vegetable receives from the animal the air (carbonic acid) which was thrown out in respiration, and lives and grows upon it; and at length the animal itself in whole or in part, and the refuse which it daily throws off, become the food of the vegetable. Even the very bones of an animal are by the aid of nature or man made to increase the growth of vegetables and really to enter into their structure; and being again eaten, animals may be said to eat their own bones, and live on their own flesh.' The lungs are formed of a substance called It will be seen from this that animal and veg- connective tissue, from which gelatine is formed etable foods contain precisely the same ele- by prolonged boiling, albumen, a substance ments though in different combinations. At analogous to casein, various fatty and organic the same time they differ sufficiently to make acids, with salts of soda and iron, and water. a due proportion of each necessary to perfect nutrition. One sterling point of difference is, that nitrogen constitutes a much larger percentage of animal bodies than of vegetables. Nitrogen is one of the most important elements of food; only such substances as con The liver consists of water, fat, and albumen, with phosphoric and other acids, in conjunction with soda, lime, potash, and iron. Bile consists of water, fat, resin, sugar, fatty and organic acids, cholesterin, and salts of potash, soda, and iron. Hence, it is requisite that the body should be provided with salts of potash, soda, lime, magnesia, sulphur, iron, and manganese, as tle heating as possible. In our own climate this law holds good as between summer and winter; in the latter season, plenty of lean meat, butter, potatoes, eggs, sugar, and similar food are necessary to keep the animal machine in working order, while in summer the diet should consist chiefly of those substances of which nitrogenous or flesh-forming elements compose the largest part. There is probably no other cause so fruitful in producing the dyspepsia and similar diseases of which Americans, as a nation, are in a peculiar degree the victims as the neglect to harmonize the food with the changing seasons. well as sulphuric, hydrochloric, phosphoric, direct relation to the prevailing temperature. and fluoric acids and water; also, nearly all In cold regions man requires such food as not the fat which it consumes daily, and probably only supplies him with nutriment, but also all the nitrogenous substances which it re- with heat; as oil, butter, fat, sugar, and other quires and which are closely allied in compo- substances in which carbonaceous elements sition, as albumen, fibrin, etc. "So great an predominate. In warm countries, on the conarray of mysterious substances, says Dr.trary, it is one of the most essential conditions Smith, " might well prevent us from feeding of good health, that his food should be as litourselves or others if the selection of food depended solely upon our knowledge or judgment; but it is not so, for, independently of the aid derived from our appetites, there is the great advantage of having foods which contain a proportion of nearly all these elements; and combinations of foods have been effected by experience which protect even the most ignorant from evil consequences. Thus flesh, or the muscular tissue of animals, contains precisely the elements which are required in our flesh-formers, and, only limited by quantity, our heat-generators also; and life may be maintained for very lengthy periods upon animal food and water. Seeing, moreover, that the source of flesh in animals which are used as food, is of vegetable origin, it follows that vegetables should contain the same elements as flesh, and it is a fact of great interest that in vegetables we have food elements closely analogous to those contained in the flesh of animals. Thus, in addition to water and salts, common to both, there is vegetable chondrin, vegetable albumen, vegetable fibrin, and vegetable casein, all having a composition almost identical with animal albumen, fibrin, chondrin and casein." The articles containing most of the three articles needed generally in the body are as follows: for fat and heat-making — butter, lard, sugar and molasses; for fleshent impunity; but young children who are or muscle-forming-lean meat, cheese, peas, beans, and lean fishes; for brain and nerves shell fish, lean meats, pease, beans, and very active birds and fishes, who live chiefly on food in which phosphorus abounds. In a meat diet, the fat supplies the carbon for keeping up the heat of the body, and the lean furnishes nutriment for the muscles, brain, and nerves. Green vegetables, fruits, and berries furnish additional supplies of the acids, the salts, and water needed. Kinds of Food. The simplest and most powerful agent in determining the character of our food is climate. In cold countries the requirements of man are very different from those felt in the tropics, and from the Esquimaux, who, according to Dr. Kane, will drink ten or twelve gallons of train oil in a day, to the Peruvians and other tropical nations for whom the banana suffices for nearly all seasons of the year, there are various gradations in which the constituents of the diet bear a very The next most important question in determining the character of our food is that of its digestibility; and it must be borne in mind that the nutritive value and the digestibility of food have no necessary relation to each other. A food may have a very high nutritive value and yet be so indigestible as to be practically useless, and on the other hand it may be very easily digested and worth little or nothing for nutrition. No general rules as to the digestibility of different foods can be laid down, because it depends very largely upon individual habits and conditions. Persons who have a strong constitution, and take sufficient exercise, may eat almost anything with appar forming their constitutions, and persons who are delicate, and who take but little exercise, are very dependent for health upon a proper selection of food. As a general thing, when the body requires a given kind of diet, specially demanded by brain, lungs, or muscles, the appetite will crave that food until the necessary amount is secured. If the food in which the needed aliment abounds be not supplied, other food will be taken in larger quantities than needed until that amount is gained; for all kinds of food have supplies for every part of the body, though in different proportions. Thus, for example, if the muscles are worked a great deal, food in which nitrogen abounds is required, and the appetite will remain unappeased until the requisite amount of nitrogen is secured. Should food be taken which has not the requisite quantity, the consequence will be that the vital powers will be needlessly taxed to throw off the excess. There are other kinds of food which are not only nourishing but stimulating, so that they quicken the functions of the organs on which they operate; the condiments used in cookery, such as pepper, mustard, and spices, are of this nature. There are certain states of the system in which these stimulants may be beneficial and even necessary; but persons in perfect health, and especially young children, never receive any benefit from such food, and just in proportion as condiments operate to quicken the action of the internal organs, they tend to wear down their powers. The same observation applies to the use of wines and other spirituous and malt liquors. Under certain conditions where the vital powers are low, they are a highly important addition to ordinary food; but when used habitually, their temporary stimulation is gained at the expense of permanently weakening the digestive organs which finally refuse to perform their work without some such external aid. It follows from the above that the requirements of food in each case may in a normal condition of things be left to the individual taste, to be selected and prepared as is indicated by experience to be most appropriate. Nutritiousness of Food. The following table from authentic sources shows the ascertained percentage of nutriment in the common articles of table consumption: KIND OF FOOD. Preparation. Nutriment. Digestion. Beans, pod.. Potatoes, Irish. Cabbage, head. Spinal marrow, animal. 30 Beef, with salt only. Apples, sour, hard. Bass, striped, fresh. Beef, fresh, lean, rare.. 45 Pork, recently salted.. Mutton, fresh.. Time of Digestion. 30 Preparation. H. M. 1 00 boiled 1 00 boiled 1 00 boiled 1 00 raw 1 30 boiled fried 1 30 1 roasted boiled roasted 2 30 30 boiled 2 H. M. Parsnips... boiled 2 30 30 Oyster soup.. boiled 00 Bread, wheat, fresh. baked 30 Turnips, flat... boiled 00 Potatoes, Irish. boiled O co co co co co co co co co co co co co co 3 15 3 3 3 3 30 3 3 3 3 30 3 3 30 3 3 30 3 30 2 00 Green corn and beans.. boiled Composition of Various Articles of the absorbents take portions of it into the cirFood. In 100 parts. Fat. Salts. 73.3 2.9 66.8 2.1 29.8 4.4 3.6 5.1 1 1.7 83.0 2.0 6.4 0.7 0.8 0.5 0.7 6.1 0.2 1.6 24.3 5.4 31.1 4.5 26.7 1.8 culatory system, and all the various bodily functions dependent on the blood are thus gradually and imperceptibly injured. Very often, indeed, intemperance in eating produces immediate results, such as colic, headache, indigestion, and vertigo; but the more common result is the gradual undermining of all parts of the human frame, shortening life by thus weakening the constitution. As to the hours of meals these are of no importance provided they are regular and come at regular intervals. This interval should never be less than five hours, as the stomach requires at least three hours to digest its supply of food, and not less than two hours should be allowed it for rest and recuperation. Eating between meals is a most injurious practice, the source in children, especially, of endless stomachic disorders. It may be well to give children under ten years of age one more meal during the day than the three which adults in this country usually allow themselves; but these, as we have said above, should be at 2.9 1.0 regular times and with stated intervals between them. 13.8 1.3 10.5 1.5 1.6 30.7 1.3 ,0.2 Biscuit 8 15.6 1.3 3.6 6.3 4.9 Corn meal. 14 11.1 64.7 1.8 0.8 Mutton, fat.. Mutton, lean.. Oatmeal. 4.1 3.0 15.45 3.0 3.49 21 3.9 0.8 5.8 0.5 1.0 over. After taking a full meal, it is very important to health that no great bodily or mental exertion be made till the labor of digestion is Muscular exertion draws the blood to the muscles, and brain work draws it to the head; and in consequence of this the stomach loses the supply which is necessary to it when 0.7 0.5 performing its office, the adequate supply of gastric juice is not afforded, and indigestion is the result. The heaviness which is felt after a full meal is a sure indication of the need of quiet; when the meal is moderate, the process of digestion will be sufficiently advanced in an hour, or an hour and a half, to justify the resumption of bodily or mental labor. 16. 2.4 0.6 15.8 4.7 10.8 66.3 4.2 2.0 1.7 Quantity of Food. With regard to the quantity of food to be taken, this also depends upon individual conditions and cannot be formed into a general rule. Where hunger is felt it may safely be assumed that when the hunger has been fully appeased sufficient food has entered the stomach. Such are the circumstances of civilized life, however, that in most cases hunger is a very rare sensation; and food is prepared and eaten more to gratify the palate than because nature demands it. On this point each individual is and must be a law unto himself, and we can only point out the consequences of eating a larger quantity than is needed. When too great a supply of food is put into the stomach, the gastric juice only dissolves that portion of it which the wants of the system demand; most of the remainder is ejected in an unprepared state, The Diet of Brain Workers.- It has long been one of the pet theories of popular physiology, that fish and other substances composed largely of phosphorus, are the most appropriate diet for brain workers; but it is now conceded that the best food for the brain is that which best nourishes the whole body with special reference to the nervous system, viz. : fat and lean meat, eggs, milk, and the cereals. Discussing this point in a recent treatise, Dr. George M. Beard says: "The diet of brain workers should be of a large variety, delicately served, abundantly nutritious, of which fresh meat, lean and fat, should be a prominent constituent. In vacations, or whenever it is desired to rest the brain, fish may, to a certain extent, take the place of meat. We should select those articles that are most agreeable to our individual tastes, and, so far as possible, we should take our meals amid pleasant social surroundings. In great crises that call for unusual exertion, we should rest the stomach, that for the time the brain may work the harder; but the deficiency of nutrition ought always to be supplied in the first interval of repose." CHEMICAL COMPOSITION OF THE HUMAN BODY. the brain and nerves; but our analyses as yet are too imperfect to allow a subdivision, and as all the mineral elements are more or less combined with each other, and all reside together in articles of food, we shall include all mineral elements under the term Phosphates. The waste, and consequently the supply, of these three classes of elements is very different, four times as much carbonaceous food being required as nitrogenous, and of the The human body is composed of the follow-phosphates not more than two per cent. of the ing elements, all of which are found also in the food provided by nature, or in air or water, and all must be supplied, day by day, or some bad results are sure to follow :: Oxygen, a gas, in quantity sufficient to 0 0 carbonates. Altogether, the waste of these principles will average in a man of moderate size, with moderate heat, more than one pound in a day, varying very much according to the amount of exercise and the temperature in which he LB. oz. GR. lives. These elements must all be supplied in vegetable or animal food, not one being allowed to become a part of the system unless it has been first organized with other elements of food, in some vegetable, or in water, or the atmosphere; but being appropriated by some animal, remain organized and adapted to the human system, so that animal and vegetable food contain the same elements in the same proportion and nearly the same chemical combinations, and are equally adapted to supply all necessary el occupy a space equal to 750 cubic feet, 111 Hydrogen, a gas, in quantity sufficient to occupy 3000 feet, which with oxygen, constitutes water, the weight of the two indicating nearly the necessary amount of water.. Carbon, constituting fat, and used also for fuel to create animal heat... Nitrogen, which constitutes the basis of the muscles, and solid tissues, and which is supplied by that part of the food which we shall denominate Nitrates.. Phosphorus, the physical source of vitali ty, and the most important of the Calcium, the metallic base of lime, which 14 0 21 0 3 0 0 ements. Albumen, 1 Sugar, 2 116 0 0 100 In Vegetable Food, Potassium, the base of all the salts of potash.. 0 0 290 Magnesium, the base of magnesia, and magnesian salts } Gluten, Albumen, and Casein. Silicon, the base of silex, which is found in the hair, teeth, and nails.......... 0 0 The elements of a man weighing 154 lbs. 2 Classification of Food.— Food may be divided into three classes. That class which supplies the lungs with fuel, and thus furnishes heat to the system, and supplies fat or adipose substance, etc., we shall call Carbonates, carbon being the principal element; that which supplies the waste of muscles, we shall call Nitrates, nitrogen being the principal element; and that which supplies the bones, and the brain, and the nerves, and gives vital power, both muscular and mental, we shall call the Phosphates, phosphorus being the principal element. These last might be subdivided into the fixed and the soluble phosphates,- the fixed being a combination principally with lime to form the bones, and the soluble being combinations with potash and soda, to work Starch, and a are furnished in little Fat. The Nitrates in The Phosphates in both animal and vegetable food are found inseparably connected with the nitrates, none being found in any of the carbonates, and generally in the proportion of from two to three per cent. of all the principles in vegetable, and from three to five in animal food. The Carbonates of both animal and vegetable food are chemically alike— fat, sugar, and starch, all being composed of carbon, oxygen, and hydrogen, and in about the same chemical combinations and proportions. The Nitrates, also albumen, gluten, fibrin, and casein, are alike in chemical combinations and elements, being composed of nitrogen, oxygen, and hydrogen, and a little carbon not digestible. These simple bodies are not, however, capable of being assimilated and converted into tissue; they must be previously combined, primarily by the vegetable kingdom. |