widely in composition and that the analyses here given represent averages. Examples of these variations are shown in the cases of oysters and of mackerel in Part II. of the table. In these, however, the differences are unusually wide, although very considerable variations are found in other materials, especially in meats. The diagram tells its story plainly, and I need now call attention to but few points. It is interesting to note, in Part I., the differences in the amounts of refuse and edible portion in the different kinds of meats, fish, etc., as they are ordinarily found in the markets. Thus in some of the specimens of beef, as the round steak, the bone and other inedible materials amount to only ten per cent. of the whole, whereas in the flounder the refuse amounts. to two-thirds, and the edible portion to only one-third, of the whole. The bone, though counted here as refuse, yields, when properly boiled, a considerable quantity of nutritive matter, chiefly in the form of gelatine and fats. Fish, as we buy them in the markets, have on the average a larger proportion of refuse and less edible material than meats. Dairy products and most vegetable foods have very little refuse. In examining the edible portion of the materials, as shown in Part II., it is interesting to note the wide variations in the proportions of water and of nutritive substances. In general the animal foods contain the most water and the vegetable foods the most nutrients, though potatoes and turnips are exceptions, the former being three-fourths and the latter nine-tenths water. Butter, on the other hand, though one of the animal foods, has on the average about nine per cent. of water. The milk from which it is made is not far from seveneighths water. As stated above, meats have more water in proportion as they have less fats, and vice versa, the fatter the meat the less amount of water in it. Thus, very lean beef (the muscle of a lean animal from which the fat has been trimmed off) may have seventy-eight per cent. of water and only twenty-two per cent. of nutrients. The rather fat sirloin of the diagram has sixty, and the very fat pork only about ten per cent. of water. The flesh of fish is in general more watery than ordinary meats, that of salmon being five-eighths water; codfish, over four-fifths; and flounder, over six-sevenths. Flour and meal have but little water, and sugar almost none. In examining the proportions of individual nutrients, protein, fats, and carbohydrates, the most striking fact is the difference between the meats and fish, on the one hand, and the vegetable foods on the other. The vegetable foods are rich in carbohydrates, starch, sugar, etc., while the meats have not enough to be worth mentioning. On the other hand the meats abound in protein and fats, of which the vegetable foods usually have but little. Beans and oatmeal, however, are rich in protein, while fat pork has very little. The comparative composition of oysters and milk is worth noting. Both contain about the same total amounts of nutrients, but the proportions are quite different, the oysters having the more protein, and the milk the more fat. Roughly speaking, we may say that there is not a very great deal of difference between the nutritive values of a quart of oysters and a quart of milk. Considering the cost, however, the oysters are far the more expensive food. I have noticed that people in looking over such tables as this sometimes get at first a wrong impression. Thus rice contains about seven-eighths, and potatoes only one-fourth nutritive material. The first inference is that the rice is much more nutritious than potatoes. In one sense this is true; that is to say, a pound of rice contains more than twice as much nutrients as a pound of potatoes. But if we take enough of the potatoes to furnish as much nutritive material as the pound of rice, the composition and the nutritive values of the two will be just about the same. In cooking the rice we mix water with it, and may thus make a material not very different in composition from potatoes. By drying the potatoes they could be made very similar in composition and food value to rice. Taken as we find them, a pound of rice and three and a half pounds of potatoes would contain nearly equal weights of each class of nutrients and would have about the same nutritive value. FLOUR AND BREAD. THE Composition of wheat flour and wheat. bread are worth notice here. The chief difference is in the water, which makes about oneninth the weight of the flour and one-third that of the bread. Of course different kinds of flour and bread vary widely in composition. The composition of wheat flour here stated is the average of a large number of analyses of American specimens, and doubtless represents very closely the average composition of the flour which people ordinarily buy. The figures for bread are the average of four analyses of loaves purchased at different times at bakeries in Middletown, Connecticut. They agreed very closely in composition with each other and with an excellent specimen of home-made bread. I infer, therefore, that this was better than the average baker's bread, a supposition confirmed by published analyses of the latter, 70 DIAGRAM III. NUTRITIVE PART I. MEATS, FISH, ETC., AS PURCHASED, INCLUDING BOTH EDIBLE PORTION AND REFUSE. Where the ingredients amount to less than one-half of one per cent. they are omitted from this table. INDICATED BY SHADED DEVICES. EXPLANATIONS.-Of the different classes of nutritive ingredients or nutrients of food the protein compounds ("muscle-formers") are the most important in the sense that they alone form the basis of the blood, muscles, tendons, and other nitrogenous tissues of the body. Protein, fats, and carbohydrates of food are all transformed into the fat of the body and all serve as fuel to yield heat and energy (strength) for muscular work. As fuel, one part by weight of fats is estimated to be equivalent to over two parts of protein or carbohydrates. A proper diet will include all the nutrients in proportions fitted to the needs of the user. PART II. MEATS, FISH, ETC., EDIBLE PORTION; DAIRY PRODUCTS; VEGETABLE FOODS. which often show a much larger percentage of water, sometimes forty per cent. or more. In using the word "better" I do not refer to flavor, color, or texture, but to the proportion of nutrients and water. In making bread, a very little butter or lard and yeast and a good deal of water, by itself or in milk, are added to the flour. In the fermentation of the dough in rising, minor transformations take place in the carbohydrates, the chief being the change of sugar to carbonic acid gas and alcohol. In the baking, the alcohol and gases are mostly driven off, and part of the water goes with it. The chief difference between the flour and bread, therefore, is that the bread is more bulky, the gases having expanded it, and that it contains more water. In other words, in making flour into bread the baker renders it more palatable and increases the bulk and weight, but adds very little nutritive material. For him to manipulate it so as to get the most bulk and weight from the least flour is perfectly natural, and his loaf is apt to contain a large percentage of water and have considerable space inside filled with air and gas. The price of the bread per pound is apt to be twice that of the flour. When the poor man buys his pound loaf of bread of the baker for seven or eight cents he thus gets no more nutritive material than the well-to-do man obtains for three cents in the flour which he has baked at home. But if the poor man's family have no conveniences for making the bread, there is nothing left for them to do but buy it from the baker. BUTTER AND OLEOMARGARINE. WITHIN a few years past substitutes for butter have become a very important article of commerce. The most important of these, oleomargarine, agrees very closely in chemical composition with butter from cows' milk, the chief difference being that the oleomargarine contains smaller proportions of the peculiar fats, butyrin, etc., which give butter its agreeable flavor. It is made by taking beef fat or lard, extracting part of the stearin, a material which is familiarly known in candles, and adding a small amount of butter to the residue. It is this small quantity of butter which gives the butter-flavor to the whole. As will be explained when we come to consider the digestibility of foods, the difference in digestibility between butter and oleomargarine is at most too small to be of any considerable consequence for ordinary use. The nutritive values of the two are very nearly the same. In fulfilling one of the most important functions of food, that of supplying heat and muscular energy, butter and oleomargarine excel in efficiency all, or nearly all, of our other common food materials; at least such is the outcome of the best experimental testimony. In appearance and flavor the common kinds of oleomargarine resemble butter so closely that it is difficult even for an expert to distinguish between them. These butter substitutes are manufactured at very low cost, so that they can be sold at retail at about half the price of butter. They are, therefore, food products of large economic importance and of great benefit to that large class of our population whose limited incomes make good dairy butter a luxury, and, for that matter, to all who need to economize in their living expenses. Like many other manufactured food products, oleomargarine is liable to be rendered unwholesome by improper materials and methods of manufacture. Butter, likewise, is often improperly made and is liable to become unwholesome. In the considerable mass of evidence which has come under my own observation there is no indication that butter substitutes, as they are actually sold in our markets, average less wholesome or healthful or are in any way less fit for human food than ordinary butter, though some observers in whose judgment I have confidence are inclined to think that on the whole the advantage as regards wholesomeness is somewhat in favor of butter. Among the chemists who are recognized as authorities in these matters, both in this country and in Europe, there is very little difference of opinion as to the value of oleomargarine for food. There is, however, a popular prejudice against imitation butter which is very unfortunate, especially for people in moderate circumstances and for the poor, whom it is most calculated to benefit. This prejudice, which a new food material very naturally meets, is fostered, and often conscientiously, by representatives of the dairy interest, which fears from imitation butter a damaging competition, though the most accurate statistics show it to be far less serious than is generally believed. On the other hand, the benefit which butter substitutes are calculated to bring is largely prevented, and an immense wrong is done by the very general sale of the imitation under the guise and name and at the price of butter. In a number of States in which the dairy interests are large, the manufacture and sale of butter substitutes has been prohibited by legislative action. In other States laws have been enacted to regulate their sale and prevent fraud. An attempt was made in Congress to check the manufacture and sale by taxation sufficient to bring their cost nearly up to that of butter. In the law as actually passed, however, the tax was very much reduced, so that while it may help toward preventing improper sale of butter substitutes and, by obliging sellers to pay high license fees, may consider ably interfere with their general use, it will not be as effective in excluding them from the markets as was desired. This is a case where mechanical invention aided by science is enabled to furnish a cheap, wholesome, and nutritious food for the people. Legislation to provide for official inspection of this, as of other food products, and to insure that it shall be sold for what it is and not for what it is not, is very desirable. Every reasonable measure to prevent fraud, here as elsewhere, ought to be welcomed. But the attempt to curtail or suppress the production of a cheap and useful food material by law, lest the profits which a class, the producers of butter, have enjoyed from the manufacture of a costlier article may be diminished, is opposed to the interests of a large body of people, to the spirit of our institutions, and to the plainest dictates of justice.* In discussing the composition of our foods we must consider not only the quantities of nutritive ingredients which they contain, but also the part each one of these classes of nutrients has to perform in the nourishment of the body, and the proportions which are appropriate for the diet of different persons. The protein compounds, sometimes called "muscle-formers," are the only ones which contain nitrogen. According to the best experimental evidence they alone form the basis of blood, muscle, tendon, and other nitrogenous tissues of the body. As these tissues are worn out by constant use they are repaired by the protein of the food. The protein, fats, and carbohydrates are all transformed into fat. They all seem to share, therefore, in the formation of the fat of the body. They all likewise serve as fuel to maintain the heat of the body and to yield muscular energy for its work. Late experiments indicate that in those serving as fuel, one part by weight of fats is equivalent to a little over two parts of either protein or of carbohydrates. The mineral matters make up a large part of the bones and teeth, small proportions are contained in the other tissues, and they are necessary for nutrition in various other ways. It is a fundamental principle of food economy that the diet should contain nutritive material adapted to the wants of the consumer. The following is from the late report of the Dairy Commissioner of Connecticut, which comes to hand just as this is being written: "As a protection to consumers the national law is a failure, and the present tax is too small to benefit our dairies to any appreciable extent; a ten cent tax VOL. XXXIV.—11. A great deal of experimenting and observation have been devoted to the determination of the quantities of protein, fats, and carbohydrates needed for the daily nourishment of individuals of different age and sex, at work or at rest, and subject to the varied conditions of life. In Germany, where the subject has been most thoroughly studied, it has come to be commonly accepted that about 4.2 ounces of protein, 2 ounces of fats, and 17.6 ounces of carbohydrates will make a fair daily ration for a laboring man of average weight and doing moderate work. Of course he can get on with less of one if he has more of the others. But there is a minimum below which he cannot go without injury, and his amount of protein should not fall much below the 4.2 ounces per day, though protein, as we shall see later on, is by far the costliest of the nutrients. In animal foods, furthermore, it is usually associated with the so-called extractives, which have a peculiarly agreeable flavor. In accordance with one of those universal processes of natural selection which science is gradually helping us to understand, the food of the poor is apt to contain too little protein and that of the rich too much. The flesh of codfish contains, aside from water, little else than protein, butter is almost wholly fat, and sugar and starch are carbohydrates. The lean meats are similar to codfish; fat pork resembles butter, and the chief nutrient of potatoes and rice is starch. Each of these materials is unfit by itself for nourishment. Milk, on the other hand, abounds in all the nutrients and is more nearly a "perfect food," for those with whom it agrees, than any other animal food material. While meats and fish are rich in protein, and most meats and some fish abound in fats, the vegetable foods generally lack protein and fats but have an excess of carbohydrates, of which the meats and fish have none. Beans and pease, however, have a good deal of protein. We have here a very simple chemical explanation of a usage which, under the promptings of experience or instinct, mankind has almost everywhere come to adopt, that of supplementing wheat and corn and rice and potatoes with meats and fish, or, when these are lacking, by beans, pease, or other vegetables rich in protein. There is a sound reason in the Hindu's practice of eating pulse with rice, in the Irishman's use of skimmed milk with his potatoes, in the Scotchman's might more nearly have accomplished what the national law was intended to accomplish, but as matters now stand the national law is simply a source of revenue to the national government, and practically levies a tax on poor people who can ill afford to bear it." |