respect to fats. The latter need not pre-exist in food, for animals may make them out of sugar or starch. A cow forms the butter in milk, though none was in the grass on which it fed; a pig will fatten on potatoes, in which no hog's lard is found; a bee can make wax for the comb from flowers in which there is no wax; and a goose fed on wheat forms fat which was not in the food. So fat, although important as a part of a diet, and forming, in fact, one of the most valuable ingredients of heat-givers, is not essential in the same sense that the flesh-formers are. In fat meat the proportion of the latter to the starch-equivalent of heat-givers, is nearly the same as in milk, viz., as 1 to 3. In cheese and in eggs the proportion of the two classes is as 1 to 2.

Going down the nutritious table we come to the leguminous plants, such as peas, beans, and lentils. With the exception of cheap cheese, this class of plants presents us with the most fleshforming food in the whole table. Lentils ought to form the chief part of the meal sold as revalenta arabica, (although much sold under that name is chiefly Glasgow peas meal, costing 2d. per lb.,) and has been long known to us as the "red pottage" for which Esau sold his birthright. In this class of highly nutritious food we find the flesh-formers and heat-givers standing in the proportion of 1 to 21. This proportion is, in fact, too small for healthy nutrition, and we find experience teaching us to augment the proportion of heat-givers to flesh-formers, so we mix potatoes with peas in making pea soup, and we take fat bacon with our beans.

The third group of food in the table comprises the cereals or corn crops, and bread made from flour; all of these contain fleshformers in marked quantity, though less in amount than in the two preceding groups. Rice stands lowest in this group, having 6 parts in the 100 of flesh-formers, while oatmeal stands highest, having 16 parts. All of them abound in starch, and contain fat in quantity varying from 1 to 7 per cent. Omitting rice, in which the proportion of flesh-formers to heat-givers is as 1 to 12, the other members of the group range between 1 to 5 and 1 to 8. Bread, which can support life by itself, though not with vigor and activity, has its flesh-formers and heat-givers in the ratio of 1 of the first to 5 of the latter.

We now come to the group which we ordinarily class in culinary language as "vegetables," including potatoes, carrots, parsnips, turnips, and succulent vegetables. They all contain so much water (from 75 to 85 per cent.), that their nutritious value in 100 parts is low as compared with the preceding group. None of them contain as much as 1 oz. of flesh-formers in 100 oz. of the vegetable. We now find, in addition to starch and fat, a notable quantity of sugar-in the case of carrots amounting to 5 per cent. Their mineral matter is rich in alkaline salts, which possibly explains their value in scurvy. Potatoes form an eminent heat-giving food, for the proportion between the flesh-formers and heat-givers is as 1 to 16, whilst in the other vegetables in this group the proportion is as 1 to 8. They are therefore all justly considered as accessory food, useful as additions to more nitrogenous foods, but not economical as a source of supply of the latter.

As we descend in the table we come to arrowroot, and similar bodies, such as sago and tapioca, and sugar. These now cease to be considered as, in many respects, entitled to be classed as food. They afford, it is true, one very important ingredient of food-fuel for the support of animal heat-but when of the best quality may be entirely free from flesh-formers, or from mineral material fitted for the supply of the system. They can never be used for nutrition proper, having nothing in them to build up the structure of the body, but they may be highly useful as additions to a diet, by increasing the quantity of heat-givers when these are deficient.

The same remarks apply to such substances as butter, suet, and lard. Like all fats, they may form powerful accessories to nutritious food, but they cannot by themselves nourish the body, having no nitrogen in their composition, or, at all events, only that which comes from their accidental mixture with fleshy matter. They are rich in carbon, which in their dry state amounts to from 77 to 79 per cent., and in their commercial state to from 67 to 70 per cent. They also contain free hydrogen, so that 100 parts of them amount in a starch-equivalent to from 206 to 216 parts.

Some surprise may be experienced that the table contains no account of the stimulating and alcoholic beverages, but it is more convenient to consider them separately. There must be some remarkable use in tea, or it would not at the present time be used by 500 millions of men, or by about one half of the human race. In the United Kingdom, not far from 3 lbs. of tea are annually used

by each person-man, woman, and child included; while coffee, although not so much taken by us, requires an annual supply of 600 millions of pounds to satisfy the consumption of the world. There are three stimulating substances-tea, coffee, and Paraguay tea-which have no relationship as regards the plants which furnish them, or as to the countries in which they were indigenous, but all of them are taken as stimulating beverages; a fourth substance, the Guarana tea, is of a like character. Now, when chemists examine these four substances, an alkaloid called Theine is found in them all. This alkaloid has very peculiar physiological properties. In small quantities, it appears to arrest the too rapid waste of the tissues. When a person has been laboring, the organs of the body necessarily waste, but the transformation begun is apt to continue when the demand for labor has ceased, and theine has the property of stopping this change. But when taken in too large quantities, as frequently happens in the present evil fashion of taking tea at all hours of the day, it acts on the nervous system, producing irritability of temper and acting unfavorably on the assimilation of food. When this nervous irritability exists, by a change from tea to cocoa (in which an alkaloid closely analogous to theine, called theobromine, exists) equanimity of temper is generally restored. Both tea and coffee contain narcotic and intoxicating oils in small quantity, the aroma and quality much depending upon these oils. Tea and coffee in their solid state contain abundance of casein, the important flesh-forming ingredient of milk; but this does not find its way into the infusion, unless indeed when poor people put soda into the water, which, thus rendered alkaline, may dissolve some of it. It is to the theine that the chief action is due; 100 oz. of tea contain about 3 oz. of theine, and 100 oz. of coffee about 12 oz. of the same alkaloid. The quantity of carbon added to a dietary by an infusion of either tea or coffee is too insignificant to be considered. Cocoa abounds in fat-in fact one half, or 50 per cent., consists of a peculiar butter, while there is also about 2 per cent. of its own alkaloid, analogous to but milder in its effects than theine. In the present state of chemistry we cannot follow the transformations of these alkaloids in the body, or explain how they produce their effects.

The alcoholic beverages so commonly used by man act, when taken in small quantities, in a manner similar to tea, but in larger quantities they operate injuriously by exciting the circulation and