substance. In the air, for example, there floats, as we have seen, an unfailing supply of carbonic acid. The same gas exists also in nearly all natural waters, and in the soil it is formed abundantly along with other comparatively simple combinations of carbon. All these the plant takes in by its leaves or by its roots, and from them, by a still obscure chemistry, extracts and makes its own the carbon they contain. So from water and ammonia it takes hydrogen-from nitric acid, ammonia, and other compounds, it takes nitrogen- and from the dead earthy matter of rocks and soils it selects and takes up the so-called incombustible, inorganic, or mineral ingredients which are necessary to the production of its perfect substance.

Of raw and simple materials like these, the animal can make nothing. Among them all, water is the only one it can with safety introduce into its stomach, and upon this it cannot live or be sustained. It is upon the results of the plant's labours-upon the substances of the plant's body, the new and usually more complex combinations which the living plant has manufactured from the simpler compounds which nature presents to it that the herbivorous animal can alone support itself. Out of these, by wonderful methods, which we cannot explain, the plant forms starch, sugar, fat, and gluten, in all their varieties. So formed by the plant, the animal eats them; digests and changes them anew by a further mysterious chemistry which we are only now beginning faintly to follow; and finally fits them into appropriate places in its own body. Thus dead nature daily labours for the food of plants; the living plant daily labours for the food of animals. In the order of nature, the plant must precede, and accompany, and unceasingly work for the animal. Alone, in the midst of physical nature, man and all other animals would be helpless, forlorn, and short-lived.

Thus far, then, our science teaches us how different in relation to external things the life of plants is from the life of animals, and yet how closely and inseparably they are connected; - how selected first from earth and air to form the plant, the same matter next builds up the more curious animal frame; and when that is worn out, or dies, returns again to earth and air, to run the same course anew. It thus shows one simple though grand idea pervading all life, embodied in the existing course of animated nature, yet by its manifold and complex details, leading us perpetually to admire the surpassing Workman from whose beneficent intellect it sprung.

And this plant, so essential to the life of all, what a miracle of chemical contrivance and chemical endowment it is! This

little sporule, which the unassisted eye can scarcely discern,— in which even by the aid of the microscope only an obscure structure can be observed-in this little germ how much discernment and concealed intention really rests! Placed in one condition, it remains unalterably the same for an indefinite period of time. If life is there, it is life in a state of quiescent torpor ; quiescent yet watchful; a life of most profound repose. Placed in another condition, it seems at once to perceive the change. It swells and moves; the inner being bursts its shell, and comes forth; slowly and cautiously expands its growing length; feels, as it were, and examines every substance it touches; selects and rejects as suits its purpose; transforms each chemical body it takes up, and fits it for the place it is intended to occupy in the building about to be erected; and with materials so collected and prepared, it builds unceasingly-without wearying, and after a predetermined plan-green leaf, graceful twig, towering stem, blooming flower, luscious fruit, nourishing seed; till through the wonderful working, mechanical and chemical, of that hidden speck of life which so long slept in the microscopic germ, beauty and grace adorn the landscape, and inert useless matter has been abundantly converted into food for man. How slow and limited is our most advanced chemical knowledge, compared with that easy skill so richly given to this tiny seedlet!

Let us leave now those substances which are naturally necessary to human life, and consider for a little those things which by habit have become to modern nations a kind of second nature. In looking to modern life in this point of view, it appears widely distinguished not only from that of classic times, but even from that of the middle ages. Sugar, tea, coffee, cocoa, brandy, and tobacco have all become familiar to Christian Europe and America within the last 300 years. By the end of the 14th century, the cultivation of sugar had already become important in Western Asia and Northern Africa. Brought into Spain by the Moors, and cultivated in Andalusia, it was planted in the Madeiras by the Portuguese, who in 1520 possessed already sixty sugar manufactories in the island of St. Thomas alone. Thence it penetrated to America with the Spaniards, and became a staple article of Spanish American growth. Now, about 4500 millions of pounds of cane sugar, produced chiefly in America, pass yearly through the hands of European and American merchants, while in addition nearly 500 millions of the same kind of sugar are extracted from the beet-root in Northern Europe, and consumed in the different countries of our more eastern continent. It was not till

the year 1659 that sugar refining began to be practised in England; and in 1700, the consumption of all England was only 20 millions of pounds. Now, we are not only the great refiners of Europe, but by far the largest consumers of sugar of every variety. In the year 1853, the consumption of the United Kingdom amounted to 818 millions of pounds of sugar, being at the rate of 28 lbs. a year-upwards of half-a-pound a week-for each of our population. What a change in the habits and modes of living of the people does this imply!

The introduction and rapid spread of the habit of using tea is still more recent and remarkable. The leaf was not brought to Europe till about the beginning of the 17th century. Sugar refineries were already in operation in England, when in 1664 the East India Company thought a couple of pounds of tea a not unroyal gift to present to the Queen of England. Now we consume at the rate of two pounds a head as the yearly allowance of every individual in the three kingdoms, and the total annual consumption of the United Kingdom is about 25,000 tons, or sixty millions of pounds! The use of this leaf is specially great in China and Thibet, in Russia, Holland, and England, and in the states and provinces of North America. The entire quantity consumed over this wide area, among about 500 millions of men, is roughly estimated at upwards of two thousand millions of pounds.

Coffee, though less a favourite among us than tea, is preferred to it by several of our Continental neighbours. On the whole, perhaps the spread of coffee drinking during the last 300 years has been more wonderful even than that of tea. It was not till the beginning of the 15th century that it was introduced into Arabia from Abyssinia. About the middle of the sixteenth, it began to be used in Constantinople, and in spite of the opposition of priests and Turkish doctors, it may now be considered as the staple minor luxury of Mahomedan life. In the middle of the 17th century (1652), the first coffee-house was opened in London; and now, two hundred years after, the yearly consumption of coffee in the United Kingdom has reached the large amount of 35 millions of pounds. The quantity of the coffee bean actually bought and sold is about 600 millions of pounds every year, and it is in daily use among perhaps 120 millions of men!

We may pass briefly over_cocoa, the ancient beverage and nutriment of the Mexican Incas, and still the favourite in modern times of Central America, of Italy, and of Spain. It is consumed to the extent of about 100 millions of pounds a year, and among 50 millions of men.

But what is the chemistry of all this new food and drink, unknown to that ancient life, the manners and features of which form so great a part of our study at school? What new craving in our common nature have they awakened, what old craving more agreeably satisfied? What is their physiological action, in short, and upon what chemical constituents does it depend? Why have entire nations so readily fallen into the new habits, and why do they so pertinaciously cling to them?

By her fireside, in her humble cottage, the lonely widow sits; the kettle simmers over the ruddy embers, and the blackened teapot on the hot brick prepares her evening drink. Her crust of bread is scanty; yet as she sips the warm beverage-little sweetened, it may be, with the produce of the sugar cane, genial thoughts awaken in her mind; her cottage grows less dark and lonely, and comfort seems to enliven the ill-furnished cabin. When our suffering and wounded soldiers were brought down frozen and bleeding from the trenches before Sebastopol to the port of Balaklava, the most welcome relief to their sufferings was a pint of hot tea, which was happily provided for them. Whence this great solace to the weary and worn? Why out of scanty earnings does the ill-fed and lone one cheerfully pay for the seemingly unnourishing weekly ounce of tea? From what ever-open fountain does the daily comfort flow which the teacup gently brings to the care worn and the weak?

The answer we are enabled to give to these questions is still very imperfect. Recent chemical and chemico-physiological researches have indeed thrown much interesting light on the nature, composition, and mode of action of the warm infusions we delight to drink, and we can so far satisfactorily account for many of their effects. We may expect our present views, however, to be materially modified by the results of future research.

In the first place, past experiment has shown us that there is a remarkable chemical analogy among the four substances Chinese tea, Paraguay tea, coffee, and cocoa, which are chiefly employed for the preparation of infused beverages. All of them in the roasted state in which they are used, contain aromatic oils in minute proportion, to which the peculiar aroma of each is due. All contain also a proportion of an astringent substance resembling the tannin of gall-nuts or oak bark. In three of them, Chinese tea, Paraguay tea, and coffee, is found a variable quantity of a peculiar white crystalline body, to which the name of theine or caffeine has been given; while in cocoa a different but similar body exists, which is known by the name of theobromine. Of these three constituents, which are all extracted by hot

water, two the volatile oil and the theine are known to exercise a peculiar action upon the system. The oil possesses* narcotic properties, intoxicates, occasions headaches and giddiness, and sometimes paralysis in those who as tea-tasters are much exposed to its influence. New tea contains this oil in larger quantity than old tea does, and for this reason it is said that the Chinese rarely use their tea till it has been kept over a year. The small proportion of it which exists in tea as we get it in Europe, is not only harmless, but is probably one source of the soothing exhilaration which tea and coffee produce. The theine, again, is a bitter substance possessing tonic or strengthening qualities, but distinguished particularly by the property of retarding the natural waste of the animal body. Most people are now aware that the chief necessity for food to a full grown animal, arises from the gradual and constant wearing away of the tissues and solid parts of its body. To repair and restore the worn and wasted parts, food must be constantly eaten and digested. And the faster the waste, the larger the quantity of food which must daily be consumed, to make up for the loss which this waste occasions. Now the introduction of a certain quantity of theine into the stomach lessens the amount of waste which in similar circumstances would otherwise naturally take place. It makes the ordinary food consumed along with it, go farther, therefore, or more correctly, lessens the quantity of food necessary to be eaten in a given time. A similar effect in a somewhat less degree,.is produced by the volatile oil, and, therefore, the infusion of tea, in which both these ingredients of the leaf are contained, affects the rapidity of the natural waste in the tea-drinker in a very marked manner.

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As age creeps on, the powers of digestion diminish with the failing of the general vigour, till the stomach is no longer able to digest and appropriate new food as fast as the body wears away. When such is the case, to lessen the waste is to aid the digestive powers in maintaining the strength and bulk of the weakening frame. It is no longer wonderful therefore,' says our author, that tea and coffee should be favourites on the one hand with the poor whose supplies of substantial food are scanty. And on the other, with the aged and infirm, especially of the ❝feebler sex, whose powers of digestion and whose bodily substance have together begun to fail. Nor is it surprising that the aged female whose earnings are barely sufficient to buy what are 'called the common necessaries of life, should yet spare a portion ' of her small gains in procuring this grateful indulgence. She can sustain her strength as well with less common food when 'she takes her tea along with it; while she feels lighter at the