exposure better than perennials; and those abounding in sap, having a spongy porous wood, and much pith, succeed with difficulty. It seems advantageous that those plants to be tried should be deprived of moisture as much as possible. Mr Street found, that, when planted above drains, several reputed greenhouse species have flourished most luxuriantly. Plants do not suffer from frost in dry situations, nearly so much as they do in moist, or when an excess of rain is followed by a severe frost. The reason is evident,-in moist situations, part only of the moisture is evaporated during the day, the rest remaining to be converted into ice by the cold of the ensuing night. This icy covering increases the cold, till the vital principle, and resistance given by the formation of the bark to the entrance of cold, are overcome; the sap is frozen, and the vessels burst by the expansive force of freezing.

Plants, in a warm climate, perspire more than in a cold one; so that in the one they require much, and in the other little moisture. The inhabitants of a hot-house must be abundantly supplied with water, to replace the constant evaporation that is going on; but, on being transplanted to a colder climate, they should have a drier soil; and, when from a colder to a warmer, a moister one, than in their native station.

It has hitherto been regarded, almost as an axiom, that no plant produced by cuttings ever becomes hardier than the parent tree, through whatever succession of progeny thus formed. Dr M'Culloch doubts the truth of this assertion, and Mr Street has found that " plants obtained from cuttings are hardier than seedlings, the roots of the former seem to possess more ability to resist severe weather;"-his experience is very considerable, and his opinions merit our attention. Mr Street always plants cuttings, if they are well rooted, in preference to seedlings. The vine is almost always propagated by cuttings, and but few will assert that grapes are not more frequently ripened in the open air now than formerly.

Numerous productions of other climes are now cultivated in our open fields, and may in time be applied to useful and profitable purposes. The Phormium tenax, or New Zealand hemp, now employed for producing the strongest cordage used in the navy, particularly on the New Holland station, has long grown in the open air in the counties of Waterford, Cork, Limerick, Louth, Wicklow and Dublin. During a period of thirty years,

it has only suffered once or twice in the extremities of the leaves, from the most severe frosts. Six leaves give an ounce of dried fibres, which it is calculated will exceed per acre the produce of either flax or hemp. It may be observed, however, that the separation of these fibres from the matter of the leaf is not at present well understood. Whether this plant may ever become an object of cultivation with us is very doubtful. Two plants, however, have succeeded well near Inverness; they require no shelter, growing in a very exposed situation. The specimens in the Royal Botanic Garden of Edinburgh are very vigorous, but have not flowered.

The Tetragonia expansa, or New Zealand spinage, was introduced from New Zealand by Sir Joseph Banks, in 1772, and treated as a greenhouse plant, but has lately been found to grow as freely as the kidney-bean, or nasturtium. As a summer spinage, it is as valuable as the orache, or even more so. Every gardener knows the trouble that attends the frequent sowing of the common spinage, throughout the warm season of the year; without that trouble it is impossible to have it good, and, with the utmost care, it cannot always be obtained exactly as it is wished, from the rapidity with which the young plants run to seed. The New Zealand spinage, if watered, or raised on a rich soil, grows freely, and produces leaves of the greatest succulency during the hottest weather. Anderson, one of its early cultivators, had only nine plants, from which he says, "I have been enabled to send in a gathering for the kitchen every other day since the middle of June, so that I consider a bed, with about twenty plants, quite sufficient to give a daily supply, if required, for a large table.”

Near Exmouth, this invaluable addition to our kitchen gardens has become quite a weed: wherever it has once grown, plants rise spontaneously.

The Zea mays, or Indian corn, is making great progress in this country. It seems that the crop may be raised to advantage in the field, on some light soils, particularly the poor sands of Norfolk and Suffolk, or on any hot burning lands: in the countries where it is indigenous, it grows on light hot soils. As breadcorn, it is far inferior to wheat, but it yields an excellent provender for horses, sheep, cattle, hogs, &c. A gentleman near Dalkeith has this year sown two acres of land with it.

Tobacco has become perfectly naturalized in this country, ripening and sowing its seed yearly in many gardens; and, were it not for its prohibition by law, this plant would become an object of cultivation and immense profit to the agriculturist.

The Arracacha has been introduced from Bogotà; but stands our winter with difficulty. This plant is one of the most useful vegetables in South America. The roots grow to the size, and nearly the shape, of a cow's horn. They yield a food which is prepared in the same manner as potatoes, is grateful to the palate, and so easy of digestion, that it frequently constitutes the chief aliment of the sick. Starch and pastry are made from its fecula, and the root, reduced to pulp, enters into a composition of certain fermented liquors, supposed to be efficacious as tonics. In the city of Santa Fé, it is universally used as the potato with us. The cultivation of this plant requires a deep black mould, which will easily yield to the descent of the large vertical roots. The mode of propagating it, is to cut the root into pieces, each having an eye or shoot, and to plant one of these in each hole. After three or four months the roots are of a sufficient size to be used for culinary purposes; and, if allowed to remain six months in the ground, they become considerably larger, without any detriment to their taste. Like the potato, this vegetable does not thrive in the hotter regions of South America, for there the roots acquire scarcely any size, but throw up a great number of stems. The Arracacha thrives in the more temperate regions, but never so well as in the mountainous districts, where the medium heat is between 58° and 60° of Fahrenheit. There it is that these roots grow most luxuriantly, and acquire the most delicious taste.

It is well known that, during the latter years of the late war, in consequence of the French colonies having been captured by Great Britain, sugar was manufactured in considerable quantities in France, from beet-root; indeed, nearly the whole consumption was obtained from this source. During the war the manufactories flourished, but as soon as the peace of 1816 took place, and caused the sudden introduction of West Indian sugar through Holland, they were ruined by the comparatively low price at which the foreign sugars were introduced, in consequence of the necessity which the government felt of relaxing its rigorous decrees against foreign commerce. As, however, the price of foreign sugar rose again after the peace of Europe

was established, several of the old beet-root sugar manufactories of France were re-opened, and profitably worked, as the supply of the French colonies was not adequate to the increasing consumption; and the duty upon the foreign growth being about 3 d. per pound, whilst the sugar made in the French colonies was also charged with a duty of about 1d. per pound. The manufactories are daily increasing, and it seems probable that the consumption of sugar on the Continent will be soon entirely confined to that obtained from beet-root. One manufactory at Arras furnished, in 1827, one hundred thousand kilogrammes of this article; and beet-root sugar seems likely soon to exercise some influence over the commerce of Europe. The consumption of sugar in France is estimated at about eighty millions of kilogrammes annually; and, if the home manufactory continues to receive as much encouragement as it has hitherto done, France will shortly grow upon her own soil most of the sugar she consumes *. In this country, the beet-root may be procured as cheap as in France; and as the cost of fuel for the manufacture would be much less, it would seem to be a profitable article of cultivation to the agriculturist, particularly as the sugar imported from the British West Indian colonies pays a duty of nearly 3d. per pound. After the juice has been extracted, the pulp is used for feeding cattle, for which it makes a good winter food. On the Continent, the farmers mix a small quantity of flax seed-cake with the root, to make it more nourishing.

Our limits do not permit us to bring forward more examples of plants that may be turned to a good account in this country, both to the manufacturer and the agriculturist. The practical advantages to be obtained by the introduction of foreign species are considerable, and will amply repay him who will devote some part of his time and attention to the discovery of those fureign plants that are, and are not, capable of bearing our cli mate. To increase the variety and beauty of our shrubberies is no inconsiderable object; and it must be with satisfaction and pleasure that we contemplate and compare those of the present day with others of the last century, which, while they point out how much has been done by care and perseverance, should encourage us to go on, and endeavour to add to the ve getable productions of our country.

• See Article on Beet-root Sugar in No. V. of this Journal.

ESSAYS ON THE ORIGIN AND NATURAL HISTORY OF DOMESTIC

ANIMALS.

&c.

By JAMES WILSON, Esq. F. R. S. E. M. W. S.

ESSAY II.

ON THE ORIGIN AND NATURAL HISTORY OF THE HORSE,

AND ITS ALLIED SPECIES.

IN the following brief notices, I do not propose to enter into any detailed account of those numerous and diversified breeds of the domestic horse which have resulted from the skill and perseverance of the human race,-knowing both my own incompetence to such a task, and the many able and experienced contributors by whom such branches of rural economy are likely to be illustrated in this Journal. I shall rather confine myself for the present to a statement of what is known or believed by naturalists regarding the origin and primitive condition of this inestimable animal, and its kindred species.

The Genus EQUUS, according to the views of modern naturalists, contains six different, though nearly allied, animals, viz. Equus Caballus, the Horse; E. Hemionus, the Dziggithai ; E. Asinus, the Ass; E. Quagga, the Quagga; E. Zebra, the Zebra, or mountain Zebra; and E. Burchellii, the Zebra of the Plains. The characters which distinguish these animals from each other, though sufficient for the purposes of the naturalist, are not anatomically considered, of an essential or important nature. They are, for the most part, superficial, and consist in the comparative size of the ears, the length and texture of the hair, and the distribution of the external colours. The size can scarcely be assumed as a specific character, because it varies remarkably in the same species. Hence the most skilful comparative anatomist can with difficulty distinguish a species of this genus merely from the inspection of a few isolated bones, although such inspection is amply sufficient for the determination of species in the case of almost every other animal of which we possess an osteological knowledge. The same observation applies to the bones of fossil horses, which present no precise character