evidence of this, and might ensure a stricter observance of these ploughings, that of twelve deities, who presided over agriculture and were invoked at the feast of Ceres, four presided over the department of ploughing. One had charge of each of the four separate ploughings, and the order in which they were invoked, describes the management of fallow.

The fallowing of the Romans will not suffer by a comparison with that of modern times, scarcely even with its most improved state, under the management of the British farmer. In those parts of the country where fallowing is best understood, from four to six ploughings are usually given with frequent harrowing and rolling between. The first is given as soon as possible after harvest, when the ridges are gathered up, and in that state lie dry during the winter months. Immediately after the spring seed-time, the ridges are cloven down, after which the land is ploughed across; and, when sufficiently dry, is rolled and harrowed repeatedly, till all the roots of weeds are brought into view, gathered into heaps, and either burned on the field or carried to the dung-hill. It is afterwards ploughed, rolled, harrowed, and gathered as often as may be necessary, completely to pulverize it, and remove all the weeds. This perhaps exhibits rather a favourable view of the usual mode of fallowing in Britain; and, should it appear to surpass the diligence and labour of the Roman farmer, it must be remembered that the fallowing of the latter was only followed by a single crop, and the process repeated every second year; whereas, in Britain, upon the manner in which the fallowing operations are conducted, depend not only the ensuing crop, but, in a great measure, all the crops of a five or six years' rotation.

We shall resume the subject of Roman agriculture in a subséquent number, when we hope to furnish much interesting information respecting their other agricultural operations and the produce and profits of their husbandry.

ON THE ACCLIMATING OF PLANTS. By JOHN S. BUSHNAN, Esq. Member of the Edinburgh Royal Medical and Plinian Societies, &c.

AMONG the many natural agents affecting the growth and maturation of plants, heat and culture stand predominant. A certain degree of heat is indispensable to vegetation, though this degree varies with the constitution of every individual; observation has fully established this; and it appears that there is a principle, inherent in every plant, and peculiar to itself, which, while it renders a certain degree of heat necessary to its vegetation, enables it also to bear without injury a certain degree of cold. Even in plants growing side by side in their native soil, the extent of this principle, and the range between the two points, constantly differ: one plant will bear a degre of cold which would kill the other, and vice versa. In the Royal Botanic Garden of Edinburgh, several trees from New Holland are growing in the open air; they were all obtained from the same neighbourhood, and are now placed, as regards each other, in nearly their original situations; yet all do not with equal facility bear the changes of our climate: a temperature of -18° of Fahrenheit does not affect the Eucalyptus cordata, while that of -6° kills the genus Cassia.

Culture acts upon plants, by bringing into action the natural agents necessary to vegetation, such as light, heat, soil, situation, &c. There is no cause so constantly and so powerfully operating in bringing plants to perfection, and there is none whose influence is so multiplied, and so considerable in increasing the number of plants in a country, by introducing new species into its fields and borders. It changes the very nature and habit of plants. Not only are the organs increased in beauty and in size, but by its agency are even altered: leaves become corollæ; corollæ, leaves. Plants, which in their natural situation are biennial, are by cultivation reduced to annuals, from the increased rapidity with which they are hurried on, in the performance of their several functions. The reverse of this position also holds true; for, if we produce a delay in the period at which annual plants flower, with many we succeed in converting them into biennials. Wheat will furnish us with a familiar example. In its natural state it is but an annual

plant, pushing from the seed in spring, flowering in summer, ripening its grain in autumn, and dying with the approach of winter, the whole period of its existence scarcely exceeding six months. From the mode in which it is generally cultivated, however, its life is often protracted to twelve, sometimes to thirteen months, being frequently sown in September, and not reaped until the October of the following year. Numerous other individuals are improved in their natural qualities by cultivation. All the varieties of apple, for example, owe their origin to the sour and unpalatable Crab, which no one would now recognize in the flavour and beauty of our choice apples. Cultivation has multiplied the varieties of the Pear almost to infinity, and produced them all from one worthless species. The peach, in its wild state, in Media, is poisonous; but cultivated in the plains of Ispahan and Egypt, it becomes one of the most delicious of fruits. In few plants are the effects of cultivation more apparent than in the Brassica tribe. However extravagant it may appear, all the varieties of red and white cabbage, Savoys, Brussels sprouts, winter greens, cauliflowers and broccolis, have sprung from one poor and insignificant-looking weed, -the Brassica oleracea, common in many parts of the kingdom. The grape and the fig are not indigenous to France, but by cultivation have become naturalized there; in like manner, the orange to Italy, and the cherry to us. The narrowleaved elm was brought from the Holy Land during the Crusades; buck-wheat, and most species of grain, came also from the East, and, along with them, several plants found among corn alone. Bruce says he found the oat wild in Abyssinia; wheat and millet have been found wild on the hills in the East Indies. To the influence of culture, in varying and improving the natural qualities of vegetables, do we owe many of the luxuries of the table and dessert; nay, man could scarcely have been civilized but for this power of culture over the vegetable kingdom. The present state of society depends for its existence on the production of grain; but grain in its natural state is not worth cultivating. Wheat, before it has been subjected to the influence of cultivation, is an insignificant and worthless seed; yet to this same seed, when improved by culture, and to others as trifling, when subjected to the same process, do we owe all the comforts of civilized life. Culture has on the brute

creation analogous effects; the colour, shape, size, flavour, and very habits of plants, are altered by cultivation, and precisely the same effects are produced upon animals. Man himself varies in colour, size and habit, according to the circumstances in which he is placed; indeed, it seems a law throughout the whole animate creation, that each individual shall become habituated to such circumstances. But the most extraordinary power of cultivation, and one to which we owe most of our flowers and fruits, is the change it produces on the natural habits of plants; delicate exotics may be made to grow in the open air in this country; vegetables truly aquatic may be made to grow in dry ground, and plants may be habituated to circumstances of a very different description from those to which they were accustomed in a state of nature. Much difference of opinion has existed as to the truth of this assertion: but, be that as it may, it is our duty to endeavour to find out by every means within our power what plants will, and what will not, bear our climate; as, by such endeavours alone can we hope to increase our vegetable productions, and thereby add to our agricultural wealth. Much has been done, but much remains to be done; for there can be no doubt, and every day's experience still farther tends to confirm the fact, that many productions of foreign climes may advantageously be introduced into this country. Cultivation is daily improving the climate; and it is by no means Utopian to suppose, that in time we shall be possessed of many of the choicest productions of tropical climates.

No example can better demonstrate the extraordinary power of Nature in overcoming, by culture, the peculiar habits of individuals of the vegetable kingdom, and habituating them to the circumstances in which they are placed, than the Siberian crab. This tree, when first introduced into this country from Siberia, put forth its leaves and flowers at the first indication of the approach of spring. While other trees yet wore the garb of winter, this was gaily decked in all the beauties of May. In its native country, the interval between winter and summer is but short; there is scarcely any spring, and that at once bursts forth into a glorious summer. There, it had not been accustomed to the second winter so common with us, or to the sudden checks vegetation so frequently receives during our deceitful spring, and it broke from a state of torpor and inactivity

with the earliest retreat of winter. The consequences were such as might have been anticipated,-with the first frost it received a check-its shoots, unable to withstand the shock, perished. But now view this tree, so ornamental to our gardens and our shrubberies; it has become accustomed to our climate; it does not so hastily put confidence in our treacherous spring; and, advancing more cautiously, escapes destruction.

Another very extraordinary example is mentioned in Leslie's Agricultural Survey of Moray and Nairn. Two sorts of barley are cultivated in that district-barley, with two rows of grain in the ear, and Scotch bear, which, with a shorter ear, has six rows, generally double the number of grains, but smaller, and ripening earlier in colder seasons and more exposed situations. Now, according to this authority, if the purest and most unmixed barley be sown in the upland districts of Morayshire, it will, in the course of a few seasons, be changed into pure and unmixed bear. We suspect, however, there has been some error in the observer; for barley and bear are distinct species of plants.

Sir Joseph Banks thought that many plants, and probably the greater number, might, by art, become inured to a climate, soil, and situation, foreign to their original habits; and certainly many circumstances, received as truths by the generality of horticulturists and vegetable physiologists, seem to warrant our acceptance of his theory.

66 some

"In the year 1791," says Sir Joseph, in the first volume of the Transactions of the London Horticultural Society, seeds of the Zizania aquatica (Canadian rice), were procured from Canada, and sown in a pond at Spring-grove, near Hounslow; they grew and produced strong plants which ripened their seeds. These seeds vegetated in the succeeding spring; but the plants they produced were weak, slender, not half so tall as those of the first generation, and grew in the shallowest water only; the seeds of these plants produced others the next year, sensibly stronger than their parents of the second year. In this manner the plants proceeded, springing up every year from the seeds of the preceding one, every year becoming visibly stronger and larger, and rising from deeper parts of the pond, till the last year, 1804, when several of the plants were six feet in height, and the whole pond was in every part covered with them as thick as wheat grows on a well managed soil."

3