the struggle became one for mastery, more than for accommodation ; and to the power from whose proceedings the contest derived that dangerous character must the evil which ensued be imputed. Thus we see in these results, that not to concede in time is to create the necessity for further concession; that in enlightened communities the great security against popular violence is to abstain from acts tending to justify popular indignation; and that it is as vain as it is unjust to expect that men should act with sobriety when we have been conducting ourselves towards them in a manner which could hardly fail to goad them into excess.'—p. 561.

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Since this article was written, a lengthy criticism on Dr. Vaughan's work has appeared in the Church of England Quarterly Review, and is to be followed, it seems, by another, on the second volume, in the next number of that Journal. The writer of that article— feeble in everything except in his rancorous bigotry-has not only shown himself capable of descending to any form of misrepresentation, but of stating, once and again, as true, what he must have known to be false. Our proofs of this serious charge we may perhaps adduce on a future occasion, as we have for some time thought, that Dissenters might not be the worse for being made a little more aware than they are, of the unscrupulous enmity with which their literature is too commonly regarded by the reverend personages who affect to represent the spirit of the ‘ Church of England. If what our authors have to expect from Churchmen, is, for the most part, this reckless hostility, or, what to them will perhaps be even less acceptable, an utter neglect of their productions, the need of a more effective patronage of Dissenting literature among ourselves ought to be sufficiently obvious. As to the critic adverted to, we have reason to know that this is not the first time he has called on the public to admire his zeal for the honors of 'Episcopacy;' and should he in this instance experience some inconvenient handling for his pains, he will be aware that it is not the first time such a lot has befallen him.

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Art. II. The Theory of Horticulture ; or, an Attempt to Explain the

Principal Operations of Gardening upon Physiological Principles.

By John LINDLEY, Ph. D., F.R.S. 8vo. Longmans. HORTICULTURE has in the main been followed as an art;

its most successful processes have been the result either of casual observation, or of innumerable trials and mistakes, and its principles not in general more than mere statements of the facts thus arrived at. The conditions that are necessary to healthy vegetation are obviously discerned, and provided for, when the plant and the cultivator are both of one clime, or when the exotic species are hardy and adapted to universal culture, as the rye and the potatoe. Moreover, he need not be deterred from the boldest experiments in his attempts to render the growths of the earth more serviceable. Much, therefore, has been done for the improvement of both native and acclimatized species. They have been increased in size and modified as to their qualities, forms, and colors. The peach, poisonous in its native soil, has become the delicious fruit we find on our tables. The celery and carrot, have lost the noxious qualities which they possess in their natural state. The cabbage, cherry, and apple, which we probably owe to the Roman occupation of Britain, have all become what we find them, by cultivation; being barely esculent as nature produces them. Few of the most

valuable of vegetable products are indigenous to the countries where they are most useful and most esteemed, but have followed the migrations and conquests of various tribes of the human family. The grape, wherever the region may be which owns it as a native, was spread originally by the Greeks; and the introduction of the most precious of the farinaceous grasses, the wheat, and also of the cotton-tree, were among the blessings which the great Ruler ordained should more than compensate

regions overrun by the Romans and Arabs, for temporary misery. It is, of course, in the cold climates least endowed by nature, where want and necessity constitute the wholesome discipline of a race formed for enterprise and success, that tillage and culture will be most studied. And they have this advantage over countries more spontaneously fruitful, that a hot climate can be imitated in a cold one, with infinitely greater ease than in the reverse case.

Were we to be content with those foreign species that easily become adapted to our climate, horticulture might remain as it is, and leave everything beyond to the larger and less refined operations of field cultivation. While the desire of novelty and enjoyment exist, this need not be feared, and the attempt now,

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we think, first made, in a way likely to be generally useful, to raise horticulture to the rank of a science, impatient of mere empirical maxims, and studious to fortify the wisest of its traditions by the knowledge of the vital laws which they unconsciously imply, is no more than might have been expected from the present advanced state of vegetable physiology. There is already available to the cultivator a great mass of well ascertained principles, without perplexing him with scientific refinements, as yet perhaps only conjectural and likely to be for ever too subtile for the worker in gardens to apply. What he needs is, not a treatise upon botany, nor a series of speculations upon " the possible nature of the influence on plants of all existing forces, nor an elaborate account of chemical agencies inappre

ciable by his senses and obscurely indicated by their visible • results; but an intelligible explanation, founded on well ascer*tained facts which he can judge of by his own means of observation, of the general nature of vegetable actions, and of the causes which, while they control the powers of life in plants, ' are themselves capable of being regulated by himself. The possession of such knowledge will necessarily teach him how to improve his methods of cultivation, and lead him to the discovery of new and better modes. It is very true that ends of this kind are often brought about by accident, without the * smallest design on the part of the gardener; and there are 'doubtless many men of uncultivated or idle minds, who think waiting on providence much better than any attempt to improve their condition by the exertion of their reasoning facul• ties. For such persons books are not written. That the amount of such knowledge is very small even among writers on horticulture we have the testimony of one well able to judge.

We shall attempt to increase the demand for the volume whose title stands at the head of our article, by referring a few of the ordinary processes of horticulture, to the physiological principles which they serve to develop. If much has been achieved by the force of accident and mere rational empiricism, we may confidently expect results far greater, from perseverance and observation, when enlightened by science. · The enormous • difference that exists between the skill of the present race of gardeners and their predecessors can only be ascribed to the general diffusion that has taken place of an acquaintance with some of the simpler facts of vegetable physiology.'

Natureuniversally employs some degree of soilor bottom heat, as a stimulus and protection to the excitability of the tissues of plants. The soil in all climates has a temperature something higher than the surrounding atmosphere. This of course is owing to the impact of the solar rays. All plants have free internal communication between their extremities, by innumer

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able air passages and chambers, so that the loss of temperature by the atmosphere in the night time, does not involve an excessive diminution of that of the plant, which would injure and perhaps destroy its excitability. For the soil, raised possibly to 150° during the day, retains a considerable warmth during the night; and through the circulation of air and fluids imparts it to the plant; thus counteracting the cooling effect of radiation. This, without referring to the probable generation of heat by the chemical re-compositions going on in plants, is a sufficient explanation of the temperature they preserve at night above that of the medium surrounding them. This elevation of temperature it is of course necessary to imitate artificially for all plants whose native habitats are in warmer climes than our

We neglect it in the orange-tree, which flourishes where the soil never sinks below 58°, exposing it in the summer to the open air when the soil seldom reaches 66°, and keeping it in winter in cold conservatories, the soil of which often falls to 36o. We

consequently lose the richness of its foliage and the perfume and juiciness of its fruit. Peach and other trees have been brought again into bearing by lessening the depth of earth around their stems, thus giving both air and heat access to their roots. The difference of temperature in the soil at the surface and two feet beneath it, usually exceeds 10°. Nature provides that the mean heat of the soil should be permanently greater than that of the air. Were it not so, the stimulus applied to the leaves would cause them to consume sap faster than the roots renewed it. It is, therefore, the proportion of soil heat to that of the air, which we must observe. We must not be content with raising the bottom heat of a tropical plant when we cannot imitate the degree of light and atmospheric warmth which it would enjoy in its native site. Whether by the occurrence of winter or the setting in of periodical rains, all plants have alternations of seasons; and these we must seek to copy in our adjustments of temperature to the varying stages of growth of our plants. The same principles of course apply to aquatic exotics, that naturally flourish in water of higher temperature than that medium retains inartificially in this country. Cisterns plunged into tanbeds, in a close heat, or on the flues of a pine-stove, secure the requisite exaltation of temperature.

There is yet wanting to horticulture some plan of providing bottom-heat, which shall more nearly resemble the natural mode. The tan-bed is too liable to fluctuations, from excess or defect, and is too insusceptible of regulation to be used as more than a succedaneum till some better contrivance be thought of.

Water is necessary, as it is itself part of the food of plants, and also a vehicle by which the soluble matters found in the earth are conveyed through the general system of vegetation. Its importance depends on its quantity: and the same regard in giving it to plants, must be had to the natural condition of the species, and to the period of its growth, as the application of heat to their soil requires. During the season of rest (with plants of climates like our own in the winter, with those of tropical regions in the dry months) plants require but little ; for perspiration is not then going on, and therefore food is not then required. Those with perennial stems, indeed, need moisture, because they lay up food against the renewal of vegetation. If, however, their soil is too abundantly supplied with it, the tissues become distended with aqueous matter, and are thus rendered liable to disorganization by frost, or the plant is driven into growth before the air is sufficiently warm to maintain the excitability of its new parts. More moisture is not needed at the period of vegetation than can be got by the capillary attraction of earthly particles. Just so much water as the soil holds by mere attraction is sufficient. Hence soils compounded of peat, loam, and sand, are found to be most suitable, in which the loam retains moisture, but is hindered from holding too much by its small masses being kept asunder by peat and sand, that of themselves would allow all their moisture to escape by percolation. In earth not only apparently but absolutely dry, plants must perish.

The younger the leaves the more sensible is the whole of their epidermis to the stimulus of light. As they grow older this hardens; their stomata are then the only passages through which vapor can fly off, and these are gradually choked up. Plants that are cultivated for the sake of their esculent leaves, need a greater supply of earth moisture to give them tenderness and succulence--as the lettuce, spinach, &c. The fruit of the strawberry is rendered large by copious watering while it is swelling, often at the expense of its flavor. The rapid evolution and infiltration of its tissue, and the increased luxuriance of its leaves, neither giving it time nor a sufficient exposure to light for the full elaboration of its crude juices. It is not yet quite clear to what causes among several probable ones, or if to all of them together, the deleterious effect on plants of too much soil moisture, or of water positively stagnant about their roots, is to be attributed. It is certain that drainage, either natural or artificial, is necessary to their health. The consequent coldness of the soil is a sufficient reason for attending to this particular. The method generally used to keep the soil humid by watering, though indispensable in the hothouse, is perhaps more hurtful than beneficial out of it. When nature waters them, the air is saturated at the same time with the soil. Perspiration in plants, as in animals, bears an inverse relation to the humidity of the air, and therefore