there is a regular and periodical circulation of the sap from the root, through the stem of the plant, to the branches, buds, and leaves; and back again through the bark to the root; and that this circulation is as essentially necessary to the life and growth of vegetables, as the circulation of the blood is to the life and growth of animals.

In the manner of propagating the species, too, there are some curious resemblances between the vegetable and animal creation. Besides that the whole classes of plants, like animals, with few exceptions, are divided into male and female, there is another resemblance, which will scarcely be considered fanciful. All the winged tribes, and most of the inhabitants of the sea, as well as amphibious animals, reproduce the species by means of eggs. In like manner, the whole races of plants, from the moss to the tree, with scarcely any exception, propagate their species by means of seeds, which, in many remarkable particulars, deserve the name of vegetable eggs.

Animals seem to differ essentially from the vegetable kingdom, in the possession of sensibility, a property which the Author of Nature has apparently denied to the latter. This quality forms the first step in the scale, by which the former rises above the latter; but, as it has pleased the Almighty to cause the various grades of existences to run, as it were, into each other, we see here, also, a connecting link of the chain, in the wonderful properties of the sensitive plant, with which most of my readers are probably familiar, which, as it were, simulates sensibility, and approaches so near this vital principle, that authors who delight in those theories which aim at confounding the distinctions that subsist among organized existences, have plausibly maintained the identity of the one with the other.

"I have said that plants as well as animals select and secrete their food; but there is a marked difference both in the nature of the food, and in the process by which

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this nourishment is conveyed and appropriated. The vegetable, adhering to the soil, draws its food from thence, through the medium of roots, by mechanical action, without volition, without feeling, and without locomotion ; and that food is inorganic matter. The animal, on the contrary, seeks for its food by a voluntary action, receives it into its system by a mouth, digests it in a stomach, and rejects crudities by an intestinal canal. Its food is organized matter, either animal or vegetable ; the Creator having appointed the nourishment of this superior class to be elaborated from crude and indigestible materials by the organized, indeed, but insentient creation below them. This is one of the wonders of that astonishing gradation of beings with which the world is stored, and cannot but be contemplated with admiration and gratitude.

The view which is presented to us, even on the most cursory contemplation of organized matter, as may be perceived from these remarks, is that of a comprehensive whole, united together with the most consummate wisdom, and beautifully harmonizing in all its parts; and this impression will be found to be mightily confirmed and strengthened, when we come to consider the details.

SIXTH WEEK-WEDNESDAY.

II. HYBERNATION OF PLANTS.-ADJUSTMENT OF THE CONSTITUTION OF PLANTS TO THE ANNUAL CYCLE.

FROM what has been already said, it appears that the chilly nature of the season is not the only cause of the changes in the vegetable kingdom, which begin in autumn, and are consummated in winter. The disappearance of flowers and fruits, the fall of the leaf, and the general sterility which prevails, are evidently the indications of a cycle, belonging to the constitution of this

department of nature, which corresponds with the cycle of the year, and affords, by its existence, a new proof of wise adaptation. The effects produced by the sudden occurrence of a tract of frosty and tempestuous weather in summer, compared with a similar occurrence in winter, has been elsewhere alluded to, as illustrative of this principle. But a thousand other illustrations might be given. There is something exceedingly interesting and instructive in this view of the subject. The nice adjustment of organic substances to climate, has already been slightly noticed; and, were this inquiry to be followed out in detail, it could not fail to afford conclusive evidence of the same kind of contrivance with that to which we are now adverting. Every where we should find the productions of the soil admirably adapted to their localities, as to nourishment and climate; and, in the physical distribution of plants, we should discover new grounds for adoring the perfections of the Creator. The most superficial comparison of the plants of tropical regions with those of the polar circle, would be sufficient for this purpose. In the diminutive Empetrum nigrum, with its well-flavoured berries, which forms probably the last link of the descending chain of fruits in our progress to the poles, we observe the same careful adaptation of vegetation to the circumstances of external nature, which forces itself on our view in the majestic and luxuriant productions of the equator.

In the extremes of climate, taken on the average, we have, as it were, permanent summer, on the one hand, and permanent winter on the other; but, in the temperate regions, we have a regular alternation of modified heat and cold, which requires a different constitution of the vegetable creation; and that constitution has been bestowed. We here find the gradual development of seeds, and shooting forth of buds and leaves, in spring; the vigour and prime of vegetation in summer r; its maturity and commencing decay in autumn; its temporary death in winter. Now, what deserves to be peculiarly

remarked in this, is the adjusted correspondence of this annual revolution in plants, to the precise circumstances of the character and duration of the seasons.

That the stimulants of heat and cold exercise a considerable influence in promoting or retarding the periodical changes in the vegetable world, there can be no doubt; and this indeed is just one of those wise con contrivances which indicate design, as, without this modifying power, a slight variation in the temperature of the season, such as frequently takes place in all countries, and especially in a changeable climate like ours, might be productive of fatal effects; but the influence of heat and cold does not extend beyond a certain range, and is undoubtedly controlled, as we have said, by another principle, which we have called the natural constitution of plants. If proof of this were wanting, we should find it in the fact, that fruit trees, for example, when trans planted from our northern temperate zone to that of the south, where the seasons are reversed, continue to flourish for several years in the winter months of these regions ; and, for the same reason, plants from the Cape of Good Hope, and from Australia, transplanted to our climate, preserve their accustomed period of blooming, notwith-standing the influence of an altered climate. Of this the heaths of those countries which bloom in the most rigorous season of our year, may be taken as a familiar example.

It appears, then, that the functions of plants have a periodical character, entirely independent of heat and: cold. Such stimulants could not produce the effects which actually take place, were not the plants formed by the Author of Nature to run their annual cycles, Now, let it be observed, that a year might, by possibility, be of any length. Instead of extending to twelve months, it might be completed in six, and all the seasons might be comprised in that period, or its revolution might be lengthened to double, or fourfold its present period. In either case, the adjustment which now takes place be

tween the seasons and the constitution of plants, would be entirely destroyed, and an utter derangement of the vegetable world would take place. "The processes of the rising of the sap," says Mr Whewell, "of the formation of proper juices, the unfolding of leaves, the opening of flowers, the fecundation of the fruit, the ripening of the seed, its proper deposition in order for the reproduction of a new plant, all these operations require a certain portion of time, which could not be compressed into a less space than a year, or at least could not be abbreviated in any very great degree. And, on the other hand, if the winter were greatly longer than it now is, many seeds would not germinate at the return of spring."

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Now, such an adjustment,” adds this author, " must surely be accepted as a proof of design exercised in the formation of the world. Why should the solar year be so long, and no longer? Or, this being of such a length, why should the vegetable cycle be exactly of the same length? Can this be chance? And this occurs, be it observed, not in one, or in a few species of plants, but in thousands. Take a small portion only of known species, as the most obviously endowed with this adjustment, and say ten thousand. How should all these organized bodies be constructed for the same period of the year? How should all these machines be wound up, so as to go for the same time? Even allowing that they could bear a year of a month longer or shorter, how do they all come within such limits? No chance could produce such a result; and, if not by chance, how otherwise could such a coincidence occur, than by an intentional adjustment of these two things to one another?by a selection of such an organization in plants, as would fit them to the earth on which they were to grow; by an adaptation of construction to conditions; of the scale of the construction to the scale of conditions."* The concluding paragraph of the chapter from which Whewell's Bridgewater Treatise, pp. 28, 29.