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 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 transplanted 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, notwithstanding 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 cycle. 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 between 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."

"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 we have just quoted, which carries the view of adjustment between organized existences and the annual cycle still farther, is also well worthy of being quoted." The same kind of argument might be applied to the animal

* Whewell's Bridgewater Treatise, pp. 28, 29.

creation. The pairing, nesting, hatching, fledging, and flight of birds, for instance, occupy each its peculiar time of the year; and, together with a proper period of rest, fill up the twelve months. The transformations of most insects have a similar reference to the seasons, their progress, and duration. It is not our business here to settle the details of such provisions, beautiful and striking as they are. But the prevalence of the great law of periodicity in the vital functions of organized beings, will be allowed to have a claim to be considered in its reference to astronomy, when it is seen that their periodical constitution derives its use from the periodical motions of the planets round the sun; and that the duration of such cycles in the existence of plants and animals, has a reference to the arbitrary elements of the solar system,——a reference which we maintain is inexplicable and unintelligible except by admitting into our conceptions an Intelligent Author alike of the organic and inorganic universe.”

SIXTH WEEK-THURSDAY.

III.-HYBERNATION OF PLANTS.-PHYSIOLOGICAL CONDITION OF PLANTS DURING WINTER.

THE beautiful variety of shades in our woods and groves, towards the close of autumn, which the most inattentive observer must have admired, arises from the preparation which Nature is making for the winter state of our shrubs and trees. The functions of the productive seasons are ended; the forest trees have completed their annual growth; the fruit-bearing trees have yielded their stores; and the leaves, which performed such an important part in these processes, being no longer useful, are to be dropped, that they may, by mingling with their parent earth, supply the waste of the vegetable soil, and repair its exhaustion from the efforts of the preced

ing year. The sap which had risen profusely in the beginning of autumn, to aid Nature in giving maturity to the fruits, and vigor to the young branches, and thus to crown the labors of the year, having performed this important office, has begun to flow downwards through the inner integuments of the bark, thus completing its periodical circulation. The leaf and flower-bud, destined to be developed in the ensuing spring, have been already formed, and are carefully shut up in their winter cerements. The tree exposed naked to the wintry blast, is rendered, by a wonderful provision of the All-wise Creator, proof against the injurious effects of frost. It is in its state of hybernation, like many beasts and insects; for here, too, the analogy of Nature is striking-it has fallen into its winter sleep.

The proofs of this state of torpidity are numerous and interesting. Among these, the most familiar is that of the capability of removal, without material injury, to another place. There is no size or age of a tree which would prevent it from enduring transportation, at this season, with perfect safety, provided only it could be effected without greatly injuring the root; and it is only in winter that such an experiment can be performed with any chance of success. Why? Because the powers of Nature are then suspended. The plant has ceased to draw nourishment from the earth, and its vital principle, though by no means extinguished, is in a state of temporary lethargy.

Now, the importance of this state of plants, in winter, will be obvious, if we consider the condition of the soil and climate of temperate regions, during that period. The genial warmth which caused the juices to flow is gone; the ground is frequently rendered, by frost, rigid and almost impenetrable; tempestuous weather would threaten the destruction even of firmly rooted trees, did not the removal of the leaves admit a free passage to the wind through the branches; the cold would blast the delicate fibre of the growing shoot. All these dangers are either entirely provided against, or at least rendered by no means formidable, by the torpidity which invades

the vegetable creation. The plant still lives, but its food is gone; its active operations would expose it to be the sport of the angry elements, and therefore it has retired within itself, like the coiled hedgehog, to sleep out the ungenial season, and to prepare, with new vigor, for the exercise of its renovated powers, in the coming spring.

Much less is known of the physiology of plants, than the interesting nature of the subject would lead us to desire; but there is one circumstance connected with their state in winter, which is too curious to be overlooked. The vital principle, whatever it may be, exerts a peculiar energy in defending them from the influence of frost. A very simple experiment, within the power of every person, will show this. Let a bud be cut off from the parent tree, and suspended, during a strong frost, either by a string, or even within a glass vessel, upon one of the branches, and it will be found that this severed bud will be completely frozen through, while all the buds still attached to the tree, are entirely unaffected by the cold. There is, then, a living power in plants which, of itself, resists, to a considerable extent, the effects of cold. But the Author of Nature does not rest the security of vegetable productions on this principle; on the contrary, the safety of the bud, on which the future existence of the plant so materially depends, is provided for by its careful envelopement in plies of scales, or within a downy substance, besides being often united together by a coat of resinous matter, of which latter state the horse-chestnut furnishes a familiar example. The intention of this kind of protection is distinctly indicated by the fact, that it occurs only in northern countries, the buds of trees in milder regions being destitute of the scaly covering. The security from injury, which the resinous coat affords, may be proved by a simple experiment. Let a bud of this kind be taken from the tree, and, sealing up the cut end, let it be plunged into the water; and in this state it may be kept uninjured for several years. In tropical regions, the leaf or flower, not requiring any such means of safety, starts into existence at once, without the intervention of buds,