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,

-another proof of the designing hand of Nature in this provision.

We have mentioned the power possessed by plants, in a living state, of resisting the effects of cold; and this fact has led some physiologists to conceive, that an internal heat is generated in plants, as it is in the animal frame. The experiments, however, which have been made to test this opinion, have been of somewhat doubtful result, though some curious facts have been adduced in confirmation of it. It is well known, for example, that snow dissolves more quickly in a meadow than on bare ground; and this has, with apparent force, been attributed to the existence of a slight degree of heat in the vegetation. In certain states of some plants, it has been ascertained, that heat is evolved. M. Hubert relates a striking example of this kind, in the spadices of a Madagascar plant, the Arum cordifolium. On applying a thermometer to five spadices, which had unfolded in the preceding night, he observed a rise of twenty-five degrees from the temperature of the atmosphere. The temperature became gradually lower, till, in the evening of the second day, the difference between the heat of the spadices and of the surrounding atmosphere, was only seven degrees. The observation which we have recorded above, of the power of living buds to resist frost, Willdenow extends to the sap of trees, which, he says, will remain unfrozen in very intense cold. The case, however, is different, as he informs us, in plants of warm and hot regions. The sap of these plants congeals on a very slight cold, and the plants themselves decay; which shows a very remarkable difference between tropical plants and those of colder climates, and strikingly indicates intention. Another observation is, that, although the sap will not congeal in winter, yet, after the buds have been forced out by warm weather in spring, it will readily congeal on exposure to cold,-an effect which Dr. Smith ascribes to "the increased susceptibility of the vital principle," at that season. Dead or diseased branches, too, are said to be more liable to be frostbitten than living and sound ones. These facts, though not

conclusive, seem to give probability to the opinion, that the degree of heat necessary to the support of vegetable life, in winter, is maintained by natural processes going on in the plant itself. But, whatever truth there may be in such an opinion, the facts themselves are sufficient to show the impress of an Intelligent Cause, in this, as in every other department of organized matter. We may

not be able satisfactorily to trace all the various steps of the process, but we are able confidently to say, Here, too, is the hand of God.

SIXTH WEEK-FRIDAY.

IV. HYBERNATION OF PLANTS.-THEIR PHYSIOLOGICAL CONDITION CONTINUED.

WE have already seen some of the provisions made for the preservation, during this inclement season, of plants of larger growth, which are exposed, leafless, and bare, to all the severity of a chilling atmosphere; and we are now to mention other provisions for a similar purpose, which are no less admirable. One reason, as we have already hinted, why trees of great dimensions throw off their summer clothing of leaves, is, that they may more readily resist the force of the winds, which frequently blow with fury in the winter. But there are some trees which are not endowed with this property; among these, the pine tribe are the most common and conspicuous. Now, remark the contrivances by which the difficulty arising from such a deviation is met. In the first place, the leaves, if they deserve that name, instead of being broad and flat, like those of other trees, are rather in the form of bristles,-which shape suffers the wind to pass freely through, and offers the smallest resistance; and, in the second place, the roots of this class of trees are spread widely along the surface of the earth, laying fast

hold of the soil, as they intertwine among each other, and insert their numerous fibres; by which contrivance they are able to stand firm upon their extended base, easily resisting the force of all ordinary tempests. This fact must have struck the mind of any one, who has happened to observe the great breadth of earth and of roots attached to a fir-tree overthrown by some furious

storm.

There is a remark, of a more general nature, which occurs here. All trees are known to attach their roots to the soil, with more or less tenacity, in proportion to their exposure to the wind. There is nothing more familiar to the wood-forester than this striking fact, or more necessary for him to know. The trees, on the outside of a grove or wood of pine, are so firmly fixed in the soil, that scarcely any tempest can uproot them; and those shelter the rest, whose hold is not so secure. Were this outer ring to be cut down, the wind, thus suddenly let in, would be sure to injure the rest, and the safety of the whole wood might be endangered. Here we find an instance of adaptation to circumstances, which cannot be too much admired.

Other kinds of evergreens, which enliven the winter months, are to be found among shrubs, and some of the lower species of trees. These are more able to resist the fury of violent winds, on account of their diminutive height, which exposes a shorter, and therefore less powerful, lever to the action of this force, while their roots are equally adapted, with those of the pine, to the peculiarities of their nature. Besides this, the leaves of these hardy plants are generally of a solid texture, and glossy surface, well suited to resist the various vicissitudes of the season. Such delightful varieties seem to have been bestowed on us, for the purpose of affording relief from the stern aspect of winter; and the grounds of the rich, show how well a judicious use of these, and of various herbaceous plants, can throw, over the bleakness of this gloomy season, some of the charms of sum

mer.

If, from shrubs and trees, we turn to the numerous