adapted to all the ordinary changes of their peculiar locality; so that the fact I have mentioned, is only a single instance of a principle of adaptation which runs through the whole system. The tropical plants, for example, are peculiarly formed, for the express purpose of enduring and flourishing under vertical suns, long droughts, and periodical rains; the vegetable productions of the polar regions, on the other hand, have their own remarkable contrivances for resisting the chilly influences occasioned by the long absence of the sun, and for starting suddenly into life, and running their short but rapid race, during the few weeks which comprise their spring, summer, and autumn. And so it is also with our temperate climates. It is not in winter, alone, that an adaptation to the season is conspicuous, but throughout every month of the year. Every parallel of latitude has its peculiarities of weather, its longer or shorter duration of mildness and of rigour,—of rain and of drought,—of light and of darkness; and to all these varieties, the plants indigenous to the soil are adapted.

But, what is more, under the very same parallel, there are localities which differ materially from the general average of the climate, on account of the elevation of mountain ranges or other accidental circumstances. Here, again, we find very striking indications of the provident care we have noticed. By whatever mysterious means the distribution has been made, there we find productions suited to the situation. Some extraordinary instances of this have been noticed on the Himalaya mountains, on the Andes, on the Peak of Teneriffe, and, indeed, in all the quarters of the globe where lofty mountain ranges are to be found. The scientific traveller, Humboldt, informs us, that there is upon the earth's surface, a geographical distribution of plants, according to its various climates, which he distinguishes into so many zones of vegetation, from the pole to the equator. In the island of Teneriffe, he observed that its various heights, which, as in all mountains, are colder

as the elevation increases, exhibited differences of plants, corresponding with the temperature; and he divided the various heights into five zones, each clearly marked by their respective vegetations. It has been a matter of curious investigation among philosophers, by what means the earth was at first supplied with productions suited to its respective climates and peculiarities; and it has been ingeniously attempted to be shown, that a single mountain, of sufficient elevation, placed in a favourable situation, and furnished, by the Creative Power, with the various vegetable productions which its different altitudes and consequent varieties of temperature required, might suffice, in the course of ages, for the dissemination of these productions over the whole face of the globe, according as its various localities might be adapted to receive them. Such an inquiry, however, is more curious than useful. It is enough for us to perceive the designing hand of a wise Creator in the adaptation of the vegetable creation to the very diversified circumstances of soil and climate, as it is found actually to exist in the different countries and regions of the world.

I shall only add, at present, that what has just been said of the vegetable, is equally applicable to the animal kingdom, as will be seen when we enter into the particulars to which these preliminary remarks refer.

SECOND WEEK-WEDNESDAY.

ADAPTATION OF ORGANIZED EXISTENCES TO THE TROPICAL

REGIONS.

ALMOST every country has its winter, as well as the other seasons of the year, differing materially, however, in different parts, and influenced not merely by its position in respect of latitude, but by various other circumstances which affect the climate generally,-such as ele

vation above the level of the sea, the neighbourhood of mountains, of forests, or of the ocean, the prevalence of periodical or constant winds, and other topical causes. Now, the observation which applies to climate, taken on the average, applies with equal truth to this uninviting season, namely, that there is, even during its rigours, a remarkable adaptation of the weather to the condition of animal and vegetable life; and, on the other hand, of animal and vegetable life to the weather. The temperature is admirably modified, and the various meteorological changes are wisely regulated, so as to correspond with the other seasons, and to be suited to the kind of organized existences which are to be found within the range of these natural operations; or, what comes to the same thing, these organized existences have been so framed, as to correspond in their nature and habits with the qualities of the weather.

In tropical climates, there can scarcely be said to be any winter, in the sense in which that word is understood, with reference to the other divisions of the earth; yet, even here, there is a period which possesses some of its distinctive characteristics. Under the equator, indeed, and in the adjoining regions, there may be said to be, in respect of temperature, two winters in the year,-the one, when the sun visits the tropic of Capricorn; and the other, when he looks down on our temperate climes with the smiles of summer, from the tropic of Cancer. Within the vast zone, bounded by the tropics, the climate is peculiar, not only on account of the extreme heat, but on account of the trade-winds, the monsoons, and periodical droughts by which it is distinguished. These phenomena, which are very various in their periods and extent, being much affected by the particular circumstances of their geographical position, wonderfully harmonize during the various seasons of the year, so as to render them, in each region, speaking generally, conducive to the salubrity of the climate; and the plants and animals which exist in these regions, are, at the same time, with sur

prising care, adapted to their respective peculiarities. This, would our space admit, might be interestingly exemplified by a detail of particulars; but, at present, I must be content to state, in general, that there are contrivances and adaptations which secure both plants and animals from the hurtful effects of the changes of temperature, of moisture, of violent and incessant rain, and of the direct rays of the sun, so striking and obvious, as to challenge attention from the most careless observer. In this fervid climate, the soil requires no lengthened rest to recruit its powers; nor do its vegetable products need to sleep for months in the bud or in the root. Under a long drought, indeed, they languish and decay; and this may, in fact, be considered as their period of winter, although it does not correspond with ours as regards the season of the year, or various other particulars; but no sooner does the equinoctial monsoon or the solstitial rain pour its refreshing streams on the surface of the parched earth, than all nature revives. Mr Elphinstone, in his account of Cabul, after graphically describing the appearances at the commencement of the monsoon in India, consisting of an incessant pouring of rain, amidst constant peals of thunder, and the most vivid flashes of lightning, attended with violent blasts of wind, proceeds to say,-" This lasts for some days, after which the sky clears, and discovers the face of nature changed as by enchantment. Before the storm, the fields were parched up; and, except in the beds of the rivers, scarce a blade of vegetation was to be seen; the clearness of the sky was not interrupted by a single cloud, but the atmosphere was loaded with dust, which was sufficient to render distant objects dim as in a mist, and to make the sun appear dull and discoloured till he attained a considerable elevation; a parching wind blew like a blast from a furnace, and heated wood, iron, and every solid material, even in the shade; and immediately before the monsoon, this wind had been succeeded by still more sultry calms. But when the first violence of

the storm is over, the whole earth is covered with a sudden but luxuriant verdure; the rivers are full and tranquil; the air is pure and delicious; the sky is varied, and embellished with clouds."

It

This change, from what may be called a tropical winter, though arising from an excess of heat instead of cold, to all the beauty and luxuriance of spring, proves, without any detail, that a constitution has been given to tropical plants, adapted to their situation and circumstances, and sufficiently marks the peculiar wisdom of the arrangement as regards the vegetable kingdom. Let it be remarked, too, that the monsoon takes place precisely at the very time when, but for this change, the heat would have become excessive and intolerable. occurs at the period when the sun is approaching his zenith in that parallel, and would have darted his vertical rays on the earth with unmitigated fierceness, were not a providential hand to interpose his veil of clouds, and cause them to pour forth their refreshing stores. This change is not the less admirable, that it is produced by the operation of known and uniform laws; and, assuredly, the wise adjustment and balancing of the great mechanical powers of nature is no unequivocal proof of Divine agency.

On turning to the animal productions within the tropics, we discover similar marks of beneficent design in the adaptation of their natures to the circumstances of the climate. M. Lacordairé,* as quoted by Mr Kirby, gives a striking account of the state of animated nature in Brazil. The great rains begin to fall in that country about the middle of September, when all nature seems to awake from its periodical repose; vegetation resumes a more lively tint, and the greater part of plants renew their leaves;—the insects begin to appear. In October the rains are rather more frequent, and with them the insects; but it is not till towards the middle of November, when the rainy season is definitively set in, that all

* Annales des Sciences Naturelle, 20 Juin 1830, p. 193.