Again, provision is made for the secretion and assimilation of the various substances received into the system of plants, for the circulation of the nutritive juices, for the deposition of the solid materials in their proper situations; and, in short, for the developement and maintenance of the whole organization. That organization, itself, is full of wonders. The elementary texture of a vegetable is formed of vesicles, the coats of which consist of transparent membranes of extreme tenuity, and of such minuteness, that, according to Kieser, the diameter of each individual cell varies, on a moderate estimate, from the fiftyfifth to the three-hundred-and-thirtieth part of an inch; so that from 3000 to 100,000 cells would be contained in an extent of surface equal to a square inch. Kirby goes far beyond this statement, and assures us that these vesicles are occasionally so inconceivably minute, as not to exceed in diameter the thousandth part of an inch; in which case, no fewer than 300,000 of them might be contained in a square inch. These adhere closely together, and form by their union, a species of cellular texture, which may be considered as the basis of every organ in the plant.

Fluids of different kinds are diffused over the plant, occupying both the cells and the intercellular spaces, which consist either of a watery sap, or of peculiar vegetable secretions. Among these vesicles are found, in most species of plants, numerous ducts, interspersed throughout every part of the system, containing air, and hence called air-tubes. There are also found, in the interior of vegetables, certain organs named glands, which perform the important function, above-mentioned, of secretion, that is, the conversion of the juices, by a kind of alchymy, into the products necessary for the nourishment of the plants.

Besides these internal parts, an external covering is provided, to protect the plant from the injurious effects of the atmosphere, and of the moisture it deposits. This is termed the cuticle, which is spread over the whole surface, investing the leaves and flowers, as well as the stem and branches; and this membrane is perforated

in various parts, but especially in the leaves, with minute oval orifices or stomata, which have the power of opening and shutting, and are intended to exhale water, and, perhaps, sometimes also to absorb air.

The form and organization of the root is not less worthy of notice. Considered as the means of attaching the plant to the ground, the contrivance is most admirably suited to its function, this provision being proportioned to the degree of power required; so that, although in low shrubs and plants, which are not destined to experience much external violence from storms, little precaution is exerted, yet in the case of lofty trees, and especially in such as are furnished with dense foliage, and wide-spreading branches, which present a large surface and powerful lever to the wind, the most studied and skilful contrivances are adapted to enable them to take firm hold of the ground, and to resist the tremendous force, with which, in tempestuous weather, they are assailed. Nor must another and still more essential function of the root be forgotten,—I mean that of drawing the nutritive juices from the soil. This is effected by means of what are termed spongioles, situated at the extremity of the rooty fibres. These, acting as sponges, from their resemblance to which they derive their name, imbibe the various vegetative qualities inherent in the earth, which, partly by means, as is generally believed, of capillary attraction, and partly by some mysterious vital power, are conveyed upward through the curiously-organized vessels, to form the food of the plant.

This rapid view of the general conformation of a plant, may suffice to show with what wonderful care the organization of the vegetable world is adapted to the condition of external nature, and how irresistibly the student of Nature in this department is led to acknowledge the existence of Creative Power and Wisdom. It is reported of Galileo, the most profound philosopher of his age, that, when interrogated by the Inquisition as to his belief in a Supreme Being, he pointed to a straw on the floor of his dungeon, and replied, that even if he had no other proof of an Intelligent Creator, the mechanism of that

fragment of a plant would be sufficient ;-and not without reason, for even in the form of a stalk of corn, there are indications of contrivance, the force of which no candid mind can resist.

Another essential property which belongs to vegetable life, is the power it possesses of propagating the species. One of the most marked conditions of organized existences is that of perpetual change. The plant rises and flourishes, and then, in a few years, frequently indeed in a few months, decays and dies. Had there not been some means employed, therefore, of preserving the species after the individuals had mingled with their parent earth, the world would have quickly been reduced to a barren and lifeless waste. But there is nothing more remarkable in the constitution both of the vegetable and animal worlds, than the careful provision which has been made for preventing this catastrophe, not only as respects organic life in general, but as respects each distinct kind of organized existence, which the plastic hand of the Creator has formed. All are endowed with an ample, and even redundant, capacity of giving rise to offspring of their own species. The manner in which this is almost uniformly effected in the vegetable world, as I formerly stated, is by means of seeds, which they propagate in various forms, preserve by various contrivances, and scatter over the soil in various ways, and which are by their peculiar conformation and properties, as will afterwards be seen, most curiously and skilfully adapted to the functions they are destined to perform.

The properties we have mentioned are common to all, or, at least, to by far the greater part of terrestrial plants; and the remarkable uniformity which exists in their general structure, is a clear indication of One Contriving Mind. But the law of diversity is not less remarkable in their formation, than the law of coincidence and analogy. There are certain definite objects to be accomplished by each species, and, in them all, there is a striking conformity of type; and yet, amidst this uniformity both of intention and of original model, there exists a variety at once interesting and surprising. This is the

PRESERVATION AND DISTRIBUTION OF SEEDS. 61

case not merely in the vegetable but animal world, in a degree which is exceedingly remarkable, even on the slightest inspection, and which grows upon us as it is contemplated. "In every department of Nature," says Mr. Kirby, from whose work the facts contained in this paper are drawn, "it cannot fail to strike us, that boundless variety is a characteristic and predominant feature of her productions. It is only when the object to be attained, is dependent on certain definite conditions, excluding the possibility of modification, that these conditions are uniformly and strictly adhered to. But wherever that absolute necessity does not exist, and there is afforded scope for deviation, there we are certain to find introduced all those modifications, which the occasion admits of. Not only is this tendency to variety exemplified in the general appearance and form of the body, but it also prevails in each individual organ, however minute and insignificant that organ may seem. Even when the purpose to be answered is identical, the means which are employed are infinitely diversified in different instances, as if a design had existed of displaying to the astonished eyes of mortals, the unbounded resources of Creative power. While the elements of structure are the same, there is presented to us, in succession, every possible combination of organs, as if it had been the object to exhaust all the admissible permutations in the

order of their union."

SECOND WEEK-THURSDAY.

PRESERVATION AND DISTRIBUTION OF SEEDS.

I HAVE already stated, that the chief method, by which the Author of Nature has provided for the reproduction of plants, is by means of seeds. This method may be considered as universal, for there is no perfect plant which is not produced by means of a seed; although other methods, also, are sometimes employed, such as

VIII.

propagation by means of runners or offsets, or by the rooting of branches. Seeds, as I have noticed, resemble, in some remarkable particulars, the eggs of fowls and insects; and, in the same analogy, the spawn of fish may also be included,—thus exhibiting one of those features, by which the various orders of organized beings appear to be so mysteriously related, and in which we trace so unequivocally the handiwork of a common Creator.

There are many tribes of vegetables, which, from year to year, depend entirely for their production on seeds. The plant having given birth to this embryo of its species, and deposited it in the soil, withers down to the root, and expires. Now, let us look at this curious production. It is composed of various parts, named cotyledons, corcle, membranes, and vessels. The cotyledons are composed of a cellular network, curiously organized, which forms the substance of the seed, and contains the albuminous matter, which nourishes the young plant in the earlier stages of its existence. The corcle is the embryo of the future plant, and lies between the cotyledons; it differs in its structure at different stages, consisting at first of a thin glairy fluid, and afterwards becoming more concrete and regularly organized, till at last it displays the rudiments of the root and of the plumale, or future stalk. We have named the seeds of plants, vegetable eggs; and every one must observe in this description, a remarkable similarity between the eggs of animals and these productions of an inferior kingdom.

These seeds, when it is intended that they shall lie dormant, in a temperate climate, through the winter, to reproduce the species in spring, are furnished with every property necessary for the intended purpose. They remain in the bosom of the ground, sometimes protected. by peculiar contrivances to preserve them from the severity of the season; but, whether this be the case or not, they are always endowed with qualities, or subject to conditions, which are sufficient for the preservation of the species, being, generally speaking, uninjured by the cold and wet, and unaffected by the alternations of