ED. Western Horticulturist: - The wonderful mechanism of the human eye; the arrangement and construction of the ear; the number and diversified uses of the muscles; the mechanical organisms of plants; the diversified combinations of the elements; the immensity, harmony and diversity of the solar system, would almost lead us to believe that variety alone, distinct from every other consideration, was the motive and aim in the mind of the Creator, or with the agents of His will. The dissecting-room, the microscope and the laboratory but partially reveals to us the arcana of nature; but the science of astronomy, beyond all others, displays to us the splendor and the magnificence of His operations. Through this the mind rises to sublimer views of the Deity, though we cannot familiarize with the minor details in this department of His works.

There are a few observations on the vegetable kingdom that it will be our aim to notice. One great object of nature, in the structure of plants, is the perfecting of the seed, and its preservation until perfected. This intention shows itself, in the first place, by the care which seems to be taken to protect and ripen by every advantage that can be given them by situation in the plant, those parts which most immediately contribute to fructification, vis.: the anthers, the stamina, the stigma. These parts are usually lodged in the center, the recesses or the labyrinths of the flower during their tender and immature state; are.shut up in the stalk or in the sheltering bud; but as soon as they have acquired firmness of texture sufficient to bear exposure, and are ready to perform the important office which is assigned them, they are disclosed to the light and air by the bursting of the stem, or the expansion of the petals; after which they have, in many cases, by the very form of the flower during its bloom, the light and warmth reflected on them from the concave side of the cup.

What is called also the sleep of plants, is the leaves or petals disposing themselves in such a manner as to shelter the stem, buds, or fruit. They turn up or fall down, according as this purpose renders either change of position necessary. In the growth of grain, whenever the plant begins to shoot, the two upper leaves join together and embrace the head, and protect it till the pulp has acquired a certain degree of consistency. In some water plants the flowering and fecundation are carried on with the stem, which afterward opens and loosens the impregnated seed. The pea tribe incloses the parts of fructification within a beautiful folding of the internal blossom, itself protected under a pent-house formed by the external petals. This structure is very artificial, and it adds to the value of it, though it may diminish the curiosity; it is very general. It has this further advantage, which is strictly mechanical, that all the blossoms turn their backs to the wind whenever it blows strong enough to endanger the delicate parts on which its seeds depend. It is an aptitude which results from the figure of the flower, and, as before remarked, strictly mechanical - as much so as the folding of the fans of the windmill, or the cap on the top of a chimney.

The poppy and many similar flowers, the head, while it is growing, hangs down, a rigid curvature in the upper part of the stem giving it that position, and in that position it is impenetrable by rain or moisture. When the head has acquired its size and is ready to open, the stalk erects itself for the purpose of presenting the flower and the instruments of fertilization to the genial influence of the sun's rays. This is a curious property provided for in the constitution of the plant; for if the stem be only bent by the weight of the head, how comes it to straighten itself when it is the heaviest? These instances show the attention of nature to this principal object, viz.: the safety and maturation of the parts upon which the seed depends. In trees,, especially in those which are natives of colder climates, this point is taken up earlier. Many trees produce the embryo of their leaves and flowers in one year, and mature them the following year. There is a winter also to be got over. Now, what we are to remark is, how nature has prepared for the trials and severities of that season. These tender embryos are wrapped up with a compactness no art can imitate, in which state they compose what we call the bud.

The bud itself is inclosed in scales, the remains of past leaves or the rudiments of future ones.

In the coldest climates a third preservative is added, by the bud having a coat of gum or resin, which, being congealed, resists moisture and frosts. On the approach of warm weather this gum is softened, and ceases to be a hindrance to the expansion of the leaves and flowers. The leaves themselves are packed in capsules or in vessels composed of coats, which, compared with the rest of the flower, are strong and tough. From this vessel projects a tube through which the fertilizing properties that issue from it are admitted into the seed.

Here occurs a mechanical variety accommodated to the different circumstances under which the same purpose is to be accomplished. In flowers which are erect, the pistils are shorter than the stamina, and the pollen shed from the anthers into the cup of the flowers is caught, in its descent, on the head of the pistils called stigma. In flowers that hang down or suspended (the crown imperial, etc.), this arrangement is reversed, the pistils being usually the longest, and its protruding summit receives the pollen as it falls to the ground.

The seed vessels are of an incalculable variety of forms in different plants, all evidently conducing to the same end, namely, the security of the seed. Of the gourd, melon, etc., the seed vessels assume an immense bulk; in stone fruits and nuts, incased in a strong shell, the shell itself incased in a pulp or husk; in numerous kinds of berries, in grapes, oranges, etc., the seed is inclosed in a glutinous syrup contained in a skin or bladder; in apples, pears, etc., imbedded in the heart of a firm, fleshy substance; or, as in strawberries, pricked into the surface of a soft pulp. These, and many other varieties exist in what we call fruits. In grain, in grasses, trees, shrubs and flowers the variety of seed vessels is incomputable. We have the seeds, as in the pea tribe, regularly disposed in parchment pods, which, though soft and membranous, are impervious to water; at other times, as in the bean, lined with a fine down. We have seeds packed in wool, as in the cottonwood, lodged between hard'and compact scales; as in pine cones, protected by spines; as in the thistle, placed under a pent-house; as in the mushroom, in ferns, in slits on the back of the leaves; or as in grains and grasses covered by strong, close tunicles attached to a stem, according to an order appropriated to each species of plant.

[CONCLUDED NEXT MONTH.]