The different manner in which vegetables exert their organic powers to effect the destruction of insects, is not perhaps unworthy of a brief notice; some, as those above mentioned, accomplish it by means of elastic or irritable actions, adhesive substances, and so forth; but we have another plant in our green-houses, the glaucous birthwort (aristol. glauca), that effects these purposes without any of these means, but principally by conformation. The whole internal surface of the tubular flower is beset with minute strong spines, pointing downwards; these present no impediment to the descent of the animal which may seek for the sweet liquor lodged upon the nectarium at the base of the blossom, nor is there any obstruction provided for its return by means of valves or contractions, the tube remaining open; but the creature cannot crawl up by reason of the inverted spines, and to prevent its escape by flying up the tube, the flower makes an extraordinary curve, bending up like a horn, so that any winged creature must be beaten back by striking against the roof of this neck as often as it attempts to mount, and falling back to the bulbous prison at the base of the flower, dies by confinement and starvation, and there we find them: a certain number of these perishing, the blossom fades and drops off. All the varieties of this snapdragon have the power of maintaining a state of vegetation in great droughts, when most other plants yield to the influence of the weather; and it is the more remarkable in these plants, as the places in which they chiefly delight to vegetate are particularly exposed to the influence of the sun. In that hot dry summer of 1825, when vegetation was in general burned up and withered away, yet did this plant continue to exist on parched walls, and draw nutriment from sources apparently unable to afford it; not in full vigor certainly, but in a state of verdure beyond any of its associates. The common burnet (poterium sanguisorba) of our pastures, in a remarkable degree, likewise possesses this faculty of preserving its verdure, and flourishing amid surrounding aridity and exhaustion. It is probable that these plants, and some others, have the power of imbibing that insensible moisture, which arises from the earth even in the driest weather, or from the air which passes over them. The immense evaporation proceeding from the earth, even in the hottest season, supplies the air constantly with moisture; and as every square foot of this element can sustain eleven grains of water, an abundant provision is made for every demand. We can do little more than note these facts: to attempt to reason upon the causes, why particular plants are endowed with peculiar faculties, would be mere idleness; yet, in remarking this, we cannot pass over the conviction, that the continual escape of moisture from one body, and its imbibition by another, this unremitting motion and circulation of matter, are parts of that wonderful ordination, whereby