getable will then thrive in it, and will restore it to its original power of sustaining animal life. Obs. Hence, the oxygen of the whole atmosphere would, in due time, be consumed by the breathing of animals and by flame, but for this provision of nature. The leaves of vegetables create oxygen in the day-time, and keep up the due proportion which is necessary to the support of animal life; the leaves of aquatic and herbaceous plants produce it, however, in the greatest quantity. 441. The saccharine and oily productions of vegetables are parts of their sap or juices; but the turpentine, the bitter, and the acid principles, are considered as the effect of preparation or secretion. The green colour of vegetables arises from the oil they contain; the rays of the sun extracting the oxygen from the outer surface, and leaving the carbon and hydrogen, which are known to be constituent parts of oil. 442. Healthy vegetables perspire water by the under part of their leaves, equal to one-third of their weight every twenty-four hours; by which part they also give out oxygen. 443. Nor do they derive their substance in a principal degree from the matter of the soil in which they grow; but they are created by a vital principle of their own, out of air and water, and of the imperceptible matters combined with air and water, from which all their distinctions of smell, taste, and substance, are derived! Hail, Source of Being! Universal Soul Of heaven and earth! Essential Presence, hail! By THEE, disposed into congenial soils, Stands each attractive plant, and sucks and swells THOMSON. 444. Some plants exhibit signs of great sensibility, besides the effects in nearly all arising from the presence or absence of the rays of the sun: these are the sensitive plant, whose leaves drop on being touched by the hand; and Venus's flytrap, which closes on any insect that goes into it, and stings it to death. Obs.-Throughout universal nature, a gradation of beings may be traced; and yet their particular differences elude the observation, like the various colours of the rainbow, blending and mixing with each other. Where vegetation ceases, or seems to cease, perception begins; and we trace some of the first rudiments, or sparks of it, in the actinia, or sea-anemone, the oyster, and the snail. The polypus ranks as the first of plants, and the last of animals, if its propagation, as some naturalists affirm, can be effected by cuttings, similar to the multiplication of plants by slips and suckers. Then, it ascends through various gradations of beings; distinguished by more enlarged and active faculties, more. perfect and more numerous organs, to those creatures which approach to the nature of man. We behold the distant resemblance of his sagacity in the elephant; of his social attachments in the bee and the beaver; and the rude traces of his form in the ourang-outang. XIX. Of Animated Nature. 445. Animals are a class of beings organized differently from vegetables; because they have different destinations, different habits, and the power of moving from place to place, called the faculty of loco-motion. See, thro' this air, this ocean, and this earth, Beast, bird, fish, insect, what no eye can see, POPE. Obs. The principal object of the study of natural history, is to teach us the characteristics, or distinctive marks of each individual natural object called classification. To distinguish a species from all others that exist in nature, it is necessary to express in its characters almost the whole of its properties. A number of species brought together, constitutes a genus or tribe. Those properties which are common to all genera, compose a character that distinguishes this assemblage or group from all other groups. Such an assemblage is called an order. By bringing together such orders as are more nearly allied, we form a more general assemblage, called a class; and by the union of several classes, we obtain a higher division, to which naturalists have given the name of kingdom. 446. When the all wise Creator determined on making beings which should be able to move from place to place, he contrived for them an organization different from that of beings which were fixed. As moveable beings could not have their roots in the ground, he provided them with the cavity of the stomach, in which they were to carry about what should be equivalent to the soil for plants; and the suckers of their nutriment centering into that cavity, were destined to act like the roots of plants in the soil. 432. Linnæus seized on the variations in the number of the stamens, as a means of classing the vegetable kingdom into twenty-four denominations. Those flowers having but one stamen, he called mon-andria; those of two stamens he called diandria; three, tri-andria; so on up to twenty stamens, and above twenty, poly-andria. When he found stamens, in one flower, and pistils in another, on the same plant, he called them monacia; and on different plants, diœcia. When altogether invisible, cryptogamia. 433. Nothing can be more easy than to remember the names of these 24 classes; they are, 1. Monandria, one stamen. 2. Diandria, two stamens. 3. Triandria, three stamens. 4. Tetrandria, four stamens, equal in length. 5. Pentandria, five stamens. 6. Hexandria, six stamens, all of equal length. 7. Heptandria, seven stamens. 8. Octandria, eight stamens. 9. Enneandria, nine stamens. 10. Decandria, ten stamens, filaments separate. 11. Dodecandria, twelve stamens to nineteen, inserted on the receptacle. 12. Icosandria, twenty or more stamens, inserted upon the calyx or corolla. 13. Polyandria, many stamens, inserted on the receptacle. 14. Didynamia, four stamens, two long, two short. 15. Tetradynamia, six stamens, four long, two short. 16. Monadelphia, filaments united at bottom, but separate at top. 17. Diadelphia, filaments united in two sets. 18. Polyadelphia, filaments united in three or more sets. 19. Syngenesia, five stamens united above in the form of a cylinder. 20. Gynandria, stamens inserted on the pistil, or on a pillar elevating the pistil. 21. Monacia, stamens and pistils in separate corollas, upon the same plant. 22. Diæcia, stamens and pistils in distinct corollas, upon different plants. 23. Polygamia, various situations; stamens only, or pistils only on one plant, and stamens and pistils on another plant. 24. Cryptogamia, stamens and pistils inconspi cuous. Obs. I have introduced beneath, a representation of the pistils and stamens of a few of the first classes; and the pupil will, doubtless, be led to observe them within any flowers which may fall in his way. VWTY 434. The class Triandria contains chiefly the natural tribe of grasses; Hexandria the lilies. The Incosandria contains the edible fruit; Polyandria, has many poisonous plants. The Tetradynamia contains the natural tribe of flowers, which are antiscorbutic. The Monadelphia is composed chiefly of the mallow tribe. |