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508. The polype is an insect of a snail or jelly-like substance. It shrinks into a round green spot, if disturbed; but, in its natural form, is a long tube, and has a head and mouth, from which eight or ten long arms are projected to seize worms and other insects. The young
issue from its side in a surprising manner; but, it is the wonderful property of this insect, that if cut into any number of pieces, and in any direction, each part will become a perfect polype in itself!
It may may even be turned inside out without injury; and the dismembered parts of one polype will unite with those of another, and make one perfect polype !
509. After a man has exerted his eyes to view the smallest insect, he will find, on applying a microscope, others so small, that ten thousand of them are not equal in bulk to the smallest which he can view with his naked eye.
Lewenhoeck tells us of insects, seen with a microscope, of which 27 millions would only be equal to a mite, and four millions to a single grain of sand.
510. Yet each of these animalculæ has an organized body, provided with a heart, lungs, muscles, glands, arteries, and veins; and with blood and other fluids passing through them!
Their vigour and powers of action are generally superior even to those of larger animals; their length of life is also great in proportion to their size.
The mite makes 500 steps in a second ; animalcules, in a drop of water, swim about with as much freedom as a whale in the sea; and those that feed on the leaves of trees resemble oxen grazing in large pastures.
Wak'd by his warmer ray, the reptile young
Swarming, they pour: of all the varied hues,
511. Animalcules are shaped like fish, reptiles, eels, stars, hexagons, triangles, ovals, and ciroles; they have horns, probosces, &c. and although the eyes of many species are not discernible, yet they move abcut with inconceivable relative velocity in the fluids they inhabit, without interfering with each other.
512. Hunter divided all animated nature into single and complicated animals. The single, are those which possess only feeling or the powers of muscular contraction, and the power of absorbing food, as chalk absorbs moisture, and appropriating it to nour.. ishment.
The Hydatid, found in sheep, consists only of a bag filled with water, and has no appearance of animal powers; but, when excited or pricked, contracts and shews its irratibility; while this vital power is supported by the nourishment which it receives through its coat.
513. From such simple animals, we ascend, through all the degrees, up to the complicated and combined powers of body and mind, in MAN!
The links are kept up, by the addition of muscles, for additional motions; by other senses, for hearing, seeing, &c. and by various degrees of irratibility in those senses.
The blood for renovation circulates through the lungs; and for action through the muscles of the heart; secretions take place by the various glands; the contraction of the muscles moves the bones; the nerves convey the effect of the mental secretions to the brain; and there produce the inscrutable powers of sensation, will, and judgment.
514. Although animals, in general, are sufficiently distinct from vegetables, yet the gradations of nature are so minute, that many animals are but slightly removed from vegetables, having not more than one or two senses; and, as in some shell-fish, have not even the power
of loco-motion. Between these and man, there is a regular succession of that cunning and sagacity which are necessary to preserve and sustain life; yet between man and most other animals, there is, in mental capacity, as great a difference as between some of those and vegetables.
Far as creation's ample range extends,