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their motion; they move however at pleasure, sometimes quick, sometimes flow. The rings of the hinder part of their body contrasting those of the fore part dart forward, and draw after them the rest os the body. What agility do not fishes discover in their various movements? They swim to every side with equal facility, darting sometimes upwards and sometimes downwards with the velocity of lightning. The wings of birds support them in the air in which / they move in all directions and cleave it with the greatest rapidity. The mole, blind and without a guide, makes itself a read under ground; This vast variety, which is observable in the motions of different species of animals, has appeared so remarkable to many authors, that they have thought it worthy of their particular attention ; but as they have not entered at large upon the motion of infects, I hope it will not be uselessto take some notice of it here, and to impart my observations on the subject to the reader.
The motion of insects Varies according to the elernent they inhabit. Those which live in water move in one way; and those which continue always on land in another. Besides, each species has a motion peculiar to itself. In the water some swim in a straight line, moving their head alternately to the right or left side, while their tail keeps a eorefponding but opposite motion, and thus the animal alwayspreserves the figure of the letter S. This is the case with the larvæ of the common gnat. Others swim from one side to another, advancing sometimes in a straight line, sometimes describing a circle or some other curve. Thus Swammerdam observed three different ways of swimming in the Monoculus Pulex, first in a right line like a fish; secondly, by an irregular motion like the flight of a sparrow, and thirdly by a sort of tumbling like some pigeons. Some spring in the
M water water from top to bottom, or from bottom to topy with prodiinous velocity. The large Dytiscus has under hh wings an aperture garnished with hiirs in which he retains a quantity of air. When he is at the bottom, he boh":., himself there with bis feet, for when he loses his hold, the air brings him instantly to the top. Some insects move with extreme slowness, while others swim with such velocity, that their members cannot be observed. Some, when they rest, adhere to such solid bodies as they find, or suspend themselves in the water; others walk on the surface of the water, or attach the cafes in which thev Uve,. to some piece of wood in order to prevent theiT falling to the bottom. The limbs of all these insects are adapted to the motions they are destined to perform. Those which are obliged to move thror water,, have an attenuated body which facilitates their progress in that element: others advance by means of their feet, or by a kind of fins made in the form of a plume of feathers. Although some are furnistied with several of these members, and one might think that if one were taken away there would still remain a sufficient number, yet their motion then appears evidently retarded, and they execute'with difficulty, what before they performed with the greatest ease. So true it is that the Creator has bestowed nothing superfluous, nor given them any thing but what is absolutely necessary.
We find on the earth certain insects which like serpents have neither feet nor wings, and which yet move with ease. They go from one place to another with .a serpentine motion which is performed by the muscles of their rings ; these contract, and making, the insect shorter, give it the power, by dilating those of the forepart of the body, to advance. Such a motion may be distinctly seen in the common earthworm. Others bend themselves, and advance by a
spring, as maggots do in cheese. They draw their tail towards the iiead, and then suddenly extending themselves, like a bow' after the arrow is iet fly, bound forward more than their own length. This motion which can be attributed only to the elasticity of their bodies is remarkable, and serves them instead of legs and mufcles, by means of which other insects leap. N . ,
Those with feet do not all move in the fame way. Some go forward in a straight line, and others bend their back ; such are the caterpillars called Geometra. In general these have but two intermediate feet. When they go from one place to another, they extend their body as far as possible, and take hold by their fix fore feet; then they draw up to these feet the posterior part of the body, which is then bent like a bow. Fixing themselves then by thtir-intermediate and posterior feet, they extend themselves anew, and thus make a step almost as long as their body. Their motion is like that of a person's hand, when he is measuring any thing by a span. Some insects move sideways like the small winged insects that infest horses. Others turn round in a circle, and others move only by leaps for which they are fitted, by having long legs and muscular thighs. Some march with ini conceivable velocity. M. l>elifle observed a fly almost invisible from its minuteness, which run f;ver three inches space in half a second, making in that time five hundred and forty steps. Q:her insects move exceeding flowly. Many of those whose bodies are long help themselves by means of their hinder part, which they fold under them, and then make vise of it to push themselves forward. Some extend themselves at full length when they go to rest, and ethers are rolled up in the manner of serpents when they sleep.
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Ai there are Insects which are obliged to seek their food in different places, and sometimes at a distance, God hath wisely provided them with wings to facilitate their frequent excursion?; but that they might be able to maintain their bodies in a perfect equilibrium, the Creator has given to some four wings, to. others little balancers, (halreres.) These are little balls placed under the posterior part of the wings on both sides, and are connected with the body by very slender filaments, which enable the infect to move them when it has occasion. In some they r.re naked, in others covered. They answer the same end t^ insects, as the poie does to rope dancers. If one of these balls is cut off, the insect inclines to one side ; if both are taken away, it no longer has that light and equal motion it had before, it cannot direct its flight, but turns tojjfy turvy, Most insects wanting the tail of feathers which birds have, do net take so equal a, flight, nor preserve lo just an equilibrium in an element so subtile and so yielding. There is a species of Butterfly which is excepted from this general rule. It is furnished with a tail by means of which it directs its flight at pleasure. There is even a difference in, the flight of the male and female, that of the former being most rapid. The reason of this no doubt is, that the females being laden with eggs, are heavier than the males, and consequently their flight is not only flower, but shorter. Might not nature mean by this to teach us, that it is the duty of women not tq wander far from home. A difference of velocity in, their flight is perceived also in the different species. Lastly some mount aloft into the air, while others Continually hover nqar the surface of the earth.
These motions of insects cannot but elevate our thoughts towards the Creator, Trie faculty of motion is not an essential property of the matter they are composed of. We fee evidently that a. body purer Jy material cannot put itself in motion, nor can quit its place without being impelled by some other body. 'But insects tnqve hither and thither in a thousand various ways. Whence do they derive this faculty? They do not receive it surely from their body, which being purely material, has not the power of motion, of itself. But it will be said it is the soul of these insects which is the cause of .their motions. Be it so; but 1 ask is that soul material or immaterial? If the materiality of the soul is maintained, the fame difficulty will recur, and I shall then ask how comes this material soul to have the power of moving itself, while every other sort of matter remains at rest, except when put in motion by some other body? Who hath bestowed on it a property so different from any we fee inherent in ether matter? If it is said that this soul is immaterial like that of a man, (hall we be nearer our purpose? I think not, till it is explained to me how a substance purely spiritual, can act on matter, and put it in motion. This difficulty is as great as the former, and neither of them can be solved without having recourse to a first mover whose power is unbounded. Of this he hath given decisive evidence by endowing animals with the faculty of motion. This proof of his power is so great that we cannot comprehend it.
He hath not only given to the motion of animals its first impulse; but he still continues to preserve to them, the daily use of it. This truth was one of those which St Paul remarked to the philosophers of Athens, when he announced to them the Gospel, *' In God we live, says he, and move and have our f being." Acts xvn. 28. We see also that when speaking by the mouths of his Prophet6, God exhibits himself as author of the motion of the Sea. "I *< am the Lord thy God, which divideth the sea,