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their motion; they move however at pleasure, fome times quick, fometimes flow. The rings of the hinder part of their body contracting those of the fore part dart forward, and draw after them the rest of the body. What agility do not fifhes difcover in their various movements? They fwim to every fide with equal facility, darting fometimes upwards and fometimes downwards with the velocity of lightning. The wings of birds fupport 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 itfelf a road under ground. This vaft variety, which is obfervable in the motions of different fpecies of animals, has appeared fo 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 ufelefs to take fome notice of it here, and to impart my obfervations on the fubject to the

reader.

The motion of infects varies according to the element they inhabit. Those which live in water move in one way; and thofe which continue always on land in another. Befides, each fpecies has a motion peculiar to itself. In the water fome fwim in a ftraight line, moving their head alternately to the right or left fide, while their tail keeps a corefponding but oppofite motion, and thus the animal always preferves the figure of the letter S. This is the cafe with the larvæ of the common gnat. Others fwim from one fide to another, advancing fometimes in a firaight line, fometimes defcribing a circle or fome other curve. Thus Swammerdam obferved three differentways of fwimming in the Monoculus Pulex, firft in a right line like a fish; fecondly, by an irregular motion like the flight of a fparrow, and thirdly by a fort of tumbling like fome pigeons. Some fpring in the

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water from top to bottom, or from bottom to top, with prodigious velocity. The large Dytifcus has under his wings an aperture garnished with hairs in which he retains a quantity of air. When he is at the bottom, he holds bimfelf there with his feet, for when he lofes his hold, the air brings him inftantly to the top. Some infects move with extreme flownefs, while others fwim with fuch velocity, that their members cannot be obferved. Some, when they reft, adhere to fuch folid bodies as they find, or fufpend themselves in the water; others walk on the furface of the water, or attach the cafes in which ' they live, to fome piece of wood in order to prevent their falling to the bottom. The limbs of all these infects are adapted to the motions they are deftined to perform. Those which are obliged to move thro' water, have an attenuated body which facilitates their progrefs 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 furnished with feveral of thefe members, and one might think that if one were taken away there would still remain a fufficient number, yet their motion then appears evidently retarded, and they execute with dif ficulty, what before they performed with the greatest cafe. So true it is that the Creator has bestowed nothing fuperfluous, nor given them any thing but what is abfolutely neceffary.

We find on the earth certain infects which like ferpents have neither feet nor wings, and which yet move with ease. They go from one place to another with a ferpentine motion which is performed by the mufcles of their rings; thefe contract, and making. the infect fhorter, give it the power, by dilating thofe of the forepart of the body, to advance. Such a motion may be diftinctly feen in the common earthWorm. Others bend themfelves, and advance by a

fpring,

fpring, as maggots do in cheefe. They draw their tail towards the head, and then fuddenly 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 elafticity of their bodies is remarkable, and ferves them inftead of legs and mufcles, by means of which other infects leap.

Thofe with feet do not all move in the fame way. Some go forward in a straight line, and others bend their back; fuch 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 poffible, and take hold by their fix fore feet; then they draw up to these feet the pofterior part of the body, which is then bent like a bow. Fixing themfelves then by their intermediate and pofterior feet, they extend themselves anew, and thus make a step almoft as long as their body. Their motion is like that of a perfon's hand, when he is measuring any thing by a fpan. Some infects move fideways like the fmall winged infects that infest horfes. Others turn round in a circle, and others move only by leaps for which they are fitted, by having long legs and mufcular thighs. Some march with inconceivable velocity. M. Delifle obferved a fly almost invifible from its minutenefs, which run over three inches fpace in half a fecond, making in that time five hundred and forty fteps. Other infects move exceeding flowly. Many of thofe whofe bodies are long help themfelves by means of their hinder part, which they fold under them, and then make ufe of it to push themfelves forward. Some extend themselves at full length when they go to reft, and others are rolled up in the manner of ferpents when they fleep.

As there are infects which are obliged to feek their food in different places, and fometimes at a distance, God hath wifely provided them with wings to facilitate their frequent excurfions; but that they might be able to maintain their bodies in a perfect equilibrium, the Creator has given to fome four wings, to others little balancers, (halteres.) Thefe are little balls placed under the pofterior part of the wings on both fides, and are connected with the body by very lender filaments, which enable the infect to move them when it has occafion. In fome they are naked, in others covered. They anfwer the fame end të infects, as the pole does to rope dancers. If one of thefe balls is cut off, the infect inclines to one fide; if both are taken away, it no longer has that light and equal motion it had before, it cannot direct its flight, butturns toply turvy, Moft infects wanting the tail of feathers which birds have, do not take fo equal a flight, nor preferve fo juft an equilibrium in an element fo fubtile and fo yielding. There is a fpecies 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 reafon of this no doubt is, that the females being laden with eggs, are heavier than the males, and confequently 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 to wander far from home. A difference of velocity in their flight is perceived alfo in the different fpecies. Laftly fome mount aloft into the air, while others continually hover near the furface of the earth.

Thefe motions of infects cannot but elevate our thoughts towards the Creator. The faculty of motion is not an essential property of the matter they are compofed of. We fee evidently that a body pure,

ly

ly material cannot put itfelf in motion, nor can quit its place without being impelled by fome other body. But infects move hither and thither in a thoufand various ways. Whence do they derive this faculty? They do not receive it furely from their body, which being purely material, has not the power of motion of itfelf. But it will be faid it is the foul of thefe infects which is the caufe of their motions. Be it fo; but I afk is that foul material or immaterial? If the materiality of the foul is maintained, the fame difficulty will recur, and I fhall then afk how comes this material foul to have the power of moving itfelf, while every other fort of matter remains at reft, except when put in motion by fome other body? Who hath beftowed on it a property fo different from any we fee inherent in other matter? If it is faid that this foul is immaterial like that of a man, fhall we be nearer our purpofe? I think not, till it is explained to me how a fubftance purely fpiritual, can act on matter, and put it in motion. This difficulty is as great as the former, and neither of them can be folved without having recourse to a first mover whofe power is unbounded. Of this he hath given decifive evidence by endowing animals with the faculty of motion. This proof of his power is fo great that we cannot comprehend it.

He hath not only given to the motion of animals its first impulse; but he ftill continues to preferve to them the daily ufe of it. This truth was one of those which St Paul remarked to the philofophers of Athens, when he announced to them the Gofpel, "In God we live, fays he, and move and have our

being." Acтs xvi. 28. We fee allo that when fpeaking by the mouths of his Prophets, God exhibits himself as author of the motion of the Sea. " I

am the Lord thy God, which divideth the fea,

"when

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