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CHAP. V.

OF THE RESPIRATION OF INSECTS.

RESPIRATION is that action of the lungs by which the air enters the bodies of animals and is expelled again without intermiffion. It is one of the most important functions of animal life, and without which no creature could fubfift; accordingly we find that every thing which lives refpires, or performs fome function nearly approaching to refpiration. It was the neceffity of this continual motion which determined the Creator to form in living creatures, thofe admirable organs which perform it. It is the fame neceffity too which makes us generally confound refpiration with life, and confider thefe things as fo ftrictly combined that they can never exist apart. It is not merely in common language, that these two terms are confidered as fynonimous; the Scripture itself often ufes them indifferently. Mofes, meaning to indicate the deftruction of all animals by the waters of the deluge, fays that "all

fiefh died that moved upon the earth, both of "fowl and of cattle, and of beast, and of every "thing that creepeth upon the earth, and of every man; all in whofe noftrils was the breath of life,

of all that was in the dry land died." GEN, vii. 21,22. David alfo expreffes himself in the fame manner, fpeaking of the death of animals; "if thou takeft away their breath, they die and return to their duft." PSAL. civ. 29. PSAL. civ. 29. St Paul,

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in the discourse he made at the Areopagus, likewife places refpiration among the best gifts of the Deity: "he giveth to all life, and breath and all things."ACTS -ACTS xvii. 25. An action fo neceffary, and which is at the fame time common to all animals, requires that I fhould ftop a moment to confider it, and endeavour to difplay all the skill and the wisdom of him who is its author.

Some antient philofphers, fuppofing that infects had neither wind pipe nor lungs, have denied their respiration; but the air pump, invented by Otto Gerickin, and various experiments have convinced the moderns of the contrary. If we put an infect under the receiver of that inftrument and then pump out the air; it first grows weak and then dies. It is not therefore to be doubted but that infects like other animals have both wind-pipe and lungs. The first gives a free paffage to the air and the last like a bellows inhale it when they dilate, and expell it when they contract. If we ftop the wind-pipe of animals they can no longer breathe and they die: the fame thing happens to infects when their refpiration is obftructed. All infects have not the wind-pipe in the fame place of the body. In fome it is found at the mouth, others in the extremity of their body toward the tail, in which they differ from all other ánimals.

All forts of air are not proper for respiration; it must be temperate; air either too thick or too thin would deftroy life; the one makes animals die in a very fhort time, and a too long abode in the other does not fail to produce the fame effect. But however neceffary air may be for life, fome there are which can difpenfe with it for four and twenty hours. If at the end of this period air is reftored to them

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they recover their strength and do not appear to have been incommoded.

But what deserves our particular attention is, that thefe minute creatures, though air is fo neceffary to them in fummer, live during the winter with very little refpiration if any at all. They are then in a fort of fleep or lethargy, in a flate between life and death. The falt and the vifcid humour which tran. fpire from their bodies grow hard by the cold, and form a fpecies of cruft around them. In this ftate the pores of their bodies are contracted and in a manner shut the vital fpirits are concentrated in the interior parts of the infect, and they lofe nothing of them by transpiration. As they make no motion, nothing' is diffipated: they remain always in the fame state, and have no occafion to refpire in order to acquire new strength.

We cannot fufficiently admire the goodness of the Creator in providing for the wants of his creatures. If air is neceffary for their exiftence, he gives it to them. The quality and quantity of this cannot be the fame for all animals; he gives to cach the organs neceffary for inhaling juft what is fufficient for them, and the kind that fuits them. He weighs and deftributes it to them as it were by measure. Men enjoy this precious gift in the fame way with infects; but how few are there who have given themselves the trouble of reflecting on a benefit without which it would be impoffible to live. How have they requited Him for it? From our birth we have breathed, the air is common to all animals, and they enjoy it with out labour or expence; and therefore instead of being grateful, men become infenfible to fo precious a gift. As each infpiration and each expiration are fo many authentic teftimonies of the power, of the wifdom and the goodnefs of God, there is not a

moment

moment of our lives which does not invite us to celebrate his perfections and to exprefs our own gratitude. The Pfalmift was penetrated with the juftice of this reflection. "Let every thing that hath breath PSALM CL. 6.

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says he, praise the Lord."

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WHEN a living creature produces another of the fame fpecies with itfelf, we fay that it has engendered it. All generation is preceded by an intercourfe between the male and the female. This is a general rule from which infects are not excepted; the only difference to be remarked with regard to them is, that the way in which the male infects couple with the females is different in different fpecies. However, this commerce fecundates the female and puts her in a condition to lay her eggs when the feafon has arrived. The Ephemera is fingular in this point; for it is only after the female has depofited her eggs on the furface of the water that the male fecundates them.

The variety among the eggs of infects is incredible: it may be faid to equal the number of fpecies. Without confidering the difference in their fize, I fhall only remark the moft ftriking diverfities among them whether from their figure or colours. The moft common figures are the round, the oval, and the conic; but it must be attended to that there are fome more and fome lefs fo, and that fome approach more to these figures than others. As to colours the difference

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ference is more ftriking. Some like thofe of fome foiders have the fplendor of little pearls; others like thofe of the filk-worm are yellow and of the colour of a grain of millet. Others are of the colour of fulphur, of gold, or of wood. Laftly there are fome green and brown, and among thefe laft there are various tinges of brown, fuch as yellowish brown, reddish brown, chefnut, &c.

The matter which thefe eggs contain is at first a liquid fubflance, and afterwards forms the infect, which is very artfully enclofed in the fhell. There it remains till the fuperabundant humidity is diffipated, and its members have acquired ftrength enough to break the ege, when it comes out. At this period it makes a hole in the fhell raises up the little broken pieces, ftretches forward the head, which hitherto had been bent in towards the belly; difplays its antennæ, and puts them in motion; brings out its legs one pair after another, attaching itfelf with the first pair. to the egg, till the whole body is drawn out.

All infects do not remain equally long in the egg. A few hours is fufficient for fome, while it requires many days, and even many months before others. break their prifon. Eggs, which during winter have been in a warm place, foon lofe their humidity and are hatched prematurely. It is worthy of remark, and must not be forgotten, that thofe caterpillars which live on green vegetables, never leave their eggs till the herbs and leaves they feed on are fufficiently. advanced. Providence has been careful to provide for their neceffities, and to infure them of food the moment they want it.

Another circumftance not lefs remarkable, is that many of these eggs, notwithstanding their minutenefs and delicacy are able to refift both cold and wet which do not deftroy them. But even though num

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