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In the difcourfe he made at the Areopagus, like wife places refpiration among the beft gifts of the Deity: he giveth to all life, and breath and all things.". -ACTS xvii. 25. An action fo neceffary, and which is at the fame time common to all ani mals, requires that I fhould ftop a moment to confider it, and endeavour to display all the fkill and the wifdom 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 firft 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 laft 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 respiration 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 animals.

All forts of air are not proper for refpiration; it must be temperate; air either too thick or too thin would destroy 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

they

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

But what deferves our particular attention is, that these minute creatures, though air is fo neceffary to them fin 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 state between life and death. The falt and the vifcid humour which tranfpire from their bodies grow hard by the cold, and form a fpecies of cruft around them. In this state the pores of their bodies are contracted and in a manner fhut the vital spirits 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 ftate, and have no occafion to refpire in order to acquire new ftrength.

We cannot fufficiently admire the goodness of the Creator in providing for the wants of his creatures: If air is neceffary for their existence, he gives it to them. The quality and quantity of this cannot be the fame for all animals; he gives to each the organs neceffary for inhaling just what is fufficient for them, and the kind that fuits them. He weighs and deftributes it to them as it were by meafure. Men enjoy this precious gift in the fame way with infects; but how few are there who have given themfelves 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 without 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 goodness 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 " fays he, praise the Lord." PSALM CL. 6.

CHAP. VI.

OF THE GENERATION OF INSECTS.

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 friking 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 dif

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ference is more flriking. Some like thofe of fome fpiders have the fplendor of little pearls; others like thofe of the filk-worm are yellow and of the clour 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 iaft there are various tinges of brown, fuch as yellowish brown, reddith brown, chefnut, &c.

The matter which thefe eggs contain is at first a liquid fubftance, 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 egg, when it comes out. At this period it makes a hole in the fhell raifes 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 infeas 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 muft 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 ncceffities, and to infure them of food the moment they want it.

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

be

bers of them fhould be deftroyed, that lofs would be eafily repaired by the fertility of the females. One infect generally lays a great number of eggs; from thirty to fixty and even fome hundreds. This I learnt by the following circumftance. On the 6th of June 1736, a forefter brought me a butterfly, the upper wings of which were dark, fpotted with eight white fpots, and the under wings orange coloured. I fixed it with a pin to a board, and on the afternoon of the fame day, found that it had laid four hundred and thirty one eggs of the fize of a grain of millet, which refembled fmall pearls. At first they were foft, as I eafily perceived because they were flat on that fide which refted on the board, and refembled the top of a loaf. Their figure cannot be obferved while they lie one upon another; they must be detached to have a diftinct view of them. In ten minutes they became fo hard that when they were pierced with a pin they cracked like the fhell of a pullet's egg. The liquor that iffued from them was whitifh like water. When put into the microscope, they appeared femi-tranfparent like a hog's bladder. The next day the fame butterfly had laid 170 eggs making in all fix hundred

and one.

The observation I have just made to fhew the fertility of infects will likewife prove that eggs are foft when difcharged by the female; this I was convinced of likewife by another experiment. I took a butterfly of another fpecies which I fixed to a board like the other. As foon as it had laid an egg I touched it with the point of a pin, and found that I could make little pits in it, nearly as in a bladder which is not quite blown. Some nutes afterwards thefe eggs became hard, and when I preffed them ftrongly, they broke in feveral places like the eggs of a pullet.

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