cause of that itching, and those small puftules which have made thefe caterpillars without any reafon be supposed poifonous. This has already been obferved by M. de Reaumur, and I have experienced it myself in repeated inftances. Among the great number of smooth caterpillars of everykind which I have had occafion to handle, not one of them ever did me the fmalleft harm. But as to the hairy caterpillars, they have often affected me with pain even without having touched them, and merely by opening with my fingers, the coques where they had left their hairs.

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The skin covers many parts worthy of attention. Although from the manner in which this Chapter begins, we are ledto expect an anatomical defcription of the principal parts which compofe the bodies of infects, we must not expect to find in it what will fatisfy the curiofity of an intelligent anatomift. In order to give fome just idea of the marvellous in the internal ftructure of the fe little animals, it would be neceffary to enter into a detail which, alone, would furnish materials for more than one volume, and which could not be interefting to any but connoiffeurs. General reflections, fuch as thofe to which MrLeffer has been here obliged to confine himself, give but a very imperfect idea of the fubject. Not author has treated it in fuch a masterly and fatisfactory way as Swammerdam has done. His Biblia Nature, which is almost entirely a collection of anatomical facts, thews clearly that there are not fewer parts required in the formation of an infect, than in the bodies of the larger animals; and, what fuppofes a much more admirable mechanifin in the former is, that many of the internal parts in a great number of species, after having subsisted for a confiderable time in one state, afterwards change their form, their functions, and their nature, and adapt themfelves to thofe new ufes which refult from the different transformations which infects undergo.

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* It may well receive the name of flesh. This we must obferve, contrary to Ariftotle, who feems to have thought that infects have no flefh properly speaking, but merely a fubflance analogous to it, when he fays; H. A. L. iv. CAP. 7. Quod autem pro carne in iis habetur, id nec teftam imitatur, neque quod in teftaceis genus carnis contine

tur;

tar; fed mediam quandam inter hæc refert naturam. The author.

If the fubftance which compofes the bodies of fome infects be poffeffed of fuch a degree of confiftence as to deferve the name of flefb, however improperly applied, that of which the bodies of the greatest part of them are formed, efpecially before their laft change, is fo foft or rather fluid, that the name of vifcfu humour feems much more applicable to it. And accordingly M. Leffer in the foregoing note, might well have fpared Ariftotle for his remark on the fubject.

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More elaboration than can be performed in a body fo fmall. I doubt if this reafon will fatisfy the intelligent reader. The great apparatus obfervable in the internal ftructure of infects, of which however we can only fee the moft obvious and coarleft parts, the exceeding minutenefs of fome, feveral thousands of which united would not equal in fize a grain of fand, and in which we muft notwithstanding fuppofe parts analogous to thofe of the largest infects, fhew evidently that it is not beyond the power of matter when in the hands of the divine Creator, to form in an infect however fmall, all the veffels neceflary for performing the requifite digeftions and filtrations in order to convert the aliments into blood. It feems, on the contrary, ftill more evident, that if infects have not blood fimilar to ours, it is because that blood would be too grofs to pafs through veffels fo delicate as theirs, and therefore it is neceffary they fhould be provi ded for this purpofe with fluids much more fubtilifed than thofe which enter into the compofition of our blood, of which a fingle globule is fometimes larger than the whole body of fome of thefe animals. But without deciding pofitively on the matter, we may at leaft confider as a certain fact, that it infects are not furnished with blood fimilar to ours, they have however fluids that perform the fame functions; and we cannot doubt that thefe fluids circulate in their veins when we attend to what paffes in plants, and the larger animals; confidering efpecially that there are infects in which we can difcover pretty convincing proofs of this circulation. Such for inftance are fleas for when we examine their legs in a microfco; e, we diftin&tly fee veffels which after hav

:

ing proceeded a certain length, return in another direct tion, towards the trunk of the body from which they fet off.

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This glutinous quality of the humours. I allow that the tenacity of the humours in infects may contribute to their tenacity of life; but what I believe to contribute still more to this quality is the circmitance of their vital principle, at least that of the far greater part of them, not refiding folely in the head, but being dispersed over their whole frame. I have feen a caterpillar continue to creep a bout for fome days after its head had been cut off. I have feen the body of the common earth-worm, which fome aquatic infect had reduced to one third of its length, live in the water for the fpace of a week after being thus maimed, and at both ends. I have seen motion in the abdomen of a wafp three days after its feparation from the thorax. If the vital principle of infects refided only in the head, we could conceive that the tenacity of their humours might contribute to detain life for a certain time in that head and the part of the trunk attached to it but how could the mere tenacity of the humours preferve life and motion in the other parts, which being then feparated from the head, would be deprived of the vital principle, and the influence of the animal fpirits? Thefe parts ought immediately to pe rish; but as they do not, and preserve their activity for a confiderable time, it seems natural to conclude that the principle of life and motion does not refide folely in the head, but is diftributed over every other part of the body.

This is not all, it may be inferred from fome experiments I have made on the animals we have mentioned, that if infects have a foul, this foul is likewife extended over the whole body, fo that when the body is divided, it too is divided of course. Every part of these divided animals appears 'to me capable of exhibiting marks of consciousnefs and fenfation. When I touched the headlefs caterpillar; it made the fame motions which it ufed to make in the fanie circumstances before it was maimed, and if I perfifted for any time in annoying it, it ran away. The trunk of the earth worm when it feemed perfectly at reft, was no fooner touched than it put itself in motion and made off with expedition. When I held the anterior part of the wafp, it bit into every thing I prefented to it, and

when

when I touched its trunk, although separated for fome days from the head, it immediately put out its fting, and darted it on all fides, and in every direction, as if endeavouring to wound me. Is it not evident that all thefe different parts of the animals, notwithstanding their feparation, had still preferved not only life and motion, but the faculty of receiving impreffions from objects, and the defire of self-prefervation; each, according to its nature, determining either for flight or refiftance? And how is it poffible to conceive that each of the parts feparated from the fame animal could retain that faculty, and that defire, if they had not at the fame time preferved the principle in which both refide, that is, the foul? and the foul cannot be found in two separated parts of the fame animal without being itself divided. Here then is the foul of infects, at least of some of them, divifible; what a ftrange paradox!

Perhaps it may be thought, that in order to establish an opinion fo fingular, more decifive experiments than thofe I have just related should be made; take then the following which seem to me unanfwerable, and appear to demonstrate that if infects are endowed with a foul, there are fome in which that foul is not only divifible, but fuch as that each of the parts into which it is divided, is fufficient to animate an entire body, and to preferve its life. The first of these experiments is made on that small aquatic animal mentioned above, P. 300, whofe body in bulk is about the fize of a feed of Dandelion (Hydra polypus.) It is an afcertained fact, that when it is cut in two, or even in three parts, each part becomes an entire animal, which performs its functions as before. My fecond experiment goes ftill further; I have several times not only cut in two, but in four, eight, fixteen or more parts, a fpecies of aquatic worm, of a reddish brown colour, about three or four inches long. The greater number of these divided parts, and often the whole of them, have not only preferved fenfation and motion, but af ter ten or twelvè days begun to push out at the two extremities, and became in three or four months each an entire animal; fo that thus a single worm fometimes furnished me with more than fixteen, which I have moreover caused to multiply in the fame way, as often as I pleased. After thefe experiments, it would feem difficult to with-hold our affent to the propofition that there are infects whofe foul, if they have one, is divifible and even into a great number of parts, all fufficient

fufficient for animating a body compleat in its parts and functions for when we examine thefe two forts of animals, we fee evidently that each is a fingle infect, not a concatenation of infects united end to end, as fome people aver of the Solitaire; and thus I do not conceive what can be alledged against the conclufions which refult from the facts we have detailed.

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Infects have an artery. This is the veffel which it is fupfuppofed forms the heart of infects; or if you will, it is a ftring of hearts running through the whole length of their back. In caterpillars the pulfations begin in it at the pofterior extremity, and go fucceffively from articulation to articulation towards the head. M. Reaumur on the fubject of thefe pulfations mentions a very fingular fact. He fays that we may obferve in chryfalids newly transformed, and still tranfparent, that these pulfations change their direction, and that the great artery which, in the caterpillar, pufh the fluid from below towards the head, pufh it in the chryfalis from the head towards the tail, a circumftance which fuppofes that in thefe two ftates the circulation of the fluid which ferves the purposes of blood proceeds in a quite contrary direction. I regret that I have hitherto neglected to repeat the experiment on chryfalids newly transformed; for although I do not doubt that the fact is fo in the caterpillars which that illuftrious author had examined, I have reason to believe that either that new motion does not continue for any long time, or that it is not common to all chryfalids. For having found a fpecies of caterpillar which furnished me with, what is very rare, a chryfalis exceedingly transparent, and through which I could fee diftinctly all the movements of the artery, I took fome of them a few days after their trans formation, and fet myfelf to examine them at different times with the greateft poffible attention, and that during the fpace of feveral months, that their transparency lasted; and I always obferved in them, with the greatest certainty, that the pulfations of their heart, or if you will, of their great artery, had in no degree changed their direction in the chryfalis; but that they continued during all that time to procced from the tail towards the head, as they had formerly done in the caterpillar.

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