1

red, and this is a third diftinctive character. But, as it is very rare to find in Natural Hiftory, any rules without exceptions, the rule that infects want red blood, fuffers an exception, both in the earth worm, whofe blood has a tinge of red, and in a certain fhelled fnail, very common in the ditches in Holland, whofe blood is purple. Perhaps too, it may be thought another exception to the rule, that many flies, when they are killed, produce large fpots, of a very bright and deep red. But it must be remarked, that these are by no means the blood of the fly. When they were in the maggot ftate, nothing fimilar was to be obferved in, them; and when changed into flies, this red matter is not found in their bodies, as it ought neceffarily to be, were it blood which circulates in their veins. It is only found in their eyes, where it affifts most probably the organ of fight. I know, that blood is fometimes remarked in the bodies of gnats, and of fome flies; but, if we attend accurately to the circumftance, we shall find, that it is not to be found, except in the bodies of those gnats and flies, which suck the blood of animals; and this blood will be found, only in their ftomachs, or in their inteftines: an evident proof, that this blood is that of the animals they attack, as the author has obferved.

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If we compare infects. Here is a fourth character, very ufeful as a diftinguishing mark of infects; for though fome of them equal, and even furpafs in fize, the fmalleft of the other animals, it may, however, be faid, confidering things in general, that, to defcend from the greateft animals to the fmalleft, infects begin nearly where the others end.

To thefe four characters, which refpect the bodies of infects, as to fubftance and extenfion, we may add five others, which have a reference to their external form, and which are not lefs proper for diftinguishing infects from the other animals, than the preceding characters. The first is mentioned by Mr Leffer, and confifts in this, that the bodies of the gi. ater part of infects are, as it were, divided by incifures, which has given rife to the name they bear. The fecond, is, that no infect without wings has only four feet, nor any flying infect but two. The third, that they have no vifible noftril, or external ears: but, that they have their organs of refpiration, either in their thorax or abdomen.

The

The fourth, that the organs of maftication, or the teeth of fuch as have any, act from right to left, and from left to right, and not up and down. Laftly, that their eyes are deftitute of eye-lids, and that they have neither iris nor pupil. Here, then, are nine characteristic marks, by which infects are difcriminated from all other animals.. They are found in general, applicable to every infect. But there are many fpecies, which want one of the laft mentioned eight characters. The number of thofe that want two of them is fmall; perhaps, there may be fome that want three of them, though I do not know any.. If fuch were to be difcovered, I would make no difficulty in acknowledging them for infects; the firft character, joined to five others, and even with four, would be fufficient. I would not venture to fay fo much, were the firft character to be wanting, becaufe that appears to me, the fundamental difcriminating character, that without which no animal can be confidered as an infect. But when, after having examined an animal, neither the first character, nor any of the other eight, which I have just mentioned, are found to belong to it, I think it would be, to confound with improper names, things which Nature has effentially diftinguifhed, were we to give such an animal the name of infect. Confequently, neither frogs, toads, ferpents, fnakes, vipers, tortoifes, lizards, crocodiles, nor other reptiles of that kind, can properly belong to the clafs of infects, although very able naturalifts have confidered them as fuch, perhaps for want of attending to the characters we have juft established. For thofe animals, far from poffeffing all these different characters, have few, if any of them. They have bones, which, in almost all of them, form a compleat fkeleton: they have flesh and blood: the fmalleft of them are larger than the generality of infects; they have no fenfible incifures; thofe which have legs, have four; they breathe through noftrils; their maxillæ act perpendicularly, and the eyes of the greater part have eye-lids, an iris, and a pupil; in a word, they are in every refpect, as fimilar to the larger animals, as they are different from infects.

But, it will be faid, if the animals I have named, belong not to the class of infects, to what clafs muft they be referred? I anfwer, that as they differ in many refpects from infects, and in many other refpects from the rest of animals, and that thus, they cannot be claffed conveniently, under any

of the four established divifions of animals, I would make no difficulty in forming them into a clafs by themfelves, which might be called, for want of a more fuitable appellation, the class of reptiles, taking the word, in a fenfe a little' lefs vague than that which it generally has; fo that, according to this idea, all the lower animals might be divided into five general claffes, to wit, quadrupeds, birds, fishes, reptiles, and infects.

PAGE 40, 1. 2.

The hydra, the crocodile. The author, by oppofing the hy dra and crocodile, to infects, fhews, that he did not confider the reptiles we have been fpeaking of, as belonging to the clafs of infects.

PAGE 40, 1. 10.

According to Leutvenhoeck. This writer goes ftill farther, and affirms, that he had found, in the feminal fluid of dif ferent animals, fuch minute animated beings, that a million of them, and fometimes ten millions, would be required to equal the fize of a grain of fand. Neither is that all. M. de Malezieux pretends, that he had obferved with his own microscope, animals, feven and twenty millions of times fmaller than a mite. Hift. of the Royal Acad. of Sciences. 1718

PAGE 40, 1. 27.

The fkin of infects is different. As the fkin of infects, like that of other animals, varies exceedingly, and as in the one, as well as in the other, fome have it foft, hard, rough, fmooth, thick, thin, downy, fpisy, &c. it does not appear to be in the quality of the fkin, that the characters proper for `diftinguishing infects from other animals are to be fought, but rather perhaps in the diveftment of thrat fkin; for it is: remarkable that quadrupeds, birds and fishes, never quit their fkins, and that the greater part of infects, as well as reptiles, change theirs often.

PAGE 40, Line laft.

Compofed of feveral rings. Among infects, fome are found that have neither rings nor incifures, such as fnails, flugs, &c. but fuch make but a very fmall part.

Deeper than thofe of the labfter. It would feem here, that

M. Leffer

M. Leffer does not confider the lobster as an infect. But as that animal has no internal skeleton, as it has its body divided by incifures, as it has neither red blood, nofe, ears, nor mouth, nor eyes, fimilar to thofe of the other animals, but, as in all these refpects it refembles infects, I think we cannot hesitate in fixing it in this clafs, although in fize, it greatly furpaffes the generality of infects.

PAGE 41, 1. 3.

They have not exactly. If the perfection of an animal were to depend on the number of its external and internal parts, the comparison, which, in this respect, might be made between infects and other animals, could not fail of turning to the advantage of the former; of this the reader will find convincing proofs in the courfe of this treatife.

PAGE 43, 1. I.

Of the divifion of infects. It is not fo eafy as one would imagine, to form a proper divifion of infects. It is not fufficient to find out fome diftinctive differences between fpecies and fpecies, and of these to make so many orders, without troubling ones felf, about their being more or less effential or accidental: the divifions must be founded on the ve-` ry nature of the things, otherwife, they will be more apt to darken, than to illuminate the fubject. A most wonderful order prevails throughout all Nature, compofed of diverfities and analogies without number. It is this order that we must endeavour to discover and to follow; it is on the just perception of thefe diverfities and analogies, that we must found the general and particular divifions of every fubject in Natural Hiftory. But this is a táík very difficult to fulfil, and without knowledge acquired by long application, it is not easy to accomplish it: accordingly, there are but few naturalifts, who have attempted to give us a fyftematic divifion of infects. I am acquainted, only with those of Valif neri, Swaminerdam, Linnæus, and our author. I fhall take the liberty of making a few obfervations on each of thefe fyftems.

I. Valifneri divides infects into four claffes, drawn from the places they are found in. The firft clafs comprehends, thofe infects which live on plants; the fecond, fuch as live in water or other fluids; the third, those that live within the earth, or among terreftrial and ftony fubftances: and the Qq2

laft

laft, thofe which live on other animals, or in their bodies. But this divifion is faulty, in being taken from characters that are rather accidental than essential to infects; and this has made him fall into another much more important error, that of reversing the order of Nature, by comprehending, in one and the fame class, infects which have no other relation to one another than that of being found in the fame places, while it feparates infects which, on account of their effential analogies, ought naturally to have been united. Add to this, that in following the fyftemn of Valifneri, we would often find ourselves at a lofs to know; in what clafs to place certain infects, either because they live indifferently in many places, like the onifci, earwigs, and millepieds, which live equally on plants, and among earthy and stony subftances, and which, consequently, ought at once to belong both to the first and third class; or because there are others, which, at different periods of their life, live fucceffively in different places. Such are many fpecies of beetles, which live as larvæ in the waters, transform themfelves into nymphs in the earth, and afterwards inhabit indifferently, either the water or the air: fuch are many other beetles, and other coleopterous infects, which live first in the earth, then on plants and fuch likewife are the dragon flies, the ephemeræ, gnats, and many different forts of flies, and even fome butterflies, which live firft in the water, then in the air, on plants, or animals, and among which are to be found fome, that before mounting into the air, have undergone their transformations in the earth. All these infects, and many others, confidered according to the different periods of their life, would, in the fyftem of Valifneri, be fometimes of one clafs, and fometimes of another, and fometimes indeed, in three of the claffes at once, which could not but caufe a deal of confufion, and which befides,' renders his fyftem impracticable.

II. The general divifion of Swammerdam feems much better imagined. He diftributes all infects into four claffes, the diftinctive characters of which are taken from the nature of the animals themfelves. The first comprehends thofe which are fubject to no change of form, and the three others are founded on their different modes of trans-formation into nymphs and chryfalids. M. Leffer explains them in his VII. chapter, and I fhall therefore difpenfe with detailing them here. I fhall only remark, that the great

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