the first cafe, God has exalted the organic mechanifm, to a degree of perfection, which matter alone does not feem çapable of attaining; in the fecond, he has raifed the brutes, to a pitch of perfection, fuperior to what we can conceive of organic mechanifin.

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Is there any thing fimilar among infects. We cannot but praife M. Leffer, for feeking, even in the conduct of infects, arguments to diffuade us from vice; but one would think, he did not perceive, that his zeal made him argue against his own principles, and that he cannot fet in oppofition what is praife-worthy in the actions of brutes,to what is blameable in thofe of men, without fuppofing, that they act like him, by fome motive of reafon. Would it, for inftance, be decent to exclaim, one mill does not deftroy another mill; a watch does not deftroy another watch; that it is fhameful in men, to make war upon, and to destroy one another? This, however, would be a mode of reafoning, ridiculous as it is, fimilar to that of thofe, who, fuppofing that beafts are but machines, would oppofe their conduct to ours. One of two things must therefore be chofen; either not to compare man with the brutes, or to allow fome degree of reafon to thefe laft.

But, to come to the example of infects, here stated, it is by no means aftonifhing, that we do not fee them kill their young; fince the greater part of thofe that are best known, are fuch as die before their eggs are hatched. As to thofe which furvive the birth of their young, there are examples of their actually preying upon them, when they have an opportunity, and others, that, though part of the fame litter, devour one another, without neceflity, and from excefs of gluttony. We have only to keep, for fome time, a fpider with its young, under a glafs, and we fhall fee an inftance of both cafes.

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In the formation of their nefts. Infects fabricate thofe nefts, or thofe habitations, which the author is about to mention here, for three very different purpofes, and which it is proper to diftinguif. The first purpose is, when they make them to live in, during their larva ftate, when they eat and grow in bulk. Thefe habitations are then general

ly

ly cafes open at both ends. The infect lodges there, eniarges them as it grows, or makes new ones. But it is not those which infects make, by rolling leaves together, which are the most worthy our admiration. The cafes, made by the land and water larvæ of certain moths, of different kinds and species, are mafter-pieces, in which art and arrangement often appear much more confpicuously.

The second purpose for which infects conftruct habitations, and which is, too, the moft frequent, is, to be the place where they undergo their transformations. These forts of habitations are commonly called coques or cones. They are generally in the form of oblong fpheroids or approaching to that form: there are, however, fome of a different figure. The infect fhuts itself up in thefe, and leaves hardly any apparent opening. Some, indeed, are fo foiid, and fo well formed, that they are quite impenetrable by water or air it is here that the infect changes into a nymph or a chryfalis.. Thefe coques feem to ferve principally three ends. The firft is, to furnish, by their internal cavity, a convenient support to the chryfalis or nymph, as foon as it appears, and while its cover is ftill tender, and to enable it to affume the attitude, fomewhat bent anteriorly, which is neceffary to make its members, particularly its wings, take the place in which they are to remain fixed, till the infect rids itself of its cover. They ferve, in the fecond place, to defend the animal, in that ftate of weakness, from the injuries of the air, and the pursuit of its enemies; and laftly, they prevent those chryfalids or nymphs, from drying by a too great evaporation: thofe coques, which have hardly any confiftence, probably ferve only the first of these purpofes. Thofe which are firmer, but without being impenetrable to air and water, feem likewife to serve the second purpose, and the reft feem deftined to perform the three different ends, according to the different neceffities of various infects.

In the ftructure of those coques, there is often observable an art and induftry altogether wonderful, and as if one alone was not fufficient to protect the infect, there are fome which have two, and even three, one within another, fabricated all by the fame animal, and not by different infects, as happens, when an ichneumon, after having caused the death of an infect, which had already made its coque, and having afterwards made its own, has been deftroyed in

its turn, by a fecond ichneumon, which it harboured in its intrails; this cafe it is eafy to convince ourselves of, because the exuviæ of each of the deftroyed animals, is found between the coque which it has made, and that of the infect which deftroyed it.

The third ufe of thefe nefts, is, for a covering to their young. This ufe is the leaft frequent. Spiders furnish us with the most common example of it, and perhaps the only one known. The large Dytifcus piceus, however, makes a much more remarkable one. The neft of this animal is whitish, and its general figure that of an oblate spheroid, the long diameter of which may be about three-fourths of an inch, the thort one fully half an inch, and there appears as if a fegment, parallel to this fhort diameter, were taken off. Near this place the young, fometime after being hatched, make an opening, and plunge into the water. Higher up, on this coque, there iffues a fort of horn, brownish, and fomewhat bent, about an inch long, broad at the bafe, but terminating in a point. I imagined at first, that the ufe of this might be to give air to the coque, that the young, which cannot difpenfe with it for any time, although they live in water, might be able to breathe, the moment they leave the egg; but, having examined these horns with more attention, and having feen the Dytifcus forming them, I found they were folid, and I could attribute to them, no other ufe, but that of retaining the coque in its fituation, when a blaft of wind, or any other accident might otherwife overturn it. For, as thefe coques generally float among reeds, or the duck-meat, if any thing fhould lay them on their fide, their horn then refting on these fubftances, prevents their turning upfide down, and, the form and weight of the coques make them foon regain their upright fituation. This coque is the more remarkable, being the work of a Dytifcus, a kind of animals, among which one would not have expected to find any, that could make fuch nefts; although the fpecies here mentioned is not the only one known to me, that does fo. I do not reckon here, among the nefts of infects, the flimy substance which envelopes the eggs of fome forts of water infects; because fuch coverings appear to be rather owing to Nature, than to their induftry; though the regular arrangement of the eggs feems to be the effect of their labour.

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*All forts of fubftances. Frifch difcovered the larva of an infect in fresh wa.er, which conftructs a moveable habitation to itfe.f, in the form of a tube, of fragments of grafs, wood, bark, leaves, &c. In this it lives, not as fnails do, in their fhell, which they cannot leave; it goes in, and comes out, at pleasure. The infide of its houfe is fmooth, and polifned with the greatest care, the outside rough and rugged. To clofe the entrance, there is a lid, which fits it exactly. When the animal changes its place, it carries the houfe along with it, fometimes with its feet, but if that is not fufficient, with its teeth. Frifch had not been able to difcover the infect produced by this larva.

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About five lines. This obfervation would be juft, if the common bafe of the two ranges of oppofite cells were flat; but, as it is compofed of folid angles, concave and convex, which serve alternately for a bottom to the oppolite cells of the comb, fo that the bottom of each cell, exceeds by fo much, that of the cells which are in a contrary position, it follows, fince the bafe of thefe cells is fo exceedingly thin, that, when the thickness of the comb is nearly an inch, the cells which compofe it fhould be, at leaft, half an inch deep.

This appears more diftinctly by the Fig. XIV. which reprefents the fection of a comb, compofed of eight cells, placed oppofite to one another on their common base. Let A B be the thicknefs of the comb D E, and C B, the depth of the oppofite cells which compose it, and let E F be perpendicular to A B. It is evident, that A B-A F+C B-C F, or A F-D E, therefore, A B. D E÷C B—C F, that is to fay, that the depth of the two cells, X and Z, taken together, furpaffes the thickness of the whole comb, A B, by the part CF; fo that, if the thickefs of the comb was an inch, the depth of each cell would exceed half an inch, by nearly the half of C F, and would by no means be lefs than fix lines, as M. Maraldi afferts.

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The bafe of each cell. Although the defcription here given of the manner in which the cells are conftructed, is very exact, yet, as it is not elucidated by any figure, it will be